You have the clamp style couplers and not the set screw type, correct? Mine don’t slip, but we have a product that we use in bicycle assembly that prevents carbon fiber parts from slipping. Its a friction paste that you could apply to the mating parts to prevent them from slipping. https://www.amazon.com/Finish-Line-Carbon-Bicycle-Assembly/dp/B0012RIEM6?th=1
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You may want to make sure your bearing blocks aren’t too tight, there shouldn’t be that much resistance to keep making the couplers come loose/slip.
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I’ll have to give that a try. I have tried everything else. 
I have already checked the bearing blocks repeatedly. If you move the y axis slowly it will run all day. a sudden reversal and the left side coupler slips. (we paint marked the shafts and couplers to be sure). The original couplers would only tighten down to .255 and the motor shaft is .247. so we bought new couplers and that was no help. any attempt to get the couplers tighter simply breaks and or strips the bolts.
I am having the same problem. Langmuir is sending me a new XL Y-axis lead screw and coupler which I hope takes care of the problem. I did notice that the Y-axis lead screw “whips” around under a rapid transit and I think that causes the set screws in the coupler to loosen. I tried blue locktite, moving the coupler more to the motor side and adjusting the bearing block to no avail. Just in case the parts they’re sending don’t work I ordered a 40mm long 1/4" to 3/8" coupler with two clamp (as opposed to set) screws on each side. ds690’s tip about the friction compound may be worth a shot too. I will say that Langmuir is going above and beyond to make me successful with this machine. They have been very responsive to every issue I’ve encountered (and there’s been a few).
These fix the problem… Made of steel and are the perfect fit.
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My lead screw measures 0.375" and motor shaft measures 0.25" so that coupler won’t work. The CLX-6-4-F is what I ordered and I look forward to trying it!!!
You must have a newer version. All my lead screws have a 25mm(1/4") couplers. The 3/8 lead screws are machined down on coupler ends to 25mm on mine. Regardless the couplers lock down tight and won’t slip at all.
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Unfortunately they are out of stock for a pair of them. They only have 1 and it’s weeks away. edit. Granger had a pair so I got em coming.
Go to Zoro. com Rutland CLX4-4-F. They have them in stock. $ 33.00 ea. Zoro is a spin-off of Grainger.
If you still can’t get them email me and I will send you some from my spare parts. You can return them when you get them from whoever you get them from.
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I can see how this “clamping” coupler will be stronger than the set screw type. It applies force to the entire face of the shaft as opposed to a small area as with set screws. I do believe this will fix the problem!!!. Along with Blue locktite on the clamping screws and the friction paste posted by ds690 I don’t believe the shaft will slip again! I find it interesting that the end of your lead screw is machined down to match the motor shaft. I guess they simplified manufacturing by using a “stepped” coupler as opposed to machining the screw .Cudos to you for posting the link to the coupler though!!! I think it will be helpful for a lot of folks!!!
I see a few responses of this same nature…something else is wrong
Hi there, not sure if this is the problem since I have a different coupler type. However, I solved my slipping problem by grinding the surface of the screw down flat (only took it down 1/32" or so) so the set screw would seat on it better. Then I locktited it. This solved my problem anyway. Good luck.
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you might want to make sure you have the correct plug in the correct socket on the computer, it matters, one moves the motor quicker than the other and makes the coupler slip, I did not see anywhere in the directions addressing this but I finally figured out that was what was causing mine to slip. I am referring to tthe left and the right axis motors that run in unison, they have to be in the correct plug.
The Y-axis motors are slaved to one another, they receive the exact same commands. Both Y-axis step drivers are also tuned identically, their dipswitch settings should match. One Y-axis motor should not be moving faster than the other.
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Is the issue you are experiencing motor coupler slippage, in other words the motor shaft spinning freely inside of the coupler? This issue would be rather quiet, or would not make any sound at all.
Or is the issue that you are experiencing a mechanical bind, in other words the motor completely jamming up and the shaft not spinning at all? In this case, the motor would make a loud noise.
Have you reached out to us about this at support@langmuirsystems.com? If this is a bind, we can walk you through some of the common causes and how to resolve them.
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I have marked the shafts and couplers. They are definitely slipping when the table makes a sudden change in direction. after the left side slips to a certain point then the table gets bound up and the motors hum loudly. we have taken all of the lead screws off and the gantry glides back and forth with ease. we have checked it for square multiple times and it is. Support is sending me new couplers (eventually) but I don’t see them fixing the problem. As I stated before, the couplers fully tight are larger than the shaft. I have some couplers on order from granger that should be here tomorrow. I’ll try those and report back.
The machine will make large lazy circles fine. But tight circles or cutting small letters it slips and eventually binds the gantry.
If you have any other checks that I may have missed, I’m all ears. Thanks
Marking the coupler and the lead screw to see whether the marks move in relation to one another is a great way to check whether coupler slippage is the issue, thank you for letting me know.
I took a look at your support ticket, it looks like we already told you about some of the tips and tricks that usually alleviate the issue. Let us know how it goes with the replacement motor couplers through us, as well as the motor couplers that you purchased elsewhere.
So I have some more information. we took the drag chains apart and installed a new machine torch. (thanks George)
We put it back together and did not touch anything else, simply unplugged and replugged the cables at the box. the table then worked perfectly for a while, eventually it started slipping again and I unplugged and replugged the cables at the box and it quit slipping again.
I’ve made several detailed cuts and no slippage. I don’t really grasp the coincidence, but thought I would share the information.
I installed the steel clamping couplers and no more slippage!! Works great now, 15 minute dry run through a detailed cut profile and not the slightest bit of slippage. I tip my hat to Bigdaddy2166 for the lead on the couplers.
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