OSB as spoil board?

I made my table like in the assembly instructions and spent 45 mins with the support braces to get the top extremely flat. Once I was satisfied I cut the center out as a removable spoil board but this took away all the integrity and now it’s very wavy and deflects in certain places with very little weight.

Since I have extra OSB I was going to just cut a new top and put my old one on top of that.

I was thinking I could just use the machine once it was built to mill the top perfectly flat and parallel to the cutting head but I’m thinking OSB isn’t a good choice for that.

I just built a new table, I’ll put some picks up in a new thread, I haven’t decided on a top for it yet. I was thinking this time I would use 2 layers like you are doing but maybe a thin full top of MDF to keep things square and make a solid torsion box, that a thicker MDF skin on top of it. Let me know what works for you.

I made my table such a crappy size I need all kids of 25" and 25.25" pieces…so much less waste if I just went with 24" or a hair under. Live and learn

I think OSB would be good for a base but I wouldn’t use it as the actual spoil board for a few reasons. I am not sure what a good one would be except maybe something soft like pine.

Yea, I wouldn’t try to flatten osb. It’s not going to plane very well. It will work for your table top though, then like vicious said, throw a piece of mdf on top of that as a sacrificial top and plane that down.

I ended up watching some videos of people with a MPCNC on youtube and went with the really nice MDF 3/4. I still used a sheet of OSB 7/16? on top of the table then the MDF on top of that. I might use the extra MDF to make a “work piece/ spoil board” but what ever I end up doing I want to face it because no matter how hard I tried the surface still deviates some.

I didn’t use the top to square the frame,I put it on my concrete garage floor, wrapped a ratchet strap around it and pulled it tight. Once I got it square I screwed it tight and removed the strap then screw the 2 tops down.

A thin OSB board would be good as a base to keep the whole table square. I cut my spoil board for easy replacement so having a solid base is a great idea.