Lathe speed basics


over40pirate

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The larger the diameter of the blank, the slower your speed, generally.  You'll turn bowls at lower speeds than spindles.  When you start with a rough blank you want a very low speed until it's trued.  Finish passes yield cleaner results at higher speeds.  I'm sure there's a ton of information on recommended speeds for various diameters...probably charts even.  That would be a good starting point...after that it's about feel and developing your own personal comfort zones.  The faster the better, generally, as long as it stays within a safe RPM for the particular thing you're working on.  Roughing is the exception.

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It depends on what you are turning.  I would recommend digging through some of the video's by Carl Jacobsen, Mike Waldt, and a few other's on this topic for more info.  I know Mike Waldt went through the effort to release a beginners series of videos, some of which did wonders for my technique.

If your piece is big, or unbalanced, low speeds are good.  As the piece becomes more true, you can slowly increase the speed.  You know when a piece is unbalanced, as your lathe will try to dance it's way out the door.  So keeping the speeds low as you start will help prevent the walking, and let you attack the high spots with less chance of catastrophic catches.  If you are not in constant contact with the work surface, like with odd shaped pieces (like live edge or winged bowls) or segmented blanks,  a slower speed is more desirable than a faster one.  A slower speed will allow to make more precise cuts on the high spots as you need. 

Also, like in a metal lathe, there is an optimum cutting speed for the tool and the wood you are using.  There is no real way to chart this out, as every tool and every blank is different, but with experience you can tell when you are too fast or too slow.   If you have a larger piece, even trued up, a higher RPM will make the actual speed of the surface higher than a smaller piece.  So while 1000 RPM may be sufficient for a particular piece that is 3" diameter, you will probably want to it to say 600 for when it is 6" across.  You also have to consider the material you are turning.  Some woods turn much nicer than others at high speeds, and vice versa.  And if you are into mixed media, plastics and other material will require different speed settings for the optimum cut.  Trial and error is the easiest way to figure this out.  It will only take a couple quick cuts to realize you are not at the optimum speed. 

Higher speeds are used on smaller pieces that are trued up already.  I can easily turn small spindles and pens at 1500+ rpm.  But always start slower and work up from there.

Finishing depends on which step of the process you are in for what speed you will be running.  For the actual application of the finish, I try to go as slow as possible so it doesn't spray the finish everywhere.  Polishing though, I try to run this at the highest speed I can that won't be unsafe and won't spray the polish anywhere, I can usually get away with 3000-4000 rpm for my highest grit polishing pads.  That said, my face shield seems to see it's heaviest use during the finishing phase. 

Sanding, again depends on the size and shape of what you are doing.  If you are using just a pad that you are holding onto, then what ever speed gets the job done well while staying safe is the best.  With a spinning bowl sander, I can usually run it faster than a pad, as the rotary motion gives a better result.  I like to do my last little bit of shaping with 60-80 grit paper to get the contours I'm looking for, and I'll usually do the finer grits at that same speed.

 

But regardless of what speed you run at, there 2 rules you should follow:

1)  Make sure the workpiece is secure!!!  A face shield will only slow down a heavy blank.  It'll turn a fatal head injury into a broken nose, it won't prevent a raw blank from doing damage altogether.  Always start your lathe at the slowest speed you can, and slowly bring it up to the desired speed.  And stand out of the firing line!  Stand off to the side as you turn it on, so if the piece does launch, it'll put a hole in something, just not you hopefully!  And use both the headstock and tail stock to secure a piece whenever you can.  If you can't get the tailstock to hold the piece,  stop and think about a way you could.  Then make a jig or something to help hold the piece in place (Giant tennis balls work great for this!). 

2) Dull tools are Dangerous tools!  Keep them suckers sharp.  A dull tool is more likely to cause a catastrophic catch than a sharp one.  A sharp tool will hopefully cut through the catch, rather than knock the piece loose.  Anytime you do get a catch, stop the lathe and recheck the security of the piece. 

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  • 2 weeks later...
Guest Randy

I am a beginning turner and just use speeds I found online with the American Association of Woodturners. They are only ranges, but the article on safety I read was very educational for a beginner. That would be a good resource and a worthwhile expense, in my opinion, to become a member. They have a lot of great online resources which are helpful to beginners.

I have really only turned small bowls up to about 7" so far and found that the "scariest" part for me is the initial stage where you true up the blank into a circle. Even though I cut the blank into a rough circle on the band saw it is, of course, not perfectly round. So that is the part I tend to keep the lathe at a lower speed for. Having said that, I haven't found any blank that I needed to turn at slower than the low end of the mid-range on my Nova Comet II midi. There is some vibration but not significant enough (mostly because I try very hard to cut the blank as close to a circle as I can).

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