I recently bought a hot wire cutter that is very similar to the hot wire knife found on Hot Wire Foam Factory's website.

I am finding it difficult to cut without having wavy edges. I would prefer smooth edges so that my hills will have nicer slopes.

Do I simply need to learn to use it better or am I doing something wrong? I am cutting fairly quickly as the hot wire tool melts the styrofoam around it if you simply leave it one spot (which results in strange holes).

(This is before I am painting the terrain)

You did not say if you can adjust the temperature?
If no, cut more slowly. If you have a wire add a larger spring.A bondo grader will smooth things out.


If you have pen gun type cut with the wire that is closer to the handle. You will have to practice with even the very expensive tools to get the best result.I have trouble cutting foam square. It is difficult even with contractor grade tools. The long wire wands are the simplest to use. You can see I have made several.

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But none were more dangerous than the Great Willow: his heart was rotten, but his strength was green; and he was cunning,

old chestnut gave some really good advice.
but there's also something else that really helps me get a clean cut.
A hot wire can cut through plastic but not through paper (or wood, etc) so if you use masking tape or cut the shape out of a piece of paper and pin it on the foam you'll get a very clean cut.
this will only help with simple things though, as you can't really use it for a slope or a hill.

if you work with a small hot wire cutter and not a hot wire table, put the paper on both sides as you'll otherwise still get uneven edges.

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“People often claim to hunger for truth, but seldom like the taste when it's served up.”
My wip

Thank you for the help. Would you recommend sandpaper at all for additional smoothing?

I have even used power sanders to good effect.

http://warplay.com/Warplay06%20FOW%20D-Day%20Game.htm

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But none were more dangerous than the Great Willow: his heart was rotten, but his strength was green; and he was cunning,

That's what I was going to say. Try going a bit slower and steadier, then do finish with sandpaper.