Can I swap spindles on a plain bearing lathe?

[D.sebens]

My spindle is a bit beat up on the bearing and might be slightly bent. The front bearing runs oil out as fast as I can pour it. I have a possible line on one AND the bronze bearings that went with it. This is for a old 11” sheldon lathe. Do you think it could be swapped over and just work(obviously I would set bearing clearance with shims.

 

[MyLilMule]

I'd check the runout of the spindle at the nose first. If you have no runout, the chances of it being bent are greatly diminished.

You can try and validate if the spindle is bent by removing it from the headstock, remove the cone pulley and bull gear. then set it back in the headstock without the bearing caps. Put a dial indicator on the spindle in various places and look for runout. I did this with my 13" SBL while it is disassembled for a full rebuild.

I have no idea of the tolerances that these lathes were machined to. I suppose there is a chance. But, unless I miss my guess, these plain bearings were line bored in placed. If there is any discrepancies on how the front and rear bearing surfaces were machined, line boring would remove all that. If all of the was done in one setup (I suppose is possible) then you might be good.

If you get the spindle and bearings at a really good price, worst case scenario is you lose a little money or unload them and try to get it back.

 

[D.sebens]

I measured on the short 5mt taper. The reason I say might is because I need to run some scotchbrite in there and make sure I’m not reading some crust. I measure 1.5 thou. I get a stacked runout of 6 thou when using the adapter for the center. The adapter could be bad also.

 

[tobnpr]

I have a Sheldon 11" military lathe, fortunately was very lightly used and I only needed to barely snug down the bolts on the bearing caps.
I'd clean out the spindle taper as you mentioned and re-check it, but clearly you've got an issue because of the oil loss. Are yours top or front oilers with wicks?

How do you know the condition of the replacement spindle/bearings? I'd be leery from a parted-out machine- usually (but not always) it's because they've worn to the point where they're no longer capable of doing the work.

 

[D.sebens]

They are top oilers. I’m thinking about putting felt in them. Also I switched to way oil in it and it seems to keep slightly better. I’ve been told “it is great shape”.

 

[D.sebens]

Also I think I am dreaming on this. I really like this lathe as it’s old and tells a story and is mine (after I bought it). It’s got sentiment. It’s also really clapped out. I don’t want another lathe but I think that’s the more sensible route if I wanted to spend money (which I don’t). I will just keep using it as it is and tinkering with the lathe. It’s made me many fine parts sometimes with loose accuracy (mainly because I continue to forget about defection when cutting and how there’s less deflecting at the final passes(causing me to undershoot the size). I aim for 0.000 tolerance and take whatever I can get and just work with it.

I really do love this old lathe. It chips a lot of carbide and I get chatter at higher speeds like 500 and up when trying to take 20-60 thou radius cuts. I should get better at hss but I can’t get the same finishes when the carbide “just works”. I’m not sure where my looseness is. I adjusted the gibs when I got it, I could probably get the compound a little bit more snug. The spindle is less than .003. I can’t remember what it was when I measured it. I know tighter than that and it wants to seize on higher speeds from the oil issue.

 

[tobnpr]

They are top oilers. I’m thinking about putting felt in them. Also I switched to way oil in it and it seems to keep slightly better. I’ve been told “it is great shape”.

Not an expert here...but if the way oil "works", and your bearings aren't overheating it's because your clearances are too great. Spindles normally need very low viscosity ( I use SAE 10) because of the tight clearance and need to maintain a lubricating film between the parts. Way oil would normally be too thick to flow between the parts.

Why not do the South Bend style test? Put a DTI on top of the spindle, put a heavy wood dowel inside with around 12"-18" sticking out. Press down on the stick hard (50 lb or so), zero the DTI than pull upwards with the same force and see what you read. Do the same sideways for horizontal runout. IIRC, it should be around .0015 at most to be "in spec".

Hey, as long as the machine makes acceptable parts for your usage it "works". Knowing the machine and its foibles allows for a lot of workarounds.
I use mine for gunsmithing, so I need to hold a thou which it'll do fine with the DRO (never looked back after installing one- compensates for compound and cross screw wear). I agree on the carbide, modern inserts of the type that don't need to be pushed so hard work just fine and I use them for profiling, facing, threading, just about everything. I have only a handful of HSS special profiles for specific applications.

Love mine too lol. Properly maintained (and it's not used very heavily, run a few hours a week on average) it'll last another 75 years.

 

[D.sebens]

I was told that southbend wants type c oil for spindles. One of the oils is medium and heavy vactra oil which is way oil. That being said due to the bearing condition the oil runs out fast and it seizes up at higher speeds.

 

[twhite]

I was told that southbend wants type c oil for spindles. One of the oils is medium and heavy vactra oil which is way oil. That being said due to the bearing condition the oil runs out fast and it seizes up at higher speeds.

Here is the SB oiling chart

Cutting oil is my blood.

 

[D.sebens]

Here’s the one I found. The one you have is hard to zoom in enough.