# Resin cast slingshots - A work in progress



## Hrawk

As some of you may already know, I have been studying CNC and CAM for the last year and a half.

Well it's getting to the point where all the theory is almost done and several practical assessment tasks are coming up. One of those tasks was to program and machine a 2 piece mold for casting a random part. These parts are quite boring really, an electrical housing, pump shaft cover and a few other small items.

Well I got speaking with the teacher and asked if I could design, program and machine my own part, to which he happily agreed. Several ideas sprung to mind at this point, mostly firearm related however that's a bit of a no no at school so I settled on making a slingshot mold for resin pouring or injection molding.

As I'll probably stuff it up first go, I settled on a smaller design to keep the materials cost to a minimum.

First step was to draw up the design. Using Inkscape I came up with a simple design based of my previous Hrawkeye template but re sized to fit the 105x100x25 stock we use (and get for free in the class).

Here's the basic design:










Once I has happy with the design and tried it out by making one from a few layers of cardboard it was time to import the design into the CAM software and create the tool paths and program required to machine it.










The two rectangles and squares you see on the above design are used to index the two halves to ensure they both line up perfectly. It took about 2 hours to get all this done. Lots of stuffing about with tooling, speeds and feeds to get it all right. Luckily the software is quite intelligent and creates a lot of this for you.

Well with the program ready to roll I decided to make a few 3D renders of the finished part to get and idea of what to expect.

It was off to 3DS MAX to create the geometry.










I love Autodesk products, they are so easy to use and very powerful indeed. Only about 8 steps were required to create the above 3D geometry from the original drawing. About 20 minutes work. Rendering the image with high quality settings, took almost half along again, but I was very pleased with the results. See for yourself 










I then played around for a bit with different colours to give myself an idea on what dyes I should order when I order the resin.










Well that's it for now. The concept, planning, design and programming is all done. Now it's a matter of getting the couple of hours machine time I need to create the molds. Fingers crossed it all goes well first attempt. Ill try and grab some photos of the operation, maybe a video.

If all goes well, I'll be picking up the resin and starting to make my first cast slingshots


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## e~shot

Wow, can't wait to see the real ones mate.


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## LBurnett

That is very Interesting! Thanks for sharing.


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## Danny0663

SWEEET! reminds me of ZDP's first run of resin Scallops. Keep us updated dude


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## Hrawk

Danny0663 said:


> SWEEET! reminds me of ZDP's first run of resin Scallops. Keep us updated dude


Will do man. It's all down to getting the machine time now. If I cant get it for a few hours this coming Wednesday, then I'm screwed for another couple of weeks during school holidays.

Once I have the mold, I'll just go with come cheap poly resin to start. If all goes well, I'll invest in some of the nicer acrylic and nylon resins available.


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## tnflipper52

Hrawk, you've really got something going one there. Being able to make them in all the colors is way too cool. Don't understand a thing about the process, but I admire your talent with the equipment. If you make them, please make a bright orange one for me. Will pay the price for it. Thanks for sharing with us.


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## Hrawk

tnflipper52 said:


> Hrawk, you've really got something going one there. Being able to make them in all the colors is way too cool. Don't understand a thing about the process, but I admire your talent with the equipment. If you make them, please make a bright orange one for me. Will pay the price for it. Thanks for sharing with us.


Cheers man, I'll keep you in mind.

I think that's one of the really cool things about making them this way. You buy clear resin in bulk and can then add whatever colour you want. I'll probably just start with clear, see how it all goes. If all goes well, I'll buy more clear and some white plus a half dozen different dyes.

The really cool part for me is having access to the machinery needed to make the mold. Normally this would cost a few grand to get done. Over the next 8 months, I sure plan on making the most of it!


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## Hrawk

I haven't even thought about cost or selling yet but to give you a basic idea:

1lt of resin (clear) costs approx $40.

The volume of the finished product is 42.255 ml. So that's an easy 20 or so per liter of resin, so about $2 each to make. Not including finishing of course.

If all goes well, I could see myself selling them for around $15 each, $20 polished.


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## flicks

Great man, I've played around as well with resin casts. A nice effect is embedding coloured into clear resin. The material can be drilled, sanded and polished easily, but the problem that caused me to stop the project for now was, that in the case of a forkhit the material will burst in pieces like glass. (I took a test shoot at one casted plate). I've used cheap poly resin, maybe acrylic and nylon resins have different characteristics. Anyway, I love the idea and look forward to see your results.





  








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## Hrawk

Well if it works out ok, I intend on casting some Sydney Funnelwebs and Red Back spiders in the frames


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## Hrawk

Well why not.

If I get more than 50 likes to this thread, I'll give away the first 3 slingshots I make with this setup.


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## Beanflip

Looks great. All that work will payoff. I admire your skill and intelligence. Those prices will make them affordable to the majority.


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## Beanflip

I see many " likes " in your future.


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## Danny0663

If you start selling, put me on the list. I'll definitely grab one or two fosho'


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## quarterinmynose

Awesome! I very much look forward to seeing what goes down with this. Very interesting stuff here, well beyond my normal scope, and such a treat to get a peek into. Thanks for the posting man.


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## Hrawk

quarterinmynose said:


> Awesome! I very much look forward to seeing what goes down with this. Very interesting stuff here, well beyond my normal scope, and such a treat to get a peek into. Thanks for the posting man.


Cheers bloke.

I assure you, no one is more excited than me to see this project through to completion.


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## rockslinger

This is very interesting. I admire your talent.


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## Imperial

this is very interesting . hope it all goes well for you . good luck !


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## Bob at Draco

What a great idea. These would be cheap enough and still classy enough to keep in the truck. You could show them off to friends and if they got stolen, it wouldn't break your heart. I'll take a couple. Good luck.


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## bigron

that is a very cool process hrawk


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## flipgun

Hrawk said:


> Well why not.
> 
> If I get more than 50 likes to this thread, I'll give away the first 3 slingshots I make with this setup.


