About 10 + years ago there was a company booth at "The Woodworking Shows" that sold a bunch of vacuum attachments and hold downs. I didn't buy from them at the show, but tried about a year later and they were out of business. They made round and square vacuum chucks with O rings top and bottom and push connect fittings in the edge for connecting 1/4" OD poly tubing, They also made a circle cutting adapter that did not require a center pivot hole to be drilled. It was held in place by vacuum. Their products were mostly made from aluminum.
I have since thought of making similar vacuum fittings using 3/4 Baltic Birch and grooving it for O rings, then drilling the needed ports and installing push connect fittings. It wouldn't be hard. I just never seemed to need them bad enough to do it. There is now a closed cell Weatherstrip type tape that they sell for CNC work that might make the construction easier, because O rings and the needed grooves for them wouldn't be required.
If you do it, I want to see pictures.
Their standard vacuum chuck was just a round slab of 3-4" diameter aluminum about the size of a hockey puck, but 5/8 or 3/4 thick. It had a hole completely drilled through the center and another intersecting hole completely drilled from one edge to the opposite side. These second holes had push connect fittings in them that allowed them to be connected together and to the vacuum source. An O ring groove and O ring almost as large as the top and bottom face formed the vacuum seal Several of these could be connected together. Then with a plug in one port of the last one, and a vacuum line connected to the first one, vacuum would hold the part in place as well as hold all of these vacuum chucks to the work bench. They also had one sided versions of these with threaded screw holes in the bottom for attaching to a fixture or bench. Their circle attachment just had one O ring on the bottom and the top had a pivot connection in the center for a router circle cutting attachment. Only one vacuum fitting was in the edge, since I guess they didn't expect this to be used along with the hold downs, but it probably could be if attached to the end of the string.
Central North Carolina
Last edited by CharleyL; 03-15-2017 at 08:13 PM.