Is there any kind of tool that is a "block" (imagine a sanding block) that accepts utility-knife blades?

Imagine cutting a piece of rigid foam. And instead of using a straight pencil mark or (blue) snap line, and trying to follow the line with a utility knife.....

You could secure a straight edge (or a level with a bigger edge) 2" from the line, and the "block" would "ride" against the level/straight edge...and the blade being in the center of the block (but 2 inches from the edge) would cut a perfectly straight line.

Whenever I use a utility knife and the straight-edge/level, I still get a little wobbling.

  • Hello, and welcome to Stack Exchange. Unfortunately, "shopping" questions are off-topic here. That said, why don't you just run the knife against the straightedge? – Daniel Griscom Nov 13 '18 at 21:48
  • As stated. I get "wobble". When I break the rigid foam, that little wobbles throw off the clean break. I have 3.5 inch thick rigid foam. I need to cut both sides of the foam and need the (not all the way through) cuts to be perfectly in line with each other. Also, the cut pieces are going in between rafters, so to prevent any air passage, I need a really clean cut. Using table saw causes too much nasty dust. Thanks. – granadaCoder Nov 13 '18 at 21:51
  • Try a jig saw with a long blade or google hot wire foam cutting – Kris Nov 13 '18 at 22:18
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    You'll never get an air-tight joint between the rafters and the pieces of rigid foam. How about leaving a deliberate 1/4" gap, and filling with spray foam? – Daniel Griscom Nov 13 '18 at 22:31
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    You could run your utility knife against a straight edge. You can also cut it with a circular Saw and a straight edge. – Alaska Man Nov 14 '18 at 4:31

They make a handy sliding block with a blade that protrudes from the bottom, just like you describe. They are great for scoring and cutting thin sheet material like laminate:

enter image description here

| improve this answer | |
  • YES! I knew I'd seen it at some point. – granadaCoder Nov 14 '18 at 13:22

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