Almost broke my finger jabbing at the like button! :lol:

My first thought when I saw this was, "Clear with inclusions would be so cool!" :bouncy:


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## Jim Williams

This is awesome! Put me down for one with some spiders in if possible please?


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## Danny0663

> Put me down for one with some spiders in if possible please?


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## Jim Williams

Danny0663 said:


> Put me down for one with some spiders in if possible please?
Click to expand...


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## Quercusuber

Awesome slingshot technology!!!!

You're always on the treshold of innovation, Hrawk!!

LucasFilms, eat your heart out!! 

Cheers ...Q


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## Knoll

Danny0663 said:


> If you start selling, put me on the list. I'll definitely grab one or two fosho'


what he said ..........


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## Hrawk

Hehe sure.

Sad thing is, the best looking spiders are also the most deadly


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## All Buns Glazing

I am so amped about this, Dude. So... amped.


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## Hrawk

Me too! I'll be machining the mold in about 2 hours time!

I've done a dry run and everything seems ok, fingers crossed I'll have my mold at the end of the day!


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## Hrawk

Just finished the first half of the mold!!!!

A few small changes to feed rates and the second half can run unattended 

I is excited.

Snapped a few pics along the way, I'll upload them later tonight.


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## Hrawk

Awesome sauce, second half is done for a total of 26 minutes 12 seconds machining time


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## Danny0663

> second half is done for a total of 26 minutes 12 seconds machining time


Pics or it didn't happen! psssshhhh .... you're losing your ways Dan, * DISAPPOINT*


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## Hrawk

You want pics huh ?

Well I start off with a lump of aluminium.










Head over to the Mill. It's 18 years old, but still gets the job done.










Clamp up the workpiece. Man these pneumatic vices scare me. You get your finger in the way when closing it, bye bye finger.










With the program loaded you hit the start button and the magic begins.










It's hard not to take a quick peek a few steps in to check on the finish etc.










Nearly done, just a bit of corner rounding and chamfering to go.










Finally after a bit under half an hour of machining (not including stops), we have this!


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## Jim Williams

Awesome! Top work man!


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## All Buns Glazing

And instantly the coolest guy on the forum.


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## Hrawk

All Buns Glazing said:


> And instantly the coolest guy on the forum.


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## All Buns Glazing

I always suspected you were a brony. 
You could put any silly stuff in a resin slingshot! Cool casino dice.... Ammo...... A mini time capsule....


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## e~shot

Fantastic .... can't wait....


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## flipgun

I am following this with a great deal of interest! anic:


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## tnflipper52

The mold looks so smooth Hrawk, I dunno if your gonna have yo polish them or not. Exactly how do you polish resin without having a problem with heat buildup? This is reallt a funtastic looking project you have here. Thanks for sharing.


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## AnTrAxX

Nice work 

26min sounds "better", the result speaks for itself.

Bet the Teacher is happy too.

Should have clamped in the middle tho. If you did it to find the same spot for the 2nd one, there are special tools for that. But i think with the feeds you used clamping on one side shouldn´t cause any problems 

Really looking forward to the first slingshot. Do you need to use some kind of release agent for aluminum?


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## Beanflip

Awesome! That looks great. You've gotta be excited. I sure am.


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## lightgeoduck

It can't get any cooler than that!

LGD


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## wombat

tnflipper52 said:


> The mold looks so smooth Hrawk, I dunno if your gonna have yo polish them or not. Exactly how do you polish resin without having a problem with heat buildup? This is reallt a funtastic looking project you have here. Thanks for sharing.


one of the easiest ways of doing it....is to steal your mom's/wife's baking pan, lay your wet/dry sand paper down, pour a little water in then start sanding. Not only does it not get hot but you also don't get any dust!


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## Hrawk

tnflipper52 said:


> The mold looks so smooth Hrawk, I dunno if your gonna have yo polish them or not. Exactly how do you polish resin without having a problem with heat buildup? This is reallt a funtastic looking project you have here. Thanks for sharing.


It all depends on the resin really. There are about as many different types of resin I can use as there are types of wood out there. The harder ones (acrylic etc) will polish up on a power buffer just as all my previous acrylic frames. For the softer resins, though I probably wont use them much due to lack of strength, it's just a matter of keeping them cool and using a light touch.


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## Hrawk

AnTrAxX said:


> Nice work
> 
> 26min sounds "better", the result speaks for itself.
> 
> Bet the Teacher is happy too.
> 
> Should have clamped in the middle tho. If you did it to find the same spot for the 2nd one, there are special tools for that. But i think with the feeds you used clamping on one side shouldn´t cause any problems
> 
> Really looking forward to the first slingshot. Do you need to use some kind of release agent for aluminum?


About the time, yeah, I finally worked out why the estimation was so long. Bit of a bug with the plunge and extract rates overriding my helix parameters. Once that was sorted, cut the time down by a factor of three.

As for the clamping, no other option. As with the retarded speeds and feeds we are required to use, we also have to ensure all jobs are mounted up high like that to prevent damage to the vice and bed. A dead zone has been set 1mm off the top of the vice.

Depending on what resin I go with, some are fine with just a light coat of carnauba wax, others come with a product specific release agent. Some resins also have a slight amount of shrinkage apon curing to aid in the process.

In future I might invest in some tapered shank tooling to give a taper to the walls to aid in removal. As this is more a test piece than anything, I stuck with the basic end and ball mills to get the job done.


