front bearing just shed a bit of rubber
October 17, 2014 11:41AM

Hi Again All!
I noticed the front carriage bearing was slipping to the side occasionally. The cause revealed itself today as a piece of the inner rubber getting stuck and finally shedding out of the bearing. There was a crash as the bearing pulled out from under the bed. I've removed the almost complete circle of rubber - looks like a thin O ring pictured next to a €1 coin, added some oil to the bar and am printing a set of added supports for the bearing to Y carriage. I pulled a profile from the Y bearings and made a quick support pictured.

The question is how fast is this going to be a major issue? I ordered a set of LM12UU Linear bearing's but replacing it will be a major task requiring the breaking down of the machine completely. Should I only print critical things and save what life the bearing has?? It didn't feel very bad after the shedding, just slightly louder. I'd prefer to simply add the braces and call it "fixed" but that may not be wise... Will this support cause other problems? Thanks again all!!


Socrates ~ The Amsterdamman
slic3r-1.2.9
Re: front bearing just shed a bit of rubber
October 17, 2014 12:17PM
Quote
Amsterdamman
..The cause revealed itself today as a piece of the inner rubber getting stuck and finally shedding out of the bearing...

a circle of rubber from one of the dust covers I guess - yes the rods should always have a thin layer of oil to prevent this

Quote
Amsterdamman
..The question is how fast is this going to be a major issue?..

I would say never if you keep it oiled, even if the rubber dust covers wear out to the point of not touching the smooth rod they will still "float" over the rod and keep the dirt out - and the bearing itself will never wear out if proper oiled

Quote
Amsterdamman
I'd prefer to simply add the braces and call it "fixed" but that may not be wise... Will this support cause other problems? Thanks again all!!

not if mounted proper, not if the support don't put a twisting force on the bearing, here's my front bearing:



Erik
Re: front bearing just shed a bit of rubber
October 17, 2014 05:20PM

Thanks Erik! So far, it works fine! [www.thingiverse.com]


Socrates ~ The Amsterdamman
slic3r-1.2.9
Re: front bearing just shed a bit of rubber
October 18, 2014 07:25AM
Looking good! - yes that will self-align and yet hold the bearing, mine I had to adjust with shims, not a problem but not as user friendly to mount as your mod

the function of the front bearing is to fix the position of the bed in the horizontal way but ideally it should float in the vertical sense as the inner smooth rod/bearings takes care of that

The saying "two's company; three's a crowd" it true for bearings too if running on the same axle/rods or anything in a fixed position

Erik
Re: front bearing just shed a bit of rubber
October 18, 2014 08:52AM
..keeping the smooth rod oiled with a thin layer of oil, that is good advice but not easily achieved - true, the bearings dust cover will make sure to leave a thin layer only (and a mess of oil under the printer) but it would be better to accumulate that oil and re-distribute when needed, e.g. mod the bearing clamps to hold a ring of felt that would accumulate the excessive oil and distribute it on the rods - there should be lots of space for that on both sides of the front bearing and on the inside of the inner bearings

while we are at it, my version on "howto clean and lubricate a linear bearing"

place bearing in container, soak in solvent to loosen and free any dirt, give it a good shake



using a high pressure air hose (and great care) you will be able to get the balls moving along the inner rail, this will help getting the dirt out but don't overdo it though!, don't let them move too fast, with out the oil it's now running metal against metal - yes you could use very thin oil instead but that would make it harder to get the dirt out as it would stick to the bearing, with the bearing totally clean and dry the dirt has nothing to stick to




soak the now clean bearing in thin oil, let drip of any excessive oil - let it stand on end for a while - and please notice that the dust covers are not oil proofed, any excessive oil will leak out between the dust cover and the outer bearing ring



Erik
Re: front bearing just shed a bit of rubber
October 20, 2014 04:30AM
We do suggest a maintenance schedule, which includes oiling the smooth rods occasionally: [reprappro.com]

Ian
RepRapPro tech support
Re: front bearing just shed a bit of rubber
October 20, 2014 11:07AM
Living in Hawaii my rods were rusting before I even finished putting it together. I lost the rubber on my X bearing the same way. Little bit of rust on the rods caught the rubber and eventually ripped it off. Ive been running the bearing with out the dust guard for weeks now and no Ill effect, however I have ordered a replacement just in case. I agree with Ian that 3 in 1 oil is great for the rods and bearings its what I have been using even before seeing it suggested here, just a dab on your finger and run it along the rod every few days depending on use. As for the rust issue, the machine is self derusting if it is used often enough. I run mine almost every day and have rust built up on the ends of all my rods but where the bearings travel is clean. I have considered writing a Gcode to cycle all the axis several times after an oiling for this purpose but... im lazy and just do it manually Cleaning the rods with a soft brass brush helps too.
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