[MARV]

Canman,
Your feed speed is at the low end but certainly reasonable. You didn't say what the dia. of cutter was. Again, its lateral cutting force thats moving the part. You may want to reduce the cutter dia. and your depth of cut. At 16 sq. in. of part size, you are on the ragged edge using only vacuum for part hold down. All the variables will have to be perfect for your system to work.

Regarding your vac gage; 15 bucks should get you a quality gage. Use it on a small panel first to test your system. While the pump is running, use something like sandwich wrap on all exposed surfaces of your vacuum box and watch the gage like a hawk. A jump in value as your covering the box reveals leaks in your system.

Another test you might try; mount you gage on your manifold close to the vacuum table. Cover the whole top working surface with cling warp. Run the vac pump and read the gage. The value your reading should be your baseline reading for a "whole sheet" part. Anything less means you may have a problem.

[ger21]

As I've noted before, my smallest part is like 16sq.in. or something

What does this part look like? A 4"x4" square is a lot different that a 16 sq in part with multiple holes in it, or small "features" that stick out.

I don't know if I would attempt cutting something that small without tabs. But it depends. Creative toolpathing can make a big difference.

Vacuum holding can be incredibly difficult by itself. Using it to cut really small parts makes it even more difficult.