1 Topic by Iceweasel44 (edited by Iceweasel44 2015-03-19 22:26:34)

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Topic: Y carriage stiff at one end or the other

Having one of two problems, and it seems like I can only solve one at a time.

When trying to get my solidoodle workbench setup, I followed the instructions laid out in this video: https://vimeo.com/55031028

Around 2 minutes in, the video maker slides the carriage back and forth to align the belt pulleys. My belt pulleys can't seem to align. No matter how much sliding the carriage back and forth I do, they will always pull left when I push the carriage forward, and right when I pull it back (both pulleys slide in the same direction). The pulleys are about 1.5-2 millimeters further left when the carriage is all the way back as opposed to all the way forward resting on the stop, so it seems like the two Y carriage rods are skewed. On top of this, there is a lot of wiggle room on the right side of the y carriage (the "loose" side without the slide bearing). The belt pulleys can be tightened in place when each side of the carriage is the same distance from the back, but then it becomes impossibly stiff sliding it further than halfway to the front. The smoothest slide comes from letting the right side of the carriage sit about 4 mm ahead of the left side.

The only way I've been able to get it so it can move all the way it needs in the Y direction is to loosen the short motor Y belt an absurd amount, which seems to (probably... can't get a print in like that to test the backlash) be causing lots of backlash in the Y direction. The other two Y belts also need to be fairly loose. I also need to slide the carriage into the middle when I tighten the belt pulleys to the rod. If it sits at the back when I tighten the rod, the motors will stop and start buzzing when the carriage is moved to the front. If it sits at the front when I tighten the rod, the opposite happens.

Any ideas on what needs fixed here?

2 Reply by wardjr

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Re: Y carriage stiff at one end or the other

Hmm, so many thoughts here.
Is the frame of the printer square?  Proper y-axis is fairly difficult if you don't know what your looking for and will be near impossible if the frame is crooked.

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3 Reply by jagowilson

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Re: Y carriage stiff at one end or the other

Also does the back Y rod spin freely with all belts off of it?

4 Reply by Iceweasel44

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Re: Y carriage stiff at one end or the other

The back Y rod does *not* rotate freely, I can't seem to rotate it at all just trying to spin it between my fingers.

5 Reply by grob

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Re: Y carriage stiff at one end or the other

Iceweasel44 wrote:

The back Y rod does *not* rotate freely, I can't seem to rotate it at all just trying to spin it between my fingers.

Sounds like that's where you should start - the fact the drive belt tension has a big impact suggests there's way too much friction on this driveshaft. Does the workbench have a bracket on the back wall with a bushing in the middle of the rod? Try unscrewing this from the back wall (leave it loose) and see if it gets any easier...

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6 Reply by Iceweasel44

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Re: Y carriage stiff at one end or the other

Also,can't really see any noticeable crookedness to the frame by eye, but I'll need to pick up a square tomorrow to check it closer. Any good ways to make the frame a little more sturdy?

7 Reply by jagowilson (edited by jagowilson 2015-03-20 02:57:58)

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Re: Y carriage stiff at one end or the other

I think I'd start by trying to take the rod out. Check it for straightness by rolling it on a counter or other smooth surface.  If it clicks when it rolls, it's bent. The rod is easy enough to remove so this is worth eliminating as a culprit. I have a feeling you may find what's binding the rod as you're taking it out.