Stepper Motor Skipping Steps (?)

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peterdaly
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Stepper Motor Skipping Steps (?)

Postby peterdaly » Mon Mar 02, 2015 11:22 am

I have an Orion with about 890 hours on it. It has printed without issue for the first 840 hours or so, other than blowing a heating resistor. When it blew the resistor, I upgraded to an E3D v6, which has also performed well.

It's developed a problem where it seems to be missing steps, potentially on the tower opposite the extruder. At this point, I am not able to complete hardly any prints, although it seems to fail at seemingly random points.

  • First few layers usually seem to look good...sometimes a dozen layers or more are fine before it goes out of whack, and the level at which is fails does not seem to be consistent.
  • Problem is consistent across three spools of ABS from two different vendors. SainSmart and Zen ToolWorks.
  • I have re-leveled the bed a number of times, using a 1 layer thick spoked wheel to look for consistent first layer extrusion height with good line to line adhesion without too much smoosh. (I've never had great success with the "watch the gap" method.)
  • I have disabled ALWAYS_CHECK_ENDSTOPS, to ensure it's not the EMI issues identified in other threads on this forum.
  • I have checked the extruder, by telling in to extrude 10cm of plastic, and verifying extruded accuracy with calipers. G1E100F90
  • I have tried with both a .4 and a .8 nozzle. (.8 is what I've used since upgrading to the E3D, but wanted to rule things out. .4 is current installed.)
  • Fails both when sending via OctoPrint, as well as printing directly from SD card.
  • The problem started happening shortly after I cleaned the bed...which may be pure coincidence.
  • I use hairspray. Over time, spray tends to build up on things. Is there any specific parts I should try to remove and clean, or potentially replace?

Related to this issue, how do I access the stepper motors? I assume they are behind the blue acrylic panels, but I'm not sure how to remove those.

Regardless of this specific issue, is there any maintenance that should be performed on a printer with this many hours?

I NEED to get this resolved this week, to ship orders that depend on parts produced by this printer. I appreciate any help.

IMG_20150301_144724.jpg

IMG_20150301_144701.jpg

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Re: Stepper Motor Skipping Steps (?)

Postby Mac The Knife » Mon Mar 02, 2015 11:36 am

The acrylic panels just pop out,,,,, Download the build manual for a Max V2, the orion is the same, just smaller. First thing to check is the drive pulley, If they come loose, it will exhibit what you posted.
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Re: Stepper Motor Skipping Steps (?)

Postby peterdaly » Mon Mar 02, 2015 12:52 pm

What's the best way to "check" them? Is there a way to check that without getting (and finding/buying) an allen key to fit in that tiny space?

From the photos, can you take an educated guess about which tower I should focus on? You can see the ezStruder, as orientation reference.

I got the acrylic off (thanks), and see where the gear attaches to the stepper (very limited access), but am not sure what exactly to do, or which tower to focus on. I tightened belts on 2 of the 3 towers, and am trying a print now...

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Re: Stepper Motor Skipping Steps (?)

Postby KAS » Mon Mar 02, 2015 12:59 pm

Turn the printer on and Home it, that should lock the steppers. See if you can grab the carriage and slide it down the tower. If it's loose it should allow the pulley to slip while the shaft is locked by torque.

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Re: Stepper Motor Skipping Steps (?)

Postby peterdaly » Mon Mar 02, 2015 3:12 pm

With two belts tightened, I got a good print my first try.

Went ahead and tightened the other belt too, and am starting another part...

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Re: Stepper Motor Skipping Steps (?)

Postby mvansomeren » Mon Mar 02, 2015 3:22 pm

peterdaly wrote:With two belts tightened, I got a good print my first try.

Went ahead and tightened the other belt too, and am starting another part...


How loose were they? Sounds like if they were skipping over the teeth on the drive gears it would be noticably flopping around... :?:
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Re: Stepper Motor Skipping Steps (?)

Postby peterdaly » Mon Mar 02, 2015 6:43 pm

There is/was no noticeable flopping around.

The inside strand of the belts felt tight. The outside strand felt very floppy, but because of how they are inside the extrusion channel, I had to feel them from "inside the acrylic" after they exit the extrusion channel to see how loose they felt.

Now, two good prints in a row...and best looking prints I have seen in months...clearly tightening helped. But the third print failed again.

OK, back to checking the drive pulleys. When I grab a cart during homing to force a skip on two of the towers...it's a "zip" sound. The third tower has a very different metallic clicking when forced to skip, although it still takes a lot of pressure. I'm guessing I just identified a slipping pulley wheel. I'll investigate how to access that pulley.

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Re: Stepper Motor Skipping Steps (?)

