Any Fabricators Out There_ Wanna Brainstorm

[DSRTEGL]

I have worked a little with high density polyurethane expanding foam and can't help but wonder how it would work as a medium for producing a good band speargun.

The stuff is rigid, resistant to rot, rust, and damage from just about anything it comes into contact with.

You would have to start with a master design and then create a mold from it but once that mold is created you could turn out just about as many gun bodies as you want. Unfortunately due to the price of the expanding foam, I think that only smaller guns would be reasonable. This works for me as I dive inshore shallows and in rocky/kelpy areas.

The master design could be fully fabricated with inlets for bands, spear channel, and trigger mechanism and with a careful mold design this could translate into a speargun body that you just add parts to and you are ready to go.

Does this make any sense? The foam floats, but can easily be made neutrally buoyant by adding weight in the right areas.

I just like the though of being able to produce a product that you can just drop a couple of parts into and you are ready to go with only minor fit/finish work necessary.

I have the IDEA for such a thing, I can come up with a rough sketch of what I have in mind. I know a skilled CAD drafter that might be able to produce a 3D template for a master that can be milled, but I need some more input.

Any Vaccu-Form Molders out there
Structural Engineers
Drafters/Designers

Losing Sleep over this concept.

:head

 

[bluewaterkiller]

do you mean : making a speargun/ barrel with integrated handle and muzzle out from an expendable foam?
???????????????????????
how rigid is this foam?
any pics?
rgds

 

[metelin]

ok i'll bite, give me a call 415 806 6285.

steve

 

[DSRTEGL]

just spent 45 minutes typing a detailed response to you guys only to have the system tell me I was not logged in?????

what the heck?

email me direct at dsrtegl2004atsbcglobaldotnet

 

[bluewaterkiller]

ha ha!!
click on remenber me next time..!!

 

[DSRTEGL]

you know what they say

HINDSIGHT is 20/20............................Sigh

 

[foxfish]

I have made many things using polyurethane foam including spearguns, I have also incorporated it into various designs, used it to fill ally barrels & for external shaping. However I don't want to give away all my secrets!
Here are a few guns that have had some form of polyurethane shaping -

 

[DSRTEGL]

Sweet.............I KNEW I WAS NOT CRAZY..........You should see some of the rifle stocks my bud turns out.

The properties of the poly foam just makes sense to me in the speargun arena. Still working on basic designs. Custom shaped handles with thumb grooves to fit the hand. A main shaft that is slotted both horizontally and vertically for easier target tracking. That sort of thing. If you want some a hook-up to some SWEET pigments I use for coloring the epoxy coatings........email me direct.

 

[foxfish]

There is a big difference between riffle stocks & speargun designs, a speargun needs to track in the water & the design is responsible for the integrity & strength of the weapon. Where as a riffle (excluding some more unconventional models) the strength comes from the barrel & action, the stock supports the gun.
So a one piece polyurethane speargun would need to have a substantial amount of lateral strength & yet be slim in profile.
I have got around this problem by using a structural core IE "T" section ally or carbon.
How do you propose to strengthen the poly, vacuum bag carbon?

 

[DSRTEGL]

I am looking at an aluminum "I" beam and maybe a carbon fiber tubing skeleton. Once the pour foam body and handle is final shaped it would be covered with a kevlar and epoxy laminate shell. Was thinking of a gun made out of recycled hardwood flooring as well but it would be tough with the tools I have on hand.

 

[foxfish]

This might inspire your project -

 

[DSRTEGL]

SWEET!...........Wow...a 10 character minimum on posts.....

Having a chemist and a structural engineer as friends is pretty interesting. The 2-part expanding foam I am looking at is not the usual stuff you see in the market.....The chemist made a handle for a 12# wood splitting maul out of it and that maul split a lot of firewood this weekend......It may not require ANY internal structure......JUst a fully inletted mold......inject the media.....allow to set and all you have to do is a little trim up, clean up, and drop in the trigger mechanism, add the bands, etc..............my thoughts were to make a mold at about 110-120% size and then put it into a pressure chamber at enough atmospheres of pressure to reduce the molded "blank" to the proper size, increasing density in the process.

