Turning speeds vs diameter and medium - Woodworking Talk - Woodworkers Forum
 
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post #1 of 14 Old 01-13-2010, 09:15 AM Thread Starter
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Turning speeds vs diameter and medium

I am not new to woodworking but am fairly new to turning. I've made a couple things on my jet mini lathe. It is a variable speed lathe. My question is about speed. I am confused on how fast or slow to turn certain materials at any given diameter. Is there an ideal velocity that the tool should see while cutting similar to a router bit? Does material matter like a drill press? Thanks for sharing your experience.
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post #2 of 14 Old 01-13-2010, 10:06 AM
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Turning speeds vs diameter and medium

First off,with most smaller lathes,you want to make sure the blank is as round as possable before mounting it.I have two lathes,a Ricon mini with a 12" swing an a Nova 1624 with a 16' swing.The nova can handle an out of round piece,say 12" with no problem,but with the Ricon it has to be pretty well bal.I think your mini has a 10" swing and is pretty light wieght,thats why I am mentioning the bal factor.With my Ricon the slowest speed is 500 rpm's and thats what I start out at,then when the piece is perfectly round and turning smooth,then I will up it to about 900 rpm's.As for the woods,I don't think that matters,but make sure your tools are as sharp as you can get them as that can have a huge inpact on your succesfull turning.Also when I 1st start to rough out the blank,I leave the tail stock with a live center up against the piece as long as I can.Hope this helps.

God Bless all
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post #3 of 14 Old 01-13-2010, 10:24 AM
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Depends on what you're turning. Spindles are usually turned at higher speeds than chuck work. Pens, for example, can be turned as high as you like.

A safe speed for bowl work depends on 1) the diameter of your work piece, 2) the balance of your work piece, and 3) your PPF (i.e. "Personal Pucker Factor"). As The woodsman stated, you'll usually want to start slow and raise the speed as you get the piece more in balance.

As for starting a piece... something in the 6" to 8" range can easily be started at around 500 to 600 RPMs. 800 RPMs is still reasonably safe if you're starting off with a relatively round and balanced piece. Much above that and you're into the realm of risk-taking.

As the diameter of your work piece goes up, these numbers should go down proportionally. A low PPF would also mean the numbers above should be lowered proportionally. And again, a lot depends on the balance of the piece. A bandsaw is your friend but some pieces of wood will have density differences that make them out-of-balance no matter what.

Once you get a piece in balance, a lot still depends on the diameter. I like to turn small pieces (3" to 8") at around 800. Sometimes I'll go to 1000 on particularly dense wood such as blackwood.

As you suggest, material can also play a factor. Those who turn stone, for example, such as alabaster or soapstone usually recommend turning at lower speeds than used with wood.

The best rule-of-thumb to use is... if the hair on the back of your neck is standing up, you're turning too fast.

Hope that helps!

Last edited by Neal Addy; 01-13-2010 at 10:29 AM.
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post #4 of 14 Old 01-13-2010, 10:32 AM
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"PPF" - I love it - well said, Neal!
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post #5 of 14 Old 01-13-2010, 02:28 PM
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There actually is a calculated most efficient cutting speed. It can be found by doing research. However in real terms it's totally impractical. The reason is the surface speed changes constantly as you move from the outside of a bowl or platter toward the middle. Think of this in terms of surface feet per minute passing the tool. In order to maintain the best cut you have to slow down how hard you push the tool as you approach the slower surface speed present as you get near the middle. The outside of a bowl may be going 60mph while the center is only going about 5mph. The RPM will be the same.
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post #6 of 14 Old 01-13-2010, 08:19 PM
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Post Speeds- here you go

Between Centers
Stock Size" up to 24" Over 24"

2-1/2" 2000 rpm 1500rpm
2-1/2" -4" 1500 rpm 1000rpm
4"- 6" 1000 rpm 750rpm
6"- 8" 750rpm 500rpm
8"- 10" 500rpm 300rpm
10" and up 300rpm Judgment call to 10 rpm

