4'x4' cutting area, 56"x63" table build question

So I opted to have a 48"x48" cutting area and I’ve come to see that my actual table top area is going to be 56"x63". I’m building the top frame out of 2x4s and using MDF as the actual top. So here’s my question as I’m unskilled in woodworking: MDF comes in 4’x8’ size, so how do I make the cuts for the top, and how do I make sure the top is flat and level?

Pic attached for reference.

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Well the next time I make a table I do not think I will skin the whole thing. Lots of people around here just center the wasteboard in the cutting area, the machine will happily drive on the rails you have. For extra strength you can skin it with thin sheet material and just use a thicker wasteboard.

This also give some more clamping options.


I built something like this for the table under my MPCNC. For LowRiders I mostly see torsion box construction. As for sheet goods, Home Depot and Lowes will cut large sheets down for you. Their cuts are not super accurate (due to the person cutting, not the machine), so it would be easiest to have them cut it a bit larger (1/2") than needed and then trim the plywood on two edges to the table. They will also cut the 2 x 4’s down for you, but again there are accuracy concerns.

I like Ryan’s idea of using thin stock to skin the frame. You can get a sheet of 5mm underlayment cheap. It is better if the the joint between the two pieces you need to cover the frame run downs the center of a 2x4. Personally I run some wood glue along the frame before I screwed down the plywood. With this setup, a single sheet of MDF (installed on top of the skin) can make two, 4x4 spoil boards, so you would have a spare.

If you have a table saw, you can do a basic jointing of your 2 x 4’s to get the top edge flat. If you look down the “top” of your 2 x 4’s, you will see they are not perfectly straight/flat. Using a flat reference like the manufactured edge of a sheet of plywood, or a long level, it is possible to make one edge significantly flatter. Look up “jointing using a table saw” on YouTube, and you will find a bunch of hits with different methods. I did this for my table, cutting off the “crown” edge of the 2 x 4’s.

It helps if you have a flat surface for constructing the frame, and construct your frame face down. Pre-drill your holes before screwing the frame together, and boards will wander less.

Note that if you don’t mind sacrificing your spoil board, and you are doing contour cutting, then the flatness of your spoil board is much less important. And you can surface (cut off the top using your MPCNC) your spoil board to make a flat surface. The general recommendation is to put in some hours, and work out any issues with your machine before surfacing the spoil board.


This is my 4’x4’ still in progress and almost finished.
Will be adding a 4’x4’ vacuum top to cut FRP.



Bonus points for the wheels

You could swap the 4x2s(?) by some pre-cut multiplex or MDF. If you put them upright it should be straight, and less chance to see your wood bending over time when the moisture from the wood completely dries out.

This is probably the best suggestion: do not worry about the surface, if the rest works fine, you can easily flatten it this way.

This! I always think: I’ll let it cut in the shop on their expensive machines, but always walk home regretting it I didn’t do it myself. :wink: