Mitered edges are curved in middle..

[Eric Mims]

10" end of board being crosscut on Steel City table saw with Forrest chopmaster set at 45 degrees to make a mitered end. When you set the sharp mitered edge upright on the table saw surface after cutting, the left and right edges touch the table but it curves toward the center of the cut.. maybe 1/32 or 1/16".

What causes this?

[Joe Vincent]

If I understand your question correctly, my guess is the stock isn't being held securely as it's going through the blade. Could particularly be a problem with a 10" wide board. Are you using a miter gauge? How long of a fence does it have?

[Ryan Sparreboom]

The only way I can think of that being caused is that the board has a cup to it. Not a perfectly flat board.

[Phil Thien]

Even small cups in a board will result in miters that are concave or convex.

I'd check your board and make certain it is absolutely flat across its width.

As a sanity check you can always cut your miter in a test piece of MDF, too.

[Eric Mims]

good idea on the cupped board issue.. I'll go check. it's my buddy's project and I'm letting him use my gear. I triple checked the miter gauge to be square with the slot, and the machine has been set so the slot is parallel with the blade.

[Gene Michael]

If I cut too fast on my miter saw, I get the same problem. I assume this is caused by too much force flexing the blade. Could your friend be pushing the wood through the table saw too fast?

[glenn bradley]

Board cupped. Face joint your board and take another cut.

[fRED mCnEILL]

When this happens on a mitre saw it is because the board moves as the cut is being made. Securing the board solves the problem,. It could be that is happening here as well.

Fred M