Best RPM for bowls.

[unidave]

I bought Bill Grumbine's DVD and I like it very much. One thing I didn't get out of it was some turning speed guidelines.
How fast for roughing, how fast for final cuts? I have a variable speed motor so changing speed is simple enough.
Thanks in advance.
Dave

 

[Jim Carroll]

The speed is dictated by the size and shape of the blank you are trying to turn.
As you have variable speed start slow and build up the speed to a level where you find comfortable and as you get the blank in better balance keep increasing the speed. You will know where you are most comfortable . As you become more competant you will find your speeds will increase , generally the faster you are able to run the lathe the cleaner the cuts will be.
Always take a safe attitude and let the timber dictate the speed. Do not run the lathe faster than you have to. You will get some people who say you should run a 800 rpm and others at 1200 rpm again this all comes down to the blank shape and size.

 

[arbud]

Speep freak

Dave, turn your blanks at a speed with which you are comforable. Don't force yourself to spin wood faster than your comfort zone. Just because "A" says 1,200rpm doesn't mean you can't spin either faster or slower.

As for myself, I tend to be a speed freak. If the blank is "true" and wobble is nonexistant then I'll spin a 12" dia. x 4" blank between 1,500 & 2,000 rpm. If there's either wobble or vibration I'll slow down considerably until the wobble/vibration have been "turned out." If the aforementioned don't "turn out" then I don't force the issue. I like all my teeth right where they are and a straight nose is nice as well. 12-20 lbs of wood flyin' around the shop is not a joy to behold.

I can't say these things often enough: 1. Know your tools and equipment. 2. Know your capabilities. 3. Know your wood. 4. Stay in your "comfort zone" until you feel you are ready to expand said zone. 5. Expand your "comfort zone" slowly. 6. Always look at your wood turning as a learning experience--some lessons can be hard if you forget 1-5--OUCH!

 

[Jeff Jilg]

I agree with the other posters. Speed of turning depends on the blank. Another factor to consider is how well the blank is held to the lathe.

If you are turning between centers and you have a stout lathe + tailstock, then you can crank it up until it starts to vibrate/shake....then back off a bit.

Safety is the main concern. Any RPM above 200 will probably let you cut the wood. Above that it's mostly how comfortable you are with high speeds. For my first 200 bowls I probably turned them at 1/2 - 2/3 the speed that I'm using now.

Another item to remember is that you should periodically check the tightness or screws used to hold the piece to the lathe. As you turn a piece it may become loose. I often use a chuck. If the piece is on the chuck for long periods it should be retightened every so often.

If you consider larger bowls in the 12-20" range, or even deep 10" bowls, then the speed should be reduced because of the mass. When large pieces launch off the lathe they become deadly. Fortunately I do not speak from experience (have never had a large one come off the lathe).

 

[Bill Grumbine]

Hi Dave

I am glad to hear that you liked the DVD. As we were reviewing the proofs for it and making the final production, I finally realized I had said almost nothing about speed. I used to tell people who asked about speed that I turn at fast, really fast, and not so fast. Now I have been spoiled with a digital readout for the past six years, so I know exactly what speed I am turning at. But it is still fast, really fast, and not so fast.

For most bowls over 10" I generally keep the lathe under 1000 rpm, and as others have mentioned, the balance of the blank has a lot to do with how fast you can go. Once you have it running smoothly, or if the lathe has the beef to keep from bouncing around, faster will usually yield better cuts. I am a big sissy pants though, compared to Bud, as I almost never get a bowl up to 1500 rpm unless it is small! 😱

Bill

 

[dkulze]

I'll jump on the thread from the "fast as is safe" standpoint. I do alot of turning on pieces with large voids. For me, greater speed equals a better "false" surface to rest my bevel on. Low speed usually ends up with the occasional jammed tool, no matter how carefully I ride the bevel.

All that said, I have about 400lb of sandbags in a lathe and stand that already weigh in at about 300lb, and always keep the tailstock up till most of the wastewood is gone. Still gets a bit intimidating at times but, if you're gonna turn voids, there's no way around that (least that I know).

I have noticed that my preferred speed in general is around the 1200-1800 range. I just never seem to find the need for more than that.

Dietrich

 

[john lucas]

I tend to turn slow. Like Bill said I'm kinda wimpy here. I just feel more comfortable with the lathe not spinning so fast especially with large pieces. I also tend to turn a lot of dryed wood and the shavings will burn my hands if I run too fast. However when turning inside-out turnings or pieces with a large void I do crank the speed up. There is less open air time for the gouge to bounce over when the speed is up. You do need to know the wood and it's limits when you do this.

