Y axis coupler - catastrophic failure

[caxton3d]

In a previous post I detailed how the y-axis coupler was loose on a new printer which resulted in loss of registration in the y-axis. Once the coupler was tightened it produced a perfect large print. Heartened by this success I started another larger print only for it to fail. On examination the y-axis coupler had snapped.





I am disappointed that on a printer only 2 weeks old that this has happened. Could the y-axis be excessively stiff placing too much of a load on the coupler, hence the working loose and final failure? What should I do next?

Thanks,

Barry.

[Charles]

Barry, I'm sure Raise will replace that part for you.

[walshlg]

these are pretty flexible, it probably had a defect when the coupler was machined.

[Vicky@Raise3D]

We are so sorry about that.
Please share your serial number to whom you bought the printer from. They will contact us to arrange you the replacement.

[mtsmetzler]

Check your motor alignment with the Y shaft. Mine was out of alignment and required some work on the motor mount and a shim to get things to line up correctly. Had the same failure on the X shaft as well, motor alignment was also the cause. These couplers are flexible to a point. It doesn't take to much deflection for a rapid failure.

[caxton3d]

My new coupler arrived today.



The original coupler besides the clamping screws had set screws to locate on the flats on the motor shaft. The new coupler does not have these set screws. Are they necessary? Which is the more appropriate part?

I can only agree with the previous post about motor alignment. The motor is only located by it's screws. There are no dowels or any other means to ensure alignment. It is all a case of accurate assembly work.

I must admit that having looked at FDM 3D printers for some time many of them appeared to have been designed and built in someone's bedroom! The Raise did seem not to fall into this category, but the problem of motor alignment does illustrate that basic engineering techniques like those employed in CNC milling machines could have been adapted to improve the robustness of the printer.

[Vicky@Raise3D]

My new coupler arrived today.



The original coupler besides the clamping screws had set screws to locate on the flats on the motor shaft. The new coupler does not have these set screws. Are they necessary? Which is the more appropriate part?

I can only agree with the previous post about motor alignment. The motor is only located by it's screws. There are no dowels or any other means to ensure alignment. It is all a case of accurate assembly work.

I must admit that having looked at FDM 3D printers for some time many of them appeared to have been designed and built in someone's bedroom! The Raise did seem not to fall into this category, but the problem of motor alignment does illustrate that basic engineering techniques like those employed in CNC milling machines could have been adapted to improve the robustness of the printer.

The right one is our standard spare part.
Please check with your supplier whether they give you some wrong parts by mistake.
We have been using the same one as your left one in our factory from last year to now.

[caxton3d]

I fitted the new coupler, checked the alignment and all seemed O.K. I then started off a new big print and 41 hours later the new coupler failed. Where do I go from here? If I fit a further coupler can I really expect it to last?

The motor did seem to be aligned and there did not seem to be any flexing of the coupler during rotation.
Any help would be appreciated as I do not seem to getting anywhere at the moment.

Barry.

[Jetguy]

Sorry you are having problems but you could use alternate style couplers that will better take misalignment.
2 or 3 jaw "Lovejoy" style with rubber or hard material inserts are potentially a method to prevent this failure.
The motor shaft is 5mm the printer side is 8mm
These are more expensive but a better part
https://www.amazon.com/Enpoint-Encoder- ... mm+coupler

[caxton3d]

Jetguy,

Thanks for the suggestion. I have just ordered one of these couplers up and should be with me on Monday. The hardness of the spider insert was selectable (hard, medium and soft), so for starters I have gone for medium - 92 shore.



My main concern is that there must be an awful lot of Raise printers out there not breaking couplers, so do I have a stiff y-axis which is placing an extra load on the coupler? By 'beefing up' (as we say in England) the coupler, will something else break?

Best wishes,

Barry.

[Jetguy]

No, rotational stiffness is not causing your failure.
#1 You'd be skipping steps like mad, the steppers are not that strong.
#2 You clearly show fatigue stress from misalignment in the broken couplers. For whatever reason, when installed, your machine was not lined up with that motor.

No, nothing else will break. Either you will skip steps if the load exceeds the motor or your new coupler will wear the spider.
I'm betting the bank that upgrading the coupler and that forces you to take it apart to install the motor will correct the issue in a permanent way. Stepper motors can skip steps all day with no damage.

[Jetguy]

FWIW, when I first got my N2, I took it all apart, I mean down to the bare frame- mostly to document the structure and teach myself how to help support all of you fellow owners, along with improvements and changes. I added Astrosyn rubber dampeners between the motor and the mounting flanges. This too gives me a tiny bit of flex to help in case of alignment issues. It also makes the printer that "extra" bit of already near silent.
See my Album here of my super earlybird N2.
https://www.flickr.com/photos/90025904@ ... 877858905/

[Jetguy]

What I mean to say, I considered putting those exact couplers I linked earlier in with red inserts, but took the "let's see what happens stock" as my intent was to see if we had failures. Honestly,while every once in a blue moon somebody gets a failure, it's mostly right after they first get the printer, after shipping i think the bumping around is the cause of the misalignment, the user doesn't take a brand new machine apart and sure enough, a few days to a week or two in, they report a failure. Most folks only have it happen once, and like I said, I see a pattern of just shipped printer, first time user, 50/50 chance the motor got bumped and bam, the coupler doesn't last long.

[caxton3d]

Jetguy,

From your experience does the top deck just lift off after removing the visible screws? With the top deck removed it will be far easier to check on the alignment of the motor.

[Jetguy]

Yes, the visible screws are all that attaches it, however, the cables that go through the top are all zip tied. I cannot lie, it's a challenge. I took all the clear sides panels off, all the screws, and then started carefully cutting the zip ties holding all the wires.I would photo document everything.
Just fair warning, this is crossing that line where it goes from anyone can do it, to probably nobody should do it.