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Proper turning speeds

Discussion in 'Getting Started' started by Steve Kephart, Jun 17, 2020.

  1. Steve Kephart

    Steve Kephart

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    Hi

    I am new to woodturning and have been viewing many videos. The videos are very good for getting a feel of the proper technique for using a gouge. But they never mentioned the the rpm that is being used. For example, they will say 'for sanding use a low speed' or in a bowl or spindle video the will be no mention of the rpm used. What is a general guide line for the correct and safe rpm.
     
  2. Gerald Lawrence

    Gerald Lawrence

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    Correct and safe can be defined as mostly what you are comfortable with. For sanding usually between 200 and 400 works well due to mostly the fact that higher speeds will cause bounce and the paper will mostly float over the surface.

    Now for turning speed is determined by what you are turning. For example a 2 inch spindle is safe at 2000 but a 12 inch bowl not so. In general terms faster gets a better cut but may not be safe. Blanks should be started slower (from 200 to 500) until irregularities are removed. then speed can be adjusted. There are some charts I am sure someone will post but I usually turn 10 inch bowls at 800 to 1000. For hollowing a bit slower may be required.

    Eventually you will get a feel for the speed and know if the lathe is vibrating either something is wrong in setup or you have the speed too high. Better to erro on the side of slower than to be too fast when that catch happens.
     
    Charles Cadenhead and odie like this.
  3. hockenbery

    hockenbery AAW Advisor Staff Member

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    I and many other turners use Vibration rather than RPM to set the speed.

    For roughing, I mount a blank, check the mounting, set the seed to lowest, turn on the lathe, bring the speed up until the lathe starts to vibrate a little. This probably the speed I want. I will advance the speed a little and let the vibration increase but never let the lathe start moving( back off imeadiately).
    Usually there is a slightly higher speed that runs More smoothly that the first vibration speed.
    This is it. If there is no smoother speed back off to where it just started vibrating.
    As I turn the pice runs smoother and smoother. I will increase the speed.

    basically within reason you want the fastest vibration free speed.
    Beginners should always stay well under 2,000 rpms for the first five bowls.

    sanding under 300 rpm.. if you can see the threads on the spindle that is under 300.

    stay within your comfort zone.
     
    Last edited: Jun 17, 2020
  4. John Walls

    John Walls

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    All good advise I follow. The bigger the piece, the slower I start cutting. I go to the slight vibration and back off a hair, especially the bigger pieces. On small pieces, if the vibration is slight, I will push past the lower speed slight vibrations and they will for the most part disappear letting me cut faster/much less..... bounce, but ONLY on small pieces. Honestly, I don't pay much attention to my speed read-out, I only pay attention to my comfort zone. I'm very new to this addiction myself and have ALOT to learn.
     
  5. Roger Wiegand

    Roger Wiegand

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    I've never had a lathe with a speed readout. I'm not at all sure they are a good thing. Much better, as others have said above to use vibration and cut quality as a guide so that you can achieve "fast enough, but not too fast". Too many beginners set their lathe to what they've been told is the "right" speed instead of paying attention to what is going on and experimenting with what happens as you go faster or slower. I recommend a piece of black electrical tape over the readout.

    I generally start by increasing speed to where things start to shake and then backing off; sometimes if you hit a resonant frequency you can go faster than the vibration point and get back to smooth running. That also applies when you start to get chatter, shifting the speed slightly faster or slower can get you away from the resonance.

    I often try to make a couple of eggs out of firewood as practice and warmup (plus people like them)-- it's a great exercise to experiment with the effect of speed. Do one fast and one slow, compare and contrast the feeling of the process and the outcome.
     
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  6. hockenbery

    hockenbery AAW Advisor Staff Member

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    I like @Roger Wiegand tip to cover the RPM readout.

    as you practice - work on feed rate to leave a smooth surface.
    feed rate of the cutting tool is determined by RPM and movement of the tool over the surface.

    hard to cut an even surface at 3 rpm most people will cut a spiral groove by moving the tool too fast.
    Each of us have an upper speed limit at which our mechanics cannot form a good curve.

    often cutting a cove with a spindle gouge is done ether at a slower speed because the turner has time to follow the curve and can better match the cut from the other side to meet in the bottom center.
     
    odie likes this.
  7. Steve Kephart

    Steve Kephart

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    Thanks for all your help. This gives me a idea of a safe speed until I get some experience. The Craft Supply site was especially helpful and now I have a reliable source for other help on turning.
     
