Replace Bearings and Smooth Rods?  

RE: Replace Bearings and Smooth Rods?

The Y-axis is especially prone to problem with slop in the bearings due to the long distance from center of print bed to periphery amplifying any rotation (around Z) of the bed. That rotation is naturally generated  because we have unequal motion resistance left vs right. Two bearings on left vs one on right, but we push/pull in mechanical center, not resistance center. Add uneven loading of the bed. Bearing slop is going to show up on Y axis most readily.

RE: Replace Bearings and Smooth Rods?

I wonder if that could be mitigated some with different belt attachment points, e.g. the rear and front of the Y frame rather than a single mount in the center. Because the "pull" of the belt is centered at opposite ends I'm guessing it should help keep the bed centered on the belt center-line as well.

RE: Replace Bearings and Smooth Rods?

I was thinking more along the lines of shifting the Y belt clamp, Y motor, and idler a bit to the left. That would put them close to center of resistance.

RE: Replace Bearings and Smooth Rods?

Of course, if even one bearing changed in motion resistance, the center of resistance would shift.

RE: Replace Bearings and Smooth Rods?

Thanks for all the input ..

Ordered new rods..

New Misumi arrive tomorrow..

Ordered Ultrasonic machine to clean oil before packing the bearings with new grease/oil.. still not decided .. (wife went into hysterical laughter at me when I asked to use hers, so I took that to mean buy my own ..) 

Operation will begin shortly after all supplies arrive ..

Regards to all..

RE: Replace Bearings and Smooth Rods?

Posted by: gary.s4

Thanks for all the input ..

Ordered new rods..

New Misumi arrive tomorrow..

Ordered Ultrasonic machine to clean oil before packing the bearings with new grease/oil.. still not decided .. (wife went into hysterical laughter at me when I asked to use hers, so I took that to mean buy my own ..) 

Operation will begin shortly after all supplies arrive ..

Regards to all..

PSA: Unless you plan to use a water-based degreaser, most ultrasonic machines are NOT rated to be used with flammable liquids (alcohols, mineral spirits, etc), nor are the electronics rated for flammable/explosive environments. It can be quite dangerous to do so because the process heats the liquid and thereby its vapor pressure, increasing the risk of ignition from sparks either internal to the machine (relays, switches) or nearby.

You have been warned.

RE: Replace Bearings and Smooth Rods?

Posted by: vintagepc

Posted by: gary.s4

Thanks for all the input ..

Ordered new rods..

New Misumi arrive tomorrow..

Ordered Ultrasonic machine to clean oil before packing the bearings with new grease/oil.. still not decided .. (wife went into hysterical laughter at me when I asked to use hers, so I took that to mean buy my own ..) 

Operation will begin shortly after all supplies arrive ..

Regards to all..

PSA: Unless you plan to use a water-based degreaser, most ultrasonic machines are NOT rated to be used with flammable liquids (alcohols, mineral spirits, etc), nor are the electronics rated for flammable/explosive environments. It can be quite dangerous to do so because the process heats the liquid and thereby its vapor pressure, increasing the risk of ignition from sparks either internal to the machine (relays, switches) or nearby.

You have been warned.

DITTO.  A clum member used one to clean rocket motor casings with disastrous results.  The solvent melted parts.  

RE: Replace Bearings and Smooth Rods?

I forgot to mention that not only does the liquid heat, but the ultrasonic vibrations will likely aid in atomizing the liquid to boot, making an even more volatile atmosphere - not only do you have vapor flashes but also atomized fuel.

Ever heard of flour mills exploding? Same problem - finely atomized combustibles burn *very* very quickly and explosively.

RE: Replace Bearings and Smooth Rods?

Oh... Oops...

I put my bearings in an open zip-loc and filled it with enough 91% IPA to fully submerged the bearings. Then I put the bag a ultrasonic jewelry cleaner we have with the open end of the bag hanging out of the machine. Ran them for 30 minutes in 5 minute intervals.

Bearings came out nice and clean and the house is still standing, but I'll try to remember that for the next time I need to clean bearings...

RE: Replace Bearings and Smooth Rods?

Posted by: gnat

Oh... Oops...

I put my bearings in an open zip-loc and filled it with enough 91% IPA to fully submerged the bearings. Then I put the bag a ultrasonic jewelry cleaner we have with the open end of the bag hanging out of the machine. Ran them for 30 minutes in 5 minute intervals.

Bearings came out nice and clean and the house is still standing, but I'll try to remember that for the next time I need to clean bearings...

It's one of those things where if it goes wrong, it goes... disastrously wrong. And you can wave goodbye to any insurance claims if they find out that was the origin of a fire.

RE: Replace Bearings and Smooth Rods?

Ok, so I have obviously misunderstood some things.. If an ultrasonic with diluted IPA is dangerous and not recommended.. what is the recommended method  to cleaning the bearings before greasing/oiling?

RE: Replace Bearings and Smooth Rods?

In a container with IPA and slosh it around manually every few minutes for about half an hour? It's what I did.

RE: Replace Bearings and Smooth Rods?

Mitsumi says their shipping oil is compatible with most or all recommended greases. 

Or, grab a wire mesh basket (strainer), a can of bicycle chain degreaser, and have some outdoor fun.  Or, a quart jar, enough alcohol to cover the bearings, soak and stir; then pour contents into the mesh basket/strainer, still holding over the sink, rinse with fresh alcohol.

RE: Replace Bearings and Smooth Rods?

I will just mention bearing wear on the rods is not even. It occurs in lines, where the balls hit.

If I had otherwise good rods, I would align the new bearing balls to hit an unworn portion of the rod. 

RE: Replace Bearings and Smooth Rods?

@charles-h13

Can you post the part number of the rods and bearings please ?

RE: Replace Bearings and Smooth Rods?

@daviddlc

I ordered mine from Prusa.  

RE: Replace Bearings and Smooth Rods?

From what I know of Igus bushings, they typically expect a press-fit that will shrink them down to the correct bore size. It's possible these are actually sized just right, but I wouldn't be surprised if they were 0.30 oversized. 

RE: Replace Bearings and Smooth Rods?

@chocki

I just changed out my Y axis bearings with PRUSA originals and used Singer machine oil as well. 

My machine repeatably gave me crash errors. I felt that the extruder was having problem. 

I'm for a bearing and shaft upgrade. 

RE: Replace Bearings and Smooth Rods?

Thank you all, I have ordered the Prusa originals, I'm worried that my machine has those.

But I will give a try to the new ones.

RE: Replace Bearings and Smooth Rods?

Caveat: All crashes are not due to bearing or shaft problems.

If the carriage moves smoothly by hand from end to end with power off - look elsewhere for your problem.