Lathe Speeds

[blackhorse]

As a relatively new turner, I don't fully understand the advantages to higher speeds beyond removing material faster. I've been doing mostly spindle work, roughing at 600-800 and detailing at 1200. What would a higher detailing speed get me?

 

[MichaelMouse]

Gives each spot more trips past the tool. If you're moving the tool faster more material can theoretically be removed in the same period of time.

I tend to move the tool at the same speed regardless of lathe speed, maybe even slowing a bit when I'm being careful, so it does me little good to go over my 688. To get the material past the tool twice as fast means four times the kinetic energy to punish a poor move. Hardly seems worth it.

 

[blackhorse]

So, Michael, then what IS the purpose of the high speed range on my machine that can go up to 3200 RPM?

 

[Bob Chapman]

Hi Blackhorse,

Imagine moving the tool, at a steady rate, a distance of two or three millimetres along the rest. If the lathe is set at a high speed it will make many revolutions while you move the tool, giving a smoother finish to the work than if you used a slow speed. Experiment by taking cuts at a low speed and at a high speed, and compare the finish. Generally, a higher speed gives a better finish.

Michael is right, though. If you have a catch at high speed the damage will be much worse. Make sure the tools are sharp and remember its the speed of the workpiece at the point of cutting that counts - the periphery of a large diameter piece will be moving pretty fast even with the lathe set on a slow speed.

Generally, I think there are only three speeds: 'too slow', 'about right' and 'wow, that's scary!' I try to avoid the first, use the second and make occasional forays into the third to make sure its still scary. If not, they all move up a notch.

Bob

 

[john lucas]

I turn at higher speeds as the diameter of the work gets smaller. I see many turners push the tool too fast for the cuts they are performing. speeding up the work or slowing down your feed rate will increase the quality of the cuts.
One example for me is when I'm turning long gently curves on a spindle. If I use too slow a speed it's hard to make your body flow with the curve. Ideally you should be using your body not your hands to control the tool. When I speed up the lathe I get a more fluid movement of my body and consequently a smoother curve.
I don't actually know what speeds I turn at because my lathe doesn't show me directly. Small 3/4" diameter spindles are near the top of the slow speed range so i think that's somewhere in the 1800rpm range.
Spindles up to 4" in diameter are slower, probably in the 1000 to 12 rpm.
Bowls start at around 200 or 300 rpm and jump over 500 as soon as they are running smooth. I never turn bowls very fast, probably 1000 is top speed. I tend to turn slower than many turners but in the last few years have increased my speed on the spindles and it has improved the quality and speed that it takes me to turn them.

 

[MichaelMouse]

Non-cutting operations benefit from higher speeds. Scraping or sanding, where you're advancing with little pressure into the wood over a broad area are two. If your tool rate is the same and your spin rate high, your bevel will burnish more. If that's what you're after, you might want to do it. With cutting operations, it makes no difference how many times you touch a cut fiber until you get the tool clear.

 

[robo hippy]

I turn at a lot higher speeds than I used to. It is a comfort thing. Whatever speed you feel comfortable at is the right one. I do find it easier to turn at high speeds, and I do seem to get a cleaner cut. For bowls, I turn between 300 or so up to 1500, depending on size, how well it is balanced, and if the lathe is shaking. I would turn smaller bowls (8 inch or so and smaller) at higher rpm, but I would have to change the belt, and that would end up being for the last core or 2 that I do, then I would have to change back..... Too much extra work. Spindles, I turn up to 3000 rpm, and some times I could see that being too slow. Some of the Myrtlewood turners on the Oregon coast turn Myrtle bowls at 4000rpm. The thought of that maked all my sphyncter muscles pucker. A friend of mine has one of the Legacy ornamental lathes, which has a top speed of 200 rpm. When he comes over to core something, he turns at that speed on my lathe. It drives me nuts, but that is what works for him.

