Home Tournaments Calendar Weather Merchandise Sponsors

Go Back   Spearboard.com - The World's Largest Spearfishing Diving Boating Social Media Forum > Spearfishing Gear > All About Guns

All About Guns What's your weapon of choice, and why? Discuss the beloved speargun here!

Reply
 
Thread Tools Rate Thread Display Modes
Old 10-17-2019, 05:05 AM   #1
Mikel_24
Registered User
 
Join Date: Nov 2016
Location: Bilbao (Spain)
Posts: 365
DIY: How to cast PU handles for guns

Hello all,

About time to contribute with something (hopefuly) useful for the community. Not rocket science AT ALL and it is just my way of doing it.

I made my first gun slaping plywood slabs (epoxy) over a stainless rib welded to a plate that integrated the trigger guard and loading pad (ala Abellan guns but with fixed handle). Boatload of work and very heavy.

For my second gun I used a cast PU handle that a friend of mine (who makes guns for sale) gave me. He makes them in batches using molds and gave me a few hints.

I thought I could illustrate the process for anyone who wants to do the same. The biggest benefit is that you will get the exact same handle everytime.

First I put together a clay model

Kids are always willing to help (allow me to introduce my now 5yo daugther)

Starts to look like something


And after some tweaking, allowing to dry, shrinking, wetting, drying again, sanding, etc... I came up with this.


As per clay manufacturer instructions, for my purpose, I didn't need to cook it, just let it dry enough.

I gave it a couple coats of clear coat to get a smooth finish


After drying and taking it home, I used some epoxy putty to fix a few dents so they didn't print on the final cast and rigged a few wires (TIG wire, mind you) to separate it from the bottom of the container. Yes, that's my kitchen countertop.



Two things are going on in this picture. I am mixing the silicone for molds up front and in the back you can see a small bottle with industrial vaseline and a brush. the vaseline is used as a release agent for the silicone not to adhere to the model.


Before mixing the silicone I took some measurements to know the volume of my model and find a suitable container to make the mold. I got lucky and realised that I could very well mix all the silicone I had bought and just place the model inside. The silicone container would make the perfect mold.


Actually the propper procedure to mix anything that needs to chemically react is to pour the two products into one container, mix, mix some more, then pour into another clean container, mix some more and then use. This prevents some material (usually at the bottom edge or walls of the container) from not getting properly mixed.

I didnt do it and this is exactly what happened to me in a couple spots (does not affect the mold) that didn't cure properly.

Now, a few things happened before taking this picture. First I cut in half the plastic container to the best of my ability with a utility knife. Then I cut through the silicone all the way to the model as little as possible to reduce future misalignment of the two parts when casting final parts. Then mocked it up for the picture


A few pictures of the mold




As you can see, I got a few bubbles in the mold. Anyone arround here owns a vacum chamber I could borrow??

Measuring the volume of the handle to see how much PU resin it required



200ml aprox.



And now the fun part. In my second gun I used a Meandros LS mech wich is somewhat heavy and it is one of my favourite mechs (screw on installation from the top) so chances are it is the one I will be using in the future). To compensate somehow this heavy mech, I decided to use a PU resin that floats. It is called Smoth On Featherlite. Usually sold for those who craft their own fishing lures. I hope it is strong enough (will be reinforced with some CF cloth wrap.

CocaCola can used for mixing the two components (volume marked on the inside).


Mixed, poured and waiting for it to cure. Silicone mold is kept in the container it was created to help with the alingment (even though is very hard and does not deform easily)


And... TADA!!!


Now it is just a matter of sanding the top off (accoding to how high you want the handle), glueing and screwing from the top, through the wood and into the PU itself (predrilling recommended to avoid splitting it)

I have one attached to a WIP gun, I can also show how I attach it if someone is interested.

Mikel
Mikel_24 is online now   Reply With Quote
Old 10-17-2019, 08:29 AM   #2
popgun pete
Registered User
 
popgun pete's Avatar
 
Join Date: Mar 2006
Posts: 3,716
Re: DIY: How to cast PU handles for guns

Very good, plus no problems about it fitting your hand. As you split the mold to get the item out you could cross hatch the mold surface to produce ribs or a checker pattern on the grip.
popgun pete is offline   Reply With Quote
Old 10-17-2019, 09:08 AM   #3
Mikel_24
Registered User
 
Join Date: Nov 2016
Location: Bilbao (Spain)
Posts: 365
Re: DIY: How to cast PU handles for guns

Quote:
Originally Posted by popgun pete View Post
Very good, plus no problems about it fitting your hand. As you split the mold to get the item out you could cross hatch the mold surface to produce ribs or a checker pattern on the grip.
I thought about that. Easiest way would have been to give the model itself some texture before making the silicone mold.

