26 Reply by IanJohnson

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Re: missing steps.

About the Z axis-

I noticed in the background of one of your pictures that your Z rod doesn't use an ABS coupling to attach to the motor like mine, which should be good because it wouldn't be as prone to wobble.  How is it mounted to the motor?  It looks like the threads stop short of the motor.  Does there seem to be a flat on the bottom of the rod, or does the mounting somehow rely on friction against a round rod?

I wonder if there is a way for slippage to occur there, so that sometimes when the motor turns, the rod doesn't.  That would certainly cause the kind of squished layers you are seeing.  You could try stepping the platform down in .3mm steps and watch the rod to see if it turns every time.

Home the Z axis.  Under the log window, there is a text box with a send button for manually sending gcode commands.

Send G91 to enable relative coordinates
Send G1 Z.03 to move down .3mm.  It will send the same command again every time you hit the button, so keep clicking it to keep stepping the platform down, watching for the rod to turn each time.

You could also run it all the way up and down in a single motion and see if you can hear anything that sounds like skipping or strain, maybe hold a finger against the bottom of the rod to feel for any catching or odd vibration.

27 Reply by zimmer62

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Re: missing steps.

I see what you are saying, I think the z axis is directly related to overheating on the stepper controller board.

I've put a mark with a sharpie on both the motor shaft, and the z axis screw.  I'll let you know if they ever slip.  I would imagine these rods have been drilled using a lathe and then pressed onto the motor which shouldn't allow for slipping.

28 Reply by ysb

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Re: missing steps.

when i receive mine, the printer miss some steps for a couple of model and i discovered that if I tighten the straps (2 or 3 screw turn) of the upper carriage (on left and right), there is no more missing step.

the missing steps was the strap that "jump" and not a motor problem.

hope it can help

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29 Reply by teejay187

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Re: missing steps.

I had the exact same problem. I tried to loosen the belt screws a little. Now it moves easily in every direction.

30 Reply by solijohn

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Re: missing steps.

teejay187 wrote:

I had the exact same problem. I tried to loosen the belt screws a little. Now it moves easily in every direction.

This is the correct solution. Sometimes our workers over tighten the belts.

Former Solidoodle employee, no longer associated with the company.

31 Reply by Jon

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Re: missing steps.

Immediately after receiving the printer, I had a similar problem with binding along the Y-axis.  I ultimately resolved it by disconnecting the right hand Y-axis band entirely (loosening alone didn't work), driving the Y-axis back and forth manually and then re-attaching the band.  I have not had any issues along the Z-axis.

Since then, I have successfully printed a box full of designs, including some commercially viable enclosures.

32 Reply by solijohn

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Re: missing steps.

zimmer62 wrote:

That's the most severe I've seen it happen.  I don't have a video yet, and it doesn't happen all the time, so it would be hard to predict with without recording for a very long time.

There is a difference in the noise of the stepper, a stalled out noise that I'm familiar with on my CNC mill if you push too hard or fast when cutting parts.

The motor that seems to be in question stays cool since it's mounted to the steel case, so it's not overheating.

Here is a pic of the first time I noticed the problem.

http://www.soliforum.com/misc.php?action=pun_attachment&item=21&download=0


May we use your pictures in our documentation?

Former Solidoodle employee, no longer associated with the company.

33 Reply by ed.baus

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Re: missing steps.

I am also facing a similar problem to this.. it is really weird but it starts out prting fine then at some point it starts getting steps into the part very similar to the part above. I have also noticed that the front pulley is also rubbing against the plastic bracket.  Another odd item is the y stepper motor cable now rubs shaft in the back i am not sure if this is supposed to be like this but if it is you should look at changing it.


Here is what i have tried over the last 2 months to get this thing to work with little success

Adjusted the stepper motor current values (Electrical engineer help me)
Circle aligment process like 20 times
pulled the rear shaft sanded it some since set screws were in there so tight it gouged the metal not allowing the pulleys to slide freely.
Adjusted the jerk and acceleration settings on the printer software to reduce the effects of stepping issue.
Flipped the front pulled around to reduce it from binding against the bracket.

