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

[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..

[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.!#

[michael]

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..

Hi Mate, are you using Mach3 with a parallel port? If so what kernel speed are you using and what is the maximum velocity for the X and Y axis.

Mike.

[fasteddy]

Hi again..

Bit more info on the problem.. It only seems to happen when moving x and y in full rapid, if one or other of the axis is not moving at full speed it does not happen i.e. it happens when rapid at 45 degrees, but not 30 degrees... If that makes sense... Sorta guessing both motors are at full throttle when moving at 45 degrees rapid..

Some more info on my setup..
X axis is a pair of SY855TH80-5504B steppers driven by a pair of PM752 drivers.. The settings on each driver is;
3200 microsteps
5.5amps

Y axis (and z) is a 3Nm nema 23 (from Zapp) on a PM540 driver, settings are;
3200 microsteps
2.5 amps

Got my specs wrong on my PSU's earlier, should be;
X axis run by a single PSU (separate outputs) which delivers 65v 8amps..
y and z share a 24v 4amp PSU..

Will test voltages tomorrow when I can get a new battery for my multimeter...
Am 99.9% sure it is something electronic as I have torn apart and rebuilt every mechanical part and everything is freely moving.. Also, I am a decent engineer and a crap electrician with only slightly more knowledge of electronics than my cat...

Steve..

[fasteddy]

Wow Jazz.. Lots to chew on...

Ought eliminate a couple of potential probs tho... I am not daisy chaining the motors/drivers with power, all have there own separate feeds/wires.. Not sure what the voltage limit is for these motors and I have been frowning a smidge at the 24v power supply as a possible weak point.. But the y axis is not stalling, and my last cnc was driven by just that one 24v psu, and it drove 4 x 3Nm motors then with no probs like this one...

Was running Mach3 at 25Khz, ramped it up to 45Khz in trying to fix this prob and it made no difference (using a dual P4 board, 2 gig ram with XP in desktop PC mode) so I left it at 45KHz..

Driver test is fine..

By ground, you mean earth right? Connect 0v and or ground to earth? Read this many times but when I look into my box of tricks, there are an awful lotta grounds and 0v points, more if you eyeball the PSU's too.. Pass the aspirin...

Mid band resonance... Is this a resonant frequency of the machines mechanical structure? If so I doubt this is a problem as the motors are very smooth and pretty quiet (apart from that dull thump caused by backlash comp in Mach3) until the very sudden growl from the nema 34's when they stall.. The fact that they both stall, and bearing in mind they are slaved together in Mach3, still suggests something electronic tho... Also as both the y and x are running at full speed simultaneously suggests it might be power, so will get a new battery for my multimeter first thing tomoz...

Will drop the steps as you suggest and check some voltages in the a.m. Starting to get intrigued by earthing, really feeling the need to get that one outa the way..

Steve..

[JAZZCNC]

By ground, you mean earth right? Connect 0v and or ground to earth?

Yes by ground I mean Earth.
One Earth point which each mains device leads back too or picks up from.

Basicly all roads lead to Rome or in this case one earth point.

[Gary]

Are your phase cables and signal cables shielded?
If not you may find that noise is being picked up on the signals.
This may be hitting the direction signals and causing one of the x axis to be changing direction?
disconnect the direction signals on the x axis and see if it still happens.

[fasteddy]

Chicken or egg?

Not sure if the problem caused this, or if this is the problem... On the power supply for the nema 34's (x axis), I have just discovered a 'crispy' component.. Think its a resistor, I can only read '8K' on its blackened surface.. I was about to check voltage outputs from this PSU when I saw a tiny wisp of smoke come from it.. I have switched it all off and will contact the chap that sold it to me to see if he knows what it is..

Steve..