However the way I attach, color and coat the handle it really wouldn't have helped much.

After shaping and attaching it to the wood (epoxy + screws) I usually reinforce the joing with some strips of CF so the texture would have been buried under the cloth and the resin.

I try to make my handles stand out so I color them in yellow or orange. I coat them with top coat epoxy resin with some tint. Two coats. And when the second coat has already cured to a gel consistency, I sprinkle salt on it. Once cured, I rinse it under the tap and all the salt disolves, leaving a bunch of tiny craters in the epoxy. Very veeeeeeeeeeeeeery grippy!

Mikel
Mikel_24 is online now   Reply With Quote
Old 10-17-2019, 10:40 AM   #4
deanmc
FII Professional
 
deanmc's Avatar
 
Join Date: Sep 2012
Location: Rocky Point, NY
Posts: 331
Re: DIY: How to cast PU handles for guns

This is great. Thanks Mikel. I will be trying this at some point!
deanmc is offline   Reply With Quote
Old 10-17-2019, 12:07 PM   #5
SEATUX
Registered User
 
SEATUX's Avatar
 
Join Date: Apr 2005
Location: Port Charlotte Fl
Age: 73
Posts: 2,336
Re: DIY: How to cast PU handles for guns

All that's missing is a picture of the finished product(s).
Sounds like you have done several.
SEATUX is offline   Reply With Quote
Old 10-18-2019, 02:25 AM   #6
Mikel_24
Registered User
 
Join Date: Nov 2016
Location: Bilbao (Spain)
Posts: 365
Re: DIY: How to cast PU handles for guns

Quote:
Originally Posted by SEATUX View Post
All that's missing is a picture of the finished product(s).
Sounds like you have done several.
I must confess that one of my (many) problems is that even if I am only going to make a one off (or two) of something... I like to do it the "right" way... Which means going full blown on tools, materials, etc.

So far I have put together two full guns and another two are WIP. Yesterday I posted a monster thread (arround 150 pics) of the build of my second one and this incorporates a glued/screwed PU handle.

Let me extract a few pictures here:

Adjusting handle to stock



Gluing with epoxy


Screws (predrilled and smeared with epoxy)


Reinforcing with CF Cloth (the divots you see are meant to insert the rearmost end of the trigger guard)
https://i.ibb.co/kM9fFps/107-Handle-Area01.jpg

Coloring and coating the handle with epoxy top coat. Last coat gets sprinkled with salt to provide texture once rinsed under the tap (once fully cured)




And the final product


In hand


I guess now DEANMC understands what I asked him in his last roller build about the reinforcement of the handle/stock joint with CF (even though his is integral in wood)

Mikel
Mikel_24 is online now   Reply With Quote
Old 10-18-2019, 02:45 AM   #7
doyenofcastle
Registered User
 
Join Date: Mar 2015
Posts: 428
Re: DIY: How to cast PU handles for guns

great lesson ,reliability of PU vs wood is their any big difference ?
doyenofcastle is offline   Reply With Quote
Old 10-18-2019, 03:09 AM   #8
Mikel_24
Registered User
 
Join Date: Nov 2016
Location: Bilbao (Spain)
Posts: 365
Re: DIY: How to cast PU handles for guns

Quote:
Originally Posted by doyenofcastle View Post
great lesson ,reliability of PU vs wood is their any big difference ?
If we are talking about toughness.... I really have no idea. Abellan guns have PU handles and I haven't heard of any braking... if that means somehting.

I have also seen (at least in Spain) several brands selling PU handles just like this for those who want to make their own gun. They are sold anywhere between 20-30€.

The great benefit for people who are pumping guns (for profit) is that you forget about the shaping part, which is time consuming. If you buy the PU resin in bulk, it is also cheap. A maker who does custom jobs could even have several molds (sizes) and ask the customer for glove size to fin the one that suits him better. Or if the customer comes to the shop, let him grab all the models and choose the one that suits better.

Also, not having grain, it doesn't want to split. Being synthetic does not absorb water, etc. I am pretty sure there are many different PU resins out there and some will certainly be perfect for this purpose.

If you are worried about it breaking, you could always cast them arround an inner metal rib. I though about it but it goes against my current light-is-right moto. We don't need huge cannons here in the north of Spain for our type of fishing so we don't have much wood to compensate heavy items.

Mikel
Mikel_24 is online now   Reply With Quote
Old 10-14-2020, 09:40 PM   #9
doyenofcastle
Registered User
 
Join Date: Mar 2015
Posts: 428
Re: DIY: How to cast PU handles for guns

Did u try the handle ?3 rubbers heavy gun recoil could break it or not?idea is great but the cross section should be accurate to distribute force equally and prevent gun from shifting as a reaction to recoil ,I checked the mechanical properties it is near to epoxy resin only difference in buoyancy so for big gun may be u can use epoxy to add ballast to ur gun .

