TooPicky said:
So a search for "MDF" turned up nothing here. I'm wondering, what are it's appropriate uses? Specifically, I want to build a manual X Y Z router table. So, I was going to use MDF because it's dimensionally stable, and consistently flat. But, I've never been a fan of "sawdust pressed together" sheet goods, ya know? So, if this IS an appropriate use, how would you fasten it? I plan to make the table slide one way, and a gantry with a carriage sliding the other way, with the Z axis on it. All hand cranked. So it will have to be somewhat ridged, and be able to put up with that hand cranking.
Before you invest a bunch of time and effort, take a look at the Woodrat, and RouterBoss. No need to reinvent the wheel. Also look at using 80/20 aluminum extrusions. Quite a few of the commercial CNC router set ups utilize the 80/20 extrusions, and they can be bought of eBay relatively inexpensively.
Back to your question: MDF is dimensionally stable. However it is not very good at holding screws from any direction. I would tend towards MDO, HDO, or phenolic sheet, listed in order of expense, and suitability.
The phenolic is the most suitable, but the most expensive. You can sometimes get decent deals on eBay. Another possible source is to talk to local plastics supply houses, and see if they are selling quantities to anyone, and then checking those folks for scraps. It can be drooled and tapped similar to aluminum.
The HDO is second best, but typically hardest to find. Your most likely source is concrete supply companies, where it is sold as forming plywood.
MDO can be bought at most well stocked lumber yards.
All three can readily be worked with carbide woodworking tools.
If you look at the commercial CNC router tables you'll see that the only place they use MDF, is on the sacrificial surface of the tables. Because it is really cheap.