Z plus - grinding, not moving

I was in the middle of a job. Changed over to a new file and was setting Z zero again. But when I tried to lower bit, it does not move and makes a terrible grinding sound. Same in the up.

I want to attach a video but forum interface will not let me. Any ideas?

Please let us know about this difficulty at support@carbide3d.com and we’ll do our best to get it worked out as quickly as we can.

Thanks. I just sent an email.

I would check your stepper motor connections for the Z axis, and also make sure the linear rails were clean and lubricated, and maybe the Z axis screw. Either the mechanicals are binding, or the connections ain’t connecting. If you let the smoke out of the drivers for the z axis, I don’t think it would make any noise.

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Nothing to add other than I LOL-ed at your username. Did a quick google bc I thought it was a butthole reference, but apparently the evil eye comes in a red color too. For courage. I was only familiar with the blue evil eye for protection. Learn all kind of things on this board.

@greekredeye you can check the lead screw/anti backlash nuts pretty easily. Possible those nuts bound up and locked it, or you could have an issue with the rails and slides. You can find out if either is the issue in about 15 minutes with the steps here:

I go into a lot of checks in there, but you can skip that and get to the part where I disassemble it. The main thing to watch is not dropping the rail slides off the end, it will make you sad when the bearings go flying everywhere. :slight_smile:

And really, you can check the leadscrew nuts even faster by putting a box under your router mount to support it, the remove the 4 motor screws and the 2 lead nut screws. (There’s no support in this photo, but the arrows are pointing to the screws to remove)


Disconnect the power connection to your motor and you can pull the leadscrew and nuts out through the top. Now you can check the nuts, see if they are bound. Then check the carriage, move it up and down on the rails. (Do not let it come off the bottom, keep something underneath to support it!) If those are all good, then it could be the stepper motor.

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Thank you both for the suggestions. Couple busy days at work so I have not tried anything yet. But tomorrow morning I will have some time. I am also in contact with Carbide support.

Those busy couple days turned into a busy couple weeks. Just tried your very good advice. Thanks! When I removed the screws I could still not move the carriage up and down. So I took the front mounting plate off. I can move 3 of the linear guides manually, although they do not slide easily (note in photo they are suspended and not sliding down under gravity). The bottom right one, however, is completely frozen and will not slide even with considerable force.

So, I found the problem. But not sure how to fix it. I guess I need to open the linear guide housing and see what is causing the binding? Not quite sure how best to do that. Will sleep on it. With figures of ball bearings dancing in my head. : )

Please let us know about this difficulty at support@carbide3d.com and we can work out your sending your Z-Plus in for a rebuild.

I sent an email a few minutes before your reply. I would like to attempt an at home fix first if it is possible before sending it in, as I live overseas.

You can try removing the screw and dropping some penetrating oil into the hole:

Removing the screws on the left and right of the top will pull off the end cap and expose the bearings, but if they’re frozen on there, may not be much good other than getting more oil in to free whatever is jamming it. Be aware that there are about 40 bearings on each side that run in a circular track. They are tiny, maybe 1.5mm, and will get lost everywhere.

But realistically, if they are that gummed up, the bearing are trash, probably flattened in spots. Hopefully Carbide can get you new rails and slides at a decent price. If not, you can pick them up on Amazon or Aliexpress. I believe they are HG15, (that’s what’s on my HDZ, if you look closely on the top of one you’ll see the number) not sure on the rail length:


They all come with rails, but they are a standard item and should work if your rails are still good and you can’t find the exact length rail. Just order the set with rails and swap them out onto your current rails. Replace all 4 bearing slides however you do it.

Last - while your there - check the lead screw nuts from my post above. If your bearings are bad, then possible those are out as well. Those are Carbide custom (as far as I can tell) so see if they’ll ship you a set if they have play in them.

(and while you’re this far, order a set of v-wheels and belts (GT2-9mm, get 10 meters to do two full swaps on a S3 XXL, maybe different if that’s not your machine), get everything tip-top :slight_smile: )

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@dandangerous Thanks for the very helpful information.

I just discovered this maintenance guide that recommends injecting a specific oil (vactra 2) into the linear guides:

I have not added oil to the guide blocks or oiled the rails themselves ever. As you do, I suspect the original oil is shipped with has dried up or is gummed up. Maybe adding oil will fix, but I fear the bearings are damaged beyond what oil can do at this point. The 3 that still slide feel a little “crunchy.”

You mention a penetrating oil. Do you mean like a WD-40 or 3-in-1? Would that react with any residual Vactra 2? Where I live (not the US) I am not sure I will be able to find Vactra 2.

So, as a lesson to others, make sure you are adding oil to the linear guides / bearing carriages regularly.