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## Viper010

Hrawk said:


> Well if it works out ok, I intend on casting some Sydney Funnelwebs and Red Back spiders in the frames


can those be exported without customs issues? CITES fines can be quite costly... anywayz... really really cool idea!

be careful with the catching though.... nasty lil buggers they are

id love me a spider shot! ima keep a close eye on this one

i smell one little problem though... if the resin gets injected at temperatures above 100 deg C the spiders might explode due to their bodyfluids coming to a sudden boil. so this might be more of n epoxy job than a molten plastic injection type deal... idunno just my 2 non-expert cents...

good luck man, keep us posted please
cheers, remco


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## Hrawk

Viper010 said:


> Hrawk said:
> 
> 
> 
> Well if it works out ok, I intend on casting some Sydney Funnelwebs and Red Back spiders in the frames
> 
> 
> 
> can those be exported without customs issues? CITES fines can be quite costly... anywayz... really really cool idea!
> 
> be careful with the catching though.... nasty lil buggers they are
> 
> id love me a spider shot! ima keep a close eye on this one
Click to expand...

Good question and I honestly don't know, I'll look into it though. I would think though, that being dead and completely encased in resin, it should be ok. I see plenty of gear knobs, jewelry etc being imported / exported.


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## quarterinmynose

Cool things in the work here. Very nice.

If you ever do get this in production mode, I would be stoked to hand you my money.


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## mr. green

Mr. H, you're so talented. Will be keeping an eye on this. A green one for me.


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## Hrawk

First few I turn out will be with a basic clear casting resin to make sure it all works ok, then I'll look at investing in some of the higher strength PU resins that can be coloured, have metal powders, glitter etc added.

I'll be picking this up tomorrow:










If it all goes well I have my eye on some of the high performance resins from Smooth-On.

http://www.smooth-on.com/specs_list.php?type=1


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## tnflipper52

Carry on soldier, there ain't no major malfunction in your camp. Can you pour in different colors of stain (or whatever it is called)and make swirling camo designs? That would be a nice touch.


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## Hrawk

tnflipper52 said:


> Carry on soldier, there ain't no major malfunction in your camp. Can you pour in different colors of stain (or whatever it is called)and make swirling camo designs? That would be a nice touch.


I've thought about this and the answer is yes.

Basically I can mix up the marble resin, and half fill each half of the mold, let it semi set, then clamp them up and pour the rest.

I might be able to get some cool multi coloured ones like this too.

Only time will tell.


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## All Buns Glazing

lol @ the glitter idea. Twilight Slingshots, anybody?


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## Hrawk

All Buns Glazing said:


> Twilight Slingshots, anybody?


I'll cut you.


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## Chepo69

Cuanto color amigo! Se ven preciosas las pequeñuelas estas! Looks great, full color!


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## Imperial

Hrawk said:


> All Buns Glazing said:
> 
> 
> 
> Twilight Slingshots, anybody?
> 
> 
> 
> I'll cut you.
Click to expand...

 :rolling:


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## All Buns Glazing

Hrawk said:


> All Buns Glazing said:
> 
> 
> 
> Twilight Slingshots, anybody?
> 
> 
> 
> I'll cut you.
Click to expand...


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## Danny0663

I has new idea!










I'll pay for the figurines, you just cast them!


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## AnTrAxX

In need of new Targets?


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## Hrawk

Just snapped a quick pic to show how closely they manage to fit together. Crap lighting sorry. I'll get a better pic tomorrow.


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## Hrawk

First pour


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## Jim Williams

Results???


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## flicks

You did a nice job on the mold. I am a little bit concerned that you are able to open it when the resin is cured. It doesn't seems that the mold flanks are tapered, so it could be a difficult job. Good luck, I am courious about the result.


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## Hrawk

Jim Williams said:


> Results???


Patience grasshopper, tomorrow.



flicks said:


> You did a nice job on the mold. I am a little bit concerned that you are able to open it when the resin is cured. It doesn't seems that the mold flanks are tapered, so it could be a difficult job. Good luck, I am courious about the result.


Cheers man.

There is a slot milled in the bottom to allow the two halves to be pried apart with a lever, I have also coated the inside of the mold with a very thin layer of wax. On top of this, the resin has a very small percentage of shrinkage, so it should pull itself away from the sides.

Anyhow, tomorrow will tell!


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## All Buns Glazing




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## phil

Can not wait to see it


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## AnTrAxX

Hrawk said:


> First pour


lol, what a cliffhanger...don´t do that!


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## mopper

Very cool. I have been trying to come to grips with Inkscape myself, but it was rough going. Inkscape is quite complex ...


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## quarterinmynose

Yarp, quite excited to see your results!


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## Hrawk

Hmmmmm,

Been about 20 hours now and my control piece is still a little soft and tacky.

Might have been a bit cold overnight out in the shed. Didn't want to leave it inside though as the resin fumes were pretty nasty.


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## Hrawk

Pretty happy with the resin quality so far though.

Not 'perfectly clear' as advertised, but then, it has obviously not finished curing yet. It was a much darker yellow colour when first mixed and poured and most of that colour has dissapeared.

Great to see that it has indeed shrunk by a very small amount, pulling away from the sides of the cup it's in. This gives me a good feeling about how well it will pull away from the mold once fully cured.

Also, no trapped bubbles inside, excellent! (The ones you can see, are the places where it has pulled away from the cup)


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## bullseyeben!

How I missed this topic I don't know! Better late than never lol. This is cool mate....looking very promising so far.


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## Hrawk

bullseyeben! said:


> How I missed this topic I don't know! Better late than never lol. This is cool mate....looking very promising so far.


Cheers Ben.

Don't be deceived by the size though.They're quite small as I didn't want to invest too much first time round if they didn't work out. 90mm high by 70mm wide, around the same size as your Ringshooter.

If everything works out ok though, I'll invest in some bigger stock and mill up a new set of molds. Probably use a quality high carbon steel so I can also use it to cast aluminium or other non ferrous metals.


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## bullseyeben!

Nothing wrong with a little pocket shooter, at all...but yea casting some aluminium..now that will be cool..and hopefully profitable for you..


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## Hrawk

bullseyeben! said:


> Nothing wrong with a little pocket shooter, at all...but yea casting some aluminium..now that will be cool..and hopefully profitable for you..


Only if I can use empty beer cans


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## Hrawk

Well I cracked the mold this morning.

