davidallen
11-05-2001, 09:50 AM
anyone tried the stepped miter joint that was shown at B.P.'s camp shopbot? I've tried several but success seems to either be dependent on the wood or I've got a variable error in X/Z alignment.
my first attempts were with an upcut bit in some scrap Catalpa. seemed to work fine so I tried to make a box from some pine. got a lot of 'fuzzies' on the steps. switched to a down cut bit and the fuzzies went away, but the steps don't align across the joint. if I line up the steps on the inside of the joint, the outside step is off by a good 0.010".
I'm wondering if the compression of wood fibers by the down cut bit would be sufficient to cause this error. I've checked calibration on the X and Z axis and over several inches, they appear to be accurate.
the only other issue I can think of is the accuracy of the X axis in small steps (.125"). I've noticed that when I'm trying to align a bit, that movements of 0.005" may or may not make a noticeable movement in the carriage. generally that's not a concern, but if I'm only moving 0.12" when I should be moving 0.125", over several steps that could add up to the error I'm seeing.
da
my first attempts were with an upcut bit in some scrap Catalpa. seemed to work fine so I tried to make a box from some pine. got a lot of 'fuzzies' on the steps. switched to a down cut bit and the fuzzies went away, but the steps don't align across the joint. if I line up the steps on the inside of the joint, the outside step is off by a good 0.010".
I'm wondering if the compression of wood fibers by the down cut bit would be sufficient to cause this error. I've checked calibration on the X and Z axis and over several inches, they appear to be accurate.
the only other issue I can think of is the accuracy of the X axis in small steps (.125"). I've noticed that when I'm trying to align a bit, that movements of 0.005" may or may not make a noticeable movement in the carriage. generally that's not a concern, but if I'm only moving 0.12" when I should be moving 0.125", over several steps that could add up to the error I'm seeing.
da