Stability of lathe when off center turning

Cadillac

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I have a 14x40 optimum lathe that came with a sheet metal type stand which has doors on each side for storing tools which I have loaded with chucks on headstock and tailstock end. Weight of machine is 1350 alone and with all the stuff I have in it it’s probably close to 1500. The lathe has six feet pads 4 on the headstock and two on the tailstock. Pads came with lathe it’s a 3/4/ threaded stud with a 2 1/2 diameter hard plastic/rubber pad. When I leveled the lathe I have the feet only as tall to level lathe they are at minimum height so lathe stand might be a 1” off ground. With any chuck on the lathe at 500-550 has a harmonic vibe to it anything lower or higher the lathe runs smooth as silk. I had a job to do awhile ago requiring a 4jaw so i mounted the one that came with the lathe and I forgot the job but the lathe was wobbling around to the point that I started looking into the chuck being garbage. It has voids in the back and I figured the casting was off so have had on the project list. I had put on my grinding wheel static balancer and was off alittle not a huge amount.
I just had a job that required between centers it was a shaft about 1/2 diameter 6 inches long. Left the three jaw on turned a center and threw on a drive dog. I turned the lathe on was at 600 rpms and man the lathe did not like it was wobbly. I slowed her down to like 350 and finished the job.
It made me really think about what’s going on with my setup. Drive dog was a homemade one just a touch larger and had a flat piece welded to it and bent driving off the chuck jaw. Can’t be more than acouple ounces off center. I’ve only ran acouple things offcenter on the lathe and nothing real heavy and I know my lathe just doesn’t like it. Ive thought about fastening the lathe to the floor but heard of some issues with a solid mount. Thought of making some holdown brackets and just securing the headstock pads and leave the tailstock move? Or just make up a new base section with some real plate and tool boxes that had some real weight to it. I’d have to adapt the foot brake, linkage and chip pan. Idk. I do feel like the base is alittle narrow for the height of the machine. The lathebed is centered on bases and the 3hp motor is arranged hanging off the back of the headstock. With the weight of the motor kind of cantilevered out there then spinning something off balance I think is starts the issues of wobble???
How’s your comparable lathe size react to offset weight spinning?
 
I had the same experience and from that point forward used a faceplate that I could balance.
 
I also think those cabinet stands are a major problem. They are not particularly rigid. My 9x20 will also rock like mad with an unbalanced work piece and you can see the case flex.
Its enough to make me consider a much stronger base.
 
I also think those cabinet stands are a major problem. They are not particularly rigid. My 9x20 will also rock like mad with an unbalanced work piece and you can see the case flex.
Its enough to make me consider a much stronger base.

I have considered taking my cabinets and filling them with concrete, as I am not using them for storage.
 
Out of balance is the cause, the flimsy base just
I have considered taking my cabinets and filling them with concrete, as I am not using them for storage.
If you do, use a concrete that expands in setting, unlike the ordinary variety.
makes it worse
 
Even our larger lathes had to be counter balanced when doing off center projects , I could imagine smaller lathes wouldn't like that at all . Kinda like bar whip .
 
I have a 13x40 on a sheet metal base, about the same weight as your machine, and I have not noticed much problem with wobbling. Maybe some additional bracing or maybe make sure all of your feet are loaded evenly.
 
I have a 13x40 on a sheet metal base, about the same weight as your machine, and I have not noticed much problem with wobbling. Maybe some additional bracing or maybe make sure all of your feet are loaded evenly.

What would be the best way to make sure the feet are loaded evenly? After my last wobble event I did pull the levels out. It was good in my book. Now the feet on the headstock I initially used the ones directly under the chuck. Then after all settled in I ran the outer ones down while watching a indicator off the floor and stopped once I saw the needle move. I didn't like so much because I was still able to spin the rubber pad so I adjusted till I couldn't spin the rubber pads. So I really don't know how much pressure is on each of them?
Ive really been kickin around the idea of making a hold down bracket that straddles the studs/nuts and bends to a 90 to the floor. Then drill a anchor in the floor and tighten the bracket down so the foot pad is sandwiched to the floor. Do that front and back. I do not want to anchor all six points for sake of drilling so many holes in the floor and how rigid it would be in case of floor movement and twisting of lathe bed. I can see where the big cast bases of the old iron really helped.
 
It is quite possible to have two diagonal pads carrying a heavy load on both ends, and the opposite diagonals carrying a lesser load on both ends. The lathe can be level with that situation, but not solidly supported. The 4 pads on the headstock and 2 on the tailstock can also cause issues. They should all require similar torque on the bolts, with the level showing constant readings along the ways at the same time.
 
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