RE: Replace Bearings and Smooth Rods?

Greasing the bearings before installation is paramount.  You could try oiling the rods and work the oil into the bearings until you get a chance to do it right.

ps: 

HWTA

RE: Replace Bearings and Smooth Rods?

Heh ..  "hwta" was "what" spelled dyslexlichly (not sure that is a word either.. the joys of Englisch).. going to order some Misumi bearings  .. not sure on new rods yet .. will wait and see condition before deciding on those .. what grease do you use ? I have been using white Lithium but am reading lately that that is not the best to use .. Regards..

RE: Replace Bearings and Smooth Rods?

There are many whom beg to differ, but I still personally think an EP2 or NGLI 2 grease is simply too thick for the linear bearings on a Prusa 3d printer esp. where people pack the bearings, it will simply stop the balls recirculating and cause them to slide along the shaft rather than roll.

EP2 grease has the consistency of peanut butter, now imagine those small balls trying to push through peanut butter at 200mm/s. (OK 100mm/s as the bearings will be rolling)

Also the soap part (Lithium) is like a sponge for the oil and requires some heat to release the oil, granted with enough load and the balls tiny load point, it could generate the necessary heat, but overall the grease will be pushed out of the way, and remain pushed out of the way since it is too thick and cold to flow back filling the void.

When you use ep2 grease on a wheel bearing on some designs of car, you don't pack all the grease into the bearing, but half fill the voids in the bearing carrier which has angled roller bearings either end with said grease which sits there until it gets warm enough to flow, until then, this grease it not doing anything, it is just a reservoir of grease to replenish the grease already in the bearing.

I've took wheel hubs apart for maintenance after 12 months (Drum brake shoe replacement) to find this reservoir of grease is still there!, it just never got hot enough to flow, and this is on a car! (Thing load and duration of operation of a car vs. a 3d printer).

There are applications where ep2 grease will get warm enough on linear bearings to release oil, but these are usually on large industrial machines, and even then, the grease is also used to push out contaminants from the ends of the bearings and excess is removed, also these bearings normally have grease nipples!.

If you are meticulous and don't mind, then oiling is the best solution, but can be messy, also you will hear the bearings moving inside and it does require oiling regularly, but for most people a thin grease is (Semi fluid) advisable, correctly matched bearings and rods will allow the seals to keep the grease in and the dirt out and ideally you want a gL000 or gL00 lithium based grease (Think consistency of ketchup), This will be thin enough to move and will release the oil easier and will quieten the bearing noise, but may also have a tendency to slump to the bottom of the bearing, whereas the load is mostly at the top.

With oiling, the seals will wipe some of the oil to the ends of the rods, but I just wipe this excess off with a paper towel, it also traps dust in this buildup at the ends, but since I do this regularly, it is not a problem, the oil will also collect at the bottom, but enough remains coating the complete rod that it provides the necessary effective lubrication, you can wipe a clean finger along the tops of the rods on my printer and you will find oil on your finger, so there is always a film there. And the grease is just a carrier for oil anyway, so oil is actually doing the lubrication, so why not just use oil.

I use Singer sewing machine oil, but there are some fully synthetic sewing machine oils (Liberty Oil) that are supposedly better, but I don't have access to them in the UK.

RE: Replace Bearings and Smooth Rods?

I will give it a try .. Thanks

RE: Replace Bearings and Smooth Rods?

If you do decide to go down the oiling route, be sure to lubricate the inside of the bearings before fitting them.

RE: Replace Bearings and Smooth Rods?

Posted by: chocki

If you do decide to go down the oiling route, be sure to lubricate the inside of the bearings before fitting them.

Will do ..  No loss situation .. bearings are probably close to gone now .. ordered some Misumi .. will try this before the new ones go on and see how it works .. sounds like a good solution ..

RE: Replace Bearings and Smooth Rods?

I replaced my bearings and rods on one printer with new hardened smooth rods and synthetic bearings.  Much quieter.  

RE: Replace Bearings and Smooth Rods?

What's the friction like on synthetic bearings?, and tolerance, and wear?. I'm not dismissing them, just want to hear from someone who actually uses them.

RE: Replace Bearings and Smooth Rods?

Superlube is NG#2, works fine. As does the typical White Lithium you get in small tubes. 

I did the Misumi bearings on old rods and regretted it. If you inspect the old rods and see no signs of wear, maybe you'll fare better.  But I suggest you get new rods.

