Good cuts, THC working good, Z loses machine coordinates?

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BoenBuilt
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Good cuts, THC working good, Z loses machine coordinates?

Post by BoenBuilt »

Maybe I missed something simple in the setup. We are using rtelligent closed loop steppers, which will reliably run the x and y at 1000 ipm. 10mm lead ballscrew on the Z. Grounding seems good, ohmic works reliably. Home switches on all axis, Y and N slaved, auto square works. Pid config trace for the divided voltage only shows a ripple from 0 to 3 counts.

Z axis coupler is a tight, diaphragm type with sleeve retainer loctite, it is not slipping, and even if it was machine coordinates for the Z would stop at 0 when you jog it all the way up.

After a few cuts with the THC enabled the machine coordinates for the Z get messed up, and you can't jog the Z back up to the top of the travel range (soft limits)

Are we not supposed to have soft limits on the Z? I have it set to +0, -7.5" just like I would on a router.

So far everything else is working great.


I reinstalled CNC12 today, set everything back up in the wizard, and ran a new torch calibration.

Thanks for any help.
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Joey
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Re: Good cuts, THC working good, Z loses machine coordinates?

Post by Joey »

Z Soft limits can be used with Plasma. Ill load your report onto my machine and check out what's going on.

I did notice that your counts per rev and overall turns ratio are quite Low.

The RTELLIGENT Stepper drives can be set to a wide range of Steps Per Revolution. Try setting to 6400 Steps per revolution for the X and Y. This should the machine better resolution for the X and Y axis.

Overall Turns Ration Could be improved but Thats usually more time consuming than just flipping the Dip switches on the Drives. So At least Upping the Counts per Rev will Help.

Also the Accel/Deccel rate looks fairly slow. For a Wood Router the Accel/Deccel rate isn't as important as a plasma Table. The Plasma table should come up to full Feedrate ASAP. More Time Spent at full Feedrate during Plasma cutting the Better the Cut Quality. I Would try to get closer to .2 If possible with your Table.
BoenBuilt
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Re: Good cuts, THC working good, Z loses machine coordinates?

Post by BoenBuilt »

Thanks,

I had thought about upping the steps per rev on the drivers. The motors are performing great so far.

The machine can do .3 to .35 acceleration, I slowed it down to see if it made a difference on Z losing machine coordinates, which it didn't.

The cuts are great in the x and y at book feeds, the Z loses its machine coordinates after a few cuts with THC enabled, and I'm not able to jog it up near the home switch. Machine coordinates get further away the more cuts we do. They should never be a positive number on the Z if 0 is at the top of travel, but I'm getting like +1.3 something when I jog Z up and it's still a few inches from the home switch. Not sure how CNC12 is letting that happen?

Let me know what you find out. This is the last hurdle before we can start making some money back on this machine.

Thanks!!

Dylan
Joey wrote: Thu Jun 08, 2023 12:13 pm Z Soft limits can be used with Plasma. Ill load your report onto my machine and check out what's going on.

I did notice that your counts per rev and overall turns ratio are quite Low.

The RTELLIGENT Stepper drives can be set to a wide range of Steps Per Revolution. Try setting to 6400 Steps per revolution for the X and Y. This should the machine better resolution for the X and Y axis.

Overall Turns Ration Could be improved but Thats usually more time consuming than just flipping the Dip switches on the Drives. So At least Upping the Counts per Rev will Help.

Also the Accel/Deccel rate looks fairly slow. For a Wood Router the Accel/Deccel rate isn't as important as a plasma Table. The Plasma table should come up to full Feedrate ASAP. More Time Spent at full Feedrate during Plasma cutting the Better the Cut Quality. I Would try to get closer to .2 If possible with your Table.
BoenBuilt
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Re: Good cuts, THC working good, Z loses machine coordinates?

Post by BoenBuilt »

ShawnM
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Re: Good cuts, THC working good, Z loses machine coordinates?

Post by ShawnM »

I just looked at your report for noises issues and see one or two pc resends but what really jumps out more is the revs/in on your plasma. They are less than 1 for both the X and Y axis. You might want to consider a different gear reduction to get much better cuts.

