How thick will the drag knife from the shop cut?

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I’ve made a promise to my wife that I’m hoping my Burly and the drag knife from the shop will help me keep. I need to cut a bunch of holes in transparency film that’s 5 mils thick to make some patterns that run on old tractor-feed style pin rollers. I’ve laid out the job in Inskape, exported a DXF, generated gcode for it, and ran a test, but hit some snags. I’m wondering if I’m pushing the knife too hard, or if there’s some other issue.

I’ve got the drag knife zip-tied to the knife mount that @vicious1 has published on Thingiverse and Printables and it seems to be working as expected. I tested the blade extension outside of the printer and have it set so it cuts fully through the transparency film but not a piece of printer paper under it.

When I ran the job in the Burly, the holes did not cut all the way through, and were much smaller than designed. I’m thinking this is due to flex in the mount and that the transparency film is harder to cut than the vinyl this cutter was originally planned for. I’m wondering if I should remix the knife holder to be more rigid, or if folks with more experience cutting tough stuff have any other suggestions.

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I should have two listed, each with different sized arms for a variable stiffness. From there you can check your print settings to make the arms thicker or thinner sometimes.

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I ended up combining the drag knife holder and the pen holder with the built-in probe and shortening the arms to improve stiffness. Got all the way through the mylar in my final test cut last night.

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Picture please, that is a lot of combining!

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I know LR family can do Mylar, but I don’t use that drag knife.

I have a highly oversized machine that does aluminized Mylar and rayon “wedding veil” cutting .

That machine uses a specialized drag knife blade a supplier of mine uses on smaller machines.

For very large format we had to tension the work to the sides with full span clamp blocks to try and avoid lifting.

I can’t share pictures or other details beyond that though.

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I haven’t added the foil tape to activate the probe, doing so may require another little clearance tweak. I may try and get that done later today. If I do, I’ll post a comparison picture when it is all done.

For work holding, I’ve got one of those sticky mats taped down to my spoil board, and the printed transparency gets set down on that.

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Pictures as promised, if a little late.

IMG_0124
IMG_01241920×2560 708 KB

Black is the pen holder with integrated probe. Blue is the original drag knife holder. This was not cutting through and was twisting a bit due to cutting force. White is the remixed as described above.

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