Machining strategy for long, thin, plastic parts?

[Fierra]

I'm machining sheets of thin 1/16" ABS sheet to affix to later affix to wood parts. My experience today was in making some rectangular, long strips. As I machine the first three edges, vibration can start to become an issue, but as I machine the final edge, the part starts to lift, vibrate, and interfere with the cut.

Tabs seem to be a potential solution, but leave a bad edge, and are a lot more finicky with plastics. Are there any other machining strategies that can prevent these small parts vibrating, and coming loose?

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[louieatienza]

I'm machining sheets of thin 1/16" ABS sheet to affix to later affix to wood parts. My experience today was in making some rectangular, long strips. As I machine the first three edges, vibration can start to become an issue, but as I machine the final edge, the part starts to lift, vibrate, and interfere with the cut.

Tabs seem to be a potential solution, but leave a bad edge, and are a lot more finicky with plastics. Are there any other machining strategies that can prevent these small parts vibrating, and coming loose?

Double stick tape

[fretman_2]

Depending on how wide the stock is, you can buy some very wide painters tape and attach that to the back of the stock, attach the tape to the work surface, then glue the two together with super glue. As long as there's very little heat generated, the stock will likely not move. You won't need any tabs that way.

[Jim Dawson]

That sounds like a job for a small table saw, they do rectangular strips really well. Or maybe a even a 4 inch circular saw mounted to a bench or held in a vice. Sometimes a CNC machine is not the best tool for the job.

[fretman_2]

Agreed!

Sometimes a CNC machine is not the best tool for the job.

[louieatienza]

Cutting long, thin strips may NOT be the best job for the tablesaw. There is a tendency for the sheet to lift and ride over the blade, and a tendency for one to attempt to push said sheet down, sometimes unfortunately at the wrong spot because the blade is covered. There is also a tendency for the sheet to slide under the fence, also causing a potentially dangerous situation. You'd also need at least an 80-tooth carbide blade, triple chip (TCG), preferably with zero or negative rake. And you have to feed it relatively quick to prevent the plastic from overheating and binding the blade. Using a power-saw is even more dangerous; I know at least two guys that cut themselves pretty bad cutting plastic with a power saw, which usually has a framing blade (low tooth count) installed.

We didn't have a laminate slitter when I had my shop, so I would cut edgebanding on the tablesaw. This is a bit tricky at first if you don't know what you're doing, especially with a 4 x 10 sheet. But a piece of Masonite is placed on the saw after the fence is set, to prevent the sheet from sliding under the fence and creating a zero-clearance for the blade (preventing chipping the backer), then the sheet is uncoiled as it is pushed through. The curve on the laminate helped when pushing it against the fence.

I still say double stick tape is the way, but you could also use 3M 77 spray adhesive; and wipe it off with naptha afterwards.
For 1/16" plastic, you can potentially use a straightedge to score the cut line, place said line against the edge of a table, and snap it rather cleanly. I do it quite a bit with acrylic and Lexan.