Have a look at this post- https://centroidcncforum.com/viewtopic. ... 232#p75232
BoenBuilt
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Re: Good cuts, THC working good, Z loses machine coordinates?

Post by BoenBuilt »

Thanks,

I'm aware we are just outside the sweet spot. Trying to work with the mechanics we had on the machine just with new motors and control. I can go to smaller pinion gears in the future, for now I'll up the step ratio on the drivers.

Any idea why the Z loses machine coordinates?

ShawnM wrote: Thu Jun 08, 2023 4:17 pm I just looked at your report for noises issues and see one or two pc resends but what really jumps out more is the revs/in on your plasma. They are less than 1 for both the X and Y axis. You might want to consider a different gear reduction to get much better cuts.

Have a look at this post- https://centroidcncforum.com/viewtopic. ... 232#p75232
ShawnM
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Re: Good cuts, THC working good, Z loses machine coordinates?

Post by ShawnM »

I'd start by wiring those drives to the DB25 and not the headers. Second, set the step rate to 100,000 for those stepper drives and lastly try slowing down the Z axis a little and see if any of these things help.

Post a link to the model number and a manual for those drives. Without a model number or manual we are just guessing.

My guess is any one or all of these are causing you to lose steps. I know you need a snappy Z for plasma but you are probably over-driving the Z axis and with the higher step rate and wiring them to open collector outputs isn't helping. The headers are for servo drives and a very limited few stepper drives. This is outlined in the manuals.
BoenBuilt
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Re: Good cuts, THC working good, Z loses machine coordinates?

Post by BoenBuilt »

The drives can take 24 volts input http://www.rtelligent.net/upload/wenjia ... Manual.pdf

The Z is not losing steps or alarming out. The machine coordinates are set to 0 after homing, with the home switch at the top of travel on the Z. After a few cuts with THC on, the machine coordinates change, and top of travel on the Z is now a positive number in the DRO, which screws up the soft limits.

If it was losing steps (which it can't because closed loop) jogging the Z up to the top of travel would still be 0 in the machine coordinates, not a positive number.

The X and Y act completely normal.
I'm at a loss.



ShawnM wrote: Thu Jun 08, 2023 9:37 pm I'd start by wiring those drives to the DB25 and not the headers. Second, set the step rate to 100,000 for those stepper drives and lastly try slowing down the Z axis a little and see if any of these things help.

Post a link to the model number and a manual for those drives. Without a model number or manual we are just guessing.

My guess is any one or all of these are causing you to lose steps. I know you need a snappy Z for plasma but you are probably over-driving the Z axis and with the higher step rate and wiring them to open collector outputs isn't helping. The headers are for servo drives and a very limited few stepper drives. This is outlined in the manuals.
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Re: Good cuts, THC working good, Z loses machine coordinates?

Post by tblough »

It may be a closed-loop servo, but it's an open loop system. Acorn does not know the servo position. It can only calculate where it should be. If the closed-loop servo loses steps, the only way Acorn knows something is wrong is if you have thecservo configured to fault on an error AND you connect that fault output to the Acorn.
Cheers,

Tom
Confidence is the feeling you have before you fully understand the situation.
I have CDO. It's like OCD, but the letters are where they should be.
BoenBuilt
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Re: Good cuts, THC working good, Z loses machine coordinates?

Post by BoenBuilt »

Alarm output from the drives are hooked to the Acorn, and tested working. These motors and drives have 4000 count per rev encoders, and I have them set to alarm if they get more than 1000 counts out( default is 4000 counts)

My main question is if I have the travel limits on the Z set to +0 -7.5" and I have the Z home to a switch on the top of travel, how do the Acorn machine coordinates end up changing from +0 -7.5" after running the machine with THC enabled.
tblough wrote: Thu Jun 08, 2023 11:10 pm It may be a closed-loop servo, but it's an open loop system. Acorn does not know the servo position. It can only calculate where it should be. If the closed-loop servo loses steps, the only way Acorn knows something is wrong is if you have thecservo configured to fault on an error AND you connect that fault output to the Acorn.
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