# Looking for sealed tapered roller bearings



## Stan the Man (Apr 8, 2022)

Hello all,
I am replacing the stock, head stock bearings in a Grizzly G8688 7x12 lathe, I am trying to find sealed tapered roller bearings that will fit. Currently I have unsealed tapered bearings but would prefer to return them and purchase the sealed kind. Can anyone post a link to where I might find them here in the U.S. or  provide a Company name and part number so I can look them up. I rather not have to import them from the UK as the shipping is outrageous. Thanks in advance.
Stan.


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## Bone Head (Apr 8, 2022)

Contact Timken.  They may have what you need.


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## Cadillac (Apr 8, 2022)

Honestly never seen or heard of taper roller sealed bearing. Now a sealed roller maybe but you usually have a separate seal. What’s your bearing numbers?


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## jcp (Apr 8, 2022)

You're looking for a rare bird indeed.


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## Al 1 (Apr 8, 2022)

Stan,  What method of lubrication is in place now?  Al.


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## addertooth (Apr 8, 2022)

Hundreds of people have done the upgrade on the 7 X 12 lathes with "unsealed" tapered bearings. I have not heard of anyone who has experienced bearing failures with them.


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## MrWhoopee (Apr 8, 2022)

Not sure if such a beast exists. I've never seen or heard of one.


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## Beckerkumm (Apr 8, 2022)

Sealed bearing have a much lower rpm limit than open.  In a spindle bearing you want tight clearance and the tapered bearing will generally have some load to reduce both radial and axial runout.  If a machine is designed for open bearings in a precision application there is no benefit to sealed and potentially additional risk.  Can you tell I'm not a fan ?  Dave


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## benmychree (Apr 8, 2022)

Never heard of such an animal ---


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## aliva (Apr 8, 2022)

A taper roller bearing cannot be sealed becuase of the cup and cone design.


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## Bone Head (Apr 8, 2022)

Find an o-ring of sufficient diameter and width, slip it over the shat and but it up against the bearing's bigger diameter.  I've done this to tapered roller bearings on my Harley.  Works fairly well.


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## Firebrick43 (Apr 8, 2022)

Bone Head said:


> Find an o-ring of sufficient diameter and width, slip it over the shat and but it up against the bearing's bigger diameter.  I've done this to tapered roller bearings on my Harley.  Works fairly well.


Any tapered roller bearing of any size is not going to have a dust shield made out of an oring.  

In machine tools, tapered rollers are all most alway protected by labrinth seal.  It has no contact but the path for dirt to get in is tortured and therefore less likely.  Easy to make on a lathe.


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## OCJohn (Apr 8, 2022)

Assuming you’re after 30206 roller bearings that fit all the Chinese 7x spindles, I think you’re out of luck. Only (good) alternative is a sealed 7206 angular contact bearing. Forget what the code is for the sealed version, but it starts with 7206: ID (Bore) 30mm OD 62 mm Width 16 mm

Not common and not cheap.


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## addertooth (Apr 8, 2022)

Most likely, you will have to thin down the spacer between the back of the spindle, and the cobbed pully the belt runs over.  Tapered bearings are thicker than the stock ball bearings, and push that whole assembly back.  You will also have to thin down the spindle so that the rear bearing set is free to slightly slide on the back part of the spindle, otherwise you pre-load will end up being wrong.  (the rear bearing which is furthest from the chuck needs to be able to move without excessive force on the spindle, otherwise, when you try to adjust pre-load for the bearings, the bearing may have a lot of "stiction" and either be too loose, or wedged to tightly).  For that, you may need to make a conical jig to spin the spindle in a drill press (or another lathe), to make sure your light sanding stays near-concentric.


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## homebrewed (Apr 8, 2022)

addertooth said:


> Most likely, you will have to thin down the spacer between the back of the spindle, and the cobbed pully the belt runs over.  Tapered bearings are thicker than the stock ball bearings, and push that whole assembly back.  You will also have to thin down the spindle so that the rear bearing set is free to slightly slide on the back part of the spindle, otherwise you pre-load will end up being wrong.  (the rear bearing which is furthest from the chuck needs to be able to move without excessive force on the spindle, otherwise, when you try to adjust pre-load for the bearings, the bearing may have a lot of "stiction" and either be too loose, or wedged to tightly).  For that, you may need to make a conical jig to spin the spindle in a drill press (or another lathe), to make sure your light sanding stays near-concentric.