 

[unidave]

Much thanks! I'm beginning to feel more comfortable with the feel of the speeds and after watching Bill's video I have a much better understanding of tool positioning which also helps a great deal.
Well....on to the homework.
Dave 🙂

 

[Bill Grumbine]

I'll jump on the thread from the "fast as is safe" standpoint. I do alot of turning on pieces with large voids. For me, greater speed equals a better "false" surface to rest my bevel on. Low speed usually ends up with the occasional jammed tool, no matter how carefully I ride the bevel.
Dietrich

You make a good point here Dietrich, especially for voids and wings and such. When I turn winged bowls, which is essentially a board with a bowl shoved through it, I run them faster, but still the speed is only around 1000 rpm.

Part of the equation is the size of the piece. My lathe weighs 700 lbs all by itself, and has an A frame stand, 3 phase 2 HP motor and so on. It is very sturdy, but when I get an 80 lb chunk of wood on there, it ain't a gonna go fast. If I am doing a 6" core, that is a different story. 😀 However, if it is dry like John mentions, I have burned my hand, so in that case I will slow it down if I have to.

But think about this for a minute. How fast do you have to go? I had two students a little over a week ago, and one of the things we did was roughing and coring on two blanks. These blanks were fairly "damp" English walnut - i.e. they were still wet, but most of the free water was gone. I roughed them out, cored the first by way of a demo, and then the students took turns coring the second one. The blanks started out at approximately 14" in diameter and 5"-6" thick. From the time I switched on the lathe until the blank was round with a tenon on it was 11 minutes, and I do not think I went above 700 rpm. And I was running my yap in the process explaining a few things as I went. I could have gone faster, but there have been times when that 700 lb lathe has started to dance around on the floor, and that is scary!

Bill

 

[Mark Mandell]

Much thanks! I'm beginning to feel more comfortable with the feel of the speeds and after watching Bill's video I have a much better understanding of tool positioning which also helps a great deal.
Well....on to the homework.
Dave 🙂

Dave,

Count me in the Whimp Brigade as well. I'd like a digital readout on my lathe (especially one like the Poolwoods have that tells you what speed you'll be at before you turn it on), but I make do with an "approximate" value for each little white dot around the speed dial. Tried a couple of winged bowls, but the noise 😱 gave me the willies; kept expecting either the WHAM!!! followed by wood, tool and tool rest flying in different directions or to get "sucked into" the damn propeller. Don't think I've ever had my lathe cranked over about 1,000 rpm except when doing a spindle and then to no more than 1,500. At 825 pounds the machine's pretty well stuck to the shop floor, but it's way too heavy to make a good dancing partner. 😀

Someone told me the same things happen at 1,500 rpm as do at 500, just three times faster. I'm not looking to test the truth of his statement 😉

Mark

 

[MichaelMouse]

Dave,

Count me in the Whimp Brigade as well.

Someone told me the same things happen at 1,500 rpm as do at 500, just three times faster. I'm not looking to test the truth of his statement 😉

Mark

Big wimp here, too. I rough low and stay low. If I want to remove wood faster, I take thicker shavings. On interrupted-edge turnings I place a card of contrasting shade behind the piece I'm turning to show it best. Between that and lamp position I only bark my knuckles once in a while.

Your friend could also have mentioned that the available energy waiting to wallop you varies by the square of the velocity. So it not only happens faster, it happens harder. Not to mention that an out-of-balance piece isn't slowed a bit by the weight of your lathe when it flies off. I think weighting a lathe is a bit like medicating someone with a head injury. Might smooth things over temporarily, but it might mask a serious symptom, too. Like a loose hold.

 

[dkulze]

Hi all,

Yah, Bill, I have to admit that "fast" when I'm turning a 16" piece of oak with HUGE voids (only about 15-20% of the wood is "there") probably tops out to 4, maybe 500 rpm, and that is usually plenty to get the lathe humming pretty strong. The scariest part is speeding it up through the harmonics.

The higher speeds are usually when I'm working on the mini, which is clamped down to a very large bench. The piece is much smaller and I can get the RPM up to where I have a really nice false surface without too much dancing. Now shrapnel at that speed is a bit more concerning but the facemask stays on whenever the lathe is lit, sanding and startup included.

Dietrich