Last stupid question for the day …
I am trying to square my freshly assembled Altmill following the instructions. I use the built-in squaring helper. I have a pointed tool in the spindle, move the spindle down to just over the table surface, put a piece of masking tape on the table under the tool, drop the spindle a bit more and make a tiny divot in the masking tape. I repeat this for the additional two points needed for squaring. The distance travelled for x and y is 1000mm for each axis.
I measure the x distance, y distance and diagonal distance and enter that into the calibration tool which then tells me how much I am out. About as straight forward as it can be.
The problem is that if I re-adjust one inductive sensor, re-home and repeat the square calibration, nothing seems to have changed.
I looked at the Altmill handbook under ‘tuning’ and $22. The documentation shows a whole bunch of config options for $22 but when I bring up $22 on the mill I only see a single setting - enable/disable.
The documentation says that ‘dual homing’ is enabled by default. I am trying to confirm that my machine has dual homing enabled but don’t know where in the configuration I would find this setting.
I found it easier to draw a triangle in Vcarve with equal distance in X & Y (ie 1000 mm) then measure from point 1 to 3 in Vcarve so you know what it should measure, then just move machine to those places, marking with a vcarve bit. Make a very precise measurement from point 1 to 3, move one of the Y homing sensors whichever way will cock your X Line to make the measurement correct, Repeat until close enough. That tool in Gsender is a little confusing (or wrong) on which way to move the sensor. Message me if you want more details in a Zoom Conference or something. I’m Larry Robinson in the Facebook Group
Thanks for your reply. I don’t have Vcarve but the gSender tool does exactly what you say you do in Vcarve. I have tried moving sensors (one at a time) but the precise measurement from point 1 to 3 didn’t seem to change. This is why I am trying to confirm that my Altmill is set up to do dual homing.
My thinking is that if, for whatever reason, dual homing is not enabled, nothing I do with the sensors will correct any out-of-square error.
BTW, both sensors show a red light when they trip so they seem to work.
Thinking about this just now, I realize that there is one thing I haven’t tried to do yet - I will manually move the gantry out of square while the power is off, power back up, re-home and see if the mill corrected the error that I introduced manually.
I am unfortunately not into zoom or facebook … sorry …
With some more playing around, I got within 0.3mm of square and my measuring abilities do not allow more precision. I ended up moving one sensor forward by probably 3 mm and had to shim the bump stop with three washers in order for it to be in front of the sensor.
The other bump stop is as far back in the other direction as it can go so I can’t tweak that.
I will double check frame squareness tomorrow.
You do not want it to touch the bumpers, make sure the sensors are adjusted just barely behind the bumpers (.060" or less. If it hits the bumpers it will effect the homing and will not be accurate.
It was a bit of a tricky balance to make sure that both bumpers did not touch the carriage side plates during homing and, at the same time, making sure the sensors did not sticky out past the bumper front. Should there be a sensor failure for any reason, the bumpers will prevent the carriage sides from running into the sensor body.
I am a bit concerned that the adjusting nuts on the sensors might loosen with vibration but maybe I am over-thinking things.
Yes, you don’t want them to be damaged if it did go back there, but all I’m saying is when it’s homing, just make sure it don’t actually touch the bumpers, maybe leave .100" or so to go when it’s homing.
Just measured with calipers, mine measures about 1.020" from the end of the sensor to the back of the nut on the rear of it. The bumpers are barely longer than the sensors on mine, by maybe .050"
I have 1.13" between the face of the sensor and the back of the nut that is on the back side of the mounting bracket. The other sensor is 0.98" for the same measurement