I went through all this recently.  I never found any seals for tapered roller bearings on my 7x12, don't seem to exist.  

I did polish the spindle where the rear bearing goes to get some believable bearing pre-load.  The original bearing interference fit on that end was much too tight to do that.  I did it by installing a length of 1/2" drill rod in the lathe spindle using an MT3 collet and then chucking the rod in my mill so I could spin the spindle while sanding it down.  I think that was about the first time I actually used my MT3 collet set for something useful .  Tested a lot so I just got a tight sliding fit.  

I also had to machine the bearing covers, which are there to keep swarf out of the bearings.  Tapered roller bearings are slightly thicker than the originals so that's necessary so the bearing covers can go back on.  For the same reason, reduced the length of the spacer on the back.  Along with the bearing covers I machined a replacement spacer out of 6061 before I tore my lathe down.  The spacer will need to have a notch filed in the ID so the spindle key (for the bull gear) goes in.  This isn't necessary if you just shorten the OEM spacer; and that can be done well enough W/O having the spacer in place.  Or so I've read.....  YMMV.

My lathe is back together and running fine.


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## Stan the Man (Apr 9, 2022)

Hi Guys,
Well I just spent the better part of two and a half hours typing up my response to you all.  After a little Log in S.N.A.F.U. I read Homebrewed's response and I think it may have answered my questions. Homebrew Where were you three hours ago? Uggg!
Its all Good.
Not wanting however for any of you to miss out on my fact finding, fun filled thought provoking dissertation I have decided to graciously and magnanimously publish for your reading enjoyment and pleasure my BLa,Bla......Bla, Bla, Bla, response to you all prior to reading Hombrew's response.

Without further ado on with the Shoe!


Hi guy’s

Thank you for so many reply's to my question regarding sealed roller bearings. I will attempt to address everyone's questions and informative advice. Ill try to keep things short and specific.

But first I would like to explain,

*What I wanted!* After watching a lot of videos I wanted a tapered bearing that I would not have to maintain, I have watched probably no less then 50 videos on mini lathe mods and a dozen of those on bearing mods. TOT included.

The consensus is a major improvement in the head stock is to remove the ball bearings and go for Tapered roller bearings (TRB’s). Some videos talked about Sealed Tapered Roller Bearings so I started looking for a set.

*They Do Exist*…...*I think? * (Cadillac, JCP, Mr. Whoopee John York benmychree: ) Unless some you tuber's are interchanging terms in there heads and mixing tapered and contact roller in the discussions to mean the same thing It seems that United Kingdom guy’s have access to some kind of *S*ealed *T*apered *R*oller* B*earings at least that is my understanding from my internet research. If I am incorrect I will be the first to admit I am wrong as I am the grasshopper and still learning.

Hearing these guy’s talk about bearing up grades to tapered ones and using there dimension info I typed in (STRB’s) into google search. The algorithm sent me to several UK web sites when I first went looking’ that will sell you( some kind of sealed bearings) for the Chines lathe. That's all well and good but shipping to the USA is usually more then the cost of the bearing. I don't know what kind of bearing they actually send ;I assumed it was sealed and tapered again from what I was reading/ hearing/understanding but now I am not 100% sure of what you get.

*7206 Sealed contact bearings:* (OC John) I watched TOT and obviously tapered roller bearings and contact bearings are two different animals both physically and cost wise. They were next up on the list but the cost was way more then I wanted to pay for a set of bearings for this modification. So I ordered Timken TRB # 30206 (obviously not sealed) the outer race fits right in place as shown on countless videos like TOT and are a touch wider then stock over all.
*My biggest concern: (*Firebrick43,Al-1) is to keep swarf/dust (alum. Brass, Plastic cast iron etc.) out of the bearings. Second concern is not having to tear the head off the bed once or twice a year to lube the bearings. Zirk fitting addition best Idea yet.(see below)

I have been watching a fellow Ades workshop as he added unsealed TRB to his head stock and noted that the new bearings are indeed wider by I believe 1 to 1.5 mm from 16mm to 17 point something, as did TOT. He was talking about wanting to protect the open bearings (the cone) from accumulated junk during daily machining process.

He also expounded on a lubricating system (Zerk fitting) with a drilled passage through the head stock housing into the new bearing (Face cover) to the end of the cone, once he sealed the bearing in place with covers. At the moment there is no way other then to per-lube the bearing with Molly-grease before installation.