Last edited by doyenofcastle; 10-15-2020 at 01:20 AM.
doyenofcastle is offline   Reply With Quote
Old 10-15-2020, 04:19 AM   #10
doyenofcastle
Registered User
 
Join Date: Mar 2015
Posts: 428
Re: DIY: How to cast PU handles for guns

Quote:
Originally Posted by Mikel_24 View Post
If we are talking about toughness.... I really have no idea. Abellan guns have PU handles and I haven't heard of any braking... if that means somehting.

I have also seen (at least in Spain) several brands selling PU handles just like this for those who want to make their own gun. They are sold anywhere between 20-30€.

The great benefit for people who are pumping guns (for profit) is that you forget about the shaping part, which is time consuming. If you buy the PU resin in bulk, it is also cheap. A maker who does custom jobs could even have several molds (sizes) and ask the customer for glove size to fin the one that suits him better. Or if the customer comes to the shop, let him grab all the models and choose the one that suits better.

Also, not having grain, it doesn't want to split. Being synthetic does not absorb water, etc. I am pretty sure there are many different PU resins out there and some will certainly be perfect for this purpose.

If you are worried about it breaking, you could always cast them arround an inner metal rib. I though about it but it goes against my current light-is-right moto. We don't need huge cannons here in the north of Spain for our type of fishing so we don't have much wood to compensate heavy items.

Mikel
Just try Smooth-Cast™ 385
doyenofcastle is offline   Reply With Quote
Old 10-15-2020, 04:38 AM   #11
Mikel_24
Registered User
 
Join Date: Nov 2016
Location: Bilbao (Spain)
Posts: 365
Re: DIY: How to cast PU handles for guns

Quote:
Originally Posted by doyenofcastle View Post
Did u try the handle ?3 rubbers heavy gun recoil could break it or not?idea is great but the cross section should be accurate to distribute force equally and prevent gun from shifting as a reaction to recoil ,I checked the mechanical properties it is near to epoxy resin only difference in buoyancy so for big gun may be u can use epoxy to add ballast to ur gun .
Currently my most powerful homemade gun with this handles is a 2x16mm 105mm stretch gun. It stays put, no sign of fatigue, cracks or anything. Handle is glued on with epoxy glue (Araldite Standar from CEYS), handle area is also carbon fiber wrapped and the screw that attaches the back of the Ermes mechanism to the stock goes all the way through and into the handle material.

I am not pumping out guns as fast as I would like but so far my main problems are related with lack of buoyancy... So I haven't added any lead or weights of any kind to my guns.


Quote:
Originally Posted by doyenofcastle View Post
Just try Smooth-Cast™ 385
Will have a look at it but I am currently using this product:
Feropur-pr55-e55-resina-poliuretano-rigida.

Once cured is a tad negative buoyant but just to make sure I add a couple spoons of glass microspheres... which helps with the sanding and insures it is neutral or buoyant.

And it is cheeeeeeeeeeeeeeeeeeeeeeap The one you just mentioned is more than double the price (I don't doubt it is a great product, but anything that comes from Smooth On is going to be pricy).

Mikel
Mikel_24 is online now   Reply With Quote
Old 10-17-2020, 09:01 AM   #12
doyenofcastle
Registered User
 
Join Date: Mar 2015
Posts: 428
Re: DIY: How to cast PU handles for guns

Quote:
Originally Posted by Mikel_24 View Post
Currently my most powerful homemade gun with this handles is a 2x16mm 105mm stretch gun. It stays put, no sign of fatigue, cracks or anything. Handle is glued on with epoxy glue (Araldite Standar from CEYS), handle area is also carbon fiber wrapped and the screw that attaches the back of the Ermes mechanism to the stock goes all the way through and into the handle material.

I am not pumping out guns as fast as I would like but so far my main problems are related with lack of buoyancy... So I haven't added any lead or weights of any kind to my guns.



Will have a look at it but I am currently using this product:
Feropur-pr55-e55-resina-poliuretano-rigida.

Once cured is a tad negative buoyant but just to make sure I add a couple spoons of glass microspheres... which helps with the sanding and insures it is neutral or buoyant.

And it is cheeeeeeeeeeeeeeeeeeeeeeap The one you just mentioned is more than double the price (I don't doubt it is a great product, but anything that comes from Smooth On is going to be pricy).

Mikel
Unfortunately that product is not sold outside spain only smooth is available ,I am thinking to try epoxy with microbaloon and carbon fiber .
doyenofcastle is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 08:10 AM.


The World's Largest Spearfishing Diving Social Media Forum Powered by vBulletin® Version 3.8.1
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Copyright ©2002 - 2014 Spearboard.com