Spindle speeds for plain bearing headstocks - Stark

I have a Stark #3 lathe with plain cone bearings in the head stock that the hardened spindle runs in and that are lubricated by drip oilers. The bearing at the spindle nose has two taper angles; a shallow angle for radial loads and a steep angle for axial loads. This lathe design is very similar to a Hardinge Cataract but predates it by about 4 decades. Stark was in business at the start of the civil war and I am guessing this lathe was manufactured some time in the 1870's or 1880's.

This lathe has a 3 step cone pulley on the spindle. What are normal and reasonable spindle speeds for this lathe?

There is a fine thread nut on the back end of the spindle that adjusts the spindle bearing slack and preloads the spindle bearings. What is the proper procedure for adjusting the spindle bearing preload on a lathe like this?

Do you need to readjust the bearing preload after using the lathe for a while and warming it up?

Is it necessary to slacken the bearing preload when you are done using the lathe for the day?

Do you need to play with the bearing preload adjustment pretty much every time you use the lathe, or is it more set it and forget it?

Are these bearings pretty robust or can they be easily damaged by misadjustment or improper operation or inadequate lubrication.

What is the proper oil to lubricate these spindle bearings with and how often and how much oil should be applied to the oilers?

Check the spindle adjustment by results and heat buildup.I would think 600 rpm would be tops.....was made in the days of carbon steel tools.A light hydraulic oil would be good ,certainly no heavier than a ISO 46 grade.Drip feed oilers would be good too,but probably too messy.Nice survivor of a bygone age.

More pics of the Stark lathe.
The stand is an original Stark cast iron stand.
I am not sure of the maker on the lever cross slide. If anyone knows for sure I would appreciate a response.
The micrometer cross slide is a Hardinge - not an original Stark - and the X axis lead screw is broken off.
I do have another Stark micrometer slide that is original but in terrible shape.
As received the lathe had an ancient electric motor mounted to the back of the chip pan - see the notches cut in it - argggg.

A nice machine. After cleaning the parts the spindle is lightly oiled and reassembled. I adjutant the nut until the spindle is easily rotated by hand with just the slightest resistance. When adjusted correctly one get this "silky" feel when rotating by hand, hard to explain. I am using very light oil. Usually no readjustment is needed after running, but sometimes a small touch of the nut if it feels little too free. If the bearing and spindle are in a good shape, with no scratches or other marks I would not exceed 1000rpm - though usually there is no need to run so fast.

I've got a #4.the bearings in these lathes should not need regular readjustment and the clearance shouldn't change noticeably when the lathe is warmed up. Adjustment is just like a watchmakers lathe - tight to the point where everything turns smoothly with no binding. This might sound imprecise, but clockmakers do this kind of adjustment everyday, so I think it was expected that the user would no trouble with it.

Professional machinist may be horrified by this, but I use 3-in-1 oil in the spindle. Runs nice and cool. Gets everywhere as these are full loss oilers. I'm not sure what speed I run it at as I've never bothered to figure the fixed ratio between the motor pulley and the headstock, so I'm not sure what the numbers on the VFD display mean. Couldn't be too fast. I'm a clockmaker, not a machinist and I'm more comfortable with the lathe moving nice and slow. BTW, don't worry about all the 'proper ' speed & feeds. If you are getting a decent surface finish and the lathe isn't complaining, you're doing OK.

aninventor,

I have a #3-1/2 & #4 Stark. From the the looks of those bearings you should be able to adjust them to original factory tolerance.

Google "adjusting bearings on a watchmakers lathe" to get how to make the adjustments. Remember The bearings run with a film of oil between the bearing surfaces. This type of bearing is not the greatest for heavy drilling.

I use Light Spindle oil in all my bench lathes (Available from McMaster Carr).

Joe

Mobil Velocite #6 is nice light oil formulated for spindles

The bearing diameter will determine max rpm. Do some searching on google and you'll find it. It's a surface speed situation. The smaller the bearing diam, the faster you can run it and vice versa. My South Bend 10L with 2" or so plain bearings can run almost 1400rpm at max speed. My 1918 18" L&S with nearly 4" diam mains tops out at 500rpm.

Big thing when running plain bearings is to warm them up if you intend to run at max speed. On either of my lathes, I'll run at lowest non-backgear speed for several minutes, either doing other work or just letting the spindle run, before ramping up to full speed. Gets oil worked into the bearings and also lets the more massive casting warm up so the spindle doesn't warm up too fast and close up the tolerances, which can cause the bearings to seize.