Nova Comet II Belt Replacement - bearing seems stuck

[Sid Sethupathi]

I'm attempting to replace my Nova Comet II belt following these updated instructions from Teknatool: https://teknatool.freshdesk.com/sup...-comet-ii-slightly-different-from-the-manual-. The instructions are different than what is in the manual, but Teknatool suggests this method is easier.

However, on step 5, Bearing 2 remains stuck in the cast iron body while the spindle slides out. I'm considering going back to the instructions from the manual but was curious if there is a way to loosen the bearing without removing the whole spindle, or if this stuck bearing is indicative of another problem.

Attached is a picture of the spindle partially slid out but the bearing not moving.

 

[Clifton C]

Both the slightly-different-from-the-manual and The Manual say, "this step requires force". How much force? Enough to shift the bearing but not enough to break something... I understand the "less steps to change the belt, but I would consider changing the bearings during the belt replacement.
Bearings that needed just a little persuasion I might consider reusing, depending on time in service. But, with more "persuading", I start to lose confidence in the old bearings and feel replacing with new is cheap insurance. Order from bearing supply house.

 

[Sid Sethupathi]

Both the slightly-different-from-the-manual and The Manual say, "this step requires force". How much force? Enough to shift the bearing but not enough to break something... I understand the "less steps to change the belt, but I would consider changing the bearings during the belt replacement.
Bearings that needed just a little persuasion I might consider reusing, depending on time in service. But, with more "persuading", I start to lose confidence in the old bearings and feel replacing with new is cheap insurance. Order from bearing supply house.

Thanks for the feedback. I considered changing the bearings out as well, but thought it was a bit more involved so I decided to try the belt first. The reason for this change is because of this sound that started happening at higher RPM (~1600+). I noticed that there were some cracks on the belt so I thought I would start there. Sound:

View: https://youtube.com/shorts/CRbe-B8OLwg


The bearings from Teknatool's site are out of stock (https://www.teknatool.com/products/...met-ii-parts/headstock-spindle-bearing-kit/)? Is 6005ZZ a universal bearing size? If I search for that on Grainger, I see several different options at varying price points.

 

[Mike Johnson]

I found several hundred matches on eBay for your 6005ZZ bearings. This is a very common bearing size. You should be able to mechanically
attach to the spindle thread on the exterior of the headstock and pull it from a stationary part of your tail-stock end of the lathe. If you rig up
a threaded shaft with a nut and washer on the other side of a stationary part of the tail-stock end you could wrench the nut to slowly pull the
spindle and bearing out of the headstock. If you remove the quill from the tailstock and lock it down to the ways you should have enough
leverage to wrench the spindle and bearing out of the headstock by running the "pulling" threaded shaft through the opening in the tailstock
after you remove the quill. You could also just remove the tailstock and bolt a block of wood to the end of the ways and run your "pulling"
threaded shaft through the block of wood and wrench on the nut on the other side of the block of wood after you drill a hole in it.

 

[Dwayne Watt]

6005 is a very standard bearing size. The ZZ is a reference to shields on both sides of the bearing. Personally, I would install sealed bearings, not shielded bearings on a lathe. 6005-2RS is a double sealed bearing. There are other designations for the seal depending upon the manufacturer, but 6005-2RS bearing from SKF, Timken, NSK, Koyo would all be good choices. The other thing to look for on the bearing is a clearance designation. C3 is pretty typical. No designation means standard clearance which is slightly tighter but may or may not be best for your lathe.
ebay is not the place to buy bearings. In a place like Champaign, there are probably several bearing supply houses from which to choose. Motion Industries is one. Otherwise order from a place like Grainger, McMaster-Carr or some other true bearing supply house. An auto supply store is not a great place to go ($$$ and unknown quality) although they will likely have this size bearing.

 

[Dwayne Watt]

Just now looked at the big online shopping site and a couple of these bearings from Timken can be had for about $16.

 

[Sid Sethupathi]

Thanks Dwayne, the info on bearings was helpful. I ordered 6005-2RS Timken bearings from Amazon like you mentioned. I'm not sure if I got counterfeit bearings because the price seemed too good to be true (2 for $16 whereas at places like Motion Industries, the same bearings seemed to go for $30+) but they fit and spun fine. I also noticed that the bearings that were already in the lathe were 6005-RS, which differed from what is in the documentation and what Teknatool sells (6005-ZZ), so maybe they were switched out at some point by the previous owner.

I ended up using the original manual method. If any other Nova Comet 2 owners stumble upon this thread, the grub screw that secures the pulley into the spindle groove has two pieces, one that screws into the other. I didn't realize this and only took one of them out. The pulley slid on the spindle but didn't move all the way over. I thought maybe it was stuck on the spindle and some motivation against the cast iron would help if I kept hammering, but that was not the case. I ended up hammering the pulley into bearing 2 (the one closer to the tailstock) and it broke the bearing, but that did

After that, the rest of the replacement went pretty smooth. I left bearing 1 alone. The sound from my video is gone so not sure if it was due to the belt or the bearing 2.