One theory of mine on the cleaner cuts at higher rpm(besides like John said about body movement being easier) is that I get more cuts per inch. By that I mean if you are moving at the same rate/pressure on the tool as when you turn slower, you will get more cuts per inch of wood. The cuts are closer, and there are less lines in the wood. The cuts also are a bit finer and lighter so less tearing.

robo hippy

 

[Joe]

There are several factors that need to be taken into consideration for the the lathe RPM. Size of the piece being turned: A 12" diameter piece will pass 36+ inches of wood over you tool every rotation. A 1" diameter piece will pass 3+ inches of wood per rotation. For the wood to have the same speed a 1" diameter piece will have to turn at least 12 times higher RPM. In most cases this multiple factor is not needed or desired but shows the point. If you use the same tool movement and pressure for both diameters at the same RPM you will break the smaller piece frequently. Remember it is the same RPM but not the same wood speed as diameters change. If you are working on very fine small pieces your cuts will be smoother at a higher RPM as you can take lighter cuts with less pressure easier. If you are roughing out a piece of wood that is fairly well balanced you will get smoother cuts and feel by turning at a higher RPM because there is less time for the tool to move in towards the center (or void area) between high spots. This should prevent major chipping and chunks flying if you are using good tool techniques. The same holds true with wood that has voids in it. Please note that there are many times when slower is better if safety is a concern. I think I have a few pieces still in orbit somewhere.
Joe

 

[odie]

There are several factors that need to be taken into consideration for the the lathe RPM. Size of the piece being turned: A 12" diameter piece will pass 36+ inches of wood over you tool every rotation. A 1" diameter piece will pass 3+ inches of wood per rotation. For the wood to have the same speed a 1" diameter piece will have to turn at least 12 times higher RPM. In most cases this multiple factor is not needed or desired but shows the point. If you use the same tool movement and pressure for both diameters at the same RPM you will break the smaller piece frequently. Remember it is the same RPM but not the same wood speed as diameters change. If you are working on very fine small pieces your cuts will be smoother at a higher RPM as you can take lighter cuts with less pressure easier. If you are roughing out a piece of wood that is fairly well balanced you will get smoother cuts and feel by turning at a higher RPM because there is less time for the tool to move in towards the center (or void area) between high spots. This should prevent major chipping and chunks flying if you are using good tool techniques. The same holds true with wood that has voids in it. Please note that there are many times when slower is better if safety is a concern. I think I have a few pieces still in orbit somewhere.
Joe

I find this to be generally true, Joe.

Faster is usually better no matter what the size, but everyone will develop a turner's sixth sense about about safety issues......and know just when to back off and choose a slower speed. Balance issues are pretty easy to figure out, but how your skill level as applied to the tool will respond to speed in general, takes some savvy that doesn't come any other way......than with hands on mileage! I've got a few pieces that are still in orbit myself!.......this is part of getting to know, and listen to that "sixth sense"! There is probably nobody who has learned to get the best/fastest speed who hasn't had a mishap because of excessive speed......those who haven't been "initiated" are probably stuck on speeds that are slower than they could be turning at!

otis of cologne

 

[Richard Baker]

BH,
John Lucas may have summarized it best. Bottom line is simply to try it and evaluate the results for yourself. But if you are turning something really long and really thin, may need a steady rest out there in the middle.

 

[Vaughn]

Like others, I find I turn faster as I gain more experience and surety about my tool presentation. I've also had enough of the pucker moments to have a pretty good feel for when things are a bit too dicey. I try to find the sweet spot speed-wise that lets me take off a lot of wood, without having a lot of wood take off.

 

[Claude]

It is quite difficult to say at which speed to turn as this depends of the size of the wood and of it’s compactness, balance… and many other parameters.
Only by experience I would say that I apply a general rule of thumb which is that the speed of the perimeter of the wood should be between 14 and 16 meters per second while roughing out and 18 to 20 when spindeling or hollowing.

This should be applied with reasoning as, if you make the calculation, you should put your lathe at over 7.000 rpm’s for pen blanks.

To help those with less experience I have done a little program where you can easily enter your diameter to see at which speed you have to set up your lathe. TURNING SPEED
After a while, like most of us, and in particular the lucky ones with an electronic speed control device, you will not be able to say at which speed you turn. You’ll always be at “the fastest possibleâ€