Still feels a little soft to the touch so I'll leave it another day or two and see how it goes.

Beginning to think I may have messed up with the ratio of or resin and hardener.

Oh well, time will tell.


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## NicklePanda

That looks beautiful!!! Great stuff there. Been following this the whole time. Nice to see the product there. Trial and error right. But that piece right there is only possible in my dreams. Hahah ... I wonder what color or colors will you do next???
Great job!!!

-Leo


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## bigron

dude those are going to kick a#$ can you do cobalt blue


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## Imperial

:rolling: it looks likes jell-o. very interesting, hope it all works out in the end for you.


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## Danny0663

Once you get the pigments mixed, it's going to look awesome.


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## flipgun

Material aside, The form is clean. That is,"Skill". So many factors affect chemistry that often it is," luck".


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## Hrawk

Completely out of the mold now.

Fork tips were a bit dodgy but hey, first attempt.

Still a little soft in places, hopefully it will harden up completely over time so I can sand out the very fine tooling marks and give it a good buff.


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## lightgeoduck

Hrawk said:


> Completely out of the mold now.
> 
> Fork tips were a bit dodgy but hey, first attempt.
> 
> Still a little soft in places, hopefully it will harden up completely over time so I can sand out the very fine tooling marks and give it a good buff.


Wow, that still turned out great. I really didn't think it was that size though.. It puts things in perspective when in the hand.... ( no jokes needed they are already running through my head  )

LGD


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## Hrawk

Crappy pic, but it shows how the forks present themselves when held in the shooting position. I find it quite comfortable. Very similar in size to BullseyeBen's ring finger shooter, the A+ BB shooter and Bill Hays BB shooter.

I was limited to a 100mm high piece of stock to make the mold so it had to be something reasonably small.


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## y.o.r.k

wow, I like it!
... and what else could you do with this mill machining center!!!!


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## wombat

If the resin is still tacky? then yeah your porportions where out a bit. that stuff is really weather dependent.
I was going to suggest you give the forks a whack with a hammer to see what happens, but from your pic, your hand is protecting them pretty well!! 

Looking good!!


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## phil

Looks fantastic may be you could mix this in one so you can find it in the dark 

http://www.ebay.co.uk/itm/BRIGHT-X3-pigment-powder-Glow-in-the-dark-GREEN-luminescent-luminous-20g-/281067844421?pt=UK_Crafts_Other_Crafts_EH&hash=item4170f2f345


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## All Buns Glazing

SQUEEEEEEEEE!!!!!!!!!!!1111eleventyone

I'm really amped about this, so much so, I've lost control of my fontz!


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## AnTrAxX

I think this is a really encouraging FIRST (!) result!

I bet a stream of awesomeness will follow that first slingshot.

I´m signing in for free samples with this post lol (NO spiders tho  )

Good job mate, use a scale next time for mixing the epoxy if you didn´t. There are some sorts that are very dependant on an exact mixture.


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## tnflipper52

It really is a grat first try. Looks fantastic in your hand and the size makes for a nice pocket shooter. Awaiting the time of perfection of the mix. Then, an orange one please. Hwrak, congrats on a well thought out project.


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## LVO

Imperial said:


> :rolling: it looks likes jell-o. very interesting, hope it all works out in the end for you.


Brings new meaning to Jello Shooter


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## Hrawk

Hahahha, when I first pulled it out, it was still a bit soft and could be bent / twisted around like a jello shot!!!!

Hardening up nicely now though.


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## AnTrAxX

Hrawk said:


> Hahahha, when I first pulled it out, it was still a bit soft and could be bent / twisted around like a jello shot!!!!
> 
> Hardening up nicely now though.


That´s what she said...


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## quarterinmynose

Yup. awesome.


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## Imperial

All Buns Glazing said:


> SQUEEEEEEEEE!!!!!!!!!!!1111eleventyone


whos the little girl i hear squeeling in the background . . . oh, its ABG :mellow: :blink:


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## Popcorn

It looks like you have a real winner there! How easy (or difficult) is it to pour the resin into the mold? And do you have to go slow and jiggle things around to keep air bubbles from forming?


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## Tentacle Toast

Came out great man, nice work & A+ efforts for sure (plus I'm glad you opted for clear)! I just hope this doesn't spell the end for your turned metal creations...something about injection molding dulls the throb a bit for me. Glad it's an option,though; when you're out in the field, it'll be nice to see what firearms related goodies you come out with whilst putting in that OT...


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## Jim Williams

Awesome sauce!


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## Bob at Draco

Very nice. Did it pop free easily like you thought it would?


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## Hrawk

Bob at Draco said:


> Very nice. Did it pop free easily like you thought it would?


The mold was easy enough to crack open but when it came to removing the job from the other half, a decent amount of persuasion was needed. I think this may had to do with it being a bit soft still.

I'm about to go pour another. I'll be a bit more generous with the wax (release agent) and take a bit more care with the resin to catalyst ratio.


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## Hrawk

Ok well I bit the bullet this morning and ordered some high quality resin, proper product specific release agent and some blue dye to start with. I'll look into some more colours in the near future but for now, ouch, that's stuff nearly as expensive as the resin itself. Kind of limited with the colour range of their high strength dyes but you can always mix and match to create custom colours.

Got to say I'm pretty impressed with the Smooth-On guys in the USA. I emailed them yesterday with project details, couple of pics and a link to this thread. This morning one of their engineers got back to me with a very detailed response with product details, reasons for his recommendation and a whole heap of handy hints to improve the process. He even gave me a link to a testimonial of one customer who uses this stuff to cast boat propellers.

To get my head around the numbers, I made a quick comparison to another known product, HDPE.









For a room temp, low viscosity resin, I'm pretty happy with the stats of this stuff and no doubt it will make a fine slingshot. I can get 20-25% extra strength out of this if I heat my mold to 65c when curing.

