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I've been making pepper mills; most start out with a 3" X 3" X 12" blank and end up around 2-1/2" diameter. I've been turning at about 1,000 RPM. I was just reading the safety section in the front of the Woodturner's Catalog and they say that diameter X RPM should equal between 6000-9000. For a 3" spindle, that says my RPM should be between 2,000 and 3,000. Does that sound right?
 

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I've been making pepper mills; most start out with a 3" X 3" X 12" blank and end up around 2-1/2" diameter. I've been turning at about 1,000 RPM. I was just reading the safety section in the front of the Woodturner's Catalog and they say that diameter X RPM should equal between 6000-9000. For a 3" spindle, that says my RPM should be between 2,000 and 3,000. Does that sound right?
The dia (inches) x RPM = 6.000 - 9.000 is a rule of thumb, not a "must do".

If you are getting decent cuts and smooth surface at your present speed that is what matters.

Try slowly increasing the speed. If a faster speed does not improve anything, I would not feel the need to have the lathe running faster just because it can.

Likely personal preference. A number of people do like faster speeds.

A catch at a fast speed is likely to be worse than a catch at a slower speed.
 

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What Dave said :thumbsup:

A catch at a fast speed is likely to be worse than a catch at a slower speed.
... but if you're "turning some air" (before the blank is completely round, or if you are doing an off-center turning), going faster reduces the likelihood of a catch.

This is because if it's spinning slowly, there's more opportunity for you to push the tool into the air before the next section of wood comes around. It comes down to practice :yes:
 

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... but if you're "turning some air" (before the blank is completely round, or if you are doing an off-center turning), going faster reduces the likelihood of a catch.

This is because if it's spinning slowly, there's more opportunity for you to push the tool into the air before the next section of wood comes around. It comes down to practice :yes:
I know what you mean. :icon_smile:

My friend was over and I had him take a try at roughing my piece of black locust. About 11-12in dia and very out of balance due to the shape of the wood. Ran the lathe around 350 RPM to minimize the vibration / bouncing of the lathe.

My friend is a little more heavy handed than I am and had several catches due to the "air".

I was very glad I had the tailstock tight against the blank.

I would have had a tough time turning up the speed due to how much out of balance the piece was at the time.
 

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If your getting a lot of vibration with an out of round piece of that size you need to work on making the lathe more stable. Possibly anchor it down or add weight. Check that the headstock and tailstock are firmly locked to the bed of the lathe and the tailstock is cranked in good and tight.
You didn't say what tool you were using to rough the piece but a properly used spindle roughing gouge should make it round with little effort.
Faster speed will help you get it round because the gaps where the tool isn't cutting will be faster so the tool tends to glide over them where as with slow speeds it wants to dip into them. also pushing on the tool creates problems of bounce so be gentle and let the tool do the work.
Here's my video on roughing.
https://www.youtube.com/watch?v=h8YYYYA-6jQ
 

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As a general rule, I turn slowly. If I turned everything based on that diameter*RPM=6,000 to 9,000 I'd be turning way faster than I like in most of my turnings. Pens for example, I turn right around 2500 RPM. They're about .5" in diameter so .5*2500=1,250. That's way less than 6,000. I'd have to have a lathe capable of 12,000 to 18,000 RPM to turn a pen according to that formula. I couldn't imagine a lathe doing 18,000 RPM. I'd kill myself if I tried to turn that fast.

Take a pepper mill blank as another example. They're 3" in diameter, about 2.5" after rounding out as you said. At 2.5" I'd have to turn it 2,400 to 3,600 RPM. to meet the guideline. That's an average of 3,000 RPM for a pepper mill. My lathe maxes out at 3,000 RPM. When I turn mills, I'm much closer to 2,000 RPM once it's rounded out than I am 3,000.

When turning something larger, about 8" in diameter, once it's round I turn at about 1,000 to 1,200 which puts me on the high end of that guideline equation. I suppose if I had a lathe capable of turning something 16" in diameter that I'd turn faster than 500 RPM, which could easily put me over that guideline equation.

I think that equation was based on turning something of a specific diameter range, probably 6 to 10 inch diameter.
 
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