Leveling z axis

When I drill holes, they are larger than the bit I’m using. (3.18mm hole ends up ~4mm). When I first started using it, it was pretty bang on, so something has shifted. Using a level/angle it seems the gantry holding the router is tilted down at the front slightly. I’ve tightened up the delrin wheels, but still getting oversized holes.

Anyone have any suggestions?

David, are you drilling or boring? Drill bit or mill? Are you mic’ing the drill or mill to be sure it really is 3.18?

Hey Bill,

Thanks for the reply. I’m using a 2 flute flat router bit https://www.amazon.com/dp/B07F3LGSS7/ref=cm_sw_r_oth_api_i_rw1hFbAWTFNPV
I tried a drill bit, and ball end mill, but these seemed to give the best edge quality on both sides of the through hole (12mm plywood).

It turns out most of my problem was side to side. I played with the eccentric nuts some more to level it out, and now it’s very close to 3.18.

David, glad you figured it out. The eccentric nuts work very well when you get them dialed in, but they have been the cause of lots of head-scratching.

By the way, drill bits are not safe in a router. The router spins way too fast, and the bit can become unstable, break, and fly around in your direction.

Hey Bill, thanks for the warning! I didn’t realize that. I ended up going with a better quality flat end mill that gave the best overall quality on either side, of the 5 bits I tried.

David, everybody is always looking for recommendations for good mills, so if you find a brand/size you like, be sure and list them on the forum. I’ve had real good luck with the Sienci 1/8" 1-flute for aluminum, even though they mic and perform as 0.118". For wood I’ve used quite a few SpeTools in all sizes and types from Amazon and have been happy.