My Lathe Spins too Fast

[Eric Meier]

I inherited an old (circa 1980) Craftsman 12" 1/2HP lathe from my grandpa, and I've been using it (somewhat) happily for the past 2 years. I've bought some upgrades for it, (live-center tailstock, 4-jaw chucks, bowl gouge, etc.) and managed to get long pretty well.

The only complaint I have is that it has 4 speeds, and the slowest it goes is 875 RPM. Is this normal? It seems way too fast to me, especially when I'm taking the 12" capacity anywhere near the max.

I just turned a 10" segmented vase, and even with 24 segments per ring, roughing it out seemed dangerously fast. Is there any clever solutions that I can use to help in this regard? I really can't afford a new lathe at this point and time, so an economical solution would be greatly preferred.

Thanks.

[Ken Fitzgerald]

Eric,

I would be a little uncomfortable roughing something out at that RPM. My previous lathe had a low speed of 500 rpm and that would widen my eyes periodically.

You might see if you can get a different pulley arrangement to slow it down some.

[Kenneth Whiting]

My lathe has a slow speed of 500 and when I put a rough log on it, it was a little scary. I also have been wondering how I could slow mine down. Does anyone make an auxilery(sp) speed control? I'm thinking about the kind they put on sewing machines.

[Scott Crumpton]

Assuming that the lathe has your normal 1720rpm induction motor, your best bet is with the pulleys. Reducing the diameter at the motor, or enlarging it at the headstock. It may be necessary to remount the motor in a different location and add an additional pulley set to do it. Parts cost would depend on you scrounging abilities.

Simple speed controls work with universal motors, the ones with brushes. Induction motors need a variable frequency drive (VFD) because the rpm is locked to the line frequency. VFDs only work with 3-phase motors. Replacing the motor and adding a VFD would get expensive, probably more than the lathe is worth.

---Scott.

[Jim Koepke]

My lathe is also a Craftsman, from the 1950s, that spins too fast for comfort. The problem is the head stock pulleys are enclosed and would be impossible to change. The motor pulley can not get much smaller. My plan is to someday put a second shaft below the motor with a big and a small pulley. Run a belt from the motor to the big pulley and another from the small pulley up to the head stock.

Of course, waiting for the parts to show up is all that is holding me back.

jim

[Jim Koepke]

BTW, another note, if you know of someone scrapping out an old blue print machine you might want to try to get the motor and speed control from one of those. Some of the bigger ones use a large motor that is DC with a speed control.

jim

[Dennis McGarry]

BTW, another note, if you know of someone scrapping out an old blue print machine you might want to try to get the motor and speed control from one of those. Some of the bigger ones use a large motor that is DC with a speed control.

jim


Also some treadmills can be used as well...

[Eric Meier]

It seems I overlooked the pulleys. I knew there was an obvious answer that I just couldn't see.

I'll have to look into a different arrangement for the pulleys and see if I can't slow things down.

[Thom Sturgill]

I don't know the lathe, but since its 1/2 hp, you might be able to adapt this (http://www.pennstateind.com/store/TCLVSKIT.html) motor to it.
At $100 it might not be too expensive and would give you variable speed control.

[Dick Sowa]

You have the right idea. I also have a 1977 vintage Craftsman tube lathe, and the only easy option is to swap out the pulleys.

[Jim Koepke]

I don't know the lathe, but since its 1/2 hp, you might be able to adapt this (http://www.pennstateind.com/store/TCLVSKIT.html) motor to it.
At $100 it might not be too expensive and would give you variable speed control.

If you read the reviews on that set up you will find it does not get good reviews from some people.

There is not enough information on the specifications to determine if it is a series wound motor or if it uses magnets for a field. From the comments about it stalling under load, it sounds like it may use magnets.

jim

[Bob Hampton]

Eric
I beleive they call that a jackshaft...my nephew craftsman lathe from the 50's and same thing ..was way to fast at the slowest speed ...again the lathe pulleys were enclosed .
We installed a shaft on the bottom shelf ..installed a 6" pulley on the right side to run off the motor belt..on the left did a cone multipulley (at least thats what i call it) and he can adjust speed at the headstock pulley..this works great and got speed down quite a bit ..

good luck
bob

[Tom Godley]

I took a class through our local club last year and the guy giving it had acquired a few older lathes to have on hand just for the classes. He had a Delta with a cast head stock and a Craftsman with the pipes as the bed -- both have headstocks that would not allow a larger pulley to be installed.

Both of these units are normally mounted on a bench with the motor mounted behind it. What he did was to remove motor and add a secondary shaft. I believe on the Craftsman the pulleys were a little strange so he needed to get a shaft to fit the motor pulley so he could keep it feeding the headstock. Then he just bought two more matching step pulleys and another belt.

He had the motor mounted on rubber bushings -- they would move just enough to allow for the belt change. All of this was behind the lathe so the footprint of the assembly was larger. You could mount the motor under the lathe to save space.

[Rob Cunningham]

I just picked up a used treadmill off of Craigslist for $20. It has a VS DC motor which I plan to adapt to my older model Delta lathe which has a low speed of 900 rpm. :eek: Very exciting when starting to rough out a bowl blank.

[robert baccus]

I once modified a grizzly lathe that was too fast. turned a 12" handwheel for the outboard shaft and cut a groove for a 1/2" v belt. on the floor i mounted an old washing machine motor on a hinge. to turn slow i simply put the belt on the pullys(small one on the WM motor) until i hade the piece rounded. cheap, tacky but very effective------------old forester