  8. robo hippy

    robo hippy

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    There are a number of formulas for figuring speed, and I consider them to be 'suggestions' and not hard fast rules. Generally smaller bowls are turned at higher rpm than larger bowls, and part of that is the vibration factor. As a production turner, I turn at speeds up to about 2200, which is the limit of my lathe on the mid range pulley (my lathe has 3 speed ranges). That is considerably higher than most recreational turners use, and it is one of those things that it can be safe for me, but not for you. You have to experiment to find out what is right for you. One thing to remember is that the higher the speeds you use are, the more spectacular your tool catches are. ALWAYS stand out of the line of fire, so when some thing does come off the lathe, the odds of it hitting you are about zero. I do have a video dedicated to that, as well as a bunch of others, mostly about bowl turning.

    robo hippy
     
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  9. Paul Lajoie

    Paul Lajoie

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    I also go more by the lathe vibrating and dancing around than a specific rpm number. But it is nice to know approximate rpm cause you know someone’s going to ask!

    Paul
     
    odie likes this.
  10. Jason Matisheck

    Jason Matisheck

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    While I agree that RPM is not an absolute metric, why would you deny yourself a piece of useful information? My lathe doesn't have an RPM readout and I wish it did. As a noob, I would at least be able to know I'm not running stupid fast while I struggle with all the other factors that contribute to vibration and cut quality. I like the Craft Supplies guide posted above. I also like the Stuart Batty rule of thumb that the surface speed shouldn't exceed 40MPH. Without RPM I have no idea where I am relative to those guidelines. Obviously I'm living without RPM by doing the things you experienced guys say, but I would be happier with it.

    I recently read Lynne Yamaguchi's article from the June 2014 American Woodturner. In there, she makes it clear that the energy of a chunk coming off the lathe can be orders of magnitude greater than what our ANSI Z87.1+ face shields are rated for. Since energy is a function of velocity squared, every little bit of speed makes a big difference when something goes wrong. When I'm still fairly likely to have a catch, I don't want any more energy in the system than is necessary. Even without vibration I'm not sure faster is always better.
     
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  11. Roger Wiegand

    Roger Wiegand

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    Jason, I think you make exactly my point-- you want to be turning at the right speed for that particular species and piece of wood, at that diameter, with the particular tool you're using, and with your skill and comfort level at that moment in time.

    A gauge on your lathe tells you none of that and, from observation, very often leads people astray. ("But my teacher said I had to us xxx rpm!")

    Start slow and watch what happens and how it feels. Turn the speed up, does the cut improve or get worse? Is it easier or harder? Is your control over what's happening better or worse? If you watch and pay attention to how the tool feels in your hands and the surface quality you'll very quickly discover that there is an optimum speed. On another day with another piece of wood that optimum is going to be different and you won't figure that out looking at a speed dial rather than what's happening on the lathe.
     
  12. Mike Johnson

    Mike Johnson

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    Surface speed or distance traveled per revolution is an important variable for wood and metal turning lathes. When you exceed the ability of the cutting tool to clear the shavings being cut from the work piece the shavings begin to load up against the cutting edge of the tool. This usually bogs the machine down or creates noise and vibrations which can lead to harmonics at different ranges of speed, which can leave a poor quality cut surface.
     
  13. Jason Matisheck

    Jason Matisheck

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    Maybe I did, but it still feels like "Good judgement comes from experience. Experience comes from bad judgement." ;)
     
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  14. odie

    odie

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    Getting the least vibration possible, is just as important as sharp tools, best tool choice, and good presentation. :D

    This may require finding the least vibration possible through other means than our human senses can detect. :eek:

    Also......I've seen new turners (as well as some experienced turners) swear up and down their tools are sharp.....when it's obviously a misconception on their part. o_O

    Rule: A sharp tool will require a faster rpm than a sharpER tool will require, to have identical results.

    -----odie-----
     
    Last edited: Jul 12, 2020
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