I recently finished a Routy build (my first CNC), and am currently testing it. I have it connected to a Synthetos TinyG controller, powered by a 30V 20A power supply. I am having trouble with the travel on the X and Y axis, as it seems to be traveling a little short of the command that I give it. For instance, if I send the following command 'G0 Y20' (inch mode), it only travels about 19-1/2 inches. But, when I send G0 Y0, it returns exactly to the starting point. There seems to be no jitter in the movement, and if I execute the above two commands several times, it always returns to the original starting point. So, I'm thinking that the motors are not skipping steps. I have it configured as traveling 40mm per revolution of the motor, and was wanting to make sure this is correct. I'm using the 20 tooth GT2 pully and cooresponding GT2 belt, with 20 teeth and a 2mm tooth pitch, I'm coming up with 40mm per revolution. Am I missing something? Thanks, Jim N.
I have the same controller, but using the acme screws on the c-beam, each motor has a calibration that you must tweak the travel per revolution is what you need to adjust, my screw was easy took 8mm x 50 = 400mm, put a metric ruler down, I used a 10 degree v bit, has a very fine point, set it on 0 and gave the command to move 400mm, took wheat it traveled divided by 50 and that gave me the value to put in the travel. never tried it but you could use the Calculator RepRap Calculator - Prusa Printers [1ma] m1 map to axis 0 [0=X,1=Y,2=Z...] [1sa] m1 step angle 1.800 deg [1tr] m1 travel per revolution 8.0000 mm [1mi] m1 microsteps 8 [1,2,4,8] [1po] m1 polarity 1 [0=normal,1=reverse] [1pm] m1 power management 3 [0=disabled,1=always on,2=in cycle,3=when moving]
Thanks for the reply. I've been through the adjustment of the potentiometers on the TinyG. Also, based on the calculator at the link you posted, 40mm per revolution on the X and Y axis is correct, although, I've seen 36.54 being shown as the value for the Shapeoko. One other thing that I'll mention is that the TinyG board is an older model, as I started building a CNC a couple years ago. It has software version 0.93 on it. I tried some more testing and found that for a given movement along an axis, the number of steps being skipped seems to be consistent, and increases as the length of the move increases. But, that increase is not linear. If I move the Y axix, say 20 inches by a series of 5 inch moves, it seems to miss more steps than a single 20 inch move. I've played with the max velocity and the max jerk values, but, it doesn't seem to make a difference.
the pots are for the max current applied to the motors, too little and you will skip, I have mine turned to about 2/3 max. do you have your controller set to mm or inch on power up. by default it comes mm, I left min in mm and let the G-code switch to inch. I have the V8 board and just updated it to 440.20 master firmware, I was about 3 versions behind. you might want to upgrade you firmware, the guys that answer the forums at synthetos will ask that first before helping. [fb] firmware build 440.20 [fv] firmware version 0.97 [hp] hardware platform 1.00 [hv] hardware version 8.00 [id] TinyG ID 3X3566-2NX
My next step was to update the firmware version, but, my board doesn't have the built in bootloader. MyISP programmer is not working, so I can't update the firmware. I just ordered a new TinyG (should be version 8), which has the onboard bootloader. I'll see what happens with the new board (and newer firmware).
Well, my new Version 8 TinyG came in last Saturday (2/6/2016), I connected it, configured it and all is well with the world. There must have been a bug in the version of the code on my old TinyG board.
