(straight) Rear leadscew is wobbling
Hi! here’s the situation: I got a used V3.1 that had a badly bent REAR leadscrew, so I bought and installed the following replacements from the official RR store:
- new leadscrew (looked 100% straight, rolling it on a table showed no imperfections)
- new coupler
- new bearing to connect motor and coupler
- reprinted the pillow part on which the coupler sits (bc the previous one didn’t let the bearing sit flush inside)
After replacing all of the above, the situation got better BUT the leadscrew still bends a bit more compared to the other two. (see the two videos, it looks wobbly AND kind of erratic, sometimes it abruptly changes its position. I removed the upper stabilizer thing just for the videos.)
Could the motor be the culprit?
Is this normal for the rear leadscrew specifically?
Am I forgetting something?
Solution:Jump to solution
@TheTik @VisualTech48 @IronBrain Thank you all so much for the answers!
I finally had some time to do some more checks and it looks like the motor shaft is seriously wobbling.
Since I just made an order on the RR website and wouldn't like to pay 14$ of shipping for a 14$ motor, could I ask:...
26 Replies
Well you can't really judge it until you A) Put the upper bracket in that hold sthe top of the lead screw, and B) if you are unsure, you ahve to unscrew the lead screw and roll it on a table to see if its actually bent.
You should not really have it floating like that.
they said they rolled it on a table
The upper bracket isn't necessary, I ran mine without it for a bit after I broke a front one, til I reprinted it
That said, the runout in that leadscrew in the second video looks excessive
Take the leadscrew off, run the motor by itself and make sure the motor shaft itself isn't wobbling. Then add the coupler with no leadscrew and see what IT does
The message is edited, so I'm not sure it was written before what you point out.
It isn't nessecery, but on a long printer it will sag. That doesn't mean it isn't flat.
But yes, he shoudl check the motor shaft or if, he didn't put the rigid coupler flat.
Doesn’t the wobble decoupling (oldham coupling) mean the nut has no lateral support. If this is true you really do need a good radial bearing at both top and bottom.
Solution
@TheTik @VisualTech48 @IronBrain Thank you all so much for the answers!
I finally had some time to do some more checks and it looks like the motor shaft is seriously wobbling.
Since I just made an order on the RR website and wouldn't like to pay 14$ of shipping for a 14$ motor, could I ask:
1) if there's any way to fix it manually (even if I don't think so)
2) what's a good place to buy them on aliexpress or european stores?
this one specifically is an LDO NEMA17 (42STH48-2504AC), I could even go for a cheaper one on the short term
I'd like to see a vid of the wobble, I'd ask in #self-sourcing for where best to get a replacement
speaking of which, it might be a really dumb question but how can I check for the wobble without the leadscrew (and the buildplate of course) installed?
I tried homing all 3 axes and doing an emergency shutdown before the other 2 leadscrews crashed on the top but it's a huge risk for those lol
(I didn't film it when I tried, I took a look at it for a couple of seconds before shutting it down)
There is a way in gcode to run only a specific motor, I'd have to check docs and I'm not at my computer atm
oh okay, got to check those out then
given this list of z stepper stuff for my specific mainboard and the command:
FORCE_MOVE STEPPER=<config_name> DISTANCE=<value> VELOCITY=<value> [ACCEL=<value>]:
(just found in the docs)
OKAY! the steppers are named:
stepper_z
stepper_z1
stepper_z2
(the rear one was stepper_z1 for me)
if anyone needed this in the future
here is the wobbling @TheTik
even more noticeable with the coupler on imo
if it is defective, shouldn't RR pay for shipping?
it was a used machine
ahhh
so I guess it doesn’t count unfortunately, also it might have been damaged during shipping so I really have no alternatives
well, where to buy them depends on where you live
Italy, I was looking for European sites and the only one I found so far is 3DO, which has 10€ of shipping fee anyway, on top of making me pay 10€ more for the motor
so like, 35€ total
gotcha - RR does have them cheap, as long as the shipping isn't prohibitive
At this point I might order again from RR, hoping it won’t take like a month like last time (even though I just ordered 1kg of filament and a bunch of spares)
https://ratrig.com/nema-17-stepper-motor.html
yeah only €13.73
@blacksmithforlife 🇺🇸 @TheTik if you happened to know:
the only spare part I have on hand is this cheap knockoff stepper I got from the assistance team of another brand for the Z axis of another (cheap) printer
it doesn’t have any labels, it’s a bit smaller and the shaft is like 1/2mm shorter
would it be a terrible idea to try it out?
you would have to figure out all the settings for it
and then override it in the config
me personally, I would not do it
prolly not worth the hassle yeah
Guess I’ll make another order
yikes! That thing got bent hard! Glad you found the root cause but holy cow 😄
Yeah you should have seen the leadscrew that was attached to it lol
that's why the problem persisted even after replacing the screw
idek if it got badly damaged during shipping or the guy who had it just didn't notice/care