# Cutting Bands With a Steel Rule Die Cutter



## ZDP-189 (Mar 14, 2010)

There have been a few developments in my bandset making these days. First, I have moved to a much more complex taper than before. The bands are highly engineered. They are radically tapered, mathematically curved, have straight sections for fork tying over specially coated fabric, are specially flared, doubled and feature a precise centre-marker. This is the band design I supplied to Jeff (shot in the foot) that offered superior accuracy, high velocity for low draw weight and have lasted over 5,000 shots so far without signs of wear. I appear to be onto a winner, so I have used this same pattern on all subsequent slingshots. However, there are a few drawbacks though all in the production process. Basically, they are very challenging to cut and there is no margin for error at all. The slightest imbalance, width miss-cut or a significant nick will render the bands useless and I have been throwing away three bands for every one made. It's already a wasteful design, as I can only get three sets from one 18" strip of Threa-band Gold. The cost of the materials, precise cutting requirements and labour input gave them a prohibitively high production cost.

I had to find a solution and turned to industrial rubber parts manufacturers. The solution was to make this steel rule die mould.










It cuts three pairs a minute by hand, or in an instant in a fly press.

It's all CNC laser cut to about 0.1mm precision. The fixed razor blades press through the latex into a plastic block and cuts perfect lines without nicks. It will cut any thickness or elastic you'd care to shoot. If the process can handle these complex shapes, simple tapers are no challenge at all. You could even set up a series of different tapers and lay rough-cut strips on top of the set that you wanted to use. The mould life is probably more than any one person would ever want and even the bigest Site Vendors would justify a very quick cost recovery compared to cutting by hand.

All you need to do is find a die cutting service on-line or in your vicinity and have them make you a mould to your specs. It was easy for me, I just took the lift down to the 7th floor!


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## smitty (Dec 17, 2009)

Wow ZDP ! I like your solution to band production. I have done rotary die cutting on printing machines for decades. This might be something for me to look in to also. Thanks for all of your ideas. I also liked you taking me to school with the pics on making micarta.


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## baumstamm (Jan 16, 2010)

that is what i´m looking 4!!!!!


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## Dayhiker (Mar 13, 2010)

Way out of the realm of my hobby and into the realm of precision manufacturing. The skill of the shooter and the uniformity of the material are way too wild a variable to render any of this more than quite marginally useful in the real world. This exercise is purely academic in my opinion. (Please do not hate me, Dan.)


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## ZDP-189 (Mar 14, 2010)

Dayhiker said:


> Way out of the realm of my hobby and into the realm of precision manufacturing. The skill of the shooter and the uniformity of the material are way too wild a variable to render any of this more than quite marginally useful in the real world. This exercise is purely academic in my opinion. (Please do not hate me, Dan.)


Not at all. Let me explain a little why I had to go to all this effort.

The band design is firstly optimised for speed for low draw weight. That requires:

Wide bands
*Aggressive taper*
Low weight at pouch end with light weight band tying
Fast latex
Great elongation at full draw
Then it is about accuracy (admittedly the user is more important here):*
*
*Wide bands must cut and doubled so as to avoid rolling and achieve a more linear stretch**
*
*Exactly balanced left and right bandsets
*
*Equal upper and lower bandsets*
Most of all the above is inconsistent with longevity/ durability, so to enhance that:

Fork tie portion to be exactly as wide as tips
*Pouch tie portion to be as wide as tip end to allow it to be rolled around the band to protect the elastic at the leather and under the tie*
*A gradual flare at the pouch tie with the narrowest part of the taper just in front of the tie, not under it*
*Gradual taper so that each section is approximately proportionally smaller than the next part in front so the elongation ratio is constant*
*No single band is any weaker than the others
*
*No blade nicks on the edges*
That's all academic. Either you'd want bands with these features or you wouldn't. This thread is not about the design of the bands but rather the challenges of making them and a solution that can be applied to all band making if you'd choose to.

I was having great trouble making these bands perfectly by hand. All the items in bold above conflicted with that. My bands were often nicked at the edge to the point of looking chewed up, unbalanced or narrower than the last set. Many ended up in the bin or were turned into tying strips. I tried roller cutters and steel rulers on rubber mats. I tried tape. I tried doing it sober without music playing. In the end I could do it, but it took too long and the reject rate was still high.

This solution is both fast and precise and I am now satisfied that I am making my bands to the standards required.

As for it's being an academic exercise, it's easily attainable. The cost is about the same as a couple of slingshots and the challenge of making it is just design and draw it, then wait 20 hours for the mould maker to tell me to come downstairs and pick it up. I slap the Thera-band on it and roll over it with a plastic rolling pin. Job done and complexity is no longer a factor.

*
*


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## Flatband (Dec 18, 2009)

Now that is some high tech stuff Dan! How drastic are your tapers Bud? I have found through experimentation that too drastic a taper( I.E. more then 2.5 to 1 really is energy defeating( there are a lot of other variables though,cut,elastomer type,length,etc.. If you have found otherwise,please-I'M interested!!! Flatband


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## pelleteer (Dec 19, 2009)

Ah! Took me awhile of looking at that to figure out what I was seeing (sort of an optical illusion). The red shaded areas are the dies for the three sets of band, yes?


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## ZDP-189 (Mar 14, 2010)

smitty said:


> Ah! Took me awhile of looking at that to figure out what I was seeing (sort of an optical illusion). The red shaded areas are the dies for the three sets of band, yes?


Yes, it's a vase-or-two-faces kind of illusion. The bands are the parts shaded for three pairs of bands. Can you see why I don't hand cut them? The inside angle by the pouch flares are potential failure points and have to be cut in one pass, not two cuts. I also make the flare on one side only because once tied, it's effectively symmetrical but it reduces the number of these angles by four per slingshot.


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## Tex-Shooter (Dec 17, 2009)

The Saunders bands are cut in a complex shape also. I dont know if they are cut with a steel rule die or a roller die. -- Tex


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## NightKnight (Dec 16, 2009)

Wow, you are really coming up with some innovative stuff! I'll bet those are some fast bands!


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## Frodo (Dec 19, 2009)

Wow...you are the man! Now i understand why you said that you sended me your best bandset!

Friedrich


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## ursu5 (Mar 13, 2011)

Have you tried cutting the bands directly using a laser cutting service?


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## dgui (Jan 12, 2010)

Brilliant.


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## bj000 (Jul 21, 2011)

could there be any chance of me getting to try out a bandset? They look awesome. I doubt i would ever get to shoot something like that.


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## Charles (Aug 26, 2010)

Wonderful work! Way to push the envelope. I can't express in words how impessive I find the band design. I would be very interested in seeing some speed tests compared to standard straight cuts.

Cheers ...... Charles


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## Beanflip (Sep 11, 2010)

I got to chat with Z one night. I think he is working on going into production. I think they will be available soon.


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## bj000 (Jul 21, 2011)

Beanflip said:


> I got to chat with Z one night. I think he is working on going into production. I think they will be available soon.


hot dawg!


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