If anyone else is interested in trying this stuff, here's the link to the resin and dye I'll be using.

http://www.smooth-on.com/tb/files/TASK_2_3_TB.pdf

http://www.smooth-on.com/tb/files/So-Strong_Tints.pdf


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## Hrawk

Ok so after measuring very carefully today I realize I was way off with the first attempt. Had less than half the catalyst I actually needed, surprised it hardened up at all really.

Fingers crossed tomorrow I'll be pulling out number two.


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## Danny0663

.


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## Danny0663

Hrawk, on 18 Apr 2013 - 12:36 AM, said:



Hrawk said:


> Hahahha, when I first pulled it out, it was still a bit soft and could be bent / twisted around like a jello shot!!!!
> 
> Hardening up nicely now though.





> That´s what she said...


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## Hrawk

Well that was a WTF moment right there.


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## Imperial

totally random :mellow:


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## Hrawk

Yeah baby.

Right mix, nice warm temps out side, the remainder of the resin in the cup has already gone pretty hard and this time, crystal clear (ish).

Following careful instructions works. Who'd have thunk it.


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## All Buns Glazing

Hrawk said:


> Yeah baby.
> 
> Right mix, nice warm temps out side, the remainder of the resin in the cup has already gone pretty hard and this time, crystal clear (ish).
> 
> Following careful instructions works. Who'd have thunk it.


Nailed it.


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## Wildwood

Awesome mate.....looking forward to the nasties embedded within the resin!


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## Bob at Draco

I can't wait, put some pictures up already.


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## Bob at Draco

I sure would like to see some pictures of the second one. Come on man, I'm going crazy here.


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## Hrawk

Here you go Bob 

First one on the left, second one on the right.

Much better clarity this time though I did get some very tiny air bubbles caught. They are right up the top of the fork tips, so I think if I back the catalyst off just a tad and let it cure a bit slower, I might have it spot on.

The slingshot doesn't seem to give me the same clarity though as the small slug you see on the right (the remainder of the resin left to cure in the cup). Ignore the slug on the left, I pulled it out while it was still tacky and it got all messed up.

Three possible reasons for this I can see:


The aluminium mold, being such a good conductor of heat, is sapping away all the heat too quickly during the curing phase. This could be why some recommend heating the mold during curing.
The release agent I'm using is not a real release agent as such, just some carnauba wax. Could be reacting with the resin.
The surface finish of the plastic cup compared to my mold.

The second one is easy to fix as my proper release agent should arrive in the next day or two.

The third I have already started to fix by hand dressing the inside of the mold with some 1200 grit paper.

Anyhow, enough rabble, here's the pic.


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## Hrawk

Although not perfect yet, I'd like to think I've made some progress.

Can't wait for the new resin to arrive, solid colors are a lot more forgiving than clear which shows up every little imperfection.


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## e~shot

Second one looks clear and solid!


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## Hrawk

Cheers man.

Starting to get the clarity I'm after, shame about those air bubbles though.

Oh well, number 3 on it's way.


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## e~shot

Hrawk said:


> Cheers man.
> 
> Starting to get the clarity I'm after, shame about those air bubbles though.
> 
> Oh well, number 3 on it's way.


Just a thought, giving some vibration or vaccum prevent air bubbles?


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## Hrawk

The thought has crossed my mind.

Clamp a small DC motor with an offset weight attached or something similar to the mold.

I gave it a good tapping for about 60-90 seconds after I poured it.

I think if I slow down the cure rate a bit, that should do the trick.

I could always do it properly too, and vacuum the resin before pouring.

If it wasn't for the fact that I want cast something INSIDE the slingshot, I could fab these up in 1/10th the time from acrylic sheet.

But I'm having fun and experimenting with something new.


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## bullseyeben!

Looking real good now... sounds like a pretty strong product too! Could you mould it with a metal frame or core?, that would look alright..


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## Hrawk

Yeah man, anything really, so long as it doesn't take away from the strength too much.

Barbed wire, insects, ball bearings, para cord, coins, razor blades, beer can ring pulls, whatever you can imagine.


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## lightgeoduck

Besides that looking cool as heck.. That process seems fun to do... One day I can do cool things to ( I hope )

LGD


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## Viper010

embedded barbed wire or creepy crawlies both sound like really cool ideas.
i also love the crystal clear 'ice' look.

vacuming the resin before casting and, if possible, the mold right after casting would for sure be the best way to illiminate airbubbles.

very cool project indeed bro. i read you were planning to eventually start selling the resin cast catties, which is very nice indeed! i would love one with a redback for sure!

but... would it maybe in the future also be possible to order a mold of my own from you?

cheers, remco


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## FWV2

I think a Hrawk makers mark coin in side the clear ones would be cool!

Fwv2


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## Hrawk

I'd love to get these to the point where I think they are solid and safe enough to sell. Recovering costs is always a good thing though I'm not really doing it to make money.

Yup, vacuuming the resin sure seems to be the advice I'm reading everywhere, just have to get a tank made up I guess and buy a small pump.

Could I make and sell you a mold, sure, however, while I have completely over engineered this project, you can get the same results with some simple and much cheaper latex mold making kits and use the same resin. Do a youtube search on Resin Mold Making / Casting, it's a pretty simple process. All you need to do is start with a quality master.

My inspiration mainly comes from having seen one of these awesome toilet seats:


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## All Buns Glazing

I just got back from a family reunion in the country. They look awesome.


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## wombat

Hrawk said:


> I'd love to get these to the point where I think they are solid and safe enough to sell. Recovering costs is always a good thing though I'm not really doing it to make money.
> 
> Yup, vacuuming the resin sure seems to be the advice I'm reading everywhere, just have to get a tank made up I guess and buy a small pump.
> 
> Could I make and sell you a mold, sure, however, while I have completely over engineered this project, you can get the same results with some simple and much cheaper latex mold making kits and use the same resin. Do a youtube search on Resin Mold Making / Casting, it's a pretty simple process. All you need to do is start with a quality master.
> 
> My inspiration mainly comes from having seen one of these awesome toilet seats:


It's funny all the research I did pointed to PRESSURE casting as opposed to vacuumning??

