# Bow Press Fingers ..... another approach. lots of pictures.



## Kinkajou (Mar 2, 2013)

So I start modelling, using some plastic caps to give me starting point on part height, adding clay and smoothing the part.


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## Kinkajou (Mar 2, 2013)

Making the mould, using some cardboard to contain the rubber








I used this silicone rubber with the hardener. Mixing and then pouring the rubber. This will make a negative cavity of the part to be reproduced.


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## Kinkajou (Mar 2, 2013)

The rubber has set and I can remove the clay from the mould.


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## Kinkajou (Mar 2, 2013)

I pour some resin with hardner to produce the first reproduction. This will help clear the mould from debris. And help me look at how the fingers will be.




Cutting some fiberglass and coremat fingers.
They were inserted one by one in the mould and impregnated with resin. I used yellow pigment for this parts. 






The plastic finger were introduced to an oven for about an hour at 80˚C. That helps complete the curing of the resin giving it more strenght.



I now have to drill a hole where the pins will hold the fingers.

So far so good.


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## cmd242 (Jul 15, 2012)

Looks good. Make me some.


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## Kinkajou (Mar 2, 2013)

Thanks to Gunner7800 for providing a starting point on the design of the fingers. It made everything easier.


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## Alaska at heart (Aug 25, 2009)

Interested in seeing the final results and how well this concept pans out in actual use over time. Thanks for sharing......


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## nuts&bolts (Mar 25, 2005)

Excellent work.

Nicely done.


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## jljjdye (Jan 11, 2007)

I'll take a set and work the dog out of em. I'll report back with results


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## Pittstate23 (Dec 27, 2010)

Wow very nice


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## Glenn58 (Mar 25, 2013)

Interesting concept!!!
I recently ordered a finger kit from 92safari...Bill really did a great job with his build thread.


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## aread (Dec 25, 2009)

Great idea!!! Looking forward to seeing how this works out.

I wonder if you could use this technique to build a string jig & stretcher similar to the Little Jon?

Thanks for posting!


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## nuts&bolts (Mar 25, 2005)

aread said:


> Great idea!!! Looking forward to seeing how this works out.
> 
> I wonder if you could use this technique to build a string jig & stretcher similar to the Little Jon?
> 
> Thanks for posting!


Scale the size up,
make the cross section size sufficiently LARGE enough,
so that you get near ZERO deflection
sure.


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## Kstigall (Feb 24, 2004)

I _think_ I would have laid up a a composite "board" and then used a band saw (or similar) to cut them out. I've thought about it but my Monster Pac Press works fine.


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## OhWell (Aug 21, 2013)

Nicely done, I have done composite moulding for about 10 years in my little shop and never thought of doing fingers out of a resin. I am sure Smooth On would have something I could pour them from. This got me thinking, I could also lay up the shape as a wide strip in carbon and then cut the individual fingers. If I went to .25" thick in solid carbon they would never flex or crack.


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## Kinkajou (Mar 2, 2013)

OhWell said:


> Nicely done, I have done composite moulding for about 10 years in my little shop and never thought of doing fingers out of a resin. I am sure Smooth On would have something I could pour them from. This got me thinking, I could also lay up the shape as a wide strip in carbon and then cut the individual fingers. If I went to .25" thick in solid carbon they would never flex or crack.


You are right, Smooth On has a variety of resigns that will help you make the proyect. FRP ( fiberglass reinforced plastic) is not new, there has been a lot of products done this way, but the problem is that manufacturing cycles are long and productions low.
Carbon fiber is the way to go but the price is a lot more and you have to use epoxy resin for that.

Polyesther resin is very rigid and cheap. There are a couple of process that can result in a very stiff part and that is vaccum casting and pressure casting. Both will ensure the full impregnation of the fiberglass with resin.
Just take a look at how the bodyshell for a Lotus Spirit was made. Fascinating stuff.


Anyway, returning to the proyect. I drilled the holes and just checked against the bow to see if everything looked ok and disaster!
The fingers are not tall enough to clear the cam!

