Default Frame Spoil Board

I am finally going to start putting my Maslow together after spending a couple years on another project. I have decided on the default frame. My question is, with the recent spike in lumber costs, is the 3/4 inch plywood spoil board necessary? Since it does not serve a structural purpose, could 1/2 Inch MDF be used in its place? If not MDF, at least 1/2 plywood? I don’t see the need for the 3/4 plywood but I’m new to this and maybe I’m missing something.
Thanks for your help

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I bought mine used. It came with a 3/8" spoil board and seems to work just fine. I wouldn’t see any issues with MDF, but I’m still a newbie.


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it actually is structual (providing anti-racking forces), but 1/2" should be

David Lang

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I’ve got a piece of particle board, so I don’t see why MDF wouldn’t work either. The only thing I would worry about would be moisture causing the MDF to expand, but that also depends on the environment you are keeping in.

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In the default plans for the frame, the 4x8 board is an essential part of the structure, and in my workflow it is not considered a waste board. 3/4 or 1/2 ply will supply the necessary rigidity, but it also serves as the base to secure the workpieces, and should be flat. I generally work with 1/4,1/2, & 3/4 ply, and often that material is warped (especially 1/4”) and needs to “get flat” to help achieve successful cuts. To accomplish this, I use an electric drill and wood screws. The base needs to provide a good foundation for securing these screws. So, thicker will be better for flatness and durability. Plywood is best for this. MDF is ok, but won’t be as durable. And chipboard like OSD doesn’t “like” screws so much. To protect the base from the router, I use 1/4” thick foam siding insulation panels as a waste board. Mine came in a 4’ wide pack with folded 2’ sections that open to at least 8’ sections, and what I got is a lifetime supply, maybe 50’).

Just my 2 cents… hope this helps!



Thanks everyone!
It sounds like 1/2 inch plywood is the best option balancing cost. I don’t know what the forces are on the MDF but I do know that it doesn’t perform well where I have to rely on it for strength.