Help!...Z Axis Going Shallow

[tgattis]

I'm wondering if your bit is actually slipping in the collet, in the initial post the stars are fine then they started getting smaller...that means the bit was pushed into the collet further or the router wasn't traveling to the same extent. Derek is correct the bits are very unforgiving of flatness, but the board appears flat enough that shouldn't be the problem...I'd try putting a piece of blue tape on the shank of the bit and see if it's getting forced into the collet.

[rowiac]

If it turns out that warped or non-flat material is the problem, you might want to try a smaller angle V-bit. For example if you are using a 90° bit now, you might try a 60°. I've even used small 30° bits for detail work. The wider the bit, the more impact a change in cutting depth will have, such as from a varying thickness board. Another option would be face the board flat as a very first step.