MDF for sacrificial backup?

Yes. Lots of folks use it. Particularly in short runs.

Gunner

thickness -

vibrations and

Yes I use it all the time. If working to very close tolerances it's not so good with coolant sprayed on it though.

AWEM

I bet if one heated the MDF up and waxed it with paraffin wax, it would (upon cooling) hold up to water-based coolant long enough for most purposes.

Joe Gwinn

How about a sheet of PVC? I don't know about uniform thickness (yet). It will burr up while making the first part, so that will have to be removed, but it will be waterproof and probably oilproof. Randy

Works ok..but tends to be not all that consistant in thickness. And its a bitch to get double sided tape to stick to.

I see a lot of MDF used in fixtures and jigs in production shops.

Gunner

I just finished a 4 x 6 x 1/8 steel plate with two 3/4 round holes and two rectangular holes 3/4 x 1 1/2 . Clamped the oversize peice to the table on a 1/2 in. particle board and used a 3/8 four flute cutter. Just went around it taking some of the board with the metal sloped oil all over the place never moved a bit. Some sort of a template for the teacher to check students work with a cutting torch. Would MDF swell with liberal application of oil ? The particle board didn't at least over the two days it was on the table. ...lew...

We always used MDF as sacrificial when running a large CNC router table. It is virtually dead flat so the bit wouldn't accidentally bite in too much. Never used coolant. The stuff is a sponge