But then I am a little less then normal according to some people

 

[DSRTEGL]

Putting the pour foam on hold for a while as it is Hellishly expensive and I have an insane amount of hardwood flooring, laminate flooring and plywood I can use. With the tools oI have on hand I plan to do a full size build out of plywood laminated together first as I can make that happen with what tools I have on hand now. I don't need a hand made Katana, a Toledo Steel Broadsword or a phase-plasma rifle in the 40 watt range. I need a STICK....A CLUB, a BASEBALL BAT WITH NAILS IN IT....MAYBE a BATTLEAXE. FOr now, just something I can throw together and beat to hell until I find out for sure if I have my bad ear taken care of. Plywood with verticle and horizontal laminates. Glued up with Titebond III and pinned with brass bolts for added structure. The whole thing sanded, primed, and painted. Still in the design stage but I plan to keep it simple for the first one. All I want to have to buy is a trigger mechanism and maybe a spear if I can't figure out my own design.

Will post pics one I get my basic drawing down and during the build if there is any interest. After the plywood one is built the next one will be out of laminate flooring.

DSRTEGL......That is short for Desert Eagle Folks

 

[foxfish]

Deeper Blue is a fantastic source of information, you need to use the search control but there is info about homemade spears & trigger units on the site.
Good luck & do keep us informed.

 

[blaiz]

Putting the pour foam on hold for a while as it is Hellishly expensive and I have an insane amount of hardwood flooring, laminate flooring and plywood I can use. With the tools oI have on hand I plan to do a full size build out of plywood laminated together first as I can make that happen with what tools I have on hand now. I don't need a hand made Katana, a Toledo Steel Broadsword or a phase-plasma rifle in the 40 watt range. I need a STICK....A CLUB, a BASEBALL BAT WITH NAILS IN IT....MAYBE a BATTLEAXE. FOr now, just something I can throw together and beat to hell until I find out for sure if I have my bad ear taken care of. Plywood with verticle and horizontal laminates. Glued up with Titebond III and pinned with brass bolts for added structure. The whole thing sanded, primed, and painted. Still in the design stage but I plan to keep it simple for the first one. All I want to have to buy is a trigger mechanism and maybe a spear if I can't figure out my own design.

Will post pics one I get my basic drawing down and during the build if there is any interest. After the plywood one is built the next one will be out of laminate flooring.

DSRTEGL......That is short for Desert Eagle Folks

You may want to look into a marine grade epoxy for gluing up your stock. I know titebond makes a great product and you plan on sealing it but during the slight chance that water is allowed in your stock I have a feeling the tightbond may fail. I used west systems epoxy for my build. easy to work with and very strong. Just my two cents. Good luck.

 

[DSRTEGL]

Unfortunately I am somewhat sensitive to many two-part epoxies....rashes....trouble breathing in a well ventilated room......That sort of thing. I may get into the water to spearfish 6-7 times a year if my ear is no longer a problem and since the water can be damn cold on this coast even with a 7mm wetsuit I tend not to stay in that long.....Just long enough to get a rockfish ot two for the table or maybe some perch or a lingcod. If I build it right it should last me a season or two and the experience gained.................. gonna try and get a few drawings together and maybe rip some plywood to length this weekend.....Will post pics if I don't get bogged down with other projects.

 

[foxfish]

dude i have been using polyurethane glue for the last few guns = Fast Grab Instant Polyurethane Glue : Buy Fast Grab Instant Polyurethane Glue at Axminster Power Tool Centre

 

[blaiz]

dude i have been using polyurethane glue for the last few guns = Fast Grab Instant Polyurethane Glue : Buy Fast Grab Instant Polyurethane Glue at Axminster Power Tool Centre

How much work time do you have with that stuff?

 

[DSRTEGL]

Blaiz.....I checked out the link and the glue has a 1 min "initial tack" time with a 5-24 hour cure if I remember right.......That tack time is a bit quick for me......I just HAVE to fiddle with things.....I just can't help myself. Will try Titebond III myself and a combination of clamps and bungie cord wraps to keep things together while it dries. Plan to do a quick and dirty laminate mockup with particle board and plywood tomorrow to get an initial feel for the process.......Now it is time for me to get ice on this knee.....It is the size of a rugby ball.......................Don't ask......I should've known better.

 

[foxfish]

Guys polyurethane glue in that 310ml cartridge form is really good, it is an expanding glue (like gorilla glue). Very economical, fast setting with no slipping like epoxy & 100% waterproof - give it a go!