He goes into a lengthy thought process and build with a specific bearing cover design and then talks about (future project) further refining the seal by ether using an oil seal, possible o-ring in a groove or felt application. One viewer suggested a labyrinth seal for the reasons stated in Firebrick43’s diagram.

*Where I am getting confused: *(Addertooth) Ades work shop is going to all this trouble to make this custom fit very professional looking cover but yet TOT just puts on the old plastic covers. I understand adjusting the spacers and all that and yes many people have made this conversion. But I have yet to hear of any one talking about bearing contamination from swarf or grit during use.

*Question:* TOT doesn't talk about the plastic cover sticking out from the new bearing unless I missed that part??? Am I over thinking this or are the plastic covers good enough and do an adequate Job and can be snugged back in place just sticking out a little?

Would aluminum covers be better and if so does any one have a drawing of what the specs on a new cover should look like as they fit against the new bearing side face. Ades points to his cover as he talks but its hard to follow him when he starts to discuss exactly what his dimension's are. His video and finished cover are beautiful if only he would provide a drawing.

*I’ll end this Discussion with: *So what is the collective wisdom as to am I over thinking this thing, what to do about the covers, old plastic back in place or new aluminum ones? If I choose to make aluminum covers to account for the added width what clearance do you guys recommend around the shaft to keep junk out from daily use.

I hope this discussion will benefit someone who is currently in my shoes or will be in the future. I always learn something new from all of you. Thank you.

Stan.
P.S. if nothing else any one suffering from insomnia is probably now fast asleep. At least my typing skills are improving!


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## Ischgl99 (Apr 9, 2022)

STRB is a spherical thrust roller bearing, that is a different design than a tapered roller bearing.


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## addertooth (Apr 9, 2022)

I was referring to the spacers which fit on the side of the spindle away from the chuck.  They are keyed and fit between the back of the spindle where gear mesh occurs.  The thicker bearings require the spacer be thinner so that gears maintain 100 percent mesh and alignment.  I am including a picture of two I made, with keyway, for this purpose. The second picture is where the spacer fits.


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## homebrewed (Apr 9, 2022)

I thought about adding some zerks to lube the bearings as well.  But, not being sure just how grease could be directed _into_ the rollers and thinking that excess grease would get all over the interior of the headstock, I gave it a pass.

I also realized that if the spindle is polished down so the rear bearing is a light friction fit, you have a setup that can actually be taken apart to lube the bearings....without risking damage to them.  Once the retainer nuts are removed, the rear inner bearing and the transmission gear are the only things keeping the spindle in the headstock.  And the transmission gear is a sliding fit as well.  Not to say it won't be a PITA but I think it could be done without removing the headstock from the bed.

It also might be possible to loosen up or remove the bearing covers and get grease into the bearings that way.  The rear cover can be completely removed so no access problem there.  The front one would be a little more challenging since it can't be completely removed.  I thought about using oil on the bearings instead of grease, just to make it easier to lube them; but all of the descriptions I found regarding bearing replacement used grease.  So I did too.


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## addertooth (Apr 9, 2022)

Yep, the grease versus oil discussion is complex. It largely has to do with "film strength" of the lubricant, along with bearing pressure and RPMs.   In some cases, you have to change your bearing selection, if you are choosing oil, as versus the typical grease. The issues with oil and film strength become more of a problem with low RPM work which is high stress.  I do note that the wheel bearings on my car use grease, and go a long time without removal and replacement. But then, it is a sealed environment (for the most part), and it has a cup which acts as a reservoir to hold additional grease.


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## Ischgl99 (Apr 9, 2022)

homebrewed said:


> I thought about adding some zerks to lube the bearings as well. But, not being sure just how grease could be directed _into_ the rollers and thinking that excess grease would get all over the interior of the headstock, I gave it a pass.


You don’t want to inject the grease directly into the rollers, grease gets injected into the housing around the bearing and acts as a reservoir where the oil in the grease is drawn into the bearing over time.  Any grease that is in the bearing gets pushed out as soon as it starts spinning, so making sure the void around the bearing has grease provides the lubricant the bearing needs.  The bearings themselves require very little grease to be properly lubricated, just think of how long a sealed bearing lasts with just the amount of grease inside the bearing.  The only exception to this is double row bearings, or back to back arrangements, that have the grease injected between the two rows of rolling elements and eject the grease outward, instead of the grease coming from the housing and going into the bearing.

