I’m looking to start cutting large sheets of leather and heavy fabrics, such as the full work area of the 4x4. A drag knife seems like the easiest way to get into it but I’m a little confused about workholding. Does anyone have experience here? My hope is that the materials are heavy enough to stay on the bed without moving from the drag knife, or perhaps putting some heavier 123 blocks on areas that aren’t being cut. Double-sided tape could be an option but I would need to do a bit of experimentation to find something that is low/no residue yet holds sufficiently / is able to hold to all of the materials.
ToolsToday shows a vacuum table (which I don’t have) but it seems to just vacuum a sacrificial piece of MDF that they lay the leather on top of. Does it not actually vacuum the leather itself?
When I did this, I used a lot of double-sided tape — felt wasteful, but worked.
Apparently MDF is sufficiently porous that it will work to lay it on a vacuum bed, then lay material such as leather on it, and have the vacuum hold both pieces in place, and MDF is reasonably kind to drag knife blades, while the usual material of a vacuum table wouldn’t be, and one wouldn’t want to cut up one’s vacuum table.
Thanks Will - yeah, DS tape might be the way for me to go once I find a suitable option / until I put together a vacuum table. Interesting note about MDF, I wouldn’t have expected it to be that porous.
One of my concerns about a drag knife at those lengths is how parallel that surface will be over such a relatively large span. I guess this shouldn’t be as big of an issue if I surface the MDF / wasteboard before hand, but it was something that I wanted to investigate prior to making that investment.
I’ve been using Fasten double-sided woodworking tape. It’s quite sticky but I’ve yet to have it leave even the tiniest amount of residue. The only issue is that, if your bit gets into it, the bit will become coated with the gummy adhesive. Since I measure from the bottom of the stock and know how thick the tape is, I zero my Z, move it up 0.01" and set Zero there. When I do that (yes, I’ve forgotten a couple of times and ended up with a very messy bit, which can be cleaned using IPA or acetone), I don’t get any residue. Depending on the material, I might get an onion skin at the bottom, but that is very easy to clean off. This does not work for thin, fragile materials as the tape is very sticky so you’d end up breaking/tearing the material. Leather should be tough enough to pull up after working it, but it would be worth trying using a few pieces of scrap.
made this key accessory for my wife’s new Jeep Renegade 3 years ago with DS tape, 1/16" (or 1/32? don’t remember) router bit. Also some palm size inner linings (“floor”) of heart shaped jewelry case. Went very well, was firm thick saddle leather. DS tape was very good, strong enough, easy to remove. BUT! only small pieces. (the key pendant for the jeep IMO looks great after 3 years daily heavy relentless use)
For small thin pieces of wood I use the painters-tape-method, tape on workhold and stock, superglue one, activator the other side, with very good results. Wonder whether that would work with leather too? At least the tape is cheap, the superglue not so much, and activator spray: don’t know. Use the same bottle for some years. Should be some aceton or even just water some say.
