Restoring Atlas 3991 Lathe

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delig

H-M Supporter - Silver Member
H-M Supporter - Silver Member
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I was given this lathe that has sat for about 30 years(as you see it below) without being used. I know it needs a new motor and am looking for a recommendation. Also, before digging into a full restoration, I'd like a list of common sense tasks I can undertake to determine if this is salvageable. It comes with both 3 and 4 tooth chucks, it's clearly been repainted and when I open the housing, I can turn the gears by hand, although it is tight.

I'm assuming the first thing is to oil it up and let it sit while I wait for it to be moved to my house (may as well get a head start). Once home, I can start cleaning it up and continue working to free the gears by hand until they turn more easily but I don't know what is acceptable resistance before I connect a motor. Is there a way to determine this before I acquire a new motor (needs to be single-phase)and turn it on, under load?

Also, if this is salvageable, Does anyone know if there are sticker kits I can find to replace the old ones that are challenging to read. I may repaint it/restore it to the original color or as close as I can get.
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Nice little lathe there that should clean up nice . The undermount motor is desirable taking up less space . Aftermarket charts are available also . Robert ( Cab ) will be able to tell you everything about your lathe . He's the resident expert and has a 3996 I believe . :)
 
If it now has a serviceable 3 phase motor, I would suggest keeping that motor and wiring in a 3 phase VFD converter. You get to run it on single phase without messing with the mechanical drive, and gain the feature of a variable speed motor. You should be able to get a simple VFD for about the cost of a new motor. In addition, the VFD lets you add other features.
 
One word of caution. If you disassemble parts of the lathe be cautious many parts are made of Zemac a zinc alloy. While it works fine for what it was designed for , it doesn’t liked to be forced. It is not as forgiving as cast iron. Not knowing any better I broke the end support for the lead screw. Parts are still available and you should be able to find quite a few hear that make parts with them.
 
I beleive the original 3 phase motor was discarded years ago but I'll double check to make sure it is not on a shelf somewhere. He likes to keep things around because you never know what may be handy.

I learned last night (and he gave me) a Northern 1HP 115/230V motor that should pull the lathe fine. It is lightly or never been used but I'll need to test it first.
 

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I moved the lathe home this past Spring, got the single phase motor running (it is not mounted). However, the legs are rusted out ( an inch or two from the bottom). Does anyone know if these stands were cast iron or steel? I was planning to cut the rusted sections and weld new steel but I noticed all panels are bolted together. Welding steel to cast iron is beyond my skill level.
 
delig said:
I moved the lathe home this past Spring, got the single phase motor running (it is not mounted). However, the legs are rusted out ( an inch or two from the bottom). Does anyone know if these stands were cast iron or steel? I was planning to cut the rusted sections and weld new steel but I noticed all panels are bolted together. Welding steel to cast iron is beyond my skill level.
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From the photo I'd say that one is probably steel, which would be much more likely to rust out anyway.

Unless the original stand is exactly the right height for you, or you just like the authenticity, I'd look into replacing it with something that has storage underneath.

If you can weld you might want to build a stand that will hold a toolbox , of which there are many examples on here.

Also popular are tanker desks and repurposed file cabinets. A nice stand can also be made from wood for this size machine.

John
 
The base is sheet metal, 11ga maybe heavier. My legs were rusty but cleaned up and used rust converter and paint.
 
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