I haven’t tried mine honestly. Been so busy and my home made coupling is working good right now. I plan to try it out when I install new water table. Im surprised they stripped bc mine seem to be all stainless. You sure they are Rulands? The LM ones are aluminum with steel screws. It looks like the Z axis LM used a higher quality coupling, looks very similar to the Ruland.
I haven’t tried mine yet either. A little disappointing they might not work. They look nicely made and at 40.00 each retail I would expect them to work better. The screws are smaller but I hoped that being doubled up they would hold.
They are still sitting on the workbench, I appreciate the heads up. I also looked at the 2 piece couplers and thought maybe it maybe a better approach by having the 2 halves tighten up to the shaft instead of putting all the stress on 1 side of the coupler. I know some people are putting a flat spot on the shaft and drilling a set screw.
With all of the discussion about this maybe the initial design needs to be looked at. Maybe knurling the shaft to give the coupler more bite would help this is what I bought it pretty much had the highest torque rating of 200in/lbs.
These are the 2 piece units.
well after 2 yrs sitting on the shop floor… I decided to assemble the PRO.
ran into similar issue of screws not strong enough to handle to torque required to seat the rigid coupler to the motor shaft and screw. after damaging several screw heads and 3/32 bits… I found this on the thread forum.
So, what I did was grabbed a hacksaw and mirrored the Ruland style by cutting the opposite side to almost half wall thickness.
When I get some new cap screws I’ll let you know how I made out.
(I have not yet measured the OD of motor shaft or screw but will in the morning).
The issue arose on the X-Axis motor coupling, but was on the motor end of the coupling not the screw…
Let ya know in a few days.
And what great information on this forum!!
Ruland CLX-4-4-F One-Piece Clamping Rigid Coupling, Black Oxide Steel, 1/4" Bore A Diameter, 1/4" Bore B Diameter, 5/8" OD, 1" Length Amazon.com
Problem solved for good.
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for simplicity trust me that’s what I would have gone with but they don’t ship to my region.
On top of that, cutting the slot on the back side essentially duplicates the CLX-4-4-F.
Amazon wants $91(CDN)+shipping+import. I spent 5 minutes in a vice with a hack saw. I’m pretty sure when I get some new cap screws it’ll be top notch… that said I still need to confirm diameters.
All goes well I’ll duplicate on the Y axis couplers.
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They are made of steel, not aluminum, like the original.
That’s your fix, like it or not.
mine are steel, just lack the back cut.
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without the back cut, the screws cannot torque enough to clamp.
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I agree the slot on the back is a great idea.
I don’t have a Pro (being definitely un-pro myself) so I used standard grub screw couplers after I took an angle grinder to the lead screw and put a flat on it. Never had a problem since.
Of course, being ‘un-pro’, there are very few problems that really affect me 
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after diameter verification, I’ll reply with how the 5 minute fix works, as opposed to the $140(cdn) + import fees…works out.
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I believe the 4-4-f has the correct config
1/4 X1/4 X5/8 or 6.35 mm to you Canadians
lol… sorry needed 10 characters to reply. the lol didn’t cut it.
The dims are not the issue… its the strength vs torque of the cap screw…
The back slot relieves that… GOOD FIX RULAND
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(I say that with a grain of salt… time will tell) BUT I anticipate great success!!
You could also use thread-lock on the set screws to greatly enhance your success.
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It is the head of the screw that is stripped so can’t get the required torque to secure clamp.
I have new 4-40x3/8 cap screws coming soon…
sure will be nice to try this unit out 
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I did mic the motor and screw and both were 0.248"