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Angular contact bearings

V

va2fsq

Active Member
Hi
I want to change the spindle bearings on my king 7x12 lathe. I understand that sealed angular contact bearings are the best to use as opposed to tapered bearings.
My question is quality vs price. I see I can get them at McMaster Carr for close to 200$ and I also see them at other sites around 30. Is there a difference in this application? Where's another source?
Finally I have to remove the headstock to access them. Any issues with realignment afterwards? How do they make sure the spindle then lines up parallel with the bed?
Thanks, Tom
 
Hi Tom,

It might be best to give us the bearing numbers - ie: what is in the lathe right now, what are you planning on replacing them with.

Links to the bearings you are considering also help.

We can then provide you with more qualified answers to your questions.
 
What is the motivation for changing out the bearings? If you only remove the spindle and reinstall it with new bearings, the alignment shouldn't change. This depends on the bearing races being removable without using a hydraulic press, etc. Lots to consider.
 
I'd be a bit surprised if angular contact bearings will improve the functionality of your 7x12 lathe over just decent tapered bearings. I also suspect getting preload adjustment on the angular contact bearings might be more difficult than regular tapered bearings.
 
I know pp are spending time and money to upgrade the little machines - but in my experience with them, which is limited, I think such time is better spent at simply upgrading to a larger machine or if you have a specialist application to a much better made machine.
 
DPittman said:
I'd be a bit surprised if angular contact bearings will improve the functionality of your 7x12 lathe over just decent tapered bearings.
Click to expand...
The DF1237 just uses taper roller bearings and the runout is very good. I assume they are 'precision' roller bearings, but still.

update: there might nnot be room for TRB if what is ther are deep groove ball bearings. Best to use the same bearings....
 
https://www.bocabearings.com , free shipping to Canada last time I ordered from them and as a big plus they tell you where the bearings are manufactured. McMaster never seems to provide that.
If your present bearings are good then personally I would leave things alone. e,g, you will need a lathe to make extractor/installation bushings, and likely won't know the size until you have the headstock apart. :-)
 
I have done this bearing replacement on my 7x14 lathe- more 'for fun' than necessity. :)
To remove and replace the bearings the tools that come with the gear set from Micromark work well; that's what I used. That set is on closeout.
https://www.micromark.com/Metal-Gear-Set-for-Mini-Lathes-and-Milling-Machines
If you have a good look at the parts in that set, you might be able to improvise something.
There is lots of info at the 7x Mini lathe group on Facebook.
Not all bearngs are the same thickness, so replacing the original bearings with angular contact or tapered bearings may requirte machining a different spacer for the gears inside the headstock...and you need a lathe for that! The cheaper angular contact bearings tend to be the open style- not sealed.
I agree with @gerritv that leaving the bearings 'as is' is probably a good option. For most 7x lathes there are other 'problem areas' that may improve performance more easily.
BTW, your King lathe was likely made by Sieg. Posting a picture of the carriage and the right end of the leadscrew would allow ID - either Sieg (most common) or RealBull. Sieg 7x lathes came with ball bearings, RealBull (usually Vevor) come with tapered roller bearings.
7x lathe headstocks are bolted to the ways and the alignment is controlled by the fit of the V groove in the headstock with the raised 'prism' part of the ways. Shimming is often needed to fine tune the spindle alignment with the ways.
 
Thanks for all the replies.
The reason I want to do this, is that the lathe is horribly loud during operation. I mean it really sounds bad. Rattling and screeching. I have narrowed it down to either the spindle bearings or the shaft that the motor pully attaches to that has the reduction gear. In fact, if I put the speed lever (high and low) in between settings, then the spindle doesn't turn and it sounds the same although much less louder. So maybe it isn't the spindle bearings but the drive shaft? Would the sound become much louder when it has engaged the spindle?
carriage.jpg
leadscrew.jpg


The tapered roller bearings are larger in width. Therefore you have to manage reducing the size of a spacer in the gear train. You need a lathe for that lol. However, the angular contact bearings are the same size as the original, 16mm. All the videos I have seen on youtube (there are quite a few) show the process but they never give part numbers.
In addition, the finish on my work is never that good.
So the bearing is 30mm IDS, 62m,m OD and 16mm wide.

