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Anyone had similar experience on the Z axis?

Posted by deaconfrost 
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deaconfrost
Anyone had similar experience on the Z axis?
June 15, 2016 08:18AM
I turned my Z leadscrew up side down and the prints are coming out with ripples along the Z wall also it ripple so bad that it breaks off every 10 layers, the ripples are equal to the leadscrew pitch. Before I turned the leadscrew upside down everything was good and well just a bit of elephant foot.

Anyone seen this before? I will turn them back the other way when I get home and do another test print
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deaconfrost
Re: Anyone had similar experience on the Z axis?
June 15, 2016 12:04PM
turned my z screw back the other way, now prints perfect
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stephenrc
Re: Anyone had similar experience on the Z axis?
June 15, 2016 12:10PM
One or both z screws are probably bent at one end.
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deaconfrost
Re: Anyone had similar experience on the Z axis?
June 15, 2016 03:12PM

Making new Z top mounts with bearing holder to help keeping it straight, it seems to wobble when rotating and there's nothing at the top to hold it just a hole for it to go through but it can still wobble at the moment.
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deaconfrost
Re: Anyone had similar experience on the Z axis?
June 15, 2016 04:39PM
yep, the new mounts tells me the right z screw was bent enough to cause visual problem on the print
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stephenrc
Re: Anyone had similar experience on the Z axis?
June 15, 2016 05:05PM
You will need perfectly straight z screws if you use anything to hold the non-motor end. Most of the time, using a bearing to hold the free end makes it worse.
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sigxcpu
Re: Anyone had similar experience on the Z axis?
June 15, 2016 06:08PM
Simple solution: get rid of the nut and its holder, create two "seats" for your X axis that "crimp" the Z rods and hold the Z nut. Put your X axis on these seats. The screw play in XY plane will have almost no effect (if they are really bent, their pitch will not be constant)

Example: [www.thingiverse.com]

Edited 1 time(s). Last edit at 06/15/2016 06:09PM by sigxcpu.
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deaconfrost
Re: Anyone had similar experience on the Z axis?
June 15, 2016 07:26PM
@ stephenrc
They were once perfectly straight, must have got hit when moving house, but not too bad.

@sigxcpu
Thanks for the link, but I'm using 10mm leadscrew with 2mm pitch, I made new mounts and grind off a bit on the nuts to mount them up, I think it's just the leadscrew got damaged during transportation. The leadscrew are actually longer, they're 400mm the bend is above 200mm once I had them turned back over, so no problem there anymore. I had them spare so I tho why not use them on the i3.
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sigxcpu
Re: Anyone had similar experience on the Z axis?
June 16, 2016 04:08AM
I'm using 8mm leadscrew with 8mm lead and 2mm pitch, so not far off. You design your seats no big deal. Of course, if this is not a Prusa like thing, maybe it doesn't apply. But decoupling the Z screws from the X axis was the best improvement I've done to my printer, considering 8mm screws and 8mm "guiding" rod.
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deaconfrost
Re: Anyone had similar experience on the Z axis?
June 16, 2016 04:32AM
Since mine is 10mm and nuts are much bigger, I can use current setup and just put the nut under the x idler and motor mount and they will rest on it. I might give that a try, I also have another 2 10mm leadscrew that I know are perfectly straight so if all else fall I can just use those 2 with bearing at top mounts to keep them straight at all time
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MCcarman
Re: Anyone had similar experience on the Z axis?
June 16, 2016 07:26AM
Prusa style machines use the plane shafts to control the X/Y position at every Z height. The Z lead screws are only there to change the Z height. Do not constrain them at the top or if not straight/properly aligned they will conflict with the other shafts. They do not need to be perfectly straight hence they can appear to wobble. They also don't need to be perfectly aligned with the motor - within limits.
I am not suggesting you tolerate poor quality parts but don't waste time and money on insignificant factors.
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deaconfrost
Re: Anyone had similar experience on the Z axis?
June 18, 2016 06:12PM


its been working out fairly well so far smiling smiley

Edited 2 time(s). Last edit at 06/18/2016 06:18PM by deaconfrost.
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deaconfrost
Re: Anyone had similar experience on the Z axis?
June 19, 2016 01:16PM

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