Bearing replacement on old lathe
- Thread starter Edwardshandmadeknives
- Start date
Edwardshandmadeknives
Well-Known Member
I’ll have to see if I can get some Plastigage tomorrow. Definitely would make things easier
MTBob
Well-Known Member
IMHO, that's not that good. .0005 (half thousand), in an inch, perhaps. Again, depends on your application. I'd need to refer back to some old lathe books but I think striving for tolerances of +/- .0001 (one tenth of a thousandth) in a foot is more common. But... it all depends on the condition of the overall lathe, particularly the ways and carriage. There are lots of variables that can change these tolerances.
Take a look at this YouTube guy that goes by Mr. Pete aka Tubalcain. He's got a ton of stuff on machine shop tools and he likes old iron, you might pick up some tips from him.
It's not too clear from the photos whether those bearings will come out, they don't look much like inserts. I'd say the babbit is poured into the bearing frame.
Edwardshandmadeknives
Well-Known Member
Oh, they are poured in place. I just thought they would come out easily. I’m mostly planning to use this for center drilling round bars of bronze, so I can cut them into rings I can then forge into sheath parts. I just need it better than “eyeballing” center best I can on my drill press lol! I’ll only be drilling about an inch deep. Accuracy as far as like a “real” machinist might like, isn’t really too important to me. I got it for the right price
and thought “I should get that thing working for drilling these”.Edwardshandmadeknives
Well-Known Member
I checked out his videos and subscribed. I can learn a LOT from that dude! Thanks
Edwardshandmadeknives
Well-Known Member
Got the spindle out today, after checking the bearings with Plastigage. I don’t know what that spindle weighs, but it’s a lot. I could barely lift it. Now I gotta get to cast in place Babbitt bearings out. They are super bad lol. They are oval by about .032”. Now wonder this thing broke tooling so bad.Edwardshandmadeknives
Well-Known Member
I thought about adding it but it would be so thin that I don’t think it would work well. I’ve already broken up the old ones beyond any hope of saving now, so I “have to” replace them now lol
MTBob
Well-Known Member
If I recall, there are companies that specialize in pouring babbit bearings. Do an InterWeb search and see if that might be a solution that's within your budget. Another "possible" option is to reassemble the bearings and line bore the existing babbit so it's oversized. In addition machine the spindle bearing surfaces to eliminate eccentric wear. It "may" be possible to then add a bronze bearing sleeve insert in the resulting gap.
Of course, there is then the age old question about whether the repair cost is worth the investment in that lathe versus buying a good used lathe in working condition.
Of course, there is then the age old question about whether the repair cost is worth the investment in that lathe versus buying a good used lathe in working condition.
Edwardshandmadeknives
Well-Known Member
This lathe, a drill press, and a bandsaw are the extent of my “machining tools”. Things like line boring, etc would all have to be hired out. I don’t even know how I would get it to a machine shop lol. I’m not doing anything that would be considered very precise, so I’m hoping to get it close. I figured out how to align the shaft and chuck with some dial indicators, so I think I can actually get it pretty decent. I’m honestly thinking about forming the bearings from .0625 bronze sheet, in two halves, then bedding each half in their bearing caps with JB Weld. I’m only running (I’m guessing) around 200 rpm, so I don’t think heat should be an issue. I did read last night that grease requires a larger bearing gap than oil to be effective, so I have to figure out if that bearing clearance will allow too much slop. I think it’s about .003 for the shaft diameter I have. I gotta read more about grease and see what I want to do.
Edwardshandmadeknives
Well-Known Member
I couldn’t get a picture to load, but I’ve got it stripped down, and now I have to get a hundred years worth of old paint and goop off so I can repaint it. I stripped the entire threading assembly off, since I cannot think of any reason I could need it. I’ve found bronze bearing the correct size for it, and I’ve figured out how to align it properly with the tailstock. The motor will be a VFD driven 3/4 hp electric. I’ve read you can bed low rpm bronze bushings in bedding epoxy. I’m going to have to do a bit more research on it, if that’s a “thing”, I’ll probably do that, if not, I’ll bed them in babbit. Anyways, that’s where I’m at with this. Might have a 10” 3-jaw chuck available too if anyone is looking for one.
MTBob
Well-Known Member
Check out Loctite's products, they may address your problem.
______________ from Gemini ________
Loctite offers a variety of products specifically designed for use with bearings, which fall under their category of "retaining compounds." These anaerobic adhesives are used to secure bearings in their housings or on shafts, preventing movement, fretting corrosion, and loosening due to shock and vibration.
Key benefits of using Loctite bearing adhesives include:
* High Strength: They create a strong, permanent bond between cylindrical parts.
* Fills Gaps: They can fill small gaps between mating surfaces, which can be particularly useful for worn components.
* Even Load Distribution: The adhesive ensures a more even distribution of stress across the joint, which helps to prevent fatigue and failure.
* Corrosion Protection: They form a seal that prevents corrosion and fretting between the parts.
Some of the common Loctite products for bearings include:
* Loctite 641: A medium-strength retaining compound designed for applications where future disassembly is required.
* Loctite 660: A high-strength, gap-filling compound ideal for use on worn bearing seats or other cylindrical parts with larger gaps.
* Loctite 680: A high-strength, medium-viscosity adhesive for slip-fit assemblies.
* Loctite 620: A high-temperature retaining compound, suitable for applications in high-heat environments.
When selecting a Loctite product for a bearing application, it's important to consider factors like the required strength, the size of the gap between the parts, and the operating temperature. Loctite also offers products in different forms, such as liquids and wax-like sticks, for different application needs.
Drew Riley
Well-Known Member
There's a handful of decent videos on youtube that show some babbitt replacement. It's not rocket surgery, but you do need some tools and materials that not everyone is going to have in their average home shop.
Here's a really good one that will give you an idea of the average process involved:
I remember (vaguely) in my much younger years, working as a maintenance manage in a roll shop at Arcelor Mittal (used to be Bethlehem steel). They had a 100 year old Farrell roll grinder that had a babbitt bearing that got wiped. A couple of local machinists came on site and repoured and scraped it. The only thing I remember really is that the older of the two machinist just had a couple of flat scraps of carbide bar stock that he used to scrap the new bearing smooth. I remember being amazed that a babbitt bearing could even work, as it looked like you were just running metal on (much softer) metal for the most part, but that thin film of oil really does the trick.
Here's a really good one that will give you an idea of the average process involved:
I remember (vaguely) in my much younger years, working as a maintenance manage in a roll shop at Arcelor Mittal (used to be Bethlehem steel). They had a 100 year old Farrell roll grinder that had a babbitt bearing that got wiped. A couple of local machinists came on site and repoured and scraped it. The only thing I remember really is that the older of the two machinist just had a couple of flat scraps of carbide bar stock that he used to scrap the new bearing smooth. I remember being amazed that a babbitt bearing could even work, as it looked like you were just running metal on (much softer) metal for the most part, but that thin film of oil really does the trick.