Anonymous User
Re: Problems with Dual Z Axis Drivers April 11, 2016 04:18AM |
Re: Problems with Dual Z Axis Drivers April 11, 2016 06:20AM |
Registered: 9 years ago Posts: 1,873 |
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the_digital_dentist
I read at one manufacturer's site that for gear-belt pulleys, you want a minimum of 6 teeth or a minimum of 90 degrees wrapped, whichever is greater. Make sure the tension is good, too.
Re: Problems with Dual Z Axis Drivers April 11, 2016 11:36PM |
Registered: 8 years ago Posts: 35 |
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JamesK
natural alignment of the X axis is slightly off
Re: Problems with Dual Z Axis Drivers April 12, 2016 04:12AM |
Registered: 8 years ago Posts: 260 |
Re: Problems with Dual Z Axis Drivers April 12, 2016 07:33AM |
Registered: 11 years ago Posts: 5,780 |
Re: Problems with Dual Z Axis Drivers April 12, 2016 07:58AM |
Registered: 8 years ago Posts: 260 |
Re: Problems with Dual Z Axis Drivers April 12, 2016 08:36AM |
Registered: 9 years ago Posts: 1,873 |
Quote
Your on a belt system with one z-axis motor. You can only see the motor missing steps though parts coming out out of spec. in z. It still probably wouldn't be very pronounced. Missing steps in a belt system won't cause misalignment which is the purpose of the belt. It sounds like your printer is large.
I've asking if you've marked your two z-axis couplers or whatever your can mark on the screws of your system. Maybe just mark the screws/threaded rod. It seems impossible for the axis to drift out alignment unless those screws also drift. When I was having z-axis problems on my build they were drifting.
Re: Problems with Dual Z Axis Drivers April 12, 2016 08:39AM |
Registered: 11 years ago Posts: 5,780 |
Re: Problems with Dual Z Axis Drivers April 12, 2016 08:42AM |
Registered: 8 years ago Posts: 116 |
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the_digital_dentist
What you have described is EXACTLY the problem with dual motor Z axes. Adjusting the X axis to the bed is perfectly wrong! The X axis has to be orthogonal to the Z axis. If you tweak the X axis to match the bed (like certain people at the makerspace keep doing in spite of having it explained to them about 100 times) it may not be orthogonal to the Z axis. The bed should be leveled relative to the X and Y axes. If the axes (all of them) are not orthogonal you cannot print accurately shaped and sized items. If your prints aren't accurately shaped and sized you'll be limited to printing Yoda heads and tugboats. Even the most hardcore Starwars fan gets tired of that eventually and wants to print something else.
Autoleveling won't help either. Autoleveling assumes the axes are orthogonal. If the X axis tilts, you may get the first layer to stick with autoleveling but the print will not be accurately shaped or sized.
Properly aligning the X axis to the Z axis requires printing a rectangular part and measuring the diagonals. When the diagonals in the XZ plane measure the same, the axes are orthogonal. With a dual motor setup, you can never be sure that that relationship will last. Some uninformed or willfully ignorant person may come along and twist one of the screws manually to "level" the bed, or some electrical or mechanical problem may cause the screws to lose sync and tilt the axis.
TLDR: Dual motor Z axes suck!
Re: Problems with Dual Z Axis Drivers April 12, 2016 08:56AM |
Registered: 9 years ago Posts: 1,873 |
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If your premise is that the motors may not do what the gcode tells them to do, then the whole machine is flawed, not just the dual-stepper Z. In theory, a single motor driving two leadscrews via a belt and pulley arrangement is flawed in that the second leadscrew is necessarily going to lag the first due to stretching, backlash, etc. In practice, I doubt this is much of a problem, but then again, in practice (at least in my experience) the dual-stepper Z is not a problem.
Re: Problems with Dual Z Axis Drivers April 12, 2016 08:57AM |
Registered: 8 years ago Posts: 260 |
Re: Problems with Dual Z Axis Drivers April 12, 2016 09:01AM |
Registered: 9 years ago Posts: 1,873 |
Re: Problems with Dual Z Axis Drivers April 12, 2016 11:18AM |
Registered: 8 years ago Posts: 260 |
Anonymous User
Re: Problems with Dual Z Axis Drivers April 12, 2016 05:43PM |
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hoxsiew
Quote
the_digital_dentist
.....
TLDR: !
I have to respectfully disagree. If your premise is that the motors may not do what the gcode tells them to do, then the whole machine is flawed, not just the dual-stepper Z. In theory, a single motor driving two leadscrews via a belt and pulley arrangement is flawed in that the second leadscrew is necessarily going to lag the first due to stretching, backlash, etc. In practice, I doubt this is much of a problem, but then again, in practice (at least in my experience) the dual-stepper Z is not a problem.
Anonymous User
Re: Problems with Dual Z Axis Drivers April 12, 2016 06:03PM |
Quote
amigob
I mounted a 3mm bold in the blocks that are glued to the glass plate.
Two self-locking nuts ( I whore then down with a tap ) one above the carrier and one below. It is easy to adjust because you can also use tension on the nut for the last 10Um
To level the bed ( orthogonal to Z ) in X I just used a big square ( don't know how it is really called in English )
then get the X axes parallel to the bed and then the single bed mount adjust on the other side with the use of the nozzle spacing with the feeler gauges.
Then adjust the Z end stop, to get the correct Z nozzle height. and done.
Don't forget to check that both Z axes are not having backlash. ( because that is worse than having a small angle between the bed and the Z )
There is a fundamental problem with belt drive for Z also , your lead screw will become part of the rigid system and if it is bend you will see this as a Z wobble. So M5 and M8 are out of the question, the lead screw need to be strait.
The nice thing about the glass plate is still, that all my objects will come loose by it self when it is cooled down, the only way to speed it up is to put a fan on it :-)
.
Re: Problems with Dual Z Axis Drivers April 12, 2016 06:06PM |
Registered: 9 years ago Posts: 1,873 |
Re: Problems with Dual Z Axis Drivers April 12, 2016 08:53PM |
Registered: 8 years ago Posts: 116 |
Re: Problems with Dual Z Axis Drivers April 12, 2016 09:01PM |
Registered: 9 years ago Posts: 1,873 |
Re: Problems with Dual Z Axis Drivers April 12, 2016 11:39PM |
Registered: 8 years ago Posts: 35 |
Re: Problems with Dual Z Axis Drivers April 13, 2016 12:07AM |
Registered: 8 years ago Posts: 116 |
Re: Problems with Dual Z Axis Drivers April 13, 2016 12:26AM |
Registered: 8 years ago Posts: 35 |
Anonymous User
Re: Problems with Dual Z Axis Drivers April 13, 2016 03:23AM |
Quote
hoxsiew
I completely re-did mine; trapezoidal leadscrews (T8x2 single start, not 4-start) and rigid couplers and bronze nuts made on a lathe. I machined the ends of the leadscrews down to 5 mm so they butt up to the stepper shaft in the coupler.
Re: Problems with Dual Z Axis Drivers April 13, 2016 06:19AM |
Registered: 11 years ago Posts: 5,780 |
Re: Problems with Dual Z Axis Drivers April 13, 2016 06:55AM |
Registered: 9 years ago Posts: 1,873 |
Re: Problems with Dual Z Axis Drivers April 13, 2016 07:14AM |
Registered: 11 years ago Posts: 5,780 |
Anonymous User
Re: Problems with Dual Z Axis Drivers April 13, 2016 10:48AM |
Re: Problems with Dual Z Axis Drivers April 13, 2016 11:38AM |
Registered: 11 years ago Posts: 5,780 |