The Right Tool
The first thing we did before starting this project was to do plenty of research online and by asking those who have done a job like this before. We heard plenty of suggestions on which tools to use to cut hard case foam inserts. We decided that we’d try the top four suggestions for ourselves and the following is what we observed.
1. Chicago Pneumatic Heavy Duty Hot Knife
We initially thought the hot knife was a great idea—that is, until we used it. The knife has a temperature control knob that allows you to adjust it from a heat setting of 1 to 5. We initially switched it on 1 and gradually went up in temperature until the knife began to cut the foam. We switched it up to 3.5 but it still wasn’t cutting. When we went to setting number 4, it went through like butter, but it also left burn marks, as you can see. With the blade being as wide as it is, it also created a ton of smoke that made it hard to see and breathe.
Generated too many fumes. If you do opt to use this tool, we suggest using it outdoors with a fan positioned so that it blows the undoubtedly toxic smoke away from you.
2. GOCHANGE Foam Cutter Electric Cutting Machine Pen
We were excited about this electric pen option. It is lightweight and very easy to control. However, an unfortunate detail is that its temperature output cannot be controlled: It’s either on or it’s off. Also, according to its instructions, it is not meant to be active for more than 30 minutes at a time. Like the hot knife we used before it, it uses heat to essentially melt the foam to cut it. Melting foam means toxic fumes. We thought that compared to the hot knife, the pen’s small surface area should create a lot less smoke. Wrong. This puppy began to smoke the instant it touched foam, almost as much smoke as the hot knife. We also noticed as we pushed through the foam its cutting power lessened and we were forced to let the pen rest before pushing into the foam further. You’ll notice that this left us with some burn marks as well.
We like this tool’s controllability, but its lack of heat adjustment took it out of contention for our project.
3. Black & Decker 9-inch Electric Carving Knife
This is one of the most commonly used types of tools to cut hard case foam, and after trying it out, we can see why. It does an effective job and creates no toxic fumes when you use it. The blade is wide however, making detailed or curving cuts difficult. It is also a challenge to hold the foam and knife in a manner that gives you perfectly 90-degree cuts.
The carving knife was our choice to use for this project due to its ease of use, quickness of use, and the fact that it didn’t produce any toxic smoke.
4. Woodland Scenics Hot Wire Foam Cutter with Foam Cutter Bow & Guide
A time-honored method of cutting any kind of foam is by using a table-mounted hot wire. Using one effectively does take time and patience, but it can probably yield the most professional results of all the methods we tried. That said, our handheld hot wire was a no-go from the get-go. The wire was hard to make taught on the tool, so that the cuts it made became wavy. Also, being hand held, it was near impossible to make clean 90-degree cuts, even with the optional bow and guide that we installed on the tool.
We like the hot wire concept and can see why many people use it to cut foam. It generated very little smoke, which can’t be said of the other two foam melting tools we tried, and the thin wire offered ultra controllability for precision cuts. The handheld version was unwieldy to use, but we imagine a tabletop hot wire would lead to fantastic results.
From left to right, these are the tools that we tested: Chicago Pneumatic Heavy Duty Hot Knife; GOCHANGE Foam Cutter Electric Cutting Machine Pen; Black & Decker 9-inch Electric Carving Knife; and Woodland Scenics Hot Wire Foam Cutter with Foam Cutter...
We cut wedges into a piece of foam to see what kind of cuts each tool made. From left to right, these are our results.