Re: Intermittant diagonal layer shift, how to diagnose? June 20, 2020 11:05PM |
Registered: 7 years ago Posts: 619 |
Indeed. The two lead screws are linked by a belt loop to a single stepper, the same type as the X/Y steppers, so plenty of power and the bed is not heavy.Quote
the_digital_dentist
I think there's something wrong with the Z axis if the nozzle is banging into the print hard enough to cause layers to shift.
Re: Intermittant diagonal layer shift, how to diagnose? June 20, 2020 11:52PM |
Registered: 10 years ago Posts: 294 |
Quote
the_digital_dentist
I think there's something wrong with the Z axis if the nozzle is banging into the print hard enough to cause layers to shift.
Re: Intermittant diagonal layer shift, how to diagnose? June 21, 2020 02:05AM |
Registered: 11 years ago Posts: 14,685 |
Re: Intermittant diagonal layer shift, how to diagnose? June 21, 2020 02:43AM |
Registered: 7 years ago Posts: 619 |
Quote
dc42
If you think the issue may be that the Z axis isn't moving enough, have you tried reducing Z axis acceleration?
Re: Intermittant diagonal layer shift, how to diagnose? June 22, 2020 12:01AM |
Registered: 7 years ago Posts: 619 |
Re: Intermittant diagonal layer shift, how to diagnose? June 22, 2020 11:54AM |
Registered: 10 years ago Posts: 294 |
Re: Intermittant diagonal layer shift, how to diagnose? June 22, 2020 12:14PM |
Registered: 12 years ago Posts: 5,796 |
Re: Intermittant diagonal layer shift, how to diagnose? June 22, 2020 02:07PM |
Registered: 7 years ago Posts: 619 |
Quote
the_digital_dentist
What does it mean that "overpowers the belt" and it slips? Is the belt slipping on the drive pulley or is the motor slipping - i.e. missing steps?
Neither of those should happen, especially not at such a low speed. Are the motor and pulley mounts solid? Adequate tension on the belts?
Excessive jerk speed or acceleration? High voltage (12V) motors? Low power supply voltage (12V)?
I have 64 oz-in motors (relatively small, low torque motors) in XY and have no problems with layer shifts or anything slipping and can drive the mechanism at over 200 mm/sec even with acceleration set to 10k.
Re: Intermittant diagonal layer shift, how to diagnose? June 22, 2020 03:43PM |
Registered: 12 years ago Posts: 5,796 |
Re: Intermittant diagonal layer shift, how to diagnose? June 22, 2020 04:37PM |
Registered: 10 years ago Posts: 294 |
Quote
the_digital_dentist
What does it mean that "overpowers the belt" and it slips? Is the belt slipping on the drive pulley or is the motor slipping - i.e. missing steps?
Neither of those should happen, especially not at such a low speed. Are the motor and pulley mounts solid? Adequate tension on the belts?
Excessive jerk speed or acceleration? High voltage (12V) motors? Low power supply voltage (12V)?
I have 64 oz-in motors (relatively small, low torque motors) in XY and have no problems with layer shifts or anything slipping and can drive the mechanism at over 200 mm/sec even with acceleration set to 10k.
Re: Intermittant diagonal layer shift, how to diagnose? June 22, 2020 09:22PM |
Registered: 7 years ago Posts: 619 |
Quote
the_digital_dentist
"Tight, but not too tight"- if they can slip on a drive pulley, the belts are definitely too loose. Usually, in a corexy printer, if the belts are so loose they slip on the drive pulleys, there's a problem with the belt positioning relative to the X and Y axis guide rails or linear guides. Be sure the pulleys are positioned so that the belts are parallel to the guide rails. When they are positioned properly the belt tension won't change when you move the extruder carriage around from one place to another.
You don't have to be an ME. Just use what you know- thin things flex, thick things don't- and start from there. Pull on the belts, see what flexes, and fix those things first.
Re: Intermittant diagonal layer shift, how to diagnose? June 22, 2020 10:14PM |
Registered: 12 years ago Posts: 5,796 |
Re: Intermittant diagonal layer shift, how to diagnose? July 02, 2020 11:03PM |
Registered: 7 years ago Posts: 619 |
Quote
the_digital_dentist
Maybe the range of adjustment for the belt tensioners is too small. It should be impossible for the motors to apply enough force to get the drive pulley to skip on the belt teeth.
Post a picture of the printer showing the XY belts from above, and maybe a few close-ups of the idler pulleys, motor mounts, and belt tensioners.
If you manually move the extruder carriage around, does the belt tension remain constant?
Re: Intermittant diagonal layer shift, how to diagnose? September 13, 2020 05:21AM |
Registered: 4 years ago Posts: 11 |
Re: Intermittant diagonal layer shift, how to diagnose? September 13, 2020 10:50PM |
Registered: 7 years ago Posts: 619 |
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RockyAussie
I noticed that de42 had suggested dropping your z acceleration speed and am wondering if you had tried that and by how much? I had a bit of an issue with the Tronxy x5sa pro when I increased the overall acceleration speed (M8008) from 100 to 700 and the Jerk (M8007) from 20 to 10 and that resulted in a total stop when the head went from front left to rear right and the z started. The fix for this eventually was to bring the maximum speed of the Z (M8013) from 20 down to 5. That worked and the prints are now smoother (Less jerky)and faster and as yet I have not seen any degradation in the prints.