Faceplate turning
Stock Size" up to 2" thick Over 2" thick
up to 8" 1000 rpm 750rpm
8-12" 750rpm 750rpm
over 12" Slowest to start Slowest to start



If you do work 6'L ~ 20'L and 24"D~ 30"D -hallow staved construction, 10rpm to start not exceeding 50rpms while being balanced through turning not exceeding 80 if at all possible- common sense !
Mr.20C

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post #7 of 14 Old 01-14-2010, 11:22 AM
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Wow you turn way slower than I do. Turning too fast is dangerous but turning too slow makes it hard to move the tool in a fluid motion. You also tend to push the tool through the cut instead of letting it do the cutting. This leads to tearout.
Really rough bowls up to 19" in diameter I start around 200 rpm and usually get up to 500 pretty quickly as it gets in balance. I probably do the finish cuts in the ballpark of 1500 rpm. Smaller bowls of course are a little faster, 12" would be around 500 rpm and finish cuts 1500 or a little higher.
I turn my hand mirrors which are 3/4" thick an 5 1/2" in diameter at 2000 rpm, the handles which are 3/4" x10" are turned closer to 3000.
Beginners should probably go slower but too slow just makes getting clean cuts harder. At least that's my experience while teaching classes.
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post #8 of 14 Old 01-14-2010, 12:43 PM
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Post speeds???

Quote:
Originally Posted by john lucas View Post
Wow you turn way slower than I do.
John,
May I ask what lathe you turn on and what you "teach"? He is looking for a guideline and fairly new to turning- you should know this since your a teacher-no offense. If you have a problem with the speed guideline I have stated, go talk to Keith Rowley, he has a book called "WOODTURNING" A Foundation Course, I am sure you are familiar with it. He stopped the speed ratings at 12" OB and 4" BC in his book. Pattern makers and Architectural turnings on a large lathe turning a large product BC or OB ,is a totally different type of turning, same principle, different tactics,tools,techniques and machinery.
EX: The OB side of my Oliver 20C pattern lathe has a 84"D capacity that is mounted on a 24"-95lb solid steel face plate which mounts to the-2-1/4" 8TPI-OBS. I could go larger if I create a pit down through my floor but it is intimidating enough to me as it is. I don't use sand bags or mounting brackets to keep my lathe from dancing all over my shop floor - it weighs 4,552 lbs , so if you want to turn something this large that fast, that's up to you, although - I would not recommend it.The BC cap is 24" diameter (30" if I put the 3-1/2" cast iron riser blocks on the HS/TS and top tier carriage) x 106" long , again - not the same animal. The 2 tier carriage gets used "A LOT" with these type of turnings and the fine shaping , detailing and carving (if called for)is done by hand.
I always say-Safety First to anyone, then the time and experience will come after until you become comfortable- then you can increase your speed (within reason "common sense"), that was told to me by a professional pattern maker years ago after showing me on his German "Zimmerman" Lathe- absolutely beautiful massive piece of engineered equipment- all 6,248lbs of it. If you calculate the outside surface of an object with these dimensions ,at a low speed,- it is not running slow, trust me. The rpm Hz indicator is low but not the outside product.
I don't turn pens,boxes, or spindles, well- once in a while I will but I mostly do column and pediment architectural orders of the Vignola, when the opportunity arises. So before you start jumping up and down about me and my speed recommended guidelines - we don't all turn the same objects John. OK This is my baby from 1909.
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post #9 of 14 Old 01-14-2010, 04:17 PM
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I turn on a Powermatic 3520A and a Nova Comet mini lathe. I also have a Carbo-tec mini a spring pole lathe and a metal lathe. Most of the lathes where I teach are powermatics or Oneways. I don't start people out fast. I observe how they are working and then quite often ask them to speed up the lathe. Not excessively or danger, just fast enough to make the cuts more efficient.
I find new turners do one of 2 things. They either turn too slow, which is fine or they turn too fast which is dangerous. I try to find the middle ground that allows them to turn safely but still get a decent cut.
Most mini lathes won't go below 500 rpm and many of the less expensive bigger lathes won't. I think this is too fast for a 10 to 12" bowl when roughing it out. However once it gets round and you've reduced some weight I think it's about right and will usually increase the speed for the final cuts.
One of the biggest problems I face when teaching is students forcing the cut. They push the gouge to make it cut faster. I don't know if it just feels more comfortable to have the gouge move at a certain pace or if they just don't have the patience to let the tool move slowly. by increasing the rpm's the tool just natually moves at a faster pace and at the same time takes a smaller bite out of the wood. consequently they get a cleaner cut and at the same time a better curve to the bowl.
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post #10 of 14 Old 01-14-2010, 06:54 PM
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Bweick7 Sorry if I sounded like I was taking you to task. I was not. I actually think I misread some of your speed ranges but still feel some of them are too slow. That's obviously just my belief and slow is better than fast if you are in doubt. You can turn a good product at ridiculously slow speeds. I do this when doing my skew demo's. I turn the lathe down to 50rpm or so so they can actually see the tool cut.
What do I teach? Just about everything. I have been turning for more than 25 years and teach several workshops a year along with many demo's. I write articles for all the woodturning magazines to try and share what I've learned. Not that it makes me an expert, just experienced. I turn a little bit of everything from larger furniture pieces to goblets so small most people can't see them without magnification.
I really try to learn all I can about tools and how they cut and try to figure out how to make them work better for me.
You may be quite skilled, I don't know. I'm always a little skeptical of people who just jump on a site and start telling us how to do everything and don't use their name. Again I'm not trying to jump on you I've just seen this happen many times quite often with unskilled people. I apologize if I came off strong. I certainly didn't mean to. Just wanted to point out another point of view.
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post #11 of 14 Old 01-15-2010, 11:40 AM
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Thumbs up Hey John,

