If I slide the feed speed adjuster to 200 percent could it potentially cause my maximum speed go past what I have the max speed set to in grbl? For example (this is not what I have mine set at). If I have max speed in grbl set to 200"/minute and I have a design that is set to cut at 110" per minute; if i slide the slider to 200 percent, would this cause it to run at 220" per minute or simply 200? I am assuming it will not allow me to go over the maximum setting in grbl even if the slider moves to 200 percent, but I am having an issue where my z axis is getting off (cutting deeper than it should) if I run a job at 200 percent. The x and y seem to be fine at 200 percent but z (I'm guessing) is losing steps when it rapids up out of the work piece for a rapid move. This causes it to "think" it is higher than it is when it drops back down in to the work piece it goes down deeper than it should. The only thing I can think of is it is causing my z to go up too fast and it looses steps. However, I can't recreate it missing steps by moving it manually up and down at the max z speed rate. Should I just lower my z max rate in grbl, or is there some way to change the retract speed prior to running the job? I am using the open builds post processor with fusion. Thanks!
No, the Max Rate in Grbl is the authoritive number. It will never be exceeded. So if Max rate is 1000, feedrate is 1000. Then 200% will still be 1000 Tune your Max rates to not allow any skipping or stalling.
Ok, one more question. I have the openbuilds high torque nema23 stepper motors. If I remember right they are rated at 3 amps. I am using dm556 drivers with the dip stick selectors to set max amp from driver. If I am running two of these openbuild steppers from one driver should I set the driver to 3 amps? Or, should I go higher since it is controlling two steppers? I assume a second driver (one for each motor) would be ideal? Thanks!
2x Steppers in parallel needs twice the amperage correct Dual drivers are the better way of doing it though. Note 3A is the MAX rating, not the ideal - set at 3A the motors will overheat Stalling in Z can often be related to acceleration parameters too - if I recall your machine has a very heavy gantry to lift with the dual Z motors right?
I would think it is fairly heavy, but I don't know how heavy. I can cut slightly over 4'. The linear rail from openbuilds is about 5' long with the router mount/router and rack and pinion all part of the weight..... I have my Max speed ($112) set at 2000 and my acceleration ($122) set to 500. What do you suggest I change them to? Thanks
Hard to say - trial and error would be better - best to tune these machine specific values with the actual machine If 500 does cause issues - try 250 - if the problem goes away, you can tweak upward again. If not, lower. If you get down to the Grbl default of 10mm/sec^2 and it still has issues, then it might be something else like Max rate, or mechanical, or electrical Consider this: LEAD1515, we run 1000mm/min Max Rate on Z on a 350mm/s^2 for the LEAD1515 profile - sure it is quite conservative, but its also lighter I think (rack can be heavy)
You acceleration feels high to me, so I am thinking we try lowering it first - and then I am a fan of changing one parameter at a time as best practice Once we trust the acceleration - we can tune Max rate too
