I want to machine some thin material (a plexiglass/wood composite). The plastic is a backer, and the wood is the target for machining. The sandwich inevitably bows, in predictable ways, making precise machining impossible with edge clamps.
I’ve tried double sided tape in the past, but if you cut through the main material, the adhesive in the tape gums up the cutters. Super glue might be better, but most people use layers of tape on each side of the super glue, so that creates the same issue. And, since the end result needs to be visually pleasing from both sides, glue residue on the bottom (plastic) would be an issue.
I wonder if it would b possible to attach a spring-loaded pressure plate under the cutter, with a window for the cutter, that ensured that the material was pressed down when it was machined. Has anyone tried this before?
That interesting, like a foot on a sewing machine holding down the fabric while the needle and thread do their thing? Chips getting under that foot may be an issue.
Yes, something like that. Perhaps a series of roller bearings, so that if one of the bearings rides up on a chip, the pressure on the underlying sandwich is maintained. Just brainstorming here.
I was just thinking about the same thing when cutting large thinner pieces where you can clamp the edge but not the center. Even if it sits pretty flat, the cutter tend to pull up on the material.
I too have been thinking about a vacuum table. I have a few smaller supplemental spoilboards , one with cutouts for a few project that I do all the time, another with the C3D vice. A small vacuum table clamped to the regular spoilboard would come in handy.
@Tod1d Interesting product. Too bad Ali Express does not allow one to ask questions of the seller, like how much pressure is applied, and what the range of travel is.
@Ed.E The plastic has a pretty strong mind of its own: I doubt that either a pressure plate or a vacuum table would overcome the warping, but a vacuum table would certainly come in handy for other projects. I tried to design one that I could cut out using the Shapeoko itself but it never had much suction. I imagine that the total cross-section of the holes has to match the vacuum source pretty carefully, and that any uncovered holes would reduce suction significantly. This is not rocket science. I imagine that this has been done many times already. Someone will pop in with some links.
My wife is a long arm quilter and she had various foots. They work well unless the material folds back onto it’s self due to uneven stretching between layers. She will “pin” the layers together to limit issues if needed.
I forget to say that the act of sewing layers stretches the materials, and sometime differently due to individual material construction and surface characteristics.
There was a guy that posted his vacuum table a year or so ago with the intent to sell kits or maybe the files. I don’t k ow if that ever happened.
I have looked at the air weights solution but it just seems kind of expensive. If it were half of their asking price it would be more enticing, but still not a trivial purchase.
It does seem like making your own should be much cheaper. I am sure there is info out there to suck you down a rabbit hole.