Oh i had to get a new power supply from Solidoodle since my burned out during the first week.

Anyone have some suggestions

34 Reply by adrian (edited by adrian 2013-07-13 17:25:24)

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Re: missing steps.

you haven't mentioned if you've tried putting a fan on your electronics or your x-stepper - although it sounds like y is more of a problem.

When the stepper drivers overheat, they will thermal shutdown (misses steps), or just do weird things as they derate... many have found to sustain reliable prints, they need cooling.

The steppers themselves derate their torque as they heatup, so will also loose steps - although the only problem child here is the x-axis because it only cools to ambient, everything else has a giant solidoodle-sized heatsink bolted to them wink

35 Reply by ed.baus

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Re: missing steps.

Adrian,
Thanks i will give that a shot

36 Reply by ed.baus

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Re: missing steps.

Adrian i think you are on to something with the electronics I printed a 300 line part and it printed accurately.
I would never believed if i didn't see it!!
I cant thank you enough!!!!

37 Reply by h.johnstone

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Re: missing steps.

We bought a solidoodle Workbench for work and I had exactly these problems described at the start of the post. After a lot of mucking around with tensioning belts and greasing shafts and still having the same problem, we found that the shaft the runs the belts for the Y axis had a lot of stiction (static friction that resists movement initially). The problem is that the shaft is over constrained and the 3rd brass bushing/bearing was actually bending the shaft and causing the stiction. The fix was to simply remove the bolts holding the 3rd bearing on and let it float. The printer works a treat now and has not missed a single step
Hope this helps

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38 Reply by hostinggeek

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Re: missing steps.

Just because I've seen a lot of mention of fans, you guys are blowing the heat away from the components, and not trying to blow cool air at it right?  It wasn't clarified, and I worry someone less mechanical might end up with swimming upstream if they used a fan backward.

Of course I know what I'm doing.  I googled it.

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39 Reply by widespreaddeadhead

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Re: missing steps.

h.johnstone wrote:

We bought a solidoodle Workbench for work and I had exactly these problems described at the start of the post. After a lot of mucking around with tensioning belts and greasing shafts and still having the same problem, we found that the shaft the runs the belts for the Y axis had a lot of stiction (static friction that resists movement initially). The problem is that the shaft is over constrained and the 3rd brass bushing/bearing was actually bending the shaft and causing the stiction. The fix was to simply remove the bolts holding the 3rd bearing on and let it float. The printer works a treat now and has not missed a single step
Hope this helps

Ours was so tight when we got our Workbench we thought about doing this same thing. Just ended up loosening it, but if it works well for you we might try it out.

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Solidoodle 2 - e3dv6 - Hobb Goblin - e3d Titan - lawsy carriages - Direct Drive Y Axis - T8 Z axis - OctoPi

40 Reply by grob (edited by grob 2015-02-19 23:34:00)

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Re: missing steps.

Yup, bronze bushings will end up creating a huge amount of friction if you put too much radial load on them. The shaft and the two outside bushings will self align quite happily, but the middle one needs to be positioned perfectly or it will add load (as the shaft and frame bend to compensate). The tension load from the drivebelt will also go straight onto that middle bushing, so you'll have to balance the tension in that quite carefully (between loose=backlash and tight=skipping motor).

Ideally, work out how to get that middle bracket into perfect alignment (shims, oversize the holes, etc.), so it can do it's job without creating new problems.

The other alternative (often discussed for earlier machines) is to replace all of these bushings with ball bearings, which don't create as much friction under radial load as the bushings - so you can get away with it! Not sure exactly how on the WB, but someone might be brave and work it out!

Also, congratulations on problem from 2012 remaining relevant all this time hehe. *clap*

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