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/diy/ - Do It Yourself

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1184818 No.1184818 [Reply] [Original]

I've got a project that involves cutting lots of 1" dia holes in 1.5" thick sheets of Styrofoam. The little particles get everywhere. Here are the things I've tried:

Making a punchout tool out of some copper pipe I had laying around. Works OK but the holes are ragged and foam crumbs get everywhere. Making a hot knife out of a wood burning tool I got at goodwill and some stripped solid core electrical wire. Works OK but it's slow as hell. Making a melting tool using a small section of the pipe heated with a torch. Works great but the heat is hard to control and leads to overheating which makes the holes too big. Hot knife v2 using a circular bit I made out of the pipe (pic related) and attached to the wood burner. Slow even when I drive the wood burner with a Variac at 140V but works best out of everything. I tinned the connection with solder to help heat transfer.

Any other ideas? Wood burner is 23W, I know a bigger heater would help. Would it help or hurt to cut more material off the tool I have now?

>> No.1184828

A wood burning iron is essentially a crippled soldering iron. Try the same thing but with the cheapest soldering iron you can find ~~at your local Radioshack~~ on Amazon

>> No.1184829

>>1184818
I'd use a hand drill. Take your existing cutter or make a new one, sharpen the cutting end, and run a bolt and nut through the mount to give the drill a shank to grab on.
Giving it a knife edge should cut the foam like butter.

>> No.1185032

>>1184818
hmm. Well the obvious thing to try next would be to use a file and sharpen the cutting edge of your v2 hot knife.
It's slow because you are trying to melt through the styrofoam, but you really want to CUT through and heat seal the edges of the cut.

>> No.1185045

>>1184818
Use a 1" hole saw, but run it backwards...I do this when drilling out the back of cabinets for plumbing, and I want it chip free...

>> No.1185098

>>1185032
Yeah that makes sense. Thanks anon!

>> No.1185172

Switch to a denser and less crumbly type of foam. Blue or pink foam.

>> No.1185178

Make a makeshift die and press, isn't that hard.

>> No.1185214

You made this exact same thread like 4 months ago. wtf

>> No.1185236

>>1184818
Cut a hole the size you want in metal plate, put that hole over the place in the styrofoam where you want the hole to be, melt styrofoam with heat gun.

Do not stick dick in heat gun.

>> No.1185240
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1185240

steel and battery, pivoted like a compass

Model plane folks use guitar strings for their foam cutters.

>> No.1185984

>>1184828
A 40w iron should be pretty cheap

>> No.1187633

>>1185236
* Do stick dick in heat gun

>> No.1188734
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1188734

I have had good sucess with a hollow-core drill. I used some aluminium pipe, but any harder material will still work even better. Chamfer the outer edge at a low angle, maybe 20-30°. I did this by holding the pipe against a grinder at that angle and turned it. A bit of burr will be visible on the inside, remove that with a round file moved parallel to the inside surface. Now if this tool is rotated when pressed in the styrofoam, this should give you reasonably nice holes. You have to push the styrofoam out of the pipe after every go though.

>> No.1189408

the less material you have to heat, the more hot it can get i guess. get some 26AWG solid core copper wire, and use that instead of your little pipe thing.

>> No.1189428

>>1184818
>I've got a project that involves cutting lots of 1" dia holes in 1.5" thick sheets of Styrofoam.
Are you trying to keep the inside or the outside?

Either way, you should make a hot wire cutter and a jig. In your case, you'll want to boards with a hole circle you want or 2 circle2 the size you want. Afix the jigs to either side of the styrofoam and run your hot wire around the jig, keeping it taught between the 2 jigs.

If you are cutting holes (aka you want to keep the outside), you'll have to do like you'd do with a jigsaw - drill a smaller hole and run your wire through that, then cut to towards the jig.