What Speed

[Jim Koepke]

My current lathe is an old Craftsman, King Sealy. The lowest speed I can get with the way it is set up is about 860 RPM.

I have been thinking of installing some pillow blocks and a pair of pulleys to lower the speed a bit more. Is it possible to make it go too slow?

With the room and pulleys available the speed can be brought down to the 250-290 RPM range.

Any thoughts on what speed you would use for turning if you could only have one speed?

Is a 1/2 inch shaft big enough to use for this kind of set up or would a larger shaft be better?

jim

[David Walser]

Jim,

What's a safe turning speed depends on a number of factors. For example, it might be safe to turn a solid piece of wood at one speed, while it might be unsafe to turn a punky piece of wood at the same speed. It might be safe to turn a blank held in a 4 jaw chuck at 1,500 rpm, but the same blank could be turned safely at 2,000 rpm if held between centers.

Taking all of these factors into account, years ago Dale Nish came up with a formula for determining a safe turning speed based on the size of the blank. The formula, and how to use it, can be found here: http://www.woodturnerscatalog.com/woodturners/Images/safe_lathe_speeds.pdf

Note: The formula is just a rule of thumb. It just gives you a good place to start.

HTH

[Steve Schlumpf]

Jim - I am no expert but I would think that the slower you go, the more that available torque becomes an issue. If you were installing pillow blocks - would you not still have options as far as belt placement?

For me personally, I don't have an answer to your question about a single speed. If turning spindles, pens, bowls, or roughing out a blank - each would require a different speed - both in terms of getting a good cut and also that of safety.

[Jim Koepke]

Thanks for the replies.


Jim - I am no expert but I would think that the slower you go, the more that available torque becomes an issue. If you were installing pillow blocks - would you not still have options as far as belt placement?

For me personally, I don't have an answer to your question about a single speed. If turning spindles, pens, bowls, or roughing out a blank - each would require a different speed - both in terms of getting a good cut and also that of safety.

With the motor at a fixed speed, wouldn't lowering the speed through pulleys tend to be less likely to stall when cutting? (equalling more torque?)

My brain is working on the best way to make the pillow blocks adjustable so different pulley arrangements can be facilitated.

Maybe my question should also have addressed things like are catches less likely or more likely at low speeds or is it all dependent on material and technique at any speed?

Are there disadvantages of turning at low speeds?

I am a little intimidated by my current turning at 860 RPM and feel like mistakes are just happening too fast to have better control.

My turning has not gotten much in to the way of bowls or pens. My turning is mostly working on tool handles and spindles. One of my hopes for the future is to be able to make some Windsor style chairs.

There is an old Windsor stylish chair next to my bed that was around the family dinner table since back in the 1950s. The shape of the turning on that gave me an epiphany one morning as my eyes opened from sleep. Part of the leg shape is the same as what I had been attempting to make for chisel handles.

Monkey see monkey make? Even without realizing it?

jim

[Thom Sturgill]

Jim, I was just watching a Jimmy Clewes video this morning, and he talked about turning speed. He claims that while high speed is often intimidating to new turners, it is more often SAFER to turn at high speed. You will get fewer catches. This is especially true for spindle turners.

On the other hand, 860 rpm is way too fast for an out of balance bowl. My midi has a lowest speed of 250 and sometimes I wish it were slower when starting on a bowl as it is just sitting on a workbench and is not bolted down. But once the blank is rounded, I find myself turning at a much faster speed (1500-2000 rpm).

[Dick Sowa]

With an additional shaft, pullies and belt, you can increase the number of speeds available...it just takes some finagling to figure it out. I know there are plenty of examples online, Google "lathe countershaft".

As far as "too slow", I don't think there is such a thing. I happen to own a variable speed lathe, and often crank it down to 50 rpms to apply finishes, do finish sanding, etc. Having a lot of different speed options will make a huge difference in what you can turn easily.

[Dennis Puskar]

Just a thought but how many speeds did the have on a pole lathe ?


Dennis

[Fred Perreault]

Dennis.... when they were using pole lathes most often, how many speeds did a horse and buggy transmission have..?:)
Fred

[Rich Aldrich]

Thanks for the replies.



With the motor at a fixed speed, wouldn't lowering the speed through pulleys tend to be less likely to stall when cutting? (equalling more torque?)

My brain is working on the best way to make the pillow blocks adjustable so different pulley arrangements can be facilitated.

Maybe my question should also have addressed things like are catches less likely or more likely at low speeds or is it all dependent on material and technique at any speed?

Are there disadvantages of turning at low speeds?

I am a little intimidated by my current turning at 860 RPM and feel like mistakes are just happening too fast to have better control.

My turning has not gotten much in to the way of bowls or pens. My turning is mostly working on tool handles and spindles. One of my hopes for the future is to be able to make some Windsor style chairs.

There is an old Windsor stylish chair next to my bed that was around the family dinner table since back in the 1950s. The shape of the turning on that gave me an epiphany one morning as my eyes opened from sleep. Part of the leg shape is the same as what I had been attempting to make for chisel handles.

Monkey see monkey make? Even without realizing it?

jim


Purely from an engineering standpoint, the torque would go up. HP= Torque x RPM / 5252. The horsepower stays the same and RPM goes down, so torque has to go up.

[Kim Ford]

My old Oliver was geared from the factory from 90 - 2900 rpm. Now I have a VFD, but there is a distinct advantage to slower speed for some applications. However, if you primary projects are spindles, I might make another suggestion. Put a dead center on both ends, you are probably a MT #1 or #2 and pratice turning without the spur. I think they make a special device for this but I have always just used the dead center. If you get a catch it slips and keeps you out of trouble.

[Bryan Morgan]

Anyone ever try putting a router speed control on a lathe? I put one on my bench grinder and it seemed to work ok to slow it down a bit...

[David Walser]

Anyone ever try putting a router speed control on a lathe? I put one on my bench grinder and it seemed to work ok to slow it down a bit...

Bryan,

Most lathes have a different type of electric motor than those used in a router. (I'm sure someone will pop in with the technical details.) The router speed controls are NOT compatible with the type of motor used on most lathes.

[Rob Cunningham]

Jim, you might be able to find a used treadmill cheap or free.(try Craigslist) It takes a little work pulling the motor and speed control out, but then you have a variable speed motor. I just did it recently on my older Delta lathe and VS is really nice.

[Jim Koepke]

Thanks to everyone for all the advice.

I do try to remember to look at Craigs Free list every morning with coffee.

jim