To keep the headstock clean, and there is room, you could install an inner bearing cover on the headstock side and inject grease in that side so it gets pushed out the spindle end.  You could add an opening towards the bottom that ejects the grease downwards.  This of course is making it much more complicated, but who doesn’t need another project??


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## homebrewed (Apr 9, 2022)

Ischgl99 said:


> You don’t want to inject the grease directly into the rollers, grease gets injected into the housing around the bearing and acts as a reservoir where the oil in the grease is drawn into the bearing over time.  Any grease that is in the bearing gets pushed out as soon as it starts spinning, so making sure the void around the bearing has grease provides the lubricant the bearing needs.  The bearings themselves require very little grease to be properly lubricated, just think of how long a sealed bearing lasts with just the amount of grease inside the bearing.  The only exception to this is double row bearings, or back to back arrangements, that have the grease injected between the two rows of rolling elements and eject the grease outward, instead of the grease coming from the housing and going into the bearing.
> 
> To keep the headstock clean, and there is room, you could install an inner bearing cover on the headstock side and inject grease in that side so it gets pushed out the spindle end.  You could add an opening towards the bottom that ejects the grease downwards.  This of course is making it much more complicated, but who doesn’t need another project??


The interior of the headstock casting is the original sand-cast surface so bearing covers in there, if they could somehow be installed, wouldn't seal.  I don't know how one could machine those surfaces, much less drill/tap mounting holes for the covers.  The bearings are 32mm ID and 60mm OD, and seat in pockets whose bottoms have a 55mm bore to accommodate the spindle.  So no 90 degree access to anything in there.

The headstock is a little under 4.5 inches wide and there are 4 transmission gears in there to select between high and low RPMs, plus a couple of spacers on either side to keep the gears lined up properly.  Not a lot of room to do much.


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## Ischgl99 (Apr 9, 2022)

homebrewed said:


> The interior of the headstock casting is the original sand-cast surface so bearing covers in there, if they could somehow be installed, wouldn't seal.  I don't know how one could machine those surfaces, much less drill/tap mounting holes for the covers.  The bearings are 32mm ID and 60mm OD, and seat in pockets whose bottoms have a 55mm bore to accommodate the spindle.  So no 90 degree access to anything in there.
> 
> The headstock is a little under 4.5 inches wide and there are 4 transmission gears in there to select between high and low RPMs, plus a couple of spacers on either side to keep the gears lined up properly.  Not a lot of room to do much.


Sounds like nothing of concern in there if some grease from the bearing gets inside.  If you are greasing it properly, very little would make it into the headstock over the life of the machine anyways.


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## Jake M (Apr 9, 2022)

Sorry I can't be a lot of help on the bearing selection, except to say that IF (and yeah, that's a big if....  The dollars and cents thing in that department is real....), but IF you went with angular contact bearings, they are way more rigid than the internet as a whole gives them credit for, and a shielded pair (not sealed, sealed wants to go slow), but shielded angular contacts would outlast that lathe with the lubricant that's pre-installed.  A simple felt (or goop) gasket and wiper on the covers would keep the big chunks out.  They really are good, but cheap is not in their vocabulary.




Stan the Man said:


> Snip.......
> 
> At the moment there is no way other then to per-lube the bearing with Molly-grease before installation.



There's a  lot of people all over the internet who swear that molly grease is the most amazing thing ever, and they might be right.  But I wouldn't recommend it in this application.  It's far better for "rough" things.  Sintered metal parts, rusty old dump truck trunnion pins, and SLOW moving bearings, bushings, and such.  Automotive CV joints love it (although it's a lower weight than you want).  Heavy truck universal joints in the driveshaft love it.  Tapered roller bearings, not so much...  Grease isn't a good/better/best thing, it's an application thing.  The "magic" that is in molly grease (molybdenum disulfide) is a solid lubricant.  Great for filling voids on uneven, imperfect surfaces, but you don't want to lift roller bearings off of their races.  If I recall, I think This Old Tony even half heartedly disclaimed that molly grease was all he had at the moment or something to that effect.