As to investing more money for a better lathe, well how much more? Anything in my budget and size is likely to just have the same low quality parts as the one I have. Then I am there again.
I believe my lathe is a RealBull but then it already has tapered bearings. How do you lubricate them? Take apart the whole setup?

I really do not want to mess with shims on the headstock. I had a heck of a time aligning the real tailstock having to add adjustment bolts.

So is this a RealBull?
Tom
 
You have answered your question, it is not the spindle bearings. :) Picture of the lathe so we can see the whole thing plus one of the LH end without the cover might help identify brand although it is not likely to make any difference in the motor/idler bearings to order.
Your lathe looks basically unused, so spending more money on another lathe might not move you further ahead.
 
va2fsq said:
In fact, if I put the speed lever (high and low) in between settings, then the spindle doesn't turn and it sounds the same although much less louder. So maybe it isn't the spindle bearings but the drive shaft? Would the sound become much louder when it has engaged the spindle?


The tapered roller bearings are larger in width. Therefore you have to manage reducing the size of a spacer in the gear train. You need a lathe for that lol. However, the angular contact bearings are the same size as the original, 16mm. All the videos I have seen on youtube (there are quite a few) show the process but they never give part numbers.
In addition, the finish on my work is never that good.
So the bearing is 30mm IDS, 62m,m OD and 16mm wide.

As to investing more money for a better lathe, well how much more? Anything in my budget and size is likely to just have the same low quality parts as the one I have. Then I am there again.
I believe my lathe is a RealBull but then it already has tapered bearings. How do you lubricate them? Take apart the whole setup?

I really do not want to mess with shims on the headstock. I had a heck of a time aligning the real tailstock having to add adjustment bolts.

So is this a RealBull?
Tom
Click to expand...
Tom-
If the squealing doesn't disappear when the spindle isn't moving, then I'd agree with your diagnosis that it's the driveshaft that's the problem.
The change gear train is powered by the spindle, so that eliminates them as well.
This is assuming that it's not the motor - you've run the motor with the belt off?

I changed to angular contact bearings (unsealed) to avoid machining a new spacer. As I mentioned, it wasn't really necessary and I don't think it made any difference in performance.
And from your diagnosis, I think you can probably take spindle bearings off the 'to do' list.

My Micromark lathe is definitely a Sieg. Your DRO scale (nice!) hides the carriage shape which is 'H' shaped on a Sieg, The leadscrew end on my Sieg is different from yours, so the ID is still a question.
mini-IMG_1056.JPG

mini-IMG_1057.JPG


I've never read of a 'factory stock' Sieg or RealBull with shims under the headstock, so you should be OK to remove and replace the headstock. The bottom of the headstock is open so you will see things clearly once it is on your bench.

I drilled a couple of holes in the top of the headstock and pipe threaded them for plugs (as Steve Jordan on YouTube did) so I can shoot think grease from a spray can on the innards.

mini-IMG_0712.JPG
 
va2fsq said:
I believe my lathe is a RealBull but then it already has tapered bearings. How do you lubricate them?
Click to expand...
Tapered roller bearings are either immersed in an oil bath, pressure oil lubricated or greased. In all cases there needs to be a separate seal on the outside to keep debris out.
 
Well since this thread has started and I'm in better shape than I thought, I just noticed that the cross slide has play in it. If I grab it and push it to the back of the lathe it moves. Same as if I pull it to the front. Shouldn't this be rigid or is it determined from the play in the dial mechanism?
 
va2fsq said:
Well since this thread has started and I'm in better shape than I thought, I just noticed that the cross slide has play in it. If I grab it and push it to the back of the lathe it moves. Same as if I pull it to the front. Shouldn't this be rigid or is it determined from the play in the dial mechanism?
Click to expand...

Tighten up your cross slide gib..... Adjust the compound gib while your at it.
 
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