m72 LAW Design questions

[jackssmirkingrevenge]

JSR, it's 550 paracord, it's practical and manly...

This is a manly use of paracord:

[Zorlord]

When you can't afford the best tools or materials, you need to be a little creative. Here's what I had done using a piston from a ordinary cheap-o footpump to make a toolies piston: http://www.spudfiles.com/forums/viewtop ... tml#304901

Also, that bracelet.

My younger brother made it for me. I would have it in a more tacticool color, but for whatever reason he only had yellow and orange lol.

And the rubber bits on the front are just rubber neoprene washers from home depot. i have 2 1" and one 1 1/2 inch ones on there, all sandwiched together.

EDIT:

JSR, would creating a hot glue piston with a rubber gasket sealing face be adequate for my piston? I just went out and purchased some marine epoxy, but id rather practice/use something cheaper first in case i screw up.

[Live1nce]

I wonder if picking up a sheet of plastic cutting board from wal-mart will work. It's about a half inch thick, very easy to cut, and is very strong. I'm sure you could make about 20-25 pistons from it.

I've used it before for my slide gloves for longboarding, and when i think about it, it should work perfect.

In that video it shows what the plastic cutting board looks like. It says he got it at lowes, but i've never checked there for it, I always got it at wal-mart.

[Zorlord]

I wonder if picking up a sheet of plastic cutting board from wal-mart will work. It's about a half inch thick, very easy to cut, and is very strong. I'm sure you could make about 20-25 pistons from it.

I've used it before for my slide gloves for longboarding, and when i think about it, it should work perfect.

In that video it shows what the plastic cutting board looks like. It says he got it at lowes, but i've never checked there for it, I always got it at wal-mart.

I'll go look after work.. I have a 24 hr wally world by me that would probably have it.. Now I just need a jigsaw.. Don't think my dremel or hand saw is gonna cut it

[Zeus]

HDPE is ideal for piston bodies, and sealing faces at very high pressures, but good luck getting it to seal at low pressure (<3-400psi).

Making the piston out of hot glue might cause problems, it can crack quite easily. Have a look at Tech's o ring piston tutorial in the How To section. Unlike JSR, I know epoxy is good, but it has some limitations.

Good to see some intelligent new members around, even if they're talking about pneubmatics.

[Live1nce]

For some of you more experienced members... I understand the importance of having a light weight piston especially with a design like this, But what is the likely hood of the cannon accidentally firing if it was ever to be dropped on its rear end on some solid surface, ie concrete.

Would the piston pop lose from the barrel seal and fire? You may want to take this into consideration zorlord. I know with airsoft, this thing will probably get banged around quite a bit.

[Zorlord]

HDPE is ideal for piston bodies, and sealing faces at very high pressures, but good luck getting it to seal at low pressure (<3-400psi).

Making the piston out of hot glue might cause problems, it can crack quite easily. Have a look at Tech's o ring piston tutorial in the How To section. Unlike JSR, I know epoxy is good, but it has some limitations.

Good to see some intelligent new members around, even if they're talking about pneubmatics.

I did see his tutorial.. Unfortunately i don't have access to a drill press.. Also, where does everyone find 2 inch orings? i cannot find them anywhere local.

EDIT:

For materials, could i use fiberglass resin to make my piston? I bought some for another project i have going on, and it's a lot cheaper than epoxy.. used the entire syringe of epoxy to make a small piston.. and the syringe was about 5 dollars... i guess i should be buying the stuff in the bottles instead of the small packs..

[jackssmirkingrevenge]

My younger brother made it for me. I would have it in a more tacticool color, but for whatever reason he only had yellow and orange lol.

Maybe it was a cunning trick and he was trying to provoke the "gaaaay!" reaction

I was of course joking, no offence intended

JSR, would creating a hot glue piston with a rubber gasket sealing face be adequate for my piston? I just went out and purchased some marine epoxy, but id rather practice/use something cheaper first in case i screw up.

I'm guessing you've seen the tutorial: http://www.spudfiles.com/forums/making- ... t8919.html

There's pretty much everything you need to know there, have a good look.

[c9d]

I went and bought a decent thickness HDPE smooth cutting board an cut out a few circles with differing diameter hole saws. I just had to use a center bit the same size as my rod. As long as you keep the cutting board very stable while cutting the pieces out of it, and round burrs from the edges with a very sharp knife... you should be good

[Zorlord]

update!

well, I decided to make a resin piston.. Cut a short piece of 2" pvc, coated the inside with a thin layer of petroleum jelly, then mixed up some resin and poured it in. here's the finished result:


And as you can see, it fits fairly well inside the chamber:


now i just need to drill a hole through it and attach it then HOPEFULLY this thing will work

[Live1nce]

That piston looks great! do you know around how much that piston cost you in resin material?

I just finished my solenoid canon, but i'm headed off to Lowe's today to pick up some more parts for a piston cannon.

[Zorlord]

That piston looks great! do you know around how much that piston cost you in resin material?

I just finished my solenoid canon, but i'm headed off to Lowe's today to pick up some more parts for a piston cannon.

Unfortunately no. I used the resin that's meant for fiberglass repairs and such. I bought the biggest container they had because i'm using it for other projects, and i think it was around 20 bucks? dont remember off the top of my head. But i used 4 oz of the resin and then 40 drops of hardener. Then i mixed it in a cup and poured it into a scrap piece of 2" pipe that had the inside coated with petroleum jelly. let it dry then i got that.

[jackssmirkingrevenge]

now i just need to drill a hole through it and attach it then HOPEFULLY this thing will work

Drill a hole why? For the bolt to attach the rubber I hope, you dont need an equalisation hole.

[Zorlord]

now i just need to drill a hole through it and attach it then HOPEFULLY this thing will work

Drill a hole why? For the bolt to attach the rubber I hope, you dont need an equalisation hole.

haha yes, to attach the bolt/rubber.

Also, has anyone thought of making these into projectiles? i feel like theyd do some damage..

[Mr.Tallahassee]

For some of you more experienced members... I understand the importance of having a light weight piston especially with a design like this, But what is the likely hood of the cannon accidentally firing if it was ever to be dropped on its rear end on some solid surface, ie concrete.

Would the piston pop lose from the barrel seal and fire? You may want to take this into consideration zorlord. I know with airsoft, this thing will probably get banged around quite a bit.

To answer this since I don't think it ever was, The pressure against the piston creates enough force that dropping the gun theoretically shouldn't cause it to pop loose and fire. I would be more worried about the body shattering if it's made of pvc, that could be worse than the piston actuating. Unless you make a valve with a seat diameter that's ridiculously close to the piston diameter, I wouldn't be too concerned.