I'd suggest a lithium complex NLGI number two grease with a CG rating (preferably without the LB rating, but that's splitting hairs, CG-LB would do fine).  You don't want EP, as you won't stress it enough to wake that feature up from it's nap, let alone put it to work.  Save that space for more oil...  Unless you figure out how to seal them.  If you figure that out, a simple, hardly modified, R&O ammended circulating oil in there would be ideal.  You wouldn't ever need to turn the lathe off, you could leave it run twenty four hours a day, seven days a week, and when those bearings wear out, your great, great grand kids will be too old to care if it ever gets fixed.  

Really, oil is the ideal solution, but for practical reasons (just like wheel bearings in cars with that type), the best answer is to use a grease which will most closely emulate that.  Your bearings will run cooler (set up properly, apples to apples of course), and rob less horsepower from your lathe.

Yeah, I know.....  Oil discussions and the internet.....  Bottom line truth of the matter-  I have never run one of the lathes like or similar to what you have, but I was given a "take out" set of bearings, just for "science".  I ended up using them to make a hand cranked hose reel.  I can tell you this, regardless of what lube or lube mechanism you choose, even if it's inadequate in it's type and it's quantity...  If you bought an off the shelf bearing from a name brand, IDENTICAL dimensions, type, style, and options to what you took out, you'd be light years ahead.  Whatever parts and methods you decide on, I think you'll be happy with it.


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## Stan the Man (Apr 11, 2022)

Ischgl99 said:


> STRB is a spherical thrust roller bearing, that is a different design than a tapered roller bearing.


You are correct Sir! STRB does stand for Spherical thrust roller bearing however in my own defense I used that abbreviation in my written piece so I didn’t have to keep writing Sealed Tapered Roller Bearing over and over. Having said that  lesson learned.  I will be sure not to do that again. Thanks for your addition to the conversation.


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## Stan the Man (Apr 12, 2022)

homebrewed said:


> I thought about adding some zerks to lube the bearings as well.  But, not being sure just how grease could be directed _into_ the rollers and thinking that excess grease would get all over the interior of the headstock, I gave it a pass.
> 
> I also realized that if the spindle is polished down so the rear bearing is a light friction fit, you have a setup that can actually be taken apart to lube the bearings....without risking damage to them.  Once the retainer nuts are removed, the rear inner bearing and the transmission gear are the only things keeping the spindle in the headstock.  And the transmission gear is a sliding fit as well.  Not to say it won't be a PITA but I think it could be done without removing the headstock from the bed.
> 
> It also might be possible to loosen up or remove the bearing covers and get grease into the bearings that way.  The rear cover can be completely removed so no access problem there.  The front one would be a little more challenging since it can't be completely removed.  I thought about using oil on the bearings instead of grease, just to make it easier to lube them; but all of the descriptions I found regarding bearing replacement used grease.  So I did too.


Homebrewed, thanks for your input to this discussion, I have a much better understanding of bearings and lub and such for this project now thanks to all the guy's that joined in.   Your idea of removing the bearing cover and painting the cone end of the bearing say once a year then buttoning it back up isn't all that unreasonable and will help me get the head back together.  Couple 3 questions for you. When you polished the spindle down for a light friction fit what product did you use?  Emery paper and what grit , scotch bright pad what color or other product? What did you have the most success with? Question 2 when you machined the inside surface that faces the bearing did you just take a few light surfacing cuts across the whole face, then test fit the cover till it was flush with the outside housing cover? Last question, do you see any advantage to machining a set of aluminum covers to replace the plastic ones?


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## Stan the Man (Apr 12, 2022)

addertooth said:


> I was referring to the spacers which fit on the side of the spindle away from the chuck.  They are keyed and fit between the back of the spindle where gear mesh occurs.  The thicker bearings require the spacer be thinner so that gears maintain 100 percent mesh and alignment.  I am including a picture of two I made, with keyway, for this purpose. The second picture is where the spacer fits.


Thanks for your input to this discussion,  I'm learning a lot talking to every one. Also thanks for the photos makes it easier to understand what your talking about. The spacers you are showing and where they go are not very thick the spacer on my grizzle without measuring in the same location is about 50-62mm in length the ones your holding look to be about 6-8 in thickness. Just curious about your set up and which machine you have.