I think I paid a $130.00 for this spray painters tank.


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## Popcorn

Hrawk, you've done a great job on this project, and I'm not trying to find any fault with it. I've given this some thought and come to a couple of conclusions. Please correct me if my conclusions are invalid.

1) To cast something into the slingshot would require a two or three step casting process, in order to insure that the enclosed objects would not come to the surface of the frame...... Unless there is a way to reliably suspend the objects so they are not touching the outer surface of the mold. Even then, whatever is used to suspend things would also be encased in the resin and would probably show and also be even with the outer surface of the slingshot.

2) For enclosing anything in the resin, the mold would easier to use if it was laying down, and filled in that position. Which would probably require making a new mold designed for that method.

What do you think?


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## Hrawk

Spot on man.

I'd start by pouring a thin layer, 1-2mm into the mold while flat, just as it starts hardening, you place your objects then pour another few mm or resin.

Once that's hardened enough to keep them in place, combine the mold halves and pour as normal.


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## Hrawk

wombat said:


> It's funny all the research I did pointed to PRESSURE casting as opposed to vacuumning??


My understanding at this point is that you can vacuum treat the resin while in the cup / container then pour as normal.

Pressure casting involves the whole mold being in the pressure chamber.

I was steering towards the vacuum option as a smaller tank would need to be made.


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## Bob at Draco

Thanks for posting more pictures, as I was just starting to dry heave.

I just think every thing about this project is great. The thought of pouring out relatively cheap sling shots that are way up there on the cool scale is just wonderful. The second one looks good to me and I know you won't stop until it's perfect but the second one in a solid would look perfect. I'll keep up on this as it is very interesting to me even though I would never do it myself.


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## Hrawk

Oh goody!


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## wombat

Hrawk said:


> wombat said:
> 
> 
> 
> It's funny all the research I did pointed to PRESSURE casting as opposed to vacuumning??
> 
> 
> 
> My understanding at this point is that you can vacuum treat the resin while in the cup / container then pour as normal.
> 
> Pressure casting involves the whole mold being in the pressure chamber.
> 
> I was steering towards the vacuum option as a smaller tank would need to be made.
Click to expand...

Yep, I did a little more checking, apparently the vacuumning degasses the resin, hopefully resulting in no bubbles. Whereas pressure is used to get into any weird little nooks and crannies, and that doesn't come into play for a cattie.


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## Hrawk

Well hopefully with the above resin I just received, it's very low viscosity and according to the product info, bubbles should be non existent.

It's about to drop below 23c here at the moment, so I'll wait till the midday warmth tomorrow to give it its first run.


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## f00by

Good luck H!


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## Hrawk

Cheers guys and thanks for taking an interest.

I know the thread seems to be dragging on a bit but as the title says, it's a work in progress.

I'd love to see someone else have a go too so I'm giving as much info as I can.


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## phil

Hrawk said:


> Cheers guys and thanks for taking an interest.
> 
> I know the thread seems to be dragging on a bit but as the title says, it's a work in progress.
> 
> I'd love to see someone else have a go too so I'm giving as much info as I can.


I think its very interesting I was looking into it but don't think I could make or get a super mould like yours keep up the great work fella its Fantastic ATB Phil.


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## All Buns Glazing

This **** just got real. Your good resin arrived, eh?! I'm soooo keen to see what the resultant products are like!

Enjoyed watching the process, so much so that I'm here, catching up on the progress at 1:30am after 12 hours straight of working on an assignment


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## e~shot

where did you order that blue dye.. .? can it mix with epoxy glue?


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## Hrawk

Well here we go with the quality stuff.

I much prefer the equal volume mixing that this solution offers. Much easier using some disposable shot glasses as my A & B measuring container, then mix in a bigger cup.

Don't feel so bad about the crazy price of the tint now either. 5 drops into the mix provided a nice dense blue. I'll try 3 drops next time and see how I go with a lighter blue.

The proper release agent seems pretty awesome too. Normally my mold needs to be pried apart via the slot in the bottom, but after treating it with this stuff, it came apart quite easily with just hand pressure.

A big hint they smooth on guys gave me was to pour in a fine as possible drizzle, and yup, worked great at removing 90% of the bubbles caused by stirring. Two minutes of tapping the mold with a screwdriver bought the rest of them too the top. The consistency of the resin is just a tad thicker than cooking oil.

Anyhow, here's the pics up to now.

Mold prepped and ready to start mixing.










Mixed and poured. Made a bit too much (again...) but that's a good think, I can use that slug to practice sanding and polishing on before messing up an actual slingshot.


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## Hrawk

e~shot said:


> where did you order that blue dye.. .? can it mix with epoxy glue?


From a smooth on supplier here in Australia. It's $26.25 a bottle.

I'm pretty sure you could use it with most epoxies no worries as you only use a VERY small amount and they recommend it for several of their epoxy systems.

I'm going to have a go adding a few drops next time I BLO a frame and see how it goes.


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## Hrawk

I'm probably getting ahead of myself here, but I've just phoned my distributor and asked if he can grab the following for me as it's not something he normally stocks.

The UV reactive fluoro pigments look da bomb.


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## Hrawk




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## Beanflip

Hrawk said:


> I'm probably getting ahead of myself here, but I've just phoned my distributor and asked if he can grab the following for me as it's not something he normally stocks.
> 
> The UV reactive fluoro pigments look da bomb.


Looks pretty cool!


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## Hrawk

Well more hiccups but I'm still smiling. I'm really stoked at how this turned out.

The bad :


Air bubbles, air bubbles everywhere, millions of them! Doh!

