Centroid Community CNC Support Forum

Thanks for the reply @eng199. Good points. Yes, I checked that the motors spun freely with the leads shorted. They do spin freely. The resistances are noted in the posting above.

The wiring for both the encoders and the motors are new. The only motor that actually moves relative to where the flexible conduit is anchored is the X. It is mounted to the table that traverses the machine and has a overall travel of +/- 20". It also has new flexible conduit. It appears that the coolant can harden the plastic and then the flexible conduit cracks. This is what happened to the original. The Y motor is mounted to the base casting of the machine. It does not move. The Z motor is mounted to the top of the machine and does not move.

The handwheel on the Y-axis is fixed to the shaft and therefore always moves with when driven. The X-Axis handwheel can be disengaged. Why Fryer chose to make it fixed on the Y and disengage on the X is a mystery.

The handwheel itself is a plastic Elesa with a diameter of 20cm [7.875"]. It weighs 1.7lbs. It has a steel hub and and a small steel insert for the folding handle. It is original equipment on this machine.
As for the transformer to step the voltage down, it has been one of the things that we discussed here. The motors and the power supply/bridge rectifier are both original and both from Analam. We think that despite the nameplate markings these two items were intended to work together and did work together. I believe that the Allin1 board is designed to handle the 167 vdc that we are getting at VM and then some. Does the Autotune cause the motor or drive to be subject to voltages or currents that it would be unusual in normal operation? The reason that I ask is that it was when we were running the auto tune sequence that the Y axis drive failed.

Would looking at the report help? We have the maximum velocity set relatively slow. You could confirm that and perhaps other settings that might be important.

This board had a problem in August and was sent to Centroid for repairs. When on the workbench, the output transistors for both the the X and Z were replaced. The Y failed this time.

The Vm voltage is higher than I would be comfortable with. ALLIN1DC can provide full Vm (100% duty cycle) to the motors if maximum current is requested. A maximum current move occurs in autotune to measure accel time. I suspect the Anilam drive did not provide full power in order to stay within motor ratings. This could have been accomplished with a duty cycle limit or different circuit topology. I am not familiar with their products, so I can't say for sure.

I have accidentally run motors with way too much voltage with no ill effects. However, it is plausible that the commutator could be damaged by voltage beyond its ratings. If the motor was damaged, the ALLIN1DC could be damaged.

I consider 168VDC the maximum for ALLIN1DC (120 AC rectified) in all cases. There is some headroom, but that should be the maximum before motion is started.

A report should always be included with questions. It reduces the amount of "free time" someone has to find to consider answering your questions. For example: 2880 in your profile is not your control serial number. Without a report, it took 15 or more minutes of "detective work" to locate the system history with reasonable certainty. I am in violation of the "no report, no support" company policy while working on your questions.

I can't see any definitive reason that your ALLIN1DC gets damaged. In these situations, I try to correct known potential problems (Vm too high for motors) and recheck everything starting from the basics.

I think the issue with Autotune is the regeneration when decelerating to a stop, at the end of the high speed move. If your VM level is already high, then trying to absorb energy back from the rapidly-spinning motor may drive it high enough to damage components. Adding flywheel weight to the ballscrew increases this issue.

My rules of thumb are:
1) Don't rectify 120VAC. Use a transformer.
2) If you must rectify 120VAC, remove any handwheels from the ballscrews
3) If you rectify 120VAC and leave handwheels in place, don't use Autotune.

cncsnw wrote: ↑Fri Sep 22, 2023 10:53 am I think the issue with Autotune is the regeneration when decelerating to a stop, at the end of the high speed move. If your VM level is already high, then trying to absorb energy back from the rapidly-spinning motor may drive it high enough to damage components. Adding flywheel weight to the ballscrew increases this issue.

My rules of thumb are:
1) Don't rectify 120VAC. Use a transformer.
2) If you must rectify 120VAC, remove any handwheels from the ballscrews
3) If you rectify 120VAC and leave handwheels in place, don't use Autotune.

this is good advice. i've seen a falling Z axis do the same thing as well, (generate power and take out the mosfets)

A transformer has been spec'd and wired in. Everything has been checked and double checked. There is no shorting of any of the motor wires as I move the X and Y through their full range of motion. The Z motor is fixed as is the Y motor. I moved the X and Y axis any way because it can move the flexible conduit.

I have to admit that the above comment by cncsnw gives me plenty of concerns. As a result, we decided that we are NOT going to Autotune the motors. We will use the settings that we had previously.

With 123VAC coming in, we are getting 144VDC out of the rectifier/power supply with no load. I expect that this is a good voltage to be at.

The Allin1 controller in back in the cabinet and the machine started up. We are using the previous tuning parameters. We moved the X, Y and Z and all motions seem to be good.

We ran a simple drill and countersink job. We wanted to start out easy and it ran good.

We are off to a good start. I don't know if I will be comfortable with this until we get about 100 hours of working time on it.

SlicedBread wrote: ↑Fri Oct 20, 2023 10:43 am The Allin1 controller in back in the cabinet and the machine started up. We are using the previous tuning parameters. We moved the X, Y and Z and all motions seem to be good.

We ran a simple drill and countersink job. We wanted to start out easy and it ran good.

We are off to a good start. I don't know if I will be comfortable with this until we get about 100 hours of working time on it.

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thanks for reporting back , watch the old mill training video now that you got things running!