Stepper upgrade

[matthewsx]

I've been using these steppers which were generously gifted to me by a fellow forum member with TB6600 drives.



But when I mocked up a direct drive for my Z-axis it became clear it just doesn't have enough umph for that configuration. Doing some research it looks like they're rated at 131oz/in which is on the lower end for Nema 23 motors.

I already have some DM542 drivers that I was planning on using with my Mesa Electronics controller upgrade and I see that Nema 23 is readily available in 270oz/in and 425oz/in versions. I've also seen that folks typically use a bigger motor for the Z-axis then X and Y. The little motors I have seem to work okay for X & Y but I did notice them struggling a bit on deep cuts.

So, I'm thinking of getting two 270oz/in for the X & Y axis and a 425oz/in for the Z-axis.

Any thoughts?


Thanks,

1ohn

 

[matthewsx]

So measuring my current base I don't think I'll be able to fit the 425oz/in. I may order just one 270oz/in motor and see if it will lift the head/spindle assembly. The little motor would almost do it and I'm thinking that the Z-axis motor mostly just has to be able to lift because gravity will help with down pressure.

1ohn

 

[coherent]

I'd just put larger (470 or 570oz) steppers all the way around and be done with it. They are only $39 ea or so at automation technology inc. I don't know what size your power supply is, but it may be a good time to just upgrade that also. The cost is minimal and the increase in stepper power is normally a good thing. Better too much than not enough. As another alternative... I've seen folks put a spring or hydraulic "assist" on their Z to counterbalance and help eliminate the weight issue and torque/lifting required on their Z with good results depending on your setup.

 

[matthewsx]

I'd just put larger (470 or 570oz) steppers all the way around and be done with it. They are only $39 ea or so at automation technology inc. I don't know what size your power supply is, but it may be a good time to just upgrade that also. The cost is minimal and the increase in stepper power is normally a good thing. Better too much than not enough. As another alternative... I've seen folks put a spring or hydraulic "assist" on their Z to counterbalance and help eliminate the weight issue and torque/lifting required on their Z with good results depending on your setup.

Yes, that's what I was thinking. Thanks for the supplier tip, they have the 425oz in a shorter form factor for only $32. That should get the job done....

Thanks,

1ohn

 

[devils4ever]

I've just completed my CNC conversion of my PM25 mill and I followed shooter123456's design and used NEMA23 motors rated at 400 oz-in for the X and Y axes. I used a NEMA34 motor rated at 1000 oz-in for the Z axis.

From my limited testing, it seems like I have plenty of torque all around. I wanted to do this once and not have to go back and upgrade.

 

[HobbyistDad]

270 in-oz NEMA 23 all three axis on my LMS 3990. TB6600 drivers set at 3 amps, 1/4 micro stepping, 24 VDC power supply.

No issues thus far and it's not fast, but it works and this setup is torquey enough for what I do.

 

[macardoso]

Be warned that the high torque motors have much steeper torque curves meaning less torque at moderate speeds. Look at the torque curves to see at what speed your motors fail (ie, 100ipm = X motor RPM = Y torque) and compare to the torque curve of the new motor to estimate what speeds you can expect.