SpudFiles

how long should this take to fully harden?

yea I'm curious as to how much it would shrink as it dries cause it might be a good candidate for a piston

think of styrofoam as having at least 50% of it being air. it would shrink up quite a bit if I recall.

But as someone pointed out to me via PM, that reduction in volume only happens as it dissolves. Still, after the acetone evaporates, it will shrink some as well.

I would suggest trying with different proportions of acetone to styrofoam, and cast a couple test pieces.

Personally, I make ammo using 3/4" Foam Backing Rod (also called caulk saver). This is for my 1/2" barrel, as it makes for a better seal. I'll do a write up in the near future, but if you know how to make stefan darts (for nerf guns) you probably know how to do most of it.

The best part is it's relatively cheap and can be bougt at almost any hardware store. I use lead sinkers, 3/8" steel shot, bolts... anything you can fit down the barrel, and I make a non-discarding sabot out of the FBR. it works great.

Big-E wrote:think of styrofoam as having at least 50% of it being air. it would shrink up quite a bit if I recall.

Styrofoam is mostly air. I just stumbled on this video of acetone and Styrofoam. Not my vid but I like the style.
[youtube][/youtube]

It takes a lot of foam to cast a slug.

Tech thats the video at the start of this thread, read before you post.