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## Larry$ (Apr 12, 2022)

Just a thought about spindle bearings based on machines that I have serviced. Wood molders, made in Germany. Spindle speeds 6 to 8,000rpm. Tooling: up to 9" long solid steel 5"+ in diameter unsupported on outer end. Heavier tooling is carried on out board bearings. Tooling end of the shaft has two angular contact ball bearings that come as matched sets and are installed so the pre-load stack of spring washers force them against their deep groove sides. Very heavy spring washers. The other end is supported by a single ball bearing that has a sliding fit to the housing allowing all heat induced movement to move that end and not the tooling end. All bearings on the lower cost machines ($100K) are lightly greased when installed and have no means of adding grease. The bearings are protected from dirt by metal labyrinth caps. No rubber seals. High speeds, large diameters and rubber generally don't play well. These are well balanced systems and will run for many thousands of hours before needing bearing replacement. Fairly expensive bearings!  It takes some special tools and a 20 ton press to service them. High production machines use oil mist lubrication systems.

I'm currently waiting for motor spindle bearings to come from Italy for a 20,000rpm spindle motor on an automatic edgebander. Luckily we keep a spare set of motors on hand. Odd bearings and they are on back order!


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## homebrewed (Apr 12, 2022)

Stan the Man said:


> Couple 3 questions for you. When you polished the spindle down for a light friction fit what product did you use? Emery paper and what grit , scotch bright pad what color or other product? What did you have the most success with? Question 2 when you machined the inside surface that faces the bearing did you just take a few light surfacing cuts across the whole face, then test fit the cover till it was flush with the outside housing cover? Last question, do you see any advantage to machining a set of aluminum covers to replace the plastic ones?


I used 200 grit wet/dry.  Before doing it I covered the entire mill table with a clean shop cloth to keep grit out of the machine workings.  It took less time than I had anticipated so if you do this start testing the fit pretty early on.  You could use one of the old bearings for this, no need to risk getting grit into one of your nice new ones.

I did NOT modify the headstock in any way---at least, not for replacing the bearings*.  I modified the bearing covers, basically machined a groove on the inside to provide enough clearance for the added protrusion of the bearings.  All the stick-out is on the outside so the spacers on the inside (on either side of the transmission gears) didn't need to be messed with.

If you have a large enough machine, there's nothing wrong with machining your own bearing covers out of aluminum.  I think it might be possible to make a 2-piece cover for the front bearing -- they would overlap in a half-lap fashion  -- which would make it possible to completely remove the bearing cover.  That would make it easier to stuff more grease in there when needed.  Now I'm wondering if the inside portion of the covers could be machined to provide a grease reservoir for the bearings.  Hmm.....

*I drilled a hole in the headstock where the speed controller mounts so I could spray lithium grease on the transmission gears.  When installed, the speed controller box covers the hole so it's a mod with almost no effort required.


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## Stan the Man (Apr 13, 2022)

Hi Hb. 
Thanks for your reply, looking back at what I posted I should have said Wet Dry rather then emery , I will do that use the wet dry. I agree covering the bed of what ever machine you grind on is important to keeping things from going south with grit. I have another larger lathe I can use to make the modified pieces for the 7 x 12.  I think I will use the plastic cover as a working model then machine two aluminum plates to replace the plastic.

 Its funny you mentioned a two piece cover as I was also thinking along those lines.  However I want to explore your idea of creating a well or reservoir for grease.  There would be more then enough room to access the back side of the bearing cover behind the mounting plate of the chuck, then its just a matter of smearing grease into the reservoir and putting it back into position. Great Idea !!!

I saw a guy add two threaded holes to the top of the case, one  directly over each gear1/4 -3/8th dia.  big enough to visually inspect the gears as well as add lube via gravity then made two brass plugs to close them up.  Another fellow added a larger plate over the top of the case with a padded surface to lay tooling on. Perhaps a combination of both ideas would allow inspection/lube when needed and a larger surface to lay your chuck wrench or other items as found on larger machines. So many options. LOL.

What mods have you done so far and which ones would you still like to do?
Stan.


