[tech_builder]

Hi,

I am having some trouble with the spindle of my mini mill (LMS SX2). It is intermittently pausing while running and even while running seems to be unstable ie. the RPM seems to vary a bit while running.

I noticed that Automation Technologies has a DC brushless motor controller for sale and I would like to know if it is compatible with the SX2 motor.
The motor on the mill says that it is 230V 2.8A 500W. Below is a link to the motor controller:

High-Torque Stepper Motor, Stepper Motor, Driver, Stepper Motor kit, DC Servo Motor, DC Servo Motor kit, Stepper Motor Power Supply, CNC Router, Spindle, and other Components. Automation Technology Inc

Has anyone tried this yet?

[Al_The_Man]

That drive is 50vdc Max. I have ran the BLDC motor from an A-M-C drive, also tried the 230v version to get max rpm.
IIRC they are 2 pole motors, this is one of the reasons they do not operate well at low RPM, a 6 pole would have been better.
Al.

[tech_builder]

Thanks for the quick reply! Could you tell me what model you have? Do you remember the cost?

Thanks so much!

[tech_builder]

Hi,

Yes this is the High Torque mini mill. I did get the replacement potentiometer from them and have had it in place for a while. It seemed to be running ok for the last while, but I just changed the bearings in the spindle to taper roller bearings because the bearings I got with the LMS high speed conversion kit were heating up quite a bit. From the little testing I have done, these new taper roller bearings seem to run cooler. The deep groove bearings in the original setup ran at 50 -70 C after a few minutes no load (at any RPM over 2500), now it seems to stay at about 43 C with the taper bearings even after running at 5000 RPM for several minutes (which I never did with the deep groove bearings).
I`m thinking the intermittent control might be due to the wiring in the control box on the back of the mill because I opened it up to look inside for any kind of obvious problems and after I put it back on it seemed to run ok...it hasn`t stalled once and I have had it running at various speeds for over 30 minutes.
A video to the problem before this can be seen here:

https://www.youtube.com/watch?v=uJDafio0W5Y

I still don`t trust this controller though and would like to replace it with something better - and easier to control from the computer for CNC applications.

[Al_The_Man]

Thanks for the quick reply! Could you tell me what model you have? Do you remember the cost?

Thanks so much!

I used a B30A40 off of ebay, if you get the AC suffix model, it comes with built in DC supply.
Or a B40A20 if running off of 120vac.
The input is ±10vdc analogue.
You can run off of Mach with one of the PWM to analogue BOB's.
That effect in the video smacks of commutation problem, it is in the Halls themselves, it could carry over to the next drive?
BTW both those drives will also run a brushed DC motor.
Al

[olduhfguy]

I would like to get my hands on a non-working Sieg BLDC controller. I currently repair the DC motor controllers and want to do a post-mortem on a BDLC controller so I can design a mockup to repair future ones.