Lathe RPM

[Harry Norford]

Hello all,
Been a wood worker for 50 yrs, but never owned a lathe. Been building my own the last few months. As retired machinist, I never liked the light weight lathes I could afford. Mine will have 8 speeds, would like to ask you pros what speeds would be most useful. This is a good size lathe, not made for little pens, etc. I guess if you tell me the max and min speeds, I can figure out the rest.
thanks

 

[john lucas]

Minimum should be below 500 especially if you anticipate doing bowls larger than 12". Maximum is usually around 3000 for doing small things like pens. I think most of us will agree that variable speed is best. Most modern lathes use a 3 phase motor that runs on 220 single phase through a Variable Phase Converter. These aren't that expensive and with the help of a 1 or 2 step pulley will give you all the range and power you need.

 

[MichaelMouse]

Hello all,
Been a wood worker for 50 yrs, but never owned a lathe. Been building my own the last few months. As retired machinist, I never liked the light weight lathes I could afford. Mine will have 8 speeds, would like to ask you pros what speeds would be most useful. This is a good size lathe, not made for little pens, etc. I guess if you tell me the max and min speeds, I can figure out the rest.
thanks

If you'll have eight speeds, might I suggest 200/400/600/800/ ... 1600. The low end is about what human patience can take in the way of slow. It's a temptation to push the tool and get it caught in gaps rather than swing it and skim the high spots at 200, so you'll have to keep saying "no, don't." Ought to do for swings up to about 20-24". I like 400 as a good place to start things, because I don't lose patience and push, but it will take a bit of balancing/trimming to keep a badly out of round or balance piece from shaking loose from what's holding it. Wood just isn't incompressible enough to take a lot of load.

Depending on your chuck, 600 may be the legal department's limiting speed, though you can probably push to 800 safely if you are balanced and in a hurry. Above 800 is a place I never really go. Truth is, above 680 is seldom selected on my Nova 3000. I like to peel, not shred the wood, and the danger increases exponentially with the velocity, as we know. For the tool feed rates I'm comfortable with, 680 is just fine.

I'm sure you misspoke, and understand it's not weight but rigidity that counts. Weight can be bolted on ad nauseam to the south end of a 1/2 x 1/2 x 36 piece of oak without affecting the flex on the north.

 

[Harry Norford]

thanks.

Thanks for the quick replies. John I'll look in the 3-phase situation, I have a number of 3phase motors and I use a converter in my machine shop, for my mills and lathes. But I don't know what a variable converter is? Do you mean that the converter regulates the RPM's. I’ll do a Google and see if I can find out more about this.
Michael, I believe weight and rigidity go together. No way a sheet metal lathe (or anything) can be as steady as a cast iron or heavy steel one. My lathe weights about 500 lbs and I haven’t installed the motor and ballast shelve yet! I notice I forgot to state its size. It’s a 14†by 6’. Made the spindle the same as my South Bend metal lathe, so I can use the chucks and faceplates, etc. I’ll post a photo when I figure out how to do that.
I seem to have created another problem. I made the spindle bore and tailstock #3MT. Tailstock is no problem. I have everything to fit that, but I can’t seem to find a spur drive larger than #2MT. I have sleeve adapters, but would like a #3MT. Guess I can make one if I have to. Anyone ever seen a #3MT spur drive?

 

[KurtB]

Harry, instead of looking for a #3MT, why not try looking for a spur drive designed to fit in a chuck? Might eliminate your problem altogether.

 

[john lucas]

It's pretty easy to make some sort of drive center. It doesn't necessarily have to be a Morse taper. It could simply screw on the spindle. I've made drive centers by regrinding the tip of older Morse tapers and I've also take hex nuts the size of my spindle and made drive centers.
The new Oneway drive center that fits in their chuck is a flat piece of steel.
http://oneway.ca/spindle/spurs.htm
Variable Frequency Drives convert 220 single phase to 220 3 phase and they vary the frequency to control the speed instead of varying the power. That way you get close to full power even at very slow speeds. They also give you the advantage of electronic braking which is very handy when turning heavier pieces. www.dealerelectric.com is just one place to get them.

 

[Joe Greiner]

Spur Drive (-ish) - #3MT

Not exactly a spur drive, but Robert Sorby makes a steb center with #3MT - found in Grizzly's paper catalog, item # H6199, along with smaller sizes.

FWIW, Grizzly also lists live centers (for tailstock) from #1MT to #5MT.

No involvement, etc.

 

[Gil Jones]

[FONT=&quot]Hey, Harry, give these a look. http://vermec.tripod.com/PDFs/drivedog.pdf
[/FONT]http://www.vermec.com [FONT=&quot]
I just purchased the 50mm Drive Dog from Vermec and it is a serious tool and is made of K1045 Medium Tensile Steel. My spindle is 1 1/4" x 8 tpi, and if I remember correctly your South Bend it a 1 1/2" x 8 tpi. Email Enzo and find out if he will make an adapter to fit your spindle, and the cost. They are in Australia, and deal in Aussie dollars, plus the shipping was around $USD 27.50 by air. The $AUD price displayed includes GST tax, so my cost was a bit less for export without the GST. My cost in $AUD was $80.91+$30.00 shipping=$AUD 110.91. In US dollars that is $101.65 delivered (at today's conversion rate).

Also, in the USA, there is an interesting screw-on drive made by Stubby USA for $USD 100.00 + shipping. It has removable drive spurs (4). So the costs are comparable. The Stubby drive does not list a 1 1/2" x 8 tpi, but a phone call could determine if they are able to machine that thread. It is a direct thread, no adapter.
http://stubbylatheusa.com/Convertible_Drive_Center.100.pdf

Hope all this is helpful,
Gil[/FONT]

 

[Ed Jarvis]

lathe speed

My lathe uses a 3 phase motor and a VFD with a adjustable speed control. I just turn the resistor to change the speed. If I need a speed that I can not get. Then I change the belt on the cone pulley. My lathe weighs 1600 lbs with out the motor. The Vfds are cheap and give unlimited speed control.

Ed

 

[odie]

My lathe weighs 1600 lbs with out the motor. .

Ed

That's quite a heavy lathe, Ed........what is it?

ooc

 

[Ed Jarvis]

Lathe

My lathe was made by Thayer, Houghton and Company of Worcester, Mass prior to 1857. I can not turn out board as the spindle is not drilled all the way thru. It is a gap bed lathe closed it swings about 27" open about 48" with the riser blocks about 60", came with a 32" face plate. I am still working on the 27" and under. It had some challenges like my raised ways are 10 1/2" apart with 8" of air between them If you want some pictures, a picture of it is at OWWM.com under lathes. If you want more contact me. I would say that I have one of the oldest working lathes arround.
Ed