HDZ bearing blocks

CNC Machines Shapeoko
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I purchased my HDZ about a year ago. Are the bearing blocks on this vintage pre-loaded to some extent?

Today I had a job fail, Z travel impeded somehow. Turning the ball screw, machine off obviously, I felt it binding randomly as it traveled up-down. I checked the rails for tightness and parallel, no issues.

Pulled the HDZ and removed the ball screw. The carriage was difficult to move by hand. Re-checked for parallel, ok. Removed 4 screws where I would guess zerk fittings would be placed. 3 drops 3 in One oil (the only light oil on hand) in each hole and a couple of drops on each side of each rail. The carriage freed up considerably and moves up and down the rails completely but still seems a bit rough. Also, it takes pound or two of effort to get it going. I wonder if I need to replace the bearing blocks?

I ask because I built an HDZ that used very similar bearing blocks and they moved silky smooth and would move with very little effort.

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Ouch,

When the linear rail bearings run out of lubricant this can happen, I have put super-lube in some with a syringe when lacking a suitable set of grease nipples and grease gun to lube them with.

I would put some real grease in rather than just oil as the oil will run out pretty quickly, avoid anything with molybdenum disuphide or graphite as these are not lubricants but are abrasives in this application.

These are the HiWin instructions on how to lube up a linear rail bearing

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@Griff

How many hours do you think you had on the rails before this happened? I want to know what type of maintenance schedule I should be implementing (z-plus here but similar rails I think)…

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Honestly, I don’t know. I’d classify my usage as light, strictly a hobby machine.

Maybe a good idea for C3D to come up with a PM schedule for linear rail machines. All machines, really.

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The advice from HiWin in that PDF I linked is that the rails should have a lubricant residue on them from the blocks sliding over them after cleaning.

So far as I can tell the procedure is to wipe down the rail to that it’s clean and dry, then jog the HDZ up and down a couple of times and wipe the rail again with a clean dry cloth / tissue and look for the grease residue.

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Just keep em “moist”

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Not sure where it was recommended but I bought the Super Lube Grease and I clean my rails and apply a light coat and move the Z up and down. I wipe off any excess. I have the version 3.2 HDZ and for the longest time it would drip oil from the bottom of the rails onto my projects.

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Haha, ok. Nice and “moist” with Super lube. Thanks all for your responses.

A few more questions. (For me and whoever else stumbles on this thread in the future.)

Source for zerk fittings so I don’t have to disassemble the thing to lube the lower blocks? And, a mini grease gun?

Since C3D won’t sell bearing blocks (per C3D support) source for identical blocks? Yes, I know there are many choices out there, I’d like to exactly match the C3D spec.

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I looked at the grease nipples supplied with my Hiwin rails, the Hiwin manual and the HDZ and there’s a few things to note.

Putting grease on the rails won’t do much, the wipers on the blocks will clean this off fairly quickly, we need to get the grease inside the rail block grease reservoir where it can lubricate the bearings.

Most linear rail blocks have a range of grease port locations scattered around their surfaces that provide access to the grease reservoir built into the block, on the Hiwin and on the HDZ rail blocks there are pre-drilled ports on both ends;

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These are M4 threaded on most HGR15 clones so US users beware, her majesty’s imperial pipe threads are unlikely to fit. There are also marked locations where you can drill through a ‘non-standard’ hole but we don’t need to do that.

Hiwin supplies some grease nipples with their blocks but I am not sure what sort of gun (other than the expensive Hiwin linear rail block 70g grease gun) you would use them with as they are hexagonal and not round.

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The other issue, and presumably the one which stops Carbide from shipping the HDZ with grease nipples installed (there’s no excuse for the lack of maintenance instructions though) is that these would stick out of the bottom of the HDZ and likely catch on the workpiece or clamps and get torn out of the rail blocks if you left them installed. If you do want to use grease nipples search eBay for “M4 zerk nipple”.

I have successfully used a small syringe (just the plastic bit no needle attached) to suck superlube out of the tube and squirt it into the blocks, a small O ring can help get a seal there so you can get a bit of pressure on the grease. Or use something like this

https://www.amazon.co.uk/Sealey-AK55-Push-Type-Grease/dp/B07WZTP4YC

Unscrew the grease port screw, syringe or otherwise squirt grease into the port, don’t over-pressure or overdo this, you’re just trying to get grease into the chamber, not jet it out the other end. Then stick the screw back in and run the block up and down the rail a few times. It’s easier to do all this with the machine powered up as it holds the blocks stationary for you and makes jogging easier to work the grease around. Remove the screw and squirt grease in again, jog around. Hiwin suggest three rounds of this.

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Again, the Hiwin instructions say that you should regularly clean and inspect the rails, so occasionally wipe them clean before using the machine, don’t use solvents or other cleaning agents. You should then be able to spot when the grease needs topping up as after wiping clean you won’t get a film of grease on the rails after the machine moves.

