1/4" aluminum plate as table surface for AltMill 2x4

I’m slated to receive my AltMill in June. The AltMill standard assembly calls for a piece of MDF as the table surface (the surface underneath the wasteboard that screws to the cross-members).
I can get a piece of 1/4" aluminum plate (6061-T651) custom cut to the required 51.75"x34.3" size for about $400. I’m OK with that cost, but I want to make sure there are no other downsides. I will likely also screw T-track to the aluminum which may add to the rigidity. With this setup, do you think the machine would be any less rigid than using MDF?

As I mentioned in another thread, my reasons for wanting aluminum as the table surface are as follows:

  • The MDF table surface screws in from the bottom of the machine and, for me, would be a major PITA to change. The aluminum would never need changing.
  • An aluminum base layer will not be harmed by stuff like bit-lubricants for cutting aluminum.
  • It will not be damaged by repeated screwing in of replacement top layer waste boards.
  • I feel I would have a secure surface to create some kind of easy attach and remove mechanism for the Vortex 4th axis. (One can unscrew from the aluminum as many times as needed, unlike MDF)
  • I’ll be using an OPT 45W laser sometimes and I like the idea that there would be no flammable layer underneath the work piece.
  • Gain a little Z-axis height.

Anyone see any downsides?

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The one down side I can see is that you need to be able to consistently locate the mounting holes on your sacrificial board that will be screwed to the aluminum. That is not a problem in itself seeing we are talking about a cnc machine - just run the original program again … BUT … what happens if your x or y home sensors move a bit for whatever reason. You put a new wasteboard on your machine and you want to pre-drill the mounting holes, you load your program, home the mill but now your hole position has moved which means the just drilled holes will not line up with the threaded holes in the aluminum plate below …
I suppose you could over-size the holes in the MDF or somehow register the home position of the mill against the threaded holes …

Oh, you better be good at tapping aluminum (unlike me) because you have a big pile of holes to tap …

He can always drill a piglet hole from underneath if anything gets off kilter.