Trial and error.
Set the acceleration low, and start increasing velocity until it stalls, then back off 25%.
Then do the same with acceleration.
I just finished my first CNC router build and I wanted to ask, how do you find the right speed for your machine (when filling in the set up wizard)?
I understand that this will be different for each machine but how do I calculate it for mine? I.e. Is there a formula or is it just trial and error? If it is the latter, how do you know when you have it right?
I am currently using a Gecko G540 with two Nema 34 465 oz / in 3.5a (for the X and Z axis) and one Nema 23 381 oz / in 3.5a for the moving table with a 48v PSU. I have 20mm pitch ball screws on all axis. What range of speeds would you typically expect to see for this sort of set-up?
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Trial and error.
Set the acceleration low, and start increasing velocity until it stalls, then back off 25%.
Then do the same with acceleration.
Gerry
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I never had any speed expectations based on my machine design. What would they even be based on? I just expected it to be able to go as fast as is necessary to make aluminum and wood parts, (or I would upgrade later). I chose electronics and motors based on what I had seen others, with similar purpose machines, using. I researched this a lot and nobody had a better way that they were willing to share.
I can see that my Nema 34 465 oz in motors can go more than fast enough. I can't seem to get my nema 23 381 oz in motor to move my table at all. It just makes a loud grinding sound at every speed I have tried. So I assume it is set-up wrong, so, I am asking for help with a starting point.
Then, as Ger21 said, it will be trial and error from there.
Try lowering the acceleration.I can't seem to get my nema 23 381 oz in motor to move my table at all. It just makes a loud grinding sound at every speed I have tried.
Gerry
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I did but I only seem to be able to change the pitch of the grinding sound and / make it shake the table back and forth. My numbers must be way off.... how many mm per second and mm / second squared would you set as a starting point for 381 oz in 3.5a motors run on 48v?
I really don't understand why this motor is having so much trouble. The moving table should be the easiest axis to move as it's the lightest and the load is horizontal. With the grinding noise it makes, you'd think I was trying to move an elephant.
The Nema 34 465 oz in 3.5a motors seem to have no trouble pushing 3x the load up a vertical axis at super high speeds and with enough torque to easily snap a 1/4" end mill (when fed too fast). I thought the 381 oz in would be somewhat similar as they draw the same power...
For accel, 100-200 should be a good starting point.
Are you sure the motors are wired correctly?
Gerry
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I am using premade motor cables from CNC Router Parts so it was pretty much plug in and play. The only wiring I had to do was connecting the 4 wires from the stepper to a DB9 connector.
I'll try lowering the acceleration to 100 (from it's current 185) to see if it helps. What would be a good test range for the speed?
Start at 1000-1500.
Gerry
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No, mm/min
If it's stalling, keep lowering both. But if you have similar settings for both motors, you probably have some other issue.
Gerry
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(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
The Nema 34 motors worked at almost every speed and acceleration setting I have tried so far. Only the Z axis had trouble when I made it too slow.
I am going to try again with the settings range you posted. If it still doesn't work, I'll try switching out the Nema 23 motor. I have two spares. Hopefully there isn't an issue with the y axis part of the drive....
I tried the suggested settings but no luck. I then tried removing the motor to see if it could move with no load and it could not. It sounds like there is some kind of mechanical lock inside the motor. The motor vibrates and jumps around on the table when I try and move it but the shaft does not rotate more than a few mm before bouncing back, like it hit something.
I guess I must have an issue with the motor or y axis on the G540.
Ahh the motor is not connected to power or is? If its connected to the powered up stepper driver and not moving thats the way its suppose to be. Remove the power the motor should have some resistance when you try turning the shaft, There are magnets inside and if you hook a meter to the leads when you try to turn you will see it generates a little voltage on both A and B winding.
If you posted a picture of your machine and the size others might be able to help with settings.
1000x750 Workbee CNC - Mach4 - PMDX USB - Windows 10 Pro
Plug the motor into a different axis and try it.
Gerry
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[URL]http://www.g-forcecnc.com/jointcam.html[/URL]
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
I replaced the motor with one of my spares and now it works....
Now I just need to find the right speed settings. The trial and error process is a lot less frustrating with a working motor. It looks like all 3 axis are capable of traveling far faster than I would ever need. I'll use the numbers suggested here and work up from there to find the stall point.
Thanks for the info.