Y axis is making X axis stall...!!

[fasteddy]

Just a thought...

Have been roving around all the cnc forums trying to find another with the same probs... I have seen an awful lot of posts about earthing, but I have to say, as a complete burp at electronics, I ended up more confused than when I started... Cant get my head aound the myriad of different advice being handed out, and much of it was american.. Do they use different terms for all that common,starpoint,earth,neutral,-ve supply/rail,0 volt stuff? Damned if I can work out what they are in English without even more varying terminology.. I ramble..

Does seem to be a big cure-all for a lot of electronics issues so I was wandering if there is a good post/guide to earthing for us feeble minded noobs? From what I have read, I ought to do this as a matter of course, if only to eliminate several potential problems...

Steve..

[JAZZCNC]

Seems to me that you have several issues that could and will be causeing this problem. . . First reduce the microstepping to 2000. Not much to gained above this it will also ease the PP work load. . . . Also good idea to run the driver test in Mach folder to test how well your PP works.
Then re tune your motors and see how it performs.

Next 24V is way too low for these motors and will restrict rapid speeds, this would be the first place I would turn to. . . . You could easily double this figure with these motors (If the drives can handle it)

Regards daisy chaining and grounding etc it's not really rocket science but is important if you want to restrict potential problems.
Basicly when running power from the power supply you want to run a separate wire to each drive not 1 wire to first drive then jump or "daisy chain" from this to next drive.

Think of the PSU as the centre of a star with all single wires running from it out to each component that needs to takes power from it.

The same applies to the ground wires, run each ground back to 1 central ground point. It's a good idea to have single ground connector with multiple connections, basicly you dont want multiple ground points around the machine other wise you can introduce ground loops which can cause noise issue's. Thou I'm pritty sure this is not your problem.

Their is another potential problem that can cause what you are experiencing. . . Mid band resonance.!!
This is caused by resonance from the machine which at a certain point in the accelleration curve interfears with the pulse stream going to the motors causing all sorts of random issue's.! rough sounding motors and poor performance as well has stalling as the speeds increase are just some of them.
Some drives have compensation for this built in some don't.! . . Not sure if yours do or not.?

If I was to place a bet on your problem I'd put money on it being down to 24V supply. . . And possibley too high on the stepping.

Also what Kernal speed are you running Mach at.?

[Karl]

Same/very similar problem here. When jogging an X-Y table with MACH3 at full speed (400mm/min) in either the Y+/Y- direction and then, at the same time, attempting to jog either X+/X- at full speed [and completely vice versa] there are a lot of loud horrible mechanical noises and the table clearly stops moving correctly. This is 100% repeatable. Not seen this happen when machining a piece - that said I'm not aware of a situation where the machine is asked to move full speed in, say, the X direction whilst it's already moving full speed in the Y direction. I assumed - for no good reason - that this was a MACH3 jogging thing. So now I'm very interested in the answer.

Setup:
Motors: SY60STH88-3008BF (x3)
Driver: PM542 @ 1,600 pulses per rev, 2.37A(Peak) [1.69A(RMS)]
Supply: 43V
MACH3 motor config': 627 steps per mm, 400mm per min

[Jonathan]

I'm not aware of a situation where the machine is asked to move full speed in, say, the X direction whilst it's already moving full speed in the Y direction. I assumed - for no good reason - that this was a MACH3 jogging thing. So now I'm very interested in the answer.

Nothing to stop you running a program like this. It's conceivable on a drilling cycle.

G21 G61
G0 X0 Y0
G0 X100 Y100
G0 X0 Y0
G0 X100 Y100
G0 X0 Y0
G0 X100 Y100

Setup:
Motors: SY60STH88-3008BF (x3)
Driver: PM542 @ 1,600 pulses per rev, 2.37A(Peak) [1.69A(RMS)]

You and Steve are both running these motors in Bipolar series, not parallel ... interesting.

No problem, let Steve have first call then it's over to you.

Thanks :)

[fasteddy]

Hi Jonathan..

I had always thought bipolar series was preferred to get the higher speeds? Is parallel better?

Steve..

[Jonathan]

I had always thought bipolar series was preferred to get the higher speeds? Is parallel better?

Yes parallel is generally faster. Bear in mind the current the drivers is set to also makes a difference as the torque is roughly proportional to the current (until you go much above the rated current and the rotor saturates). If the nearest current setting to the current in series is greater than the parallel setting then it may not make much difference. Karl has the motors on 2.37A, and the rating is 2.1A so it's already 13% over. The PM542 maximum is 4.2A, so the same as the motors ... so if putting in parallel gains less than 13% then you may not gain anything though it would be nicer. There's more to it than that though... in the end it's easiest to just try it and see. Keep an eye on the motor temperature too.

[JAZZCNC]

You and Steve are both running these motors in Bipolar series, not parallel ... interesting.

If so then it's very likely your way under voltage and just simply running out of torque, the torque drops off very quickly when wired series.!#

[Jonathan]

If so then it's very likely your way under voltage and just simply running out of torque, the torque drops off very quickly when wired series.!#

However, for completeness, the torque when wired in bipolar series is greater at low speed than the same motor wired in parallel.

It looks like in Steve's case it's the Y/Z axis motors that are in series, and they're not at fault. Still worth trying, as long as the power supply can take it.

[JAZZCNC]

However, for completeness, the torque when wired in bipolar series is greater at low speed than the same motor wired in parallel.

It looks like in Steve's case it's the Y/Z axis motors that are in series, and they're not at fault. Still worth trying, as long as the power supply can take it.

Yep exactly, thou as the speed rises the torque drops away very quick in series and because the X axis needs the most torque due to it's mass and it's happening when rapiding I'd be changing to parallel.

Edit: That said I still don't think this is Steves problem due to him having the problem at lower speeds.?????

[Karl]

Just taken some motor current measurements on my machine - measured at the output of the star-wired PSU:

- Powered up but stationary the 3 drivers and motors together pull 0.87A (DC) total. Motors bipolar series. Driver PM542 settings now 2A (RMS) limited.
- MACH3 jogging X,Y or Z axis individually pulls 1.36A during acceleration levelling at 1.25A - this is the machine's full MACH3 limited speed of 400mm/min.

Jogging in, say, X and then also jogging Y - ie causing the horrible mechanical noises and poor movement - pulls 1.6A to 1.9A total.

Jogging the Z full speed and then - at the same time - jogging either the X or Y in any direction does not cause any problem (likewise moving either X or Y and then engaging Z causes no problem).

My PSU is rated at (43V) 5+ amps so, given the figures above, current does not seemed to be an issue.

I'm wondering if this problem is due to inertia/momentum/twisting forces in the, not very expensive, X-Y table?