Spindle speeds/rpm of the Atlas 12" lathe

Interesting. Note that this is a 25 cps motor.

Robert D.
 
im at work right now, but when I get home Wednesday I will snap a picture, I looked at a motor here at work and it also has different rpm ratings but looking at that one I know it has to do with the hertz, at 50 cycles it does this rpm, but at 60 cycles it does that rpm, so that also is probably the case with my motor, but I coulda sworn it was voltage but I prolly just read that label wrong it was just a glance at the label and was like hmm, maybe that's why I always run the lathe 1-2 speeds higher than recommended by the book, sometimes even 3 speeds faster just seems to cut better and with a nice finish...


BTW the 1480 was just a guess, I know its in the 1400s so I just through the 80 on there cause that's what I thought it was.....like I said im at work and while home I glanced at the label while I was doing the hole layout for mounting the lathe on the concrete pad I poured for it to rest on
 
I don't quite understand the last post. Was the motor also be supposed to run on European current? Theirs is 50 cycles. If you take a European motor and use USA current of 60 cycles on it,it will run fine,but will run 20% faster.
 
We'll just have to wait until Wednesday to find out what he actually has.

Robert D.
 
Hi my sphere 5" lathe(atlas clone) has 16 speeds 30 rpm to 2000 and will screw cut down to 4 tpi the spindle speeds and coarse pitch ability are far superior to a lot of the asian lathes where you have to buy a much larger machine to get the same ability.Thanks.Ronnie.
 
Ronnie,

Yes, I assume that's what in US practice is called a 10". The 12" models are the same. But the spindle speed charts all assume a nominal 1725 RPM motor. Which is the question to be answered.

Robert D.
 
How did you measure the speed of the motor? The difference between 1400-1500 rpm and 1700-1800 is somewhat to difficult to judge by eye. An inexpensive photo tachometer will tell you for sure.

Motor tags will sometimes list things in a strange way. I suspect that this tag is really telling you the rpm for 50 hz. Often listed like this.

120/240vac
50/60 hz
1480/1750hz

As someone said above, assuming 60 hz, it is not possible to construct a squirrel cage induction motor to run at 1480 rpm. Induction motors need an even number of coils, usually 2, 4, or 6, sometimes more. This is where you find motors in the 3600 rpm range, with 2 coils, 1800 rpm with 4, and 1200 with 6.

The formula for this is
RPM= 120*frequency/# of poles.

So for a four pole motor, at 60 hz, you get an RPM of 1800. Of course, a motor will not run at 1800 rpm, due to slip, which is what generates torque.

Still curious to see a photo of the nameplate on this motor to be sure.

-Cody
 
You must log in or register to reply here.
Back
Top