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Good stuff Liam, as usual, thanks!

To be honest, I’ve been reluctant to lube the linear blocks. I work wood and make believe wood (mdf) mostly and am concerned about gunking up the bearings with lube/fine dust. Guess we’ll rely on the seals to do their job.

I wonder if a flush with some sort of seal-safe solvent at a set number of hours of operation might be wise? To clean out any gunk.

Any ideas about setting up an hour meter?

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They make a grease applicator for chainsaw bars, it has a small tip. Just load in the lube you want to use, place the tip against the hole and give a push.

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I would not worry so much about flushing and cleaning. As long as you keep it lubed it will do that job.
The thing I would wonder about is if they were installed correctly. Should be assembled on the beam instead of a fully assembled unit being forced onto the beam.
The block should be installed without the wipes. Then slide on the wiper seals from opposing ends and install the keepers. If the blocks were installed completely assembled, one of the wipers was probably damaged during install…

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I also didn’t want to do anything to the HDZ bearings in case I did them some harm. It was only when I started putting my own rails on the X beam and discovered that some of the Hiwin blocks I had bought only had a protective grease coat and needed filling that I was forced to go figure it out…

In terms of keeping the bearings clean, I think the idea is that so long as grease is moving out of the bearing and keeping the grease layer between the seal and the rail that’s supposed to keep the inside clean. Nothing I’ve seen in THK or any of the other manufacturer’s docs says you should need to take the blocks apart and clean them, just replace them after they wear out.

This guy shows what’s inside and that if there’s foreign material inside the bearing block it needs to be stripped down for cleaning as there are many small passages and areas to trap the contaminant;

I decided to try hard not to do that, it looks like a lot of trouble.

Unless there’s an obvious problem with the bearings going lumpy I’d just add grease to them via the ports and keep wiping down the rails.

One of the bigger design constraints on the Shapeoko is that there isn’t really room to install bellows or any of the other common mechanisms for keeping dust and chips off your rails so I run dust extraction all the time and wipe the rails down after anything messy. I hope this gives the seals on the rail blocks a decent chance to keep the insides clean.

There is some guidance in the mfr manuals about lubrication intervals but it is mostly about distance travelled and the applied load on the bearing blocks so in our case it would probably be a total steps count on that axis or something like that. Not sure we can do that with Carbide Motion, maybe CNCjs or one of the open source senders would let us do a counter for total mm moved on an axis in the GCode it sends?

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Good description of what I observed when I had the HDZ disassembled on the bench. Note: I did not remove the blocks from the rails, I’ve chased little balls across my bench on previous projects.

Anyway, the movement on the rails after my attempt at 3inOne lube was far from smooth, lumpy if you will. And, as noted in my original post, there was a lot of friction to overcome to get the carriage moving.

Syringes and Superlube on the way, hopefully get these things smoothed out. Need to get some spares on the shelf whatever happens.

Maybe @neilferreri can comment on the step counter?

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The “lumpy” movement is probably from the thin oil you used (3 in 1). what is the word… hydrodynamic? film or barrier something like that, I don’t remember so well anymore… anyhow, grease will provide this as will weighted oil. The odd feeling movement would be from the too thin oil allowing the wipes to grip the slide instead of sliding on a very thin film of lube.
If I were to run across this situation, and I cared about longevity of the unit, I would remove the assembly disassemble it and clean with wd-40, re-lube just enough to hold the bearings in place, re install properly and then load with grease.
though, I would bet c3d will advise against this procedure.

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Yep, the balls run round the race along the rail and back around inside the block on a track and need the lubricant to make that path not feel steppy.

Just be sure to get all that WD naughty purged out before greasing, remember it’s a solvent for cleaning lubricants out and not a lubricant itself, whatever it says on the tin.

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it is funny, the things I take for granted…
Yes, use the wd-40 as a “pressurized” cleaner, then remove the wd-40 ( myself, I would use brake parts cleaner)… and now I am seeing why c3d might advise most against doing this…
so, I amend…
If the parts are not working properly, contact c3d support…
sometimes I think I should just stick to “lurking”.

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I only learnt that a few months ago watching one of the videos about cleaning out the cheap clone bearing blocks, I’d always cleaned and wiped dry bearing races before greasing them but I am guilty of having squirted the WD into locks and things and assuming it was going to stay there as a lubricant.

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This is not such a bad thing. WD stands for water displacement. It has a lubricating effect, but you need the variant with PTFE in it to properly lubricate things.

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Not exactly sure about if PTFE is appropriate either.
WD-40 is a dry lubricant (the propellant and carriers evaporate and leave a dry film) not so sure how PTFE fits into this, but dry as well?
teflon … if nothing sticks to it, how do they get it to stick in a skillet… j/k

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