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This is my latest, a lightweight pocket target shooter. I fancied this candy apple red cast acrylic sheet. The shape was based around two concentric circles for the fork and then a fat handle with a cut out for three fingers.





I wanted it to look like pooled candy or burgundy wine and I think I have achieved that. The edge is radiused and the whole thing finished to a high polish. Clear acrylic is easy to polish, but shows up every surface imperfection and it took hours to get it like this.



I have finished the deep tie-on grooves with black tape.



It's sporting red bands which are a little thinner than Theraband silver and taper from 3/4" to 1/2" with a 8-9lb draw. These suit the light frame. I have changed the tying method at both the forks and the pouch to reduce wear. It would probably handle strong bands, but I like the light set-up. The entire thing weighs 34g (1.1oz) including the bandset.



Combined with a very ergonomic grip and low forks, the resulting fork and bandset is highly accurate. There is almost no tremor at full draw and the bands are very fast up to the weight of 8mm steel BB, giving a very zippy and fast trajectory.

I can't complain about energy either. 6mm BBs consistently clear both sides of an empty soda can, punching out neat little round exit holes.



I plan other variants of this design in carbon fibre, micarta, G-10, polycarbonate, thick black acrylic and Gun-Koted steel.
 

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Thanks!

Here's a couple more variants on the same pattern, a 1/8" polished carbon fibre and a 1/2" synthetic wood (reversed for holding in the right hand). So, something for the artsy crowd, something for the tactical/ technical guys and one for the (semi) traditionalists.



Yes, those are Hunter Bands in the middle. I prefer them on a full large handled ergonomic frame, but they shot OK.
 

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Discussion Starter · #12 ·
The wood is Timbertech or Exwood, which is recyled (I think) wood dust in a plastic matrix. It is an absolute dream to work; it positively revels in being bullied into shape, more than any other natural or stabilised wood or plastic. It comes in widths and thicknesses that are ideal for frames. You can pencil, mark with a permanent pen, or scribe in it. A bandsaw just about glides through it like a rip cut through pine, except it has neither grain nor knots. It does not snatch, blow out or burn when drilling; it doesn't splinter or chip, but gives long curls. You can scrape it with a knife edge. Sanded particles don't particularly irritate. Finishing is very quick and easy and it hides scratches. It looks attractive and much like wood when oiled. It polishes to a high finish and it absorbs stain if needed. It is fire rated, has good tensile strength, never rots or moulds. It is fully recyclable. It won't destroy the earth and it doesn't cost the earth. I feel it is the very best material for many applications that you can work or own. However, it just isn't Desert Ironwood, spalted maple, zebrawood, etc. and so it doesn't make for a top dollar product. I hope that it will catch on with knife and slingshot makers.
 

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Discussion Starter · #16 ·
It looks to be the same. Builders' merchants often give out samples and see if it's like I described. If you buy a plank later, it'll cost more than heat-treated lumber but much less than hardwood like teak.
 

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Discussion Starter · #29 ·
I wonder if I cast it thick enough could I use actual red candy.
probably if you u used a steel frame to strengthen it
I don't know. It's a strong design and I'm thinking of a 1" slab, recast in a GRP/silicone mould. I'd use a traditional candy apple recipe (minus the apple). We have the beginnings of a serious plan to do a silly experiment.
 

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Discussion Starter · #35 ·
Scott (Fork Hunter),

Last night I laid up the camo print for your slingshot in a close equivalent to realtree, as requested in your PM.



The results are very encouraging; it's as good as any I've done before. The polyester resin has solidified thoroughly, there don't appear to be dry spots, voids or bubbles and the press has produced a laminate plate of uniform 1/2" thickness. Moreover, the print came out well without much darkening and without the colours running. The surface texture is lovely too.

I have now trimmed the slab now that it has had 24 hours to fully set. Examination if the cut cross-section looks good. I've just now rescaled the template to your hand size and I'll cut the board them take a piece of scrap the size of one of the forks and use that to determine the laminate's static breaking strain (hopefully more than 30lbs per fork). Only at that point will I truly know whether the process has been successful and I can begin the simple process of actually making your board-cut frame. Don't worry; my back-up plan is just to put a layer on each side of commercially produced micarta, which is what I might do on a production item, but I feel a full lay-up is so much more satisfying.

I'll keep you posted on my progress over the weekend.
 

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Discussion Starter · #39 ·
They are precious!

And yes you have total confidence in the materials at the time of throwing? or it only is for slight shots?

Muy Chula la Manzanita! ZDP




Cjepo
Cjepo, the acrylic really is only for light bands (compared to Hunter Bands, anyway.) The first post showed those light bands punching holes through both sides of a coke can, so they're not really weak at all. Those are exit holes. The front of the can was caved in.



Nevertheless, acrylic (polymethyl methacrylate, Perspex, plexiglass) is no better than wood. It was used in WWII aircraft canopies and still finds use in structural and engineering applications like large aquarium tanks and submersibles. The main problems are that eventually it may snap under sufficient force, and its ability to resist failure can be severely degraded by weathering. Polycarbonate (Lexan, Makrolon) is similar in flexural and tensile strength to acrylic on specification, but when working with it you get the sense that is not as hard and brittle. Acrylic chips out when you drill through it, whereas Lexan does not. When you sand acrylic on a belt sander, it just disappears, whereas polycarbonate leaves big fluffy burs. Acrylic chips also when you cut it, whereas polycarbonate is a dream to cut. I would have said then that polycarbonate is a better choice, though it is expensive, does not come in such a variety of colours and is not as beautiful when polished to a high finish, which is why I picked it for the Candy Apple project.

See this link for reference: http://www.hydrosight.com/technology/polycarbonate_vs_acrylic.php

The carbon fibre was a lot stronger, as was the G-10 FR4 that I used in the Clone Trooper project. It was no surprise that half an inch thickness of G-10 was strong enough; I could use it as a crowbar. Here are the G-10 specs:

http://www.jjorly.com/g10_fr4_technical_specifications_data.htm

The synthetic wood is basically just like wood but without grain. I'd consider it similar to MDF in strength, but with the weathering properties of PVC or Nylon.

In short, yes, these materials aren't bad at all. You still need to understand how things fail and be careful, as you should with any slingshot, especially board cuts.
 

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OK Scott, here you go.





This was actually my second attempt from that slab. I ruined the first one by applying CA glue, trying to put a hard surface on that could be smoothed and would take a shine. No matter; I always have a backup plan.

There's some more details of stress-testing in the Laminate tutorial: http://slingshotforu...inate-tutorial/
 
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