The Good :


The hand dressing of the mold I did has worked wonders on surface finish
The colour and texture is fantastic (ignoring bubbles of course)
That release agent is amazing, it pulled straight out of the mold with next to no effort at all
The areas sans bubbles are pretty much perfect, no sanding or polishing needed. Such a lovely shiny smooth finish

Coming out of the mold, the outer skin was nice and firm, not leaving any finger prints or anything like that. Can be handled without fear of ruining the surface. Still a bit soft on the inside though. When I gripped it as you would shooting it, I felt the forks bend in slightly. Luckily as soon as I let go, they sprung back into shape in a second or two.

Looks like I'll definitely have to invest in some sort of vacuum chamber to degas the resin. Looks around, plenty of 20mm clear acrylic in stock, half the problem solved already, now for a pump.

I'm getting more and more excited as this project moves on. Building stuff is fun 

Moving on, here's the pics


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## Hrawk

In addition to the above 'good' points.

This was 3 hours from pour till open and out. Sure as heck beats waiting 24/48 hours for that cheap crappy resin I used on the first two.

Sure it needs another 48/72 hours to reach maximum strength but it means I can easily turn out 3, maybe 4 a day time permitting.


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## Danny0663

Shaaaazam! color looks good ... its a shame about the air bubbles


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## Hrawk

Danny0663 said:


> Shaaaazam! color looks good ... its a shame about the air bubbles


Yeah but am I bovvered ? Do I look bovvered ?

Pretty sure I can manage a home made vacuum chamber pretty soon. Just need to find a pump.

Also, the instructions told me to shake the sh*t out of the bottles before mixing. I realize now that this is where 99% of the bubbles came from. Next time I will shake and wait (no, not shake weight).


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## tnflipper52

Congrats Hwrak on a well done project. I long for the day you start to market these babies. And the blue looks fantastic.


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## Beanflip

Exciting results! Keep it up.


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## phil

Hi it looks fantastic I no nothing about the proses but do you think if you put the resin into a large syringe and put it into the mould under a little pressure it would work? ATB Phil.


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## August West

Hrawk said:


> Danny0663 said:
> 
> 
> 
> Shaaaazam! color looks good ... its a shame about the air bubbles
> 
> 
> 
> Yeah but am I bovvered ? Do I look bovvered ?
> 
> Pretty sure I can manage a home made vacuum chamber pretty soon. Just need to find a pump.
> 
> Also, the instructions told me to shake the sh*t out of the bottles before mixing. I realize now that this is where 99% of the bubbles came from. Next time I will shake and wait (no, not shake weight).
Click to expand...

Pump for bleeding brake lines should work great.


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## All Buns Glazing




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## Tirador

WOW that's awesome! You have your own slingshot factory!

Do you think you can use JB Weld to make a slingshot? I think that would be a pretty strong slingshot, but be careful not to glue your mold together. lol

Great design as well!!!


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## AnTrAxX

Can you improvise a small vibrating table where you can clamp the mold to?

Just a left over motor or a belt drive from a drillpress with an excentic wheel on the small table...should do the trick.

And i think a longer setting time might help the bubbles escape.

But concidering your still in the "try and error" phase of your project...i think the results are amazing.


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## flicks

There are two ways to avoid bubbles, but don't shake anything! If the resin is colored, apply a thin layer with a brush into the mold and let it cure a little bit before you fill the mold. In this case you do not avoid the bubbles, but you won't see them on the surface. If you want to use clear resin, you have to put the can with the mixed resin into a vacuum chamber for a few minutes before you fill it in the mold. You can use a compressor of an old refrigerator as a vacuum pump.


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## Hrawk

Cheers for the input Flicks.

Pretty much decided on the vacuum de gassing option.

Going to have another go today, without the shaking. Looking now, the resin has no bubbles in it. Mix and pour carefully.

I have an old fridge compressor here, but I've been using it as a HPA compressor. I like the ides of a brake bleeder, not sure how many inches it will pull though.


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## quarterinmynose

epic project, epic results, and epic post. and, I'm enjoying every bit of it. Thanks.


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## Imperial

AnTrAxX said:


> Can you improvise a small vibrating table where you can clamp the mold to?
> 
> Just a left over motor or a belt drive from a drillpress with an excentic wheel on the small table...should do the trick.
> 
> And i think a longer setting time might help the bubbles escape.
> 
> But concidering your still in the "try and error" phase of your project...i think the results are amazing.


or lay it on one of them motel massaging/vibrating beds.


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## Hrawk

Well that was stupid.

Searching Google for 'Hand Operated Vacuum Pumps', not the greatest Idea


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## Imperial

Hrawk said:


> Well that was stupid.
> 
> Searching Google for 'Hand Operated Vacuum Pumps', not the greatest Idea


dont you own one of those already ? :neener: maybe thatll explain as why some consider you the biggest "richard" on this here forum. :rolling:


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## The Warrior

Epic thread man. Really nice work.


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## Hrawk

Far from perfect I know, but it hasn't stopped me from banding it up and killing a few cans with 1/4" ammo and 2040 tubes.

Although small in size, I find it a very capable shooter.

One thing I did learn though, I'm going to need to groove those fork tips.

Even after cleaning the tips, bands and ties with alcohol as I normally do, the plastic remains VERY slippery. You can see here how I've tied them a bit further down to save having one come back in my face.


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## FWV2

Truly amazing Hrawk!

Fwv2


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## e~shot

PUKKA!


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## Bob Fionda

I like this project, your research, the studying and, of course, the result. Bravo Daniel.


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## Hrawk

Thank you Bob, that's high praise indeed coming from you.


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## Bob Fionda

Hrawk said:


> Thank you Bob, that's high praise indeed coming from you.


And it's well-deserved, not many are dedicated to research and offer their work with dedication and passion like you do.


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## Btoon84

That turned out awesome for the first go with the new "good" resin. So hrawk, are you thinking of making a new mold WITH band grooves, or are you going to do them by hand with a file or router or something? Keep it up.


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## All Buns Glazing

Loving the updates, Hrawk. You're a credit to us Aussie slingers!


