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

[fasteddy]

Hi all..

One day, in the dim and distant future, I will finally kick all the bugs outa this cnc build, but not today it seems...

When I am jogging the x axis (dual drive nema 34's, slaved together in Mach3) it moves freely, until I try to also move the y axis simultaneously.. Then an awful grinding noise and the x axis completely stalls (no movement)... First picked this up last week when it was cutting a circle and it was rapid moving (G0) to the next cut, it stalled the x axis and therefore did not move to the right place..

I have since redone all the wiring and triple checked all mechanical movement which has made no difference, in fact I would say it has got slightly worse if anything..

I am using a Uniport controller, 2 x PM752 drivers (x-axis) and a PM540 driver for the y.. I have wired it all according to the plan shown here..



Anyone encountered this before? Any ideas? Wanna lend me a really big hammer..?


Steve..

[fasteddy]

Just to mention, I have reduced the motor tuning speeds and accelerations in mach3 until it now crawls at snail speed, no difference...


Steve..

[ptjw7uk]

Is the power supply man enough as your simultaneously driveing 3 motors when you move both X and Y.
Just a thought as I assume each drives well on their own.

Peter

[mocha]

If you'll forgive my ramblings, do you get the same problem with X and Z?

[fasteddy]

Hi guys..

In order..

PSU has plenty of power, am using a 55v 5amp for the nema 34's, and a separate 24v 2.5amp for the nema 23 (y axis, 3Nm)...
Dont get the same prob with the z and x... Only the x is stalling... And only in rapid, regardless of what I set the motor tuning to...



Steve...

[Gary]

it could be the psu? can you measure the DC voltage on the driver and see if it drops when you move the other axis? Also are you daisychaining the DC or comming back to a star point?

[Web Goblin]

Steve,
what current setting do you have the drivers set to?

Ian

[fasteddy]

Hi again..

Just gonna pop my lad to bed then will check what you guys have asked/suggested..

Steve..

[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.?