Ever since I saw a vacuum bed in action at the ShopBot factory last year, I’ve wanted to have a vacuum system on NextFab’s ShopBot. As part of our renovations, I finally got to build one.
For those of you who aren’t familiar with vacuum systems, the biggest challenge in working with a CNC router is holding material in place. Until now, I’d been using screws, double-sided tape, tabs and clamps to hold material down while the ShopBot did the cutting.
Now, instead of these laborious methods, we can use the power of vacuum to hold down plywood and other flat materials as the ShopBot cuts them. So, how does it work?
A vacuum system has essentially three parts: A vacuum source (in our case a powerful Fein shop-vac), a plenum, and a bleeder board. The plenum is the distribution system for the vacuum, and the bleeder board is the final layer of material which covers the plenum and is in contact with the material being cut.
Here’s a picture of the ShopBot with the plenum pattern and PVC plumbing installed. The grid pattern is cut into a sheet of ultralight MDF and sealed with polyurethane. The three valves under the machine let me isolate different vacuum ‘zones’, depending on the size of the material I’m cutting.
With the bleeder board installed, the system draws vacuum right through a solid sheet of ultralight MDF. When the system is turned on, the vacuum hold is so strong that I can push against the edge of a sheet of plywood without moving it at all.
Here’s the first piece I cut to test the system- Look Ma, No Tabs! Believe me, I’m delighted at the thought of never trimming another plywood tab. I’ll be putting it through some more tests in the coming days, but for now, NextFab has a much faster and cleaner way to cut your parts on the ShopBot!