I saw a conversation starting about spoil boards and thought I’d share some of what I’ve learned. I started as a CNC Operator in a shop where nobody knew anything about it. The previous operator quit and it had just been sitting. I kept running into issues loosing parts and started researching ways to resolve it.

I tried everything: Sealing the edges with glue, using paint, covering parts of the table, fly-cutting at different speeds, different materials, etc… One night I stumbled upon an article about the “vacuum in space” and how someone had applied it to vacuum pumps. (For some industry other than wood products.) So, I took what they learned and matched it up with some of what I had read.

For instance, when people recommend using Tru-Pan or another lightweight MDF, it’s because there are less particles per cubic foot. This means more air underneath the part. Over the next month I tried all kinds of things.

Here’s what the end result was:

1. Different vacuum pumps are geared differently. Lightweight MDF may work for you or may make the problem worse. It all depends on whether your pump pulls fast or strong. (Think hp vs. torque.)

The more space you can get under a part, the better. This is why the larger parts hold better. Not just because of the coverage.

2. Thicker spoilboards work too! (Again, this depends if your pumps can handle it.) Seriously, I used 1 1/8″ MDF. Same theory as lightweight. The benefit is it’s even longer between replacements. The negative is it’s heavy as hell! For those of you that monitor your pressure digitally, you can actually see a difference as your thickness decreases.

3. You should surface both sides of the spoilboard and the spoilboard should feel a little fuzzy. (Just a tad.) If it isn’t, you need to adjust your speed.

4. Sealing the edges help. I tried different methods, even painting glue on with a brush. (4 coats! It sucked – pun intended.) The best thing I found was rubberized undercoating. Same stuff as flex-seal but they’ve been selling that for autos forever.

I guarantee there are a thousand other things about vacuum that I don’t know but it blew my mind to know I had been looking at the problem all wrong.