Photos Thinning blade on belt sander, not pretty

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May 20, 2015
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https://photos.app.goo.gl/oMaZzBePAG3gEumEA
I needed to cut very thick (0.10-0.13 inch) cardboard for a model I am making. The cardboard from concrete cardboard forms was resistant to knives which were too thick behind the edge. I bought a $21 sacrificial knife with D2 blade and thinned it on a belt sander with a 60 grit zirconia alumina belt. My fingers pressed it against the platen so I could feel the heat and remove it as needed. It's ugly but it works for its purpose.
 
Should cut at least a good bit better now. I think if I were presented with that situation I'd start with something that had a very thin spine. How thick is that one?
 
What does any of that have to do with thinning the thickness of blade stock?
I think he was referring to using the jig saw and coping saw to cut the cardboard rather than the knife. But he is often all over the place, so I’m really not sure.

You might find that a regular utility knife/blade will cut the cardboard better than just about any knife out there. Razor sharp and super thin.

1/8” thick blades need good edge geometry to cut cardboard well. A thinned out convex edge will cut quite decently.
 
I think I would saw it on a table jig saw or use a coping saw over a jeweler's sawing fork .
Link to photo>>>>
Link to photo>>>>
Link to photo>>>>
Use a "zero clearance" throat plate for best edge finish.
I am cutting 7-inch rounds from the actual cardboard tube. The tubes are as large as 16" diameter from the store; after splicing, one is 26" diameter. Each is capped top and bottom with 30 ply chipboard, also 0.10" thick. The glue is hot-melt. The geometry almost requires a hand-held non-power tool for initial cutting (except the flat chipboard for which I used a portable jigsaw) and final trimming. A knife is safe and allows me to position the workpiece with my free hand. For the curious, the model is the Tower of Babel (reference Peter Bruegel). Yes, I'm nuts.
 
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