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## Stan the Man (Apr 13, 2022)

Larry$ said:


> Just a thought about spindle bearings based on machines that I have serviced. Wood molders, made in Germany. Spindle speeds 6 to 8,000rpm. Tooling: up to 9" long solid steel 5"+ in diameter unsupported on outer end. Heavier tooling is carried on out board bearings. Tooling end of the shaft has two angular contact ball bearings that come as matched sets and are installed so the pre-load stack of spring washers force them against their deep groove sides. Very heavy spring washers. The other end is supported by a single ball bearing that has a sliding fit to the housing allowing all heat induced movement to move that end and not the tooling end. All bearings on the lower cost machines ($100K) are lightly greased when installed and have no means of adding grease. The bearings are protected from dirt by metal labyrinth caps. No rubber seals. High speeds, large diameters and rubber generally don't play well. These are well balanced systems and will run for many thousands of hours before needing bearing replacement. Fairly expensive bearings!  It takes some special tools and a 20 ton press to service them. High production machines use oil mist lubrication systems.
> 
> I'm currently waiting for motor spindle bearings to come from Italy for a 20,000rpm spindle motor on an automatic edgebander. Luckily we keep a spare set of motors on hand. Odd bearings and they are on back order!


Thanks Larry interesting stuff, can't imagine why you would need a 20K spindle speed on an edge bander unless its trimming off the excess width of the edge as in say a router spindle then it makes sense.


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## Cadillac (Apr 13, 2022)

This is the only tapered roller bearing I’ve ever seen with a seal attached to it. I’m a maintenance mechanic and these have been in a box for a long time. Havent  Come across where they would be used but they do make them. These are timken LM-67000L-A
 Is there no room to install a separate seal?


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## Ischgl99 (Apr 13, 2022)

Cadillac said:


> This is the only tapered roller bearing I’ve ever seen with a seal attached to it. I’m a maintenance mechanic and these have been in a box for a long time. Havent  Come across where they would be used but they do make them. These are timken LM-67000L-A
> Is there no room to install a separate seal?
> 
> View attachment 404011
> View attachment 404012


Timken has those in a very limited number of bearing sizes, and the seal is only on one side.  It looks like those are only available in inch series as well.  I’ve never seen one and not sure where they would be used, but the catalog has sizes up to 2.6875” bore.  Maybe axle bearings?  The way the seal is installed it is outside the bearing dimensions, so I’m guessing that does not conform to ISO sizing specifications and why the European bearing manufacturers don’t do that in the metric size bearings.


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## homebrewed (Apr 13, 2022)

Stan the Man said:


> Hi Hb.
> Thanks for your reply, looking back at what I posted I should have said Wet Dry rather then emery , I will do that use the wet dry. I agree covering the bed of what ever machine you grind on is important to keeping things from going south with grit. I have another larger lathe I can use to make the modified pieces for the 7 x 12.  I think I will use the plastic cover as a working model then machine two aluminum plates to replace the plastic.
> 
> Its funny you mentioned a two piece cover as I was also thinking along those lines.  However I want to explore your idea of creating a well or reservoir for grease.  There would be more then enough room to access the back side of the bearing cover behind the mounting plate of the chuck, then its just a matter of smearing grease into the reservoir and putting it back into position. Great Idea !!!
> ...



As far as mods I've done, in addition to bearings they currently are:

1.  A plinth to replace the compound.
2.  I added a crank to manuallly drive the lead screw.  It is attached to the right end of the lead screw.
3.  A DRO for the Z axis.  It's mounted behind the bed.  I'm currently working on adding one to the cross slide.
4.  I replaced the right hand leadscrew bushing block with a version that uses thrust bearings to remove lead screw backlash.  I made it with my mill.
5.  I replaced the saddle gibs (also called slide plates) with solid gibs that are adjusted using shims rather than the OEM overly-fiddly jack screws.
6.  A cover plate for the apron gears.  While I had the apron removed, I drilled and tapped some M6 holes for a future DRO mount for the cross slide.
7.  I replaced the cross slide nut adjusting arrangement with a double nut design similar to the type seen on anti-backlash nuts for ACME screws.  The nuts are solidly bolted to the cross slide, using shims to get them properly aligned to the feed screw.  I made the two nuts by cutting an OEM nut in half.
8.  I totally worked over the tailstock, which started out life as a POS (unfortunately a common occurrence).  That included turning the fixing screw that holds the base to the top around so it can be loosened from the top (making it MUCH easier to adjust the tailstock), and milling the base/top mating surfaces so the top is level and aligned to the bed, both horizontally and vertically.  I also replaced the tailstock hold-down nut with one that is tightened using a tommy bar (rather than the more complicated camlock design).  It's simple and much easier to use than a wrench.
9.  While I had the headstock removed for the bearing replacement job, I also shimmed it so the spindle was better-aligned to the bed.   It's a little fiddly because shims rotate the headstock around its rather short width, while you're trying to achieve a small value about twice that far away on the other side.  I had to resort to a piece of .0005" shim in the stack to get it right.

