Archive for May 11th, 2018
The overall XY travel is slightly smaller than the initial configuration, because the router sticks out further than the penholder I’d been using. Increasing the
$27 Homing Pulloff distance to 3 mm leaves a comfortable space beyond the limit switches after homing to the positive end:
$13 XY travel distances and switch positions on the other end of the rail leaves a similar comfort zone at the negative end:
Both switches now live on the rear X-axis rail and appear as seen from behind the bench; they just look backwards. The Y-axis switches are on the left rail and look exactly the same.
The XY travel works out to 630 × 460 mm = 24.8 × 18.1 inch, which is Good Enough.
Some fiddling with the Z axis limit switch tape mask produces a nice round 100 mm = 3.9 inch vertical travel. The Z-axis rails just barely clear the table at the lower limit and just barely stay in the bottom bearings at the upper limit, so it’s a near thing. In practical terms, the rails or the tool will smash into the workpiece sitting atop the table before the limit switch trips.
$20=1 Soft Limits and
$21=1 Hard Limits may be excessive, but I vastly prefer having the firmware detect out-of-range moves and the hardware forcibly shut down if the firmware loses track of its position, rather than letting it grind away until I can slap the BRS. The steppers aren’t powerful enough to damage anything, of course, so it’s a matter of principle.
$N0=F150 sets the initial speed, as the default
F0 seems to (sometimes) confuse bCNC’s auto-level grid probing.
$N1=G10L2P1X-633Y-463Z-3 sets the default
G54 coordinate origin to the front-left corner, with
Z=0 at the home position up top, so as to prevent surprises. I expect to use
G55 for most work holder touchoffs, although we’ll see how that plays out.
G30 settings depend on the tool change location and the Z-axis probe location, so they’re still not cast in concrete.