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robthebrew
Posts: 763
So I got 3 of these couplers:
http://www.ebay.com/itm/4-5-6-7-8mm-Shaft-Coupling-Rigid-Coupling-Coupler-Motor-Connector-A-Spanner/331200440243?_trksid=p2045573.c100033.m2042

Make sure you get these blue ones, the yellow don't fit.
So far I have put one on the X and one on the Y.
When you have assembled the motor/rod you need to grind the fixing screw flat to the coupler.
A quick dremel of the stop sensor holder allows the coupler to fit without rubbing.

After this I already saw massive improvements in X, but Y was still wobbling.
Turns out the threaded rod was actually bent. So I marked the high spot of the curve, rested the ends on 4mm aluminium blocks and carefully clamped the middle down (past the straight point).
This fixed the curvature.
Now when I move Y end to end I no longer see the rod moving up and down.
Printing a cuba now, that has no wobble!!

2021-06-15 18:51
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robthebrew
Posts: 763
By the way, this was shamelessly stolen from hon pi's hard work ;)
https://plus.google.com/111735302194782648680/posts/FnxxchfPeHF
2021-06-15 18:57
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Citizen_Snips
Posts: 88
Are the ones we need the 5mm to 8mm ones?
2021-06-16 01:49
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robthebrew
Posts: 763
yes. make sure they are the blue ones.
2021-06-16 01:51
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Citizen_Snips
Posts: 88
The picture for the item shows a blue one but the picture doesn't' change when you select a different size. So should I email the seller before hand just to make sure? And thanks for leaving this info in the forum I haven't been looking at the google+ pages lately otherwise I probably wouldn't have seen this.
2021-06-16 02:06
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robthebrew
Posts: 763
This seller was absolutely fantastic. I actually ordered the yellow ones, but then contacted him to say blue. Job done.
So, yes just contact him to say you need the smaller blue ones
2021-06-16 02:53
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Citizen_Snips
Posts: 88
I ordered them before contacting him so I could secure them because there are only a few left. But I just sent him a message asking him which ones they were and if he could give me the blue ones if they were in fact the yellow ones so hopefully this works out. Now with these new couplers will the Z wobble reducer mod not be needed any more?
2021-06-16 03:02
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sethmo38@gmail.com
From: Keokuk, United States
Posts: 84
I can confirm, the yellow ones do not fit without cutting the acrylic panels. I going to order some blue ones. Thanks!
2021-06-16 04:10
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robthebrew
Posts: 763
I haven't fitted the Z one yet, so I still see Z wobble. I'll update when I have fitted and tested.
The X & Y wobbles have gone.
2021-06-16 12:00
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Citizen_Snips
Posts: 88
robthebrew, are you in the states? If so about how long did shipping take? I'm hoping the x wobble will be fixed by the coupler but I have a feeling it's the threaded screw design that creates that wave instead of the plastic coupler so the coupler may not completely get rid of the problem.
2021-06-16 12:35
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robthebrew
Posts: 763
I'm in the UK. and it took 2.5 weeks.
2021-06-16 13:04
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rhercher
Posts: 345
iconCitizen_Snips:
I have a feeling it's the threaded screw design that creates that wave instead of the plastic coupler so the coupler may not completely get rid of the problem.


If the screw is defective (either bent or the threading is off), you will still have wobble. You'll also get wobble if your screw is moving at the non-motor end. However, the plastic couplers have had a pretty high failure rate, as well as many reports of bad/lopsided fittings. I know at least one report of the rod just falling out of the coupling mid print! As far as bent screw, I read a report where the user rolled the rod enough to make it straight again. Ymmv
2021-06-16 13:19
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robthebrew
Posts: 763
Both my x and y have worked off the motor spindle in the past. As to rolling the screw to straighten, I doubt it based on how much I had to deflect mine in the opposite direction to the curve to get it to straighten
2021-06-17 00:43
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robthebrew
Posts: 763
Just an update on the Z axis:when removing the screws from the motor (in place - I like the easy life) I found they had loosened a bit.
I took the motor off and added the blue coupler. Screwed 3 of the 4 screws back (the 4th is a pain).
Booms: no hot plate wobble to and frow!
I don't know if it is the coupler or the fact the screws were a little loose...

BUT RESULT!!
2021-06-19 03:53
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andybox
Posts: 132
test cube pic or it didn't happen
:P
2021-06-20 03:27
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