# Arthritisandra



## jazz (May 15, 2012)

Hi all,

I already wrote about this but I made a better prototype and I need some advice on ergonomics so I will go through it again with some better details, I hope.

So, having pains in my knuckles, more and more, and never going to see the doctor I assume that I might have some begining of arthritis.

Sometimes I have no problems, but sometimes, especialy when holding my palm at an angle in relation to my arm while shooting sideways, thumb support, I do.

So I said to myself, how can I avoid this holding (gripping the handle):









And how can I avoid this holding (thumb support):









That is, is there a frame that would alow me neither to grip the frame like pistol grip nor to put my palm at an angle, but that would fit my hand when I put it relaxed in the position when I simply stretch it/point it towards the target, like this:









So I came with a frame which is basicaly derived from a revolver or a pistol grip but with much extended distance between fingers side and the thumb, like this:









I aded the fork 90 degrees to it; the frame is made from some maple plank with leather glued with atomic glue on both sides (just an experiment) and the fork is from the plastic meat pad I just bought cheep some days ago (another experiment here). This is the finished product:









And this is and how it is held when shooting:









I shot couple of shots and everything is fine - I even have a couple of centimeters longer draw! - except couple of things where I need some help:

first, even when you take into account that the forks are cut a bit longer than needed, the stability/ease of hold is not perfect, the wrist tends to "brake"; it would be much more so with stronger bands (these are TBG singles 1.5 to 1 cm taper

second, the point where the thumb is fastened to the palm does not face the frame directly as with the pistol or revolver, but at some 45 degrees and I simply can not figure the proper ergonomics; I tried to make a deeper bevel at that point but it is still uncomfortable, like this:









Any suggestions are welcome,

thanks,

jazz


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## Metropolicity (Aug 22, 2013)

maybe you need to make less of a curve at the thumb webbing and more of a 'ball' with more meat to hang onto. I know you are limited to a board cut right now but some more support on the top and bottom of the thumb grip area may spread out the pressure.

On a side note, maybe you can look into a pinch grip frame again, has more meat in the hand webbing area to spread the pressure AND use a wrist lanyard to take most of the draw of the bands. That way, your fingers and thumb aren't really doing the work, the lanyard is.


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## GrayWolf (May 14, 2012)

Check out this video from Bill Hays....






I had this frame at the MWST and it quickly became a favorite for several shooters. Everything lines up very naturally and there is no strain on the wrist or hands with normal bands....Extreme heavy bands will always cause some strain, no matter what frame is used.

I think you are on the right path....maybe just a small adjustment on the angle of the forks and you will be there.

Todd


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## Byudzai (Aug 31, 2013)

hey jazz,

I feel like my alien/goldfish designs achieve the open, neutral hand position -- that was my goal anyway.

http://slingshotforum.com/topic/39852-goldfish-coming-along/

http://slingshotforum.com/topic/39330-the-alien/


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## J Stacy (Aug 7, 2014)

If you bend your thumb down, like in the pictures,you put more strain on the tendons from your wrist to your thumb. If you can hold your thumb straight it will strain you thumb and wrist less.


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## Charles (Aug 26, 2010)

Not sure where your pain is located. Mine is right at the bottom of the thumb, where it joins the wrist. I use a finger hook and thumb brace to shoot comfortably. I cannot pinch the frame with my thumb without having a LOT of pain. So any sort of choker grip or hammer grip is out for me. Anyway, your problem might be quite different from mine. Essentially, you need to frig around with your designs to find what suits your condition.

I would issue one word of warning. I used to use those thin, HDPE cutting boards for frames, but I do not any longer. I had a couple break when friends were shooting with more of a hammer grip than I use. They are fine for quick and dirty check of a design, but I would never use one for a slingshot that is to be seriously used with anything but the lightest bands.

Cheers .... Charles


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## jazz (May 15, 2012)

Hi all,

Thank you for your ideas and suggestions, I realy got more than I expected (and deserve, probably..) so that I can experiment now not with one but with few new variations!

Hi Metroplicity,

Both suggestions I find useful, especialy in the first paragraph; I am already making some plans to try it, thanks!

Hi GrayWolf:

I thought I saw all of his videos, but then comes this one! If I saw it before making this prototype I might do some things different, but next first or second experiment I will try to use it, thanks!

Hi Byudzai:

I remember these pictures, and I think that part where thumb is holding agains the frame, also those areas that go against palm close to the thumb are the most interesting ones for me in this case, thanks!

Hi J Stacy:

Hm, I never thought of that but I when I try it - it works, somehow.. I am still not sure is this what I want but thanks anyway!

Hi Charles:

My pains are mostly in every second joint of every finger so for that reason I do not like to grip the handle. I am trying to hold my hand as "flat" as possible and this is what I am trying here. You are right about the board - it is simply an experiment now and soon I will have better materials to play with, thanks for the warning!

cheers,

jazz


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## Bill Hays (Aug 9, 2010)

My suggestion would be to use a wristbrace... and if that is not feasible, then you can go with an extended beavertail like on the Hammer Takedowns... if you make the thing about 1 1/2 inches thick and have a good roundover for the thumbweb, you should be golden.

Other suggestions like the Alien Menace would help some I think, but not as much as the hammer grip type slingshot...

One other thought.. maybe a modified Scorpion would do the trick... the one I made for the MWST is pretty good at taking all the stress off the fingers and places the fulcrum right in the thumb web and meat of the palm... here's a picture:










On this hammer takedown, which is in the templates section... you can see what I'm talking about with the extended beavertail. That and the roundover really spread out the stress points:










Or you can go for a more pocketable design... if you make one like this just use a thicker board and make a thumb web support.. makes it very comfortable as well:


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## jazz (May 15, 2012)

Hi Bill,

You gave me another set of very promising ideas, thanks!

As far as I can see now, as soon as I get some new materials (january, hopefuly) I will set off for lots of experimenting.

Thanks again,

jazz


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