Changing the step pulleys on my lathe?

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Forum topic by JoeinGa posted 11-26-2014 10:18 PM 1243 views 0 times favorited 11 replies Add to Favorites Watch
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7374 posts in 1428 days

11-26-2014 10:18 PM

Been watching a bunch of you-tube videos on lathe turning and I see where some guys run their lathes as slow as 200 and 400rpm.
The speed chart on my lathe (a HF clone) says:
@50hz , 850, 1250, 1800, 2620
@60hz, 980, 1240, 2060, 3000

Even though I’ve only been turning a few weeks, it sure feels fast to me, so I’m thinking of ordering a set of 5-step pulleys that’ll get me a slower speed. I may have to cut a bit of the housing away to fit a bigger pulley in there, but that wont be too big of an issue for me.

The step pulleys on mine are 1-9/16 on the narrow end and 2-3/4” on the wide end. That’s the OUTTER edge, and not down in the groove where the belt rides (if that matters)

My question is …. anyone know how to do the math to figure out what size pulleys I need, and how to figure out what speeds it’ll run at?

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11 replies so far

View Don W's profile

Don W

17878 posts in 1988 days

#1 posted 11-26-2014 10:33 PM

you can’t use the new “common core” math, but google “pulley speed to find more,

-- Master hand plane hoarder. -

View Rick M.'s profile

Rick M.

7703 posts in 1801 days

#2 posted 11-26-2014 10:49 PM

Pulley math is easy once you wrap your brain around it. A word of caution if you decide to use any online calculators—check them with your own math first or against each other. When I last did pulleys I found that more than one online calculator was just flat out wrong. How they screw that up I don’t know.

Also, ditch the pulleys and just go variable speed.


View MrUnix's profile


4031 posts in 1620 days

#3 posted 11-26-2014 11:06 PM

This one works just fine:

And yes, the math is dirt simple (pulley ratio * motor speed)


PS: I wouldn’t advise changng the pulleys.. unless you are turning really huge stuff, you don’t need to go much slower than your machines lowest speed. Get some practice in and you will be fine.

PSS: My lathe has a 4-step pulley setup as well, with speeds similar to yours (930,1400,2140 and 3200) and I’ve never needed anything slower.

-- Brad in FL - To be old and wise, you must first be young and stupid

View JoeinGa's profile


7374 posts in 1428 days

#4 posted 11-26-2014 11:36 PM

Thanks DonW. “Common core”.... HA, what a joke. Takes 10 STEPS to subtract 5 from 7. SHeeeesh!

Yeah Rick, I’ve seen yours with the treadmill motor, and I’d love to do that but I’ve never seen any free ones (or even “cheap”) ones within even REASONABLE driving distance of me. And I check CL at least once a day.

Mr Unix, I know I do need more experience (MUCH MORE) but I’ve seen so many guys running slower speeds I thought it might be easier to turn. If slower speeds really doesn’t help, I’ll just keep pluggin’ away with what I got..

I will be posting my newest bowl (#3 )in the next day or so.

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View Todd Swartwood's profile

Todd Swartwood

257 posts in 1146 days

#5 posted 11-27-2014 01:33 AM

Hey Joe I agree, you don’t really need anything slower than what you have.

Have a good evening, Todd

-- Todd Swartwood (Todd Swart-Woodworks)

View REO's profile


883 posts in 1495 days

#6 posted 11-27-2014 03:36 PM

I have to second or third the feeling that your slow speed is likely slow enough. You will get used to it lol. A friend stopped over a while back. He knew I did turnings and wanted my opinion on a problem he was having. His turnings were rough and always out of round when done sanding.He had been turning a couple years and asked me to turn something so he could watch. I explained that my process was not traditional as I placed a 10” long 2” square blank between centers. He stood right at my shoulder watching. I have a clutch on my lathe so I can disengage the motor without stopping it. This saved the lives of lots of motors over the years from stopping and starting thousands of times during a run. I reached over and flipped the switch. the drive roared to life and he took a step back. I glanced back over my shoulder and explained that I would turn the piece in three passes and pointed out the template, follower and cutting tool. he had taken a half step forward to view as I spoke. I reached over and flipped the clutch and the piece instantly came up to speed 2600 rpm. I made my first pass and disengaged the clutch. I glanced back and waved for him to come forward to see the surface finish on the first pass. I kept on talking but realized he was not close by, so I turned to get a visual. he had backed up to a bench about five feet away and slid over to place me as a shield between himself and the lathe. I laughed out loud and asked him “whats up”? He said “thats way to fast!” I still laugh when I think of it and when I see him the first thing I usually say is “too fast?” we did discuss how slow speeds will allow the tool to sink and ride on the different grains, shear cutting instead of scraping etc. Speed is like food not enough you suffer, the right amount keeps you healthy, too much you suffer.

View JoeinGa's profile


7374 posts in 1428 days

#7 posted 11-27-2014 03:44 PM

Thanks REO !

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View Wildwood's profile


1851 posts in 1556 days

#8 posted 11-27-2014 04:26 PM

Cannot remember if your headstock is steel or cast iron, but only way know to slow down your lathe is remove the reeve drive and add new pulleys to both headstock spindle & motor. Will definitely have to do some cutting or removing on the headstock cover. Adding a motor bracket that swings in and out to allow moving belt over the pulleys to change speeds. That bracket will have to be bolted to side of the bed so will lose your rotating headstock.

What is the proper speed to use and when depends more on that wood you are turning. Has the wood reached EMC or soaking wet? Whether dealing with slightly out of balance dry long or short spindle blanks verus wet out of round bowl blanks makes a difference. You cannot get clean cuts until the wood is somewhat balanced regardless of speed!

-- Bill

View JoeinGa's profile


7374 posts in 1428 days

#9 posted 11-27-2014 05:38 PM

Thanks Bill. So far the 3 bowls I’ve turned have been from wood that was in storage for almost 8 years. A guy that used to have a big cabinet shop passed away 7 years ago and recently a few of us helped his wife to clean out a bunch of stuff from the shop so she could sell the building. She gave us a bunch of boards (mostly rough cut oak, maple and some cedar) for helping her.

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View bigblockyeti's profile (online now)


3573 posts in 1142 days

#10 posted 11-28-2014 02:06 PM

The outer edge measurement of the pulleys will get a rough estimate of your speed reduction. To find the actual speed reduction you need to know first the motor speed in rpm and you need to know the pitch diameter of each pair of grooves the belt will ride in. While the math in theory is fairly simple, the cross section belt size and width of each groove will determine the effective pitch diameter. Your best be is to consult a reference guide from whom ever you’re considering buying from.

View Rick M.'s profile

Rick M.

7703 posts in 1801 days

#11 posted 11-29-2014 02:19 AM

You’re talking a difference of maybe a few dozen rpm on a wood lathe, the simple math is close enough.


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