RE: Replace Bearings and Smooth Rods?

I used these and not issues thus far.  About 500 hours and no wear. https://www.amazon.com/Igus-RJ4JP-01-08-Printer-Bearing-replacement/dp/B07B3PZ7JH/ref=asc_df_B07B3PZ7JH/?tag=hyprod-20&linkCode=df0&hvadid=312163444503&hvpos=1o1&hvnetw=g&hvrand=7405203387355591870&hvpone=&hvptwo=&hvqmt=&hvdev=t&hvdvcmdl=&hvlocint=&hvlocphy=9010348&hvtargid=pla-569809586365&psc=1

RE: Replace Bearings and Smooth Rods?

Someone else reported bed wobble and slop with the plastic bushings and has gone back to metal bearings. I think Vesconite was what he was using - had two varieties, both with problems. Search the forums, was a recent report.

RE: Replace Bearings and Smooth Rods?

Going to order new rods from Prusa.. best price.. anyone feel that that would be a bad decision..

Charles .. any oil, grease treatment before usage? .. for the price, I will mostly likely try .. The Misumi (using as both singular and plural..language is so much fun..) well the bearings are on the way, but love information and sure will use them for this or for some other project.. 

RE: Replace Bearings and Smooth Rods?

Misumi bearings technical sheet:

https://us.misumi-ec.com/pdf/fa/2012/p1_0265.pdf

RE: Replace Bearings and Smooth Rods?

Thanks for all the info .. Charles .. I was wondering if you used any oil or grease with  the synthetic bearings?

RE: Replace Bearings and Smooth Rods?

I don't disagree that Ep2 type grease is recommended for bearings, but my argument is it is also down to the application the bearings are being used for.

See this link: https://www.thomsonlinear.com/en/support/tips/what-should-be-used-to-lubricate-linear-bearings

If you want to play safe though just go with the recommended grease from Prusa. MOGUL LV 2-EP and don't go filling the bearings with grease, just smear a light coating on the rods as this grease packed into the bearings will most likely stop the balls recirculating.

https://manual.prusa3d.com/Guide/Printer+maintenance+tips/1437?lang=en

So we are back to my suggestion that if you are having to smear the rods and not fill the bearings, then why not just use oil, just more frequently, it works just as well and is easier to keep clean.

RE: Replace Bearings and Smooth Rods?

Posted by: gary.s4

Going to order new rods from Prusa.. best price.. anyone feel that that would be a bad decision..

Charles .. any oil, grease treatment before usage? .. for the price, I will mostly likely try .. The Misumi (using as both singular and plural..language is so much fun..) well the bearings are on the way, but love information and sure will use them for this or for some other project.. 

I did not.  

RE: Replace Bearings and Smooth Rods?

Posted by: chocki

What's the friction like on synthetic bearings?, and tolerance, and wear?. I'm not dismissing them, just want to hear from someone who actually uses them.

I believe the bearings are covered here

RE: Replace Bearings and Smooth Rods?

Posted by: Tim

Someone else reported bed wobble and slop with the plastic bushings and has gone back to metal bearings. I think Vesconite was what he was using - had two varieties, both with problems. Search the forums, was a recent report.

I've been using the vesconite offerings since sometime in May, they're holding up nicely so far.

(More info: https://forum.prusa3d.com/forum/english-forum-general-discussion-announcements-and-releases/anyone-tried-vesconite-yet/#post-139373 )

RE: Replace Bearings and Smooth Rods?

Posted by: Tim

Someone else reported bed wobble and slop with the plastic bushings and has gone back to metal bearings. I think Vesconite was what he was using - had two varieties, both with problems. Search the forums, was a recent report.

That may have been me (though it was before the forum change I think), but I was using Drylin bushings. I still have them on my X and Z axis, but had to go back to the factory bearings on the Y which I packed with Lithium grease. All has been happy on all three axis since and my X & Y ghosting has all but disappeared.

The Drylins on the Y just had too much slop. Tried the factory U bolts as well as some printed carriers that were supposed to compress the bushings. Either things were too loose and the bed wobbled terribly every time it changed directions or they were too tight and the printer would throw errors.

I do have to watch how much I tighten the X carriage too or I'll get X errors even if manually moving it back and forth feels smooth. I can get things tight enough that there is no play in the X carriage though so I'm happy enough as is.