Replacing the fiber disc with thrust bearing on my 15" South Bend Lathe

[Technical Ted]

My South Bend 15" lathe was made around 1935 and has the older style spindle bearings with the oil cups up on top of the spindle bearings. It also has the fiber thrust washer on the spindle; not the needle thrust bearing like my newer 13" South Bend.

The fiber disc works well as long as it was adjusted properly. But, therein lays the problem.... In the summer when the humidity gets high in my basement shop the washer swells and locks my spindle up tight as a drum! Every summer I go through this routine of trying to spin my spindle by hand, finding it locked up, and having to back off the adjusting collar. Then, in the late fall early winter I have to tighten things back up because of chatter. I've been putting up with this for years and I finally decided No More!

The only tricky part was getting the gear off the end of the spindle. It's pressed on and there isn't much room between the gear and the adjusting collar even when the collar is all the way forward. All of my pullers were too thick. So, into the press it had to go! I lacked about 1/8" room between the adjustable base on my press so I used a couple of hold down studs with double nuts on each end as jacks to spread it open enough to make the spindle fit. I think I'll cut apart the pieces welded in to hold the channels together and replace them with bolt through spacers so I can easily adjust things in the future. I used four 1/8" thick pieces around the bottom of the gear and after a pop the gear came right off. You can't beat those Harbor Freight 20 ton presses for the money (I got it on sale too).

I ordered a needle bearing from McMaster Carr yesterday and I will get it Tuesday. My spindle diameter where the thrust bearing goes is 1.685" and they only had a 1.750" ID bearing (closest size). I was on the fence whether to just use it as is or make/add a spacer and decided to go with a spacer (1/32" thick). I also thought about going with a bigger bearing so the spacer could be thicker, but decided to try this first. The bearings are cheap enough if I have to make another one up (the shipping will probably be as much as the bearing).

So, now my spindle is patiently waiting in the press for Tuesday when I get the bearing.

Ted



Had to squeeze another 1/8" out of it!



Bearing surface not in too bad of shape for a machine made in 1935...



The 1/32" shim I made on my 13" South Bend. Boy, it's handy to have two lathes!



All set for Tuesday.

 

[woodtickgreg]

Very cool!

 

[T Bredehoft]

I'm enjoying the work bench you built around the end of the spindle. Good thinking.

 

[Technical Ted]

I'm enjoying the work bench you built around the end of the spindle. Good thinking.

I wanted to have my two hands free to work the press and align the gear without worrying about holding onto the spindle to keep it aligned and from tipping over. It's amazing what a few pieces of wood and a couple of clamps can do to help out!

Ted

 

[Technical Ted]

Well, mission accomplished! All back together and running. I haven't adjusted the thrust or spindle bearings per the book yet, because I want to run it to get everything worked in good before doing so. It's close now, but will probably need fine tuning. While I had it apart, I had some left over felt the correct size from refurbishing my 13" SB so I replaced all that I could on the spindle bearings, which was all but one piece. I cleaned that the best I could and it will have to do for now.

Not wanting to use any more force than necessary and being a little concerned that it might be difficult to line up the key way in the gear with the key in the spindle I decided to take a different approach than just pressing it back on. I put a bag of ice around the end of the spindle and the gear into my wife's oven (bless her heart!) at 325 and it gave me enough clearance that I got the gear about 3/4 of the way on (key well into the keyway) and then hit it with the press to send it all the way home. The end of the spindle is fairly thin and once that gear got on there and I got the key way lined up it had expanded enough from the heat transfer that it started to set up. I guess I wasn't quick enough lining that key up, but I got it well started which was my main concern. I also didn't want to over heat that hardened gear. I did some research and found that about the coolest temperature used for tempering was around 350 degrees F. So, I felt 325 was safe and I more than likely could have gone higher. The gear was a 1/2 thousandth press fit and I calculated that the heat difference between the chilled spindle end and the heated gear would be ~2 thousands so I didn't see the need to heat it more. Worked great!

I had to add a 0.001" shim on one side and a 0.002" shim on the other for the larger front spindle bearing. Must be cleaning things up I removed a burr or some crud that was giving me a little more clearance before. It doesn't take much!

The needle bearing makes some running noise and that is different because with that old fiber washer and the gear drive train disengaged all you could hear was the motor running and a little belt noise. I used a needle bearing and if I remember correctly my 13" has a ball bearing thrust with thicker washers. But, I don't think I have run on my 15" for that thick of a thrust washer and I'm sure I'll get used to the little bit of noise it makes.

So, now onto the next project... installing the DRO on my mill!

Ted

 

[dlane]

When I did the needle thrust bearing conversion on my SB10L I lightly oiled the bearings, I don’t notice any extra noise.

 

[Technical Ted]

When I did the needle thrust bearing conversion on my SB10L I lightly oiled the bearings, I don’t notice any extra noise.

Interesting... Did you use a needle bearing from McMaster Carr like this one? https://www.mcmaster.com/5909K42

I used two 0.032" washers with it.

I had plenty of spindle oil on it. Maybe a heavier oil might quiet it down some, but it gets spindle oil via the backside bearing in normal use.

Thanks,
Ted

 

[FOMOGO]

Ted, are you sure that your spacer isn't preventing you from getting the proper preload/clearance on your thrust bearing, giving you the noise issue? Just a thought. Mike

 

[Technical Ted]

Ted, are you sure that your spacer isn't preventing you from getting the proper preload/clearance on your thrust bearing, giving you the noise issue? Just a thought. Mike

I made the spacer narrower than the bearing and two washers so I don't think so. I'll play with it some more when I adjust the clearances per South Bend's specs. One thing it might be is the fact that the two halves of the spindle bearing are not keyed to keep the ends flush where it rides against the thrust washer and I might have a little mis-alignment there because I can hear a rhythmic oscillating sound when running the spindle at higher speeds.

I think it's also possible that the bearings are just a little noisy with the light spindle oil at higher speeds since the retainer is very thin as well as the two washers and there are a lot of needles??? The ball thrust in my 13" is a lot heavier and there is a lot less surface contact with balls vs needles and there are a lot more needles than balls as well.

I'll play with it and see how it turns out in time.

Thanks for the thought,
Ted

 

[dlane]

https://www.hobby-machinist.com/threads/removing-gears-on-heavy-10-spindle.51541/

I did mine as per the pdf on this post.