Surfacing a Spoilboard

How and why to "flycut" an MDF spoilboard. August 17, 2006

What is fly cutting? I have been buying MDF from a local lumber dealer - do I need to machine it first for it to be a more effective spoilboard? I saw in a woodworking catalog that when selling spoilboards, you had to machine it first to "remove the skin", what does this mean?

Forum Responses
(CNC Forum)
From contributor A:
Fly cutting is a term for surfacing a sheet. In the manufacturing of MDF it get a hard skin on both sides and if you are using a vacuum table this can sometimes reduce the effectiveness of your part holding because air can not move freely. I find that surfacing lets me hold smaller parts without movement. MDF also is not perfectly uniform in its thickness. The surfacing assures that you will not be cutting any tapered parts. I surface my sheets when they first go on the table and then anytime they get cut up too badly. I use a 3" cutting and it take very little time to do the job.

From contributor B:
Contributor A pretty much described fly cutting. Use an insert tool, as this will last a lifetime - just change the inserts. When fly cutting, speed up the tools feed speeds to 1000 IPM. This will leave a fir (hair) on the spoilboard, which will provide a non-slippery top, and it holds small parts better.