1 Topic by chopperwalker

  • chopperwalker
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Topic: Y-Axis Issues Solved - I hope

I just wanted to add this since I didn't find anything about it in my forum searches. After a long battle with Y-axis issues focused around skipping I finally have discovered that its the original stepper motor on my SD3. I think it is the bearing on the front/top/shaft side, but regardless I believe it is the mechanics of the stepper. It seems that randomly the rotor will seize up. So for the numerous people looking to issues on their y-axis, give this a check this, too.

Here's how I got to my conclusion and all mods related to the Y:

I first went to all new hardened rods and linear bearings. I then upgraded to all GT2 aluminum pulleys and belts. I also added two pillow blocks. I started getting large jumps and multiple offsets in my prints both forward and backward on only the Y. I checked everything* and adjusted the belt tension, realigned the carriages, adjusted motor current, played with motor settings, double-checked level on the bed, etc. Still kept happening. I changed slicers and hosts. I changed computers. I finally upgraded the board to an Azteeg X3 Pro with SD8825s. During this upgrade I kept noticing the problem persisted as I was dialing-in. So went for flanged bearings in the frame on the 6mm rod. I thought this had to be the last stop so I went back to dialing-in the new controller. Some unrelated issues related to firmware had me take all the load off the stepper. I was holding the shaft of the motor while dialing-in home and travel speeds when I noticed I could feel skips. I played with the microstepping and currents settings again. I bridged the decay to high on the drivers. The problem persisted. I switched drivers and that didn't help.

At one point I had the power off and I was spinning shaft manually and I felt it seize completely. It would not spin at all until I backed off and spun again. It kept happening at random in either direction. Some google searches later and I found people with similar issues. I took the motor apart, checked the parts, cleaned out any debris and reassembled. Still an issue. Opened up again, and checked the bearing more closely. I noticed the shaft-side bearing had a bit of noise when spun. I couldn't see any play, but I'm guessing the bearing is bad from over-tightening the driver belt. I ordered a replacement motor and it gets here Tuesday. I am fairly confident in the rest of my setup at this point so I am fairly confident this will solve my problem. I will let you know what happens.

SD3, E3d v5, Lawsy Carriages with linear bearings, Precision ground SS rails, G2T Belts and Pulleys, plexi case, Z ballscrew, Y-axis flanged bearings and idler pulleys, MK2A print bed with custom alu/glass slide-on assembly, Azteeg X3 Pro and SD8825 drivers, SSR controlled power supply

2 Reply by jagowilson (edited by jagowilson 2015-07-27 16:26:26)

  • jagowilson
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Re: Y-Axis Issues Solved - I hope

hey there! that's really bizarre. I know personally I've had an issue with steppers seizing up when the back isn't properly secured--if the back plate rotates out of square with the rest of the motor it locks up the armature. I'm sure you already noticed this, though. hopefully a new motor does you some good!

I highly recommend a direct drive setup--driving the shaft directly instead of using a short belt. you'll be impressed at the difference in print quality.

3 Reply by chopperwalker (edited by chopperwalker 2015-07-27 17:30:14)

  • chopperwalker
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Re: Y-Axis Issues Solved - I hope

Yeah, I noticed that. The issue was happening even when tightened down.

I saw somebody with a direct drive setup just last night. As soon as I saw it I thought it was obvious improvement. I definitely plan to do it now, but need to be able to print the adapter first. I also need to order a longer rod. I hadn't read about print quality changes, but  I can imagine it only helps.

I have a question about pillow block idler pulleys (see attached). I bought two and have them "installed", but they aren't really bolted down. In fact, the do not help with the vertical pull the driver belt causes. I have them shimmed since there is gap between them. They have a +/-5 deg self aligning play and the base is about 3.5 mm off the wall. I haven't found a good way to measure and align a spacer or their bolt holes. I try with my calipers, but it just isn't repeatable in measurement (esp with the angle play). Does anybody have a clever idea on how to get these "precisely" mounted? I suppose I wont really need them as much if I go to direct drive and with a new hardened steel rod.

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SD3, E3d v5, Lawsy Carriages with linear bearings, Precision ground SS rails, G2T Belts and Pulleys, plexi case, Z ballscrew, Y-axis flanged bearings and idler pulleys, MK2A print bed with custom alu/glass slide-on assembly, Azteeg X3 Pro and SD8825 drivers, SSR controlled power supply

4 Reply by chopperwalker

  • chopperwalker
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Re: Y-Axis Issues Solved - I hope

New stepper is in and currently printing. So far so good. I think I need a few more prints under the belt to check this off, but it looks good so far. Printing the y-stabilizer bar with bearings. I think my next print will be a direct drive bracket.  I want to stick with 6mm rod since I have the flanged bearings in the frame, but I will order a new rod and a 5-6mm spider coupler. I have seen two out there at least. Any recommendations on which to use?

SD3, E3d v5, Lawsy Carriages with linear bearings, Precision ground SS rails, G2T Belts and Pulleys, plexi case, Z ballscrew, Y-axis flanged bearings and idler pulleys, MK2A print bed with custom alu/glass slide-on assembly, Azteeg X3 Pro and SD8825 drivers, SSR controlled power supply

5 Reply by mdrVB6

  • mdrVB6
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Re: Y-Axis Issues Solved - I hope

Oldham coupling from Misumi.

But really, if you are already tearing down the whole Y axis I strongly encourage you to go to 8mm, even if you already have the 6mm bearings.  KP08's are sold on aliexpress and will get to you in 5- 15 days.  8mm will be much stronger and you can really get good belt tension without worrying about bending the rods.

SD4 w/ RUMBA, E3D Volcano, all bearings, glass bed