I am not by any means very knowledgeable with this stuff but I reasoned out that the Z does not need all that current draw at the same time as all the others are sucking it up and the board seems to agree with me so far. If you are doing anything on your Tronxy like this you need to do your extruder speeds at the same rate as the others, (8007 I10 and 8007 E10 and 8008 I700 and 8008 E700. I hope this may be of some help. Regards Brian
Re: Intermittant diagonal layer shift, how to diagnose? September 14, 2020 06:21AM |
Registered: 4 years ago Posts: 11 |
Re: Intermittant diagonal layer shift, how to diagnose? September 15, 2020 08:09PM |
Registered: 12 years ago Posts: 5,796 |
Re: Intermittant diagonal layer shift, how to diagnose? September 15, 2020 11:42PM |
Registered: 7 years ago Posts: 619 |
Quote
RockyAussie
To Quote - I am quizzing the Exoslide guy about this, I am using Exoslides for my X and Y axis
I have looked at the design of these on the tube over and over and I have to say I would be quite concerned about having so many rollers continually running along soft and sometimes dirty aluminium. I have seen some applications where running 3 rollers has worked better than 4 let alone 16 as shown in their intro video. That is a LOT of surface area waiting for the rolllers to pick up any little nick or dust particles. Just another observation over time to consider.....many people try and make the top as solid and inflexible as possible and I have noticed way less problems when the hot end is able to move/flex upward just enough to not get knocked out of line when it hits some cold parts of the print. It generally all smooths out fine in the end.
Re: Intermittant diagonal layer shift, how to diagnose? September 16, 2020 12:26AM |
Registered: 12 years ago Posts: 5,796 |
Re: Intermittant diagonal layer shift, how to diagnose? September 16, 2020 12:43AM |
Registered: 7 years ago Posts: 619 |
Hmm. Those are good ideas. Figuring out if the entire rig is perfectly square is a challenge. I am a programmer, not an ME. What is a good way of determining this? Can it be done without a fancy tool?Quote
the_digital_dentist
The way you know if the belt tensions are correct relative to one another is that the X axis is square with the Y axis. The absolute tension is another matter- it should be tight but not too tight. In my printer the belt tension is adjusted by sliding the motor mounts back so I get a direct feel for how hard I am pulling on them. If your belt tension adjustment uses a screw it might be harder to get a feel for it. Try plucking a long span of belt - it should ring at a very low frequency. If you suspect the mechanism is binding, try loosening the belts a bit.
Re: Intermittant diagonal layer shift, how to diagnose? September 16, 2020 01:15AM |
Registered: 4 years ago Posts: 11 |
Re: Intermittant diagonal layer shift, how to diagnose? September 16, 2020 10:04AM |
Registered: 4 years ago Posts: 31 |
I am trying to figure out how mine can be anything but square and I can't see it. However, If it is far enough off it could cause binding in the movements. Also if you print a square, it will be a parallelogram but not square. A perfect square will have equal diagonals. So print a square in a few lines/layers at the limits of your bed and measure those.Quote
dlc60
Hmm. Those are good ideas. Figuring out if the entire rig is perfectly square is a challenge. I am a programmer, not an ME. What is a good way of determining this? Can it be done without a fancy tool?
Thanks,
DLC
Re: Intermittant diagonal layer shift, how to diagnose? September 16, 2020 10:58AM |
Registered: 12 years ago Posts: 5,796 |
Re: Intermittant diagonal layer shift, how to diagnose? September 16, 2020 11:26AM |
Registered: 4 years ago Posts: 31 |
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the_digital_dentist
If the frame is square, and the Y axis rails are parallel to the frame rails, all you need is a ruler to check if the axes are square- move the X axis to one end of the Y axis and measure the distance from the end of the X axis to the edge of the frame at both ends of the X axis. if it's square the distances will be the same. Verify by printing a rectangular object and measure diagonals.
Re: Intermittant diagonal layer shift, how to diagnose? September 16, 2020 02:55PM |
Registered: 12 years ago Posts: 5,796 |
Re: Intermittant diagonal layer shift, how to diagnose? September 16, 2020 04:14PM |
Registered: 4 years ago Posts: 31 |
Quote
the_digital_dentist
If the frame is square it works fine. if your frame isn't, all bets are off.
Re: Intermittant diagonal layer shift, how to diagnose? September 16, 2020 06:40PM |
Registered: 7 years ago Posts: 619 |
I printed a 40mm cube, and it was square, and very close to 40mm on each axis.Quote
dustinoff
Quote
the_digital_dentist
If the frame is square it works fine. if your frame isn't, all bets are off.
Well, isn't the question about how to determine squareness. The only way to do that, other than a lab instrument to measure 90°, is to measure the diagonals. But on printer hardware, measuring two diagonals accurately seems to me to be pretty difficult. The easiest thing one can do is to print a big square/rectangle and measure its diagonals. Then you can relate that back to your hardware. Otherwise, you will just be hand grenade close.
Re: Intermittant diagonal layer shift, how to diagnose? September 16, 2020 09:48PM |
Registered: 4 years ago Posts: 31 |
Re: Intermittant diagonal layer shift, how to diagnose? September 16, 2020 11:57PM |
Registered: 7 years ago Posts: 619 |
"square, and very close to 40mm on each axis"Quote
dustinoff
Quote
dlc60
I printed a 40mm cube, and it was square, and very close to 40mm on each axis.
DLC
measuring each side does not tell you it is square. You must measure the diagonals.
Re: Intermittant diagonal layer shift, how to diagnose? September 17, 2020 09:19PM |
Registered: 12 years ago Posts: 5,796 |
Quote
dustinoff
Quote
the_digital_dentist
If the frame is square it works fine. if your frame isn't, all bets are off.
Well, isn't the question about how to determine squareness. The only way to do that, other than a lab instrument to measure 90°, is to measure the diagonals. But on printer hardware, measuring two diagonals accurately seems to me to be pretty difficult. The easiest thing one can do is to print a big square/rectangle and measure its diagonals. Then you can relate that back to your hardware. Otherwise, you will just be hand grenade close.