The first 4 items were a suite, prompted by a ball-turning tooll I got for the lathe.  It's pretty inexpensive but I paid a price for that -- it replaces the compound so it relys on moving the carriage in small controlled steps to turn balls.  I did that by adding the handwheel and DRO (there went the "bargain" part of the ball turner  ).  The carriage is moved by closing the half nuts and turning the crank.  And then I realized that the combination was ideal for using a much-more rigid plinth to replace the compound....so I made one.  I scraped the plinth and top of the compound so there was plenty of contact for an even more rigid setup.  I also scraped the top of the plinth so tool holders also would be well supported.  I do still use the compound for some things like cutting threads, turning short tapers and sneaking up on ID's and OD's where I need very precise dimensions.

Item #4 was prompted by my observation that there was a huge amount of backlash when driving the carriage with my hand crank.  It was caused by a lot of built-in clearance between the shoulders on the lead screw and the bushing blocks.  It wasn't a deal-killer because normal turning operations will take out the backlash, but sometimes it made it difficult to sneak up on a dimension.

I owned and used my lathe for years before doing any of these mods so don't feel like you HAVE to do any of this before you can start making stuff.  The mods started to arrive as my confidence in machining grew.

Future mod plans (dreams?) include the cross slide DRO, telescoping lead screw covers and a retractable cover for the lathe bed.  The latter is based on a scheme that only an electrical engineer-turned-hobby-machinist could think of....more fun than practical, but that's the nature of the hobby. 

I don't turn threads often enough to justify ELS, and so far haven't encountered a problem that would be best solved by doing a CNC mod.


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## Stan the Man (Apr 13, 2022)

Wow, sums it up nicely, Lots of improvements made on your end and I am sure you enjoyed doing most if not all of them. It's that personal satisfaction thing. I'm enjoying researching, learning and tinkering with my lathe.

 I keep hearing and reading about the tail stock and problems people have. once I get the head stock back together and set aside I will turn my attention to mounting the bed to a more rigid surface. Then address the tail stock. 

When my shop was fabricated on site, the frame was built from 2.5 x 2.5 x .078 square tubbing which they gave me a stick that was left over. My thought was to cut up several pieces and weld them side by side then taking some 3/16 flat sheet stock I have and sandwiching the tubing between the sheets to form a rigid base. Then bolt the lathe bed to it shimming and what not to square it up. 

I don't know whether or not I would need to fill the tubing with say concrete or epoxy/granite mix. for additional mass. then I could ether keep the lathe mobile (sort of) for now and just clamp it to the work bench when I need to move it. then  later dedicate a mobile base with draws, wheels and feet, still mobile but can also plant it rock solid when in use. Your thoughts.


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## homebrewed (Apr 13, 2022)

Stan the Man said:


> Wow, sums it up nicely, Lots of improvements made on your end and I am sure you enjoyed doing most if not all of them. It's that personal satisfaction thing. I'm enjoying researching, learning and tinkering with my lathe.
> 
> I keep hearing and reading about the tail stock and problems people have. once I get the head stock back together and set aside I will turn my attention to mounting the bed to a more rigid surface. Then address the tail stock.
> 
> ...


I just have my lathe resting on a home-made wood bench.  Not bolted down.  I used some scrap plywood from our house-building project for the top.  I really haven't noticed a vibration problem when using my lathe.  The mill is a different story, I'd sooner upgrade the bench it's sitting on.

But more to the point, I really don't have any insights to offer w/regard to bench design....other than not to repurpose a wood potting bench, even it the top is made with 2x4's .  Folks on this site have described lots of bench builds you can draw on for inspiration.


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## Stan the Man (Apr 13, 2022)

Thanks Ill let you know how it goes.


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## kopcicle (Jun 6, 2022)

Bearings , the struggle is real 








						Atlas 101.21200 Non Restoration
					

I'm still a little hung up on bearings. I have 7205 w/o seals and frankly don't care for the idea. So the parts keep coming in. The federal test indicator is a welcome addition. The old skool Starrett base is personal preference. I detest mag bases around magnetic swarf. The armature chucks are...




					www.hobby-machinist.com


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