You, and turners like you have more expertise than I do turning boxes,pens and the like. I am behind on the learning curve there and I still have a lot to learn. I have the utmost respect for people like you , especially since you teach this type of turning, so my hat goes off to you. My name is Brian and I don't do a lot of turning on boxes,pens and the like which is what most turners on here are doing. I am on several wood forums and found this through ContractorTalk.com. I don't believe in giving a "guess" on something I don't know about and I will be the first to tell you if I don't know how to do something-for instance- bowl turning- I have a lot to learn and can't give any useful information because I have "no" experience in this type of turning what so ever. I am not a jack of all trades and don't know everything but I do know a lot about architectural orders and how to produce them. No hard feelings John, Like I said - My hat goes off to you
Brian
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post #12 of 14 Old 01-15-2010, 12:02 PM
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Brian Good to meet you. I do some architectural work but try to avoid it when I can. I simply don't have time to do a lot of duplicates. I am testing a duplicator right now to see if it would work for me. I do all my duplicates right now with calipers and my eye. I have the utmost respect for guys that do your sort of work day to day. Takes a lot of skill.
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post #13 of 14 Old 01-17-2010, 07:29 AM Thread Starter
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Smile Thanks to all.

I just wanted to say thanks to all. especially Brian and John. You have definetly helped me. Personally I think the PPF should some how become a national standard or something. I laughed so loud my wife looked at me funny, she just wouldn't understand. Anyway, I've got 3 pens and two 6 inch bowls under my belt now. I have learned that sharp tools are a huge part of feeling confortable with the process...PPF. As a matter of fact I pretty much left my grinder running next to my lathe on my last project. Anyway, thanks again. I think I am now on my way to more bowls and pens....
I think I'm hooked.
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post #14 of 14 Old 01-18-2010, 10:23 AM
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Thumbs up Your Welcome Rz

you have fallen into the vortex- be prepared. John's the guy for these types of turning projects your doing should you have any questions- Good luck
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