Foam tools


L

LoudMusic

Member
I asked in another thread and it seems the general tools for sculpting foam are saws and blades, with some people using hotwire tools occasionally.

It also looks like most guys are still using cork roadbed on top of the foam.

I was wondering if anyone is cutting roadbed out of the foam? If the roadbed was cut down into the foam the surrounding area would need less 'mounding up'. It could also be cut down and away as needed. A lot of roadbed does actually have a lower base layer than the surrounding earth anyway.

To that end, it seems like a little "car" or "cart" could be built to hold a hotwire shaped to cut roadbed out of the foam as it rolls over it. The wheels could be locked to any radius, or just straight. And if you wanted to get really fancy, gearing could be included so that as the cart rolled over the foam it would raise/lower the hotwire at a determined grade.

Anyway, seems an interesting idea.
 
And to really go crazy with it, a robotic "3D printer rover" could be constructed to cut down foam to create the whole base layer of the layout. But that's just a pipe dream ;)
 
I just use a 'sure form' tool and sand paper to create the correct grade on the foam.
Then Laun as sub-roadbed with Homabed glued to the laun.
See my build thread for details and pics.
 
LoudMusic said:
And to really go crazy with it, a robotic "3D printer rover" could be constructed to cut down foam to create the whole base layer of the layout. But that's just a pipe dream ;)
Click to expand...

Did you mean a CNC router? I always thought that would be an interesting way to do it. Most 3D apps like Blender can generate terrains using grayscale-to-height maps, or by using sculpting tools. The downside is that if you make a mistake in the placement of something, it might be a pain to relocate it once it's already been carved into the foam.

Steve S
 
I carve with a hot wire, a steak knife, one of those little micro-plane things for shredding cheese, really whatever's at hand. In fact I've made small depressions in terrain by heating the foam with a cigarette lighter. The nice thing about the lighter/hot wire/hot knife stuff is that it doesn't make hordes of little blue Klingons. The nice thing about the hand tools is that it doesn't make the basement smell like cancer.
 
I got a hot knife foam cutter from MicroMark. The picture on the magazine shows this chick nicely shaping a mountain with ease out of pink foam insulation using the foam cutter.

Reality is that even in my garage with the ceiling fan going and big door open. It still creates fumes so bad you want to evacuate. Then the foam melts on the blade and creates more smoke as it burns. Your constantly scraping the knife to get melted foam off. It worked good for rough cutting but it also leaves a hard melted shell everywhere you go with it.

They should call it the "hot foam melter that fumigates your garage at the same time."
 
I have to admit to a brief wondering why roadbed is not formed directly in the foam base 'cause it would deaden noise just as effectively without cork. It wasn't till the OP mentioned the use of a guide car as a way of guiding a hot wire cutter that the impracticalities became obvious.

What would you use to guide the car itself so that it followed radius's evenly and accurately? Unless you could develop some very high tech mini GPS sensor that would keep it on the straight and narrow (or curved, dipped etc, etc.) and didn't cost an arm and leg.

Something for the Geeks to come upwith, maybe.
 
No it's much easier than all that. For straights the wheels are all in alignment. For curves the wheels are set to a fixed turn radius. Apply pressure so it doesn't slip and roll it along the chosen route.

I don't see what's so obvious about impracticalities - seems more obvious in ease of use. It would be like those picture matte cutters, but instead of holding a mounted razor blade it would be a loop of hot wire.

17102-0000-3ww-l.jpg


But for that matter it could just be a wicked sharp blade and have the same effect?
 
Blades, even sharp ones, tend to make the foam bunch up and tear rather than cutting. The challenge would be making a wire thin enough to heat up (without becoming a space heater) but big enough to hold its shape.
 
RW&C said:
Blades, even sharp ones, tend to make the foam bunch up and tear rather than cutting. The challenge would be making a wire thin enough to heat up (without becoming a space heater) but big enough to hold its shape.
Click to expand...

I agree the blade would probably be a bad idea.

Would it be any benefit to have the wire be more like flat ribbon? It would have a thin leading edge, potentially less total mass, and still be broad enough to provide support against the pressure of pushing through the material. Cutting curves would be only slightly more difficult than with a round tool.

How well do rotary tools such as a Dremel work in foam? Seems like a thin cylindrical bit used as a plunge router might really make quick work of foam - but it also might make a quick mess :D
 
On my last layout i had a lot of foam around my trestle bridge, it was all cut with a electric carving knife. The foam was the regular blue foam, the knife cut it any way or angle. I even cut it into slices as shims under some sections of track.
There is also very little mess.

cheers ironman
 
LoudMusic said:
How well do rotary tools such as a Dremel work in foam? Seems like a thin cylindrical bit used as a plunge router might really make quick work of foam - but it also might make a quick mess :D
Click to expand...

Yes, it would make quick work of foam. And yes, it will make a mess. Here's a video of a CNC machine carving blue foam (Not my video.) He must have vacuumed up most of the dust prior to filming because in most vids there's dust over everything.

[YOUTUBE]6n5Rlp57Fzg[/YOUTUBE]

Steve S
 
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