1.75 hp D.C. Motor for SB 9??

Sounds a little slow to me. I would think you would want it to be capable of approx 3000rpm so you can slow it, and speed it up without changing it. if you limit to 1750 you cannot take advantage of your higher speeds since you will have to adjust the belt.
Tonight I used the highest speed cones while in back gear. I needed to take some big honking cuts but wanted to get it done as quickly as I could. So I went to back gear and fast for torque and speed.

you may not need the 3000, but 1750 is too slow...

Yep, I plan on still using the cone pulleys and countershaft assembly to drive the spindle. I am thinking I would just set the belt on the higher speed pulley and adjust the speed downward with the controller. And not averse to moving the belt around as need be.

Not sure if this is a treadmill set up or not. He says it is all new equipment. No pics except for the original Craigslist ad. Haven't seen the motor in person yet - just emailing back and forth...

I asked him to limit the motor RPM's to 1750 as that was/is what AC Motors generally were on these older manual machines.

(Note this is a 1925 9" x48" lathe)

