In grbl the F command is mm/minute.
F is feed and would depend on the $13 setting.
It would also depend on the settings of the sender program too.
Maybe one or all of these have to be set lower.
They can certainly be a little lower (maybe 1200, 1200 and 350) as the machine is tuned for LASER operations.
I also have all the jumpers installed for microstepping.
Guys, thanks a lot for your help and clarification.
I learned something here with GRBL.
It was actually the max. speed of the motors. What works now is approx. 350mm/min per axis. Is this a value that seems reasonable to you for a CNC machine?
Furthermore, the lead screw inside of the wagon seems to be not 100% in line with the motor and the bearing on the other side. Unfortunately, I have a big design flaw here: I cant adjust the position of the lead screw as it is clamped not 90 degrees along the screw but 0 degrees... that way I cant adjust the position and there is a lot of resistance when turning the lead screw when the bearing on the other side is inserted. If I remove it works.
Unfortunately, I have to redesign the axis to get the necessary posibility to adjust the nut.
Thanks guys for your help!
Ther maximum speeds depend a lot on the thread starts of the lead screw.
There are a few places you can do the calculations online
AT the end of the day you will have a set calculation but you can use that as a dental starting point and the sender software will do the rest in terms of faster or slower.
Just get the initial values plugged into GRBL.
Each axis should be able to move from one end of its travel to the other end with only very minor resistance (power off).
If you have any points with higher mechanical resistance you should take care of those prior to using the machine.
If you look at my figures I have a MAX feed rate of 300 ( $ 25) but a max Z of 450 ( $112) so you appear to be in the ballpark.
Mine is set a little higher as I can get away with it for laser work.
There's your problem - you absolutely need microstepping for an undamped stepper motor to work at speed - leadscrews are typically very undamped so I'd immediately say x8 or x16 microstepping is required here to greatly reduce mid-band resonance.
Belt drive typically is well-damped, so you seldom see issues in 3D printers, but for a
CNC machine with ballscrews its crucial to address resonance.
Adding mechanical damping is a great idea too, some shaft couplers work well for this (the jaw type with rubber inserts).
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