@WillAdams and the Carbide team: for your awareness on longevity of these bearings. I bought the Z plus upgrade in April 2021, but did not get around to installing it until January 2022. So it failed exactly 1 year later. This is a hobby machine, with what I estimate to be only 400 to 500 hours on it, total. About half that, 200 to 250 hours, on the Z-plus. Maybe you are doing this now, but I recommend you ship a bottle of the Vactra 2 oil and printed bearing maintenance instructions with the machine. It is something I was not even tracking.

EDIT: I clarified the number of hours for the machine since original purchase with stock head and hours for the Z-plus head which was purchased later as an upgrade.


Yeah, IMO, probably doesn’t matter too much what you put in there at this point - based on your description, they’re shot. WD-40, PB Blaster, something like that. In the end, you’ll probably want to replace the rails as well anyway assuming the bearing have been grinding on them.

I re-lube mine with Super Lube and have been happy with that. It’s an NGLI-2 grease, which is one manufacturers recommend for linear rail bearings, in addition to machine oil depending on the application. As this is a hobby machine and I prefer to not have oil dripping out of the ends of my Z axis, Super Lube has worked well for me. I load it into a medicine syringe (same as they show in the doc) and push a little into the grease hole, the run it up and down a dozen times. Did this 2x on my Zplus and it seemed to work great. No dripping oil and when I disassembled to replace the leadscrew nuts, the bearing slid right off and were well lubed, no debris in them. Need to do it on my HDZ as I think most of the Vactra has dripped out at this point.

As usual, YMMV, and not my fault if you follow this non-advice and it makes things bad for you (insert all kinds of warnings about grease and oil interacting, load applications, speed applications, manufacturers differences, blah blah blah…) Do your own research and use what you’re comfortable with. :wink:

Is this the oil you use?

I confirmed the bearing carriage is HG15 (printed on top of the carriage - thanks for the tip). Sales sites offer HGH15 and HGW15. A quick search of the specs from the manufacturer (HIWIN) show that HGH is squared off and the type used in the Shapeoko. The HGW has a flange on either side.

It looks like the rail is 240mm, but I will more carefully measure it tomorrow. Unfortunately, none of the Amazon vendors seem to carry 240mm or they are out of stock. I will check AliExpress and Ebay to see if I can find it or special order it. That said, the current rails still look pretty good. The bottom of the right rail, however, appears to be gouged a bit (that is where the carriage that failed was running, so no surprise). But to my touch it is almost imperceptible.

@WillAdams Can you confirm if Carbide 3d sells the bearing carriages and rails separately? If not, can you at least confirm the rail length for the Z-plus? Thanks!

I actually use the Super Lube grease variety on rail bearings (but I use both the grease and oil in my garage workshop). After a lot of reading, actually where you started with HIWIN maintenance manual - page 24 section 7 Lubrication, decided to switch to the grease on the rails.

Oils and very low viscosity greases tend to be used in very high speed applications and need to be reapplied more frequently. The Shapeoko is not moving at the speeds that would necessitate an oil over a grease, IMO. They list a lot of recommended greases in the doc. If I were running a critical piece of multi-million dollar equipment (like the robots we use at work), I’d follow their recommendation and source the specific grease or oil for the application.

Not sure why Carbide recommends an oil or specifically Vactra, which is expensive, hard to source in small quantities (they don’t even sell it), needs to be reapplied more frequently, and specced for higher speed application. It’s created a lot of confusion, discussion, and over-thinking. There are other gear oils more readily available, like Mobil 630, that are recommended by manufacturers and perfectly suitable for this application. It would be nice if Carbide expanded their list to include more options.

But I still believe a grease is more appropriate per the stated the specs of the bearings and use case on a hobby/semi-pro grade machine. For the small hobby machine sitting my garage - even if I’m using it for production/for-sale work - the Super Lube grease is a suitable, affordable, and available substitute for my use. And it meets the basic specifications of the bearing manufacturers for the use (without over thinking it too much).

Whatever is used, just like on a car, regular maintenance is required. I was guilty of this and missed a lot of maintenance on my machine. Belts, wheels, loose screws, lead screw nuts, couplers, greased bearings, etc. are all part of the regular maintenance that is easy to forget about on a machine like the Shapeoko that generally just runs well - until it doesn’t. :slight_smile:


Great conversation going through the same thing.

@dandangerous your knowledge is first class.

Appreciate the detailed comments. Many thanks.

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Thank you! I was able to get a tube of super grease. After using a syringe to fill the carriages with grease I was able to get them all moving again!

They are all a bit crunchy, but I can get the machine working again and eventually replace the rails and bearings.

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