Spoilboard Tips

Advice on how deep to cut into the spoil board, and when to discard the sheet. August 17, 2006

How far should you be cutting into the spoilboard and how thin do you fly cut to before you discard the MDF sheet?

Forum Responses
(CNC Forum)
From contributor A:
Different CNC manufacture recombined different dimensions. We run a Cosmec 510 and we cut throw 0.01 below the material when route cutting or .02 for throw drilling. On our fly cuts we take off 0.02 at a time, usually depending on the spoil board after we get down to a 0.25 thick. To get the most out of your spoil board, seal all four edges well and flip every few fly cuts. But I recommend that you contact your CNC manufacturer and see what they recommend. It also depends on the type of bits you are using and what you are cutting. The dimensions I enclosed are for mostly plywood, melamine and particleboard.

From contributor B:
I cut MDF and I've found that all sheet goods have a variance. I usually cut .03 through. Sometimes this will not through cut Ė even though itís the same bundle, cutting one sheet after another. I've also found that some sheets vary between areas in the same sheet. I'll through cut sheet A. Sheet B gets put on right next and it will through cut the panel except in the upper corner. Then the next sheet cuts clean again. I've tried measuring the sheets with a caliper. It's just differences in sheets. I'm in Florida with a lot of humidity. I use .25 MDF for a spoilboard and flycut .03 when I need to. At .125 I put a new spoilboard on. I know one guy who uses .75 MDF. He cuts large panels.

From contributor C:
You will notice that you will get as many answers here as there are vacuum configurations. Horsepower, table size, type of pump, part size, touching off top of part or top of spoilboard, etc. - all of these factor into how deep people cut for production. Find someone who is successful with a similar configuration as yours and then adjust for your specific needs.

From contributor D:
I can't say that what we do is right but we attempt to hold our thru cuts to .003 - .005 with excellent results. When we dress the spoilboard we attempt to take .005. I only change spoilboards about once a year which is 3/4 double refined MDF.

I should add that on my first machine this was not possible. It had a phenolic table 5 x 12 machine that weighed in at approx 8,000 lbs. The table had flex in it that I could not get around. I changed machines and now have as SCM Routech 220. This machine weighs in at over 22,000 lbs. with a 4 x 10 aluminum table that is as solid as a rock. I am now in the camp that thinks weight has a lot to do with machine capabilities.

From contributor E:
We touch off on the spoilboard, 3/4" MDF, cut through .004 and surface both sides before we start using a new spoilboard and then whenever it gets really chewed, .004 using a 4" diameter inserted bit. When the board gets to 1/4", itís time for a new one. Thru bore bits need the 1/4". We are running a 40hp vacuum on a 5x10.