Postby KAS » Mon Mar 02, 2015 6:53 pm

Sounds like you found the slipping one or maybe two in your case. The hard click should be the belt slipping over the teeth of the pulley.



Off topic question but how the heck did you get filament splatter on your towers? or is that filament?

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Re: Stepper Motor Skipping Steps (?)

Postby peterdaly » Mon Mar 02, 2015 7:49 pm

Argg. What is the size of "the included" allen hex wrench!? :-)

Is removing the stepper motor the best way to tighten this?

I think the splatter is from a combination of hairspray and misprints. No joke, I've probably printed 6 pounds of spaghetti in the last month or two.

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Re: Stepper Motor Skipping Steps (?)

Postby KAS » Mon Mar 02, 2015 8:21 pm

Should be a 1.5mm or it is on the Max v2.

Here is the magic angle to reach both set screws, just make sure one of them is on the flat section of the stepper shaft before tightening both down. I'd suggest picking up some blue loctite as-well.

Image

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Re: Stepper Motor Skipping Steps (?)

Postby peterdaly » Mon Mar 02, 2015 8:30 pm

Ahh...so it can be done. Thanks for the "magic angle" photo. You named it well.

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Re: Stepper Motor Skipping Steps (?)

Postby peterdaly » Mon Mar 02, 2015 9:02 pm

Well...maybe it CAN be done...but not by me. I took out the stepper. I don't think it was the pulley...I think the belt was just a tad too lose. Still made the click sound after tightening the pulley, so my son helped be my third and forth hands to get the belt nice a tight, and now all three towers make the same "zip" sound when forced to skip.

Fingers cross...warming up for the next attempt.

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Re: Stepper Motor Skipping Steps (?)

Postby DanHall » Mon Mar 02, 2015 9:41 pm

Take another look at the belt tightening section in the V2 manual. There is a pretty good descrption of how to accomplish that with only your own two hands. I'm assuming it is very similar to the Orion. Basically an open end wrench and screwdriver in one hand to tension and hold the nut and a screwdriver in the other to tighten the screw on the idler bearing. I can only imagine what it is like with another pair of hands in there...

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Re: Stepper Motor Skipping Steps (?)

Postby peterdaly » Mon Mar 02, 2015 9:54 pm

Dan - Well, I tried that method once, and it still skipped after I was done. I did not have a nice small wrench like in the photos. My much larger adjustable wrench could not achieve the suggested angle, and kept slipping off the nut until a third hand became available.

So far so good on this print...

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Re: Stepper Motor Skipping Steps (?)

Postby geneb » Tue Mar 03, 2015 9:20 am

Forcing the cheapskates to move with the motors energized is just insane.

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Re: Stepper Motor Skipping Steps (?)

Postby Polygonhell » Tue Mar 03, 2015 1:07 pm

geneb wrote:Forcing the cheapskates to move with the motors energized is just insane.

g.


Agreed you'll very likely destroy your belts like that.
Because of the long belt runs, trying to force a skip usually just results in the pulleys eating the belts.

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Re: Stepper Motor Skipping Steps (?)

Postby peterdaly » Wed Mar 04, 2015 9:18 am

Still having failures, with some good parts, but high percentage spaghetti producing of failures. The same gcode produces both great looking parts, as well as "skipping steps" failed prints.

I'm thinking I've got nothing to lose by replacing the belts and pulleys. What is the length of the belts on the Orion 3D?

Do NEMA 17's go bad? Any reason I should not just replace them too? Are appropriate steppers available on Amazon with Prime shipping? It would be great to have parts here tomorrow, without paying more for overnight shipping than the value of the parts. I've got deadlines I am trying to crank out parts for. I love you guys, but overnight shipping for 3 steppers calculates out to $142...just for shipping. Ouch.

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Re: Stepper Motor Skipping Steps (?)

Postby peterdaly » Thu Mar 05, 2015 7:07 pm

Steppers, glass plate, thermocouple, G2 Belt, layer fan are ordered. Overhaul Monday night.

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Re: Stepper Motor Skipping Steps (?)

Postby bot » Fri Mar 06, 2015 6:06 pm

Holy crap that magic angle is amazing.

*Crosses fingers it's the same angle on a rostock*
*not actually a robot

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Re: Stepper Motor Skipping Steps (?)

Postby KAS » Fri Mar 06, 2015 7:17 pm

bot wrote:Holy crap that magic angle is amazing.

*Crosses fingers it's the same angle on a rostock*



That's a Rostock Max v2 :)

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Re: Stepper Motor Skipping Steps (?)

Postby bot » Sat Mar 07, 2015 10:53 pm

Oh sweet! I thought it was OP posting that pic! :mrgreen:
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