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## Dayhiker

Hrawk said:


> Far from perfect I know, but it hasn't stopped me from banding it up and killing a few cans with 1/4" ammo and 2040 tubes.
> 
> Although small in size, I find it a very capable shooter.
> 
> One thing I did learn though, I'm going to need to groove those fork tips.
> 
> Even after cleaning the tips, bands and ties with alcohol as I normally do, the plastic remains VERY slippery. You can see here how I've tied them a bit further down to save having one come back in my face.


Dude! "*Far* from perfect. . ." ?

Fix the slippyness and you're home free. But I think I understand you better, now, Hrawk. I think you are looking at it from the standpoint of a design engineer who is working for a manufacturer. This is to be their next product. Okay. Well done then, so far.

But from where I stand -- you nailed it, bud!!! :bowdown: Fix the slippery and let's make another mold. How about we try a Chalice this time? :lol:


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## Imperial

looking good, to fix the slipperyness, the next mold can have some sort of grip texture added. dimpled like a golf ball, mini x patterns or checkered. or you can also have it to imprint your makers mark on it also. once you get it going, i see a destruction test coming up. put them up in the distance and shoot at them. in a vise and pull on the forks. let a koala chew on one. and it all has to be videoed. continued success to you H.


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## Mr.Teh

Nice update, looks awesome your project :thumbsup:


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## Hrawk

Btoon84 said:


> That turned out awesome for the first go with the new "good" resin. So hrawk, are you thinking of making a new mold WITH band grooves, or are you going to do them by hand with a file or router or something? Keep it up.


Definitely going to make another mold and incorporate the band grooves into it, possibly a makers mark of some sort.

Probably do the Hrawkeye as this has proven itself a solid design.

I won't worry about machining the next mold though as it's a bit of an overkill seeing as I'm not injection molding, using heat or pressure casting.

I'll start with a master and make a silicone mold up. I think for this project the benefits of the silicone mold process outweigh the 'cool factor' of having a CNC machined mold.


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## Btoon84

I'd love to see your process in doing the silicone mold! I think that might be something more of us "normal" folk could tackle...


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## Hrawk

Btoon84 said:


> I'd love to see your process in doing the silicone mold! I think that might be something more of us "normal" folk could tackle...


Totally man. It's pretty basic.

At school at the moment, but when I get home, I'll throw up a post with a couple of great tutorial vids I've found.

I'll leave this now to 'wet your appetite'


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## Wildwood

Mission accomplished Hrawk man! :blink:

Appetite is....you know....wet!

Take custom orders for own designs?


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## All Buns Glazing

Hrawkeye!

Hrawkeye!

Hrawkeye!

Hrawkeye!

Hrawkeye!

Hrawkeye!

hoo hoo hoo


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## AnTrAxX

Nice Hrawk.

Glad to see you finally aim for Silicone too.

I think we chatted about it once, a mate of mine casts a lot with silicone molds and they are very true to the original form and will last at least for 50 pieces or more if you handle them with care.

I wish i had more time, seems like a lot of fun to do....one day....one day...


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## Hrawk

AnTrAxX said:


> Glad to see you finally aim for Silicone too.


If there is a lazy way to do something, trust me, I will find it!


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## AnTrAxX

Wish i could tripplelike some posts


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## wombat

Hrawk said:


> Btoon84 said:
> 
> 
> 
> That turned out awesome for the first go with the new "good" resin. So hrawk, are you thinking of making a new mold WITH band grooves, or are you going to do them by hand with a file or router or something? Keep it up.
> 
> 
> 
> Definitely going to make another mold and incorporate the band grooves into it, possibly a makers mark of some sort.
> 
> Probably do the Hrawkeye as this has proven itself a solid design.
> 
> I won't worry about machining the next mold though as it's a bit of an overkill seeing as I'm not injection molding, using heat or pressure casting.
> 
> I'll start with a master and make a silicone mold up. I think for this project the benefits of the silicone mold process outweigh the 'cool factor' of having a CNC machined mold.
Click to expand...

glad to see you've discovered silicone molds, life will be a lot easier!!


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## leon13

that is so nice i rely like this thread ,and this forum

chears

ps:and when its time to drop orders let me know


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## Imperial

ever think of casting the left over resin into a slug mold and pack a couple of "invisible" ammo slugs with it as a lil joke.


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## Hrawk

Imperial said:


> ever think of casting the left over resin into a slug mold and pack a couple of "invisible" ammo slugs with it as a lil joke.


What, like a clear marble ?

Sorry there haven't been any updates lately, waiting on my vacuum pump to arrive before wasting more resin.


----------



## Imperial

Hrawk said:


> Imperial said:
> 
> 
> 
> ever think of casting the left over resin into a slug mold and pack a couple of "invisible" ammo slugs with it as a lil joke.
> 
> 
> 
> What, like a clear marble ?
> 
> Sorry there haven't been any updates lately, waiting on my vacuum pump to arrive before wasting more resin.
Click to expand...

not marble shaped, but cylindrical . or perhaps in your case, looking like a beer barrel.










dont worry bout the updates, rather it come out great than half arsed.


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## S.S. sLinGeR

Wow that is cool! I can't wait to see the finished product. Great work Hrawk.


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## Dr J

Fantastic project! As jewelry manufacturing is another one of my hobbies, I find that metal molds work best for prolonged use. However if only a few pieces are required, or in research and developing new designs the silicone molds are are more economical. After all the bugs have been eliminated the metal molds are used. 
I have the greatest respect for your talent Hrawk, and wish you the very best in all your lawful endeavors.


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## leon13

hello again

so when ever there is a chance to get one of thees beauty`s let me know ;-) they are really nice

cheers


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## troutokie

Any progress updates?


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## Djones02021985

I love your work and your designs.


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## pult421

Things like this .. make me want to go to school.. sorry to bring this to life again. I just admire the skill yo!


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