Lathe speeds???

[Bill White]

Have had my Grizz 1067Z for about a year with satisfaction. Just not sure I get the hang of choosing correct speeds for my projects.
I've heard some say turn as fast as is safe (certainly I start a turning slowly for safety), but I don't want to launch anymore than I do now.
So given the fact that I now have the bowl/spindle blank roughed out and in balance, what next as to how fast? I understand the surface speed concept.
TIA
Bill

[Bruce Shiverdecker]

The general rule of thought is:

Diameter X Speed = 6000 to 9000 (Note. Keep piece between headstock and tail stock, for stability, till balanced.)

However Out of balance blanks reduce the speed dramatically. Here, I use the Rattle factor. If the lathe is trying to walk away, you are going too fast.

Bruce

[Paul Engle]

Just remeber some stuff may never " smooth out" so dont do what i tried once and sped up to try to get it smooth.... only to find later the belt half gone causing the " out of balance" .....:o when the piece finally launched itself into the wall ..... boy was that dumb....

[Mike Vickery]

Bruce's formula is a good guidline that I have heard many demonstrators use. I doubt you will get a better answer since most turners kind of do it by feeling.
Personally I have no idea what speed my lathe is usually going at and use the somewhere before it vibrates or I am scared to stand in fornt of the lathe method. At a Stuart Batty demo he said you should have it going fast enough that you are a little nervous but not so fast you are scared.

[Mark Pruitt]

I can't say it any better than Bill Grumbine in one of his DVDs; "If the lathe's not shaking and you're not shaking, you're fine." That's a very close paraphrase anyway.

[Richard Madison]

Bruce,
Just for reference, that's diameter in inches and speed in rpm, right?

[Reed Gray]

Turn as fast as you feel comfortable with. My lathe (PM3520A) has no speed indicator, so I just turn it up till it wobbles (either the wood and/or the lathe) then back the speed off. I will turn larger bowls slower say 500 plus, and smaller bowls up to 1500, which is the highest speed in the low range. On spindles, it is the same thing, if it is shaking, then I back off. Rolling pins 3 inches in diameter are around 1500 to 2000, and spurtles are at 3000. I have a friend who comes over once in a while to core, and he has a Legacy ornamental lathe. He turns at around 200 rpm which is what he is comfortable with, but it would drive me crazy.
robo hippy

[George Tokarev]

Dissent again. Turn as slowly as you're comfortable with. Adding speed adds danger for you from flying objects, increases the kinetic energy available for a catch to launch a chunk off of or the whole piece, and demands more from chucking.

Remember your basic Physics and think of how doubling the speed will bring the same point past twice versus once, but increase the kinetic energy exponentially. Are you really in such an all-fired hurry to crank something out, or are you turning for pleasure?

[Sean Troy]

Are you really in such an all-fired hurry to crank something out, or are you turning for pleasure?

The main reason for higher speeds is not to get done quicker but get a better and smoother cut.

[George Tokarev]

The main reason for higher speeds is not to get done quicker but get a better and smoother cut.

How? You get a smooth cut with your spokeshave, plane, carving tool or knife, don't you? Apply your edge properly, and no problem.

[Keith Burns]

Aw, man, here we go again......................................

Bill, the rule I use is whatever speed I am comfortable with based on what I'm turning. Some pieces require faster speeds to accomplish the task at hand. If you have a burl with voids, you will need to turn faster to get decent cuts, otherwise your tool will tend to drop in the voids and give you a lousy cut plus increse the opportunity for a catch.

[Mark Pruitt]

The main reason for higher speeds is not to get done quicker but get a better and smoother cut.


How? You get a smooth cut with your spokeshave, plane, carving tool or knife, don't you? Apply your edge properly, and no problem.
The answer to "how?" has to do with the "basic physics" that you referred to earlier. Take a piece spinning at a slow speed and draw a gouge across it at a fixed rate. Make it a fast enough rate that the result is a cut that is visibly spiral. Now crank the RPMs up high and draw the tool across at the same feed rate, and examine a smoothly cut surface as opposed to the ugly spiral. Again, "basic physics."

But then, you already knew that.

[Bill Grumbine]

Are you really in such an all-fired hurry to crank something out, or are you turning for pleasure?

Turning fast is turning for pleasure George. Not everyone gets a kick out of plodding along at 360 rpm or whatever it is you advocate. I just test drove the new Rikon 16" machine at our local Woodcraft a couple of weekends ago, and I ran a 90+ lb blank of walnut at 700 rpm to start. I had a blast, and judging by the response from the audience, they enjoyed it as well. Of course, people like fast cars, fast boats, fast planes, fast bikes, and some even like fast women. :eek: ;) :D It beats the heck out of watching the paint dry - well, except for that fast women part. I do not advocate that.

Bill, to answer your question, Mark has already quoted me from my second video, but the essence of the quote is that you need to feel comfortable with the speed at which you are turning. Faster surface speeds will result in a better surface overall, despite what some might say. It is a combination of the tool speed as you move it across the wood and the speed of rotation. But, it is not worth getting hurt if you are concerned for your safety. I like going as fast as I can, but there are times when I have to turn the speed way down low and be patient. But when I crank it up... :cool:

[Kaptan J.W. Meek]

Like the guy in the video said.. " If your lathe is shakin' or tryin' to walk, turn the speed down.

[Bruce Shiverdecker]

You a definitely Right, Richard. Sorry for the mixup.

Bruce

[George Tokarev]

The answer to "how?" has to do with the "basic physics" that you referred to earlier. Take a piece spinning at a slow speed and draw a gouge across it at a fixed rate. Make it a fast enough rate that the result is a cut that is visibly spiral. Now crank the RPMs up high and draw the tool across at the same feed rate, and examine a smoothly cut surface as opposed to the ugly spiral. Again, "basic physics."

But then, you already knew that.

You're missing something. The spiral is not produced by the speed of the turning or the transport of the tool, but the shaving spanning a differential diameter. By taking advantage of the curved edge (it is a gouge) you can skew the gouge to take very broad shavings indeed, and by taking advantage of the curved profile, you gain good support by referencing where you're going by where you've been. Means much less ridging than trying to skate fast over a rapidly rotating surface.

My I suppose that you have difficulty with the surface in the center of your bowls where the velocity is less? Only way I can see that you can make such a statement.

It is well said that the best cut is the one you feel least. Next time you get a chance, check out Ol' Roy Underhill rotating by hand and taking off that neat spiral. Scoop and skew is what to do.