Problem is that I got carried away and used the design posted in AT for dimensions and they are not long enough to be used with the Bear Method that is the main bow I intend to use the press with.
Anybody has found out t that the design of the fingers could be a little short for their bow? The bear Method uses de H13 cam that is enormous for this cam design.

So I am working on the part again, making it taller by 1 1/4 of an inch longer, then making another mould and some fingers again.
Actually I am cheating, a finger will be cut, some resin used to make it larger. The mould cut strategically and teh finger will be inserted so I only need to pour more silicone rubber in the void.
Picture will be posted later.

By the way, the fingers seem to be very light and tough. I am thinking on a way to test them with a lot of load, maybe install them on a car jack and lift a car by the fingers.


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## OhWell (Aug 21, 2013)

This is a great project. You can use polyester resin with carbon. I tend to react very poorly to may resins from the many years I have been using them. I may make a set using Uni-carbon and fiber glass. I can run the glass on the bias to keep them from twisting. I would of course use my vacuum system to press them onto a form to get the shape. This way I would only have to have a one sided form. 

I can make two templates and hot wire a form from high density foam.

I really like your mould building technique, it is very clean. Most of the moulds I have made needed to be capable of 100psi so they were big and ugly with bolts everywhere.


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## OhWell (Aug 21, 2013)

I just went through your pics again and now I have a couple of questions.

What model glue gun is that???? I love that fine tip. What is the yellow string for on the top of your mould?

Boy have you got my wheels turning.....


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## onyx48166 (Feb 9, 2011)

instead of building the mold it could be 3D printed


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## oldschoolcj5 (Jun 8, 2009)

very cool approach


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## OhWell (Aug 21, 2013)

I don't know much about 3-D printing but I do not know of a thermal material that can take the loads a press would apply.


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## slowen (Jun 27, 2006)

I just ont have the skills, patience or time to do what you did. Nice job.


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## BE2000 (Jul 13, 2011)

Kinkajou said:


> You are right, Smooth On has a variety of resigns that will help you make the proyect. FRP ( fiberglass reinforced plastic) is not new, there has been a lot of products done this way, but the problem is that manufacturing cycles are long and productions low.
> Carbon fiber is the way to go but the price is a lot more and you have to use epoxy resin for that.
> 
> Polyesther resin is very rigid and cheap. There are a couple of process that can result in a very stiff part and that is vaccum casting and pressure casting. Both will ensure the full impregnation of the fiberglass with resin.
> ...


Take a look at this picture from Archerytalk's 2014 ATA photo thread. I don't use a linear press so I am not that familiar with the latest on them, but it looks like maybe LCA has made adapters for this same reason? Not sure how closely sized the H13 cam is to the E3 cam that is pictured, but I remember seeing this picture and though it might be helpful.


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## Kinkajou (Mar 2, 2013)

OhWell said:


> I just went through your pics again and now I have a couple of questions.
> 
> What model glue gun is that???? I love that fine tip. What is the yellow string for on the top of your mould?
> 
> Boy have you got my wheels turning.....


When I started I cut a steel plaque that was used as a guide to produce the clay model and cut fiberglass. When Inwas making the mould I thought it would be usefull to have an impresion cast at the same time so I hung the metal part with the strings so it would be at the surface of the mould until it was hard.

The glue gun is very old, I do not remember well but maybe it is Black and Decker.

Great idea of hot wiring the foam to produce the model!


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## Kinkajou (Mar 2, 2013)

BE2000 said:


> Take a look at this picture from Archerytalk's 2014 ATA photo thread. I don't use a linear press so I am not that familiar with the latest on them, but it looks like maybe LCA has made adapters for this same reason? Not sure how closely sized the H13 cam is to the E3 cam that is pictured, but I remember seeing this picture and though it might be helpful.
> 
> View attachment 1852905


This picture is really usefull , I can now make some adjustments that will make the press work great, thanks


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## orarcher (Jun 3, 2006)

Dude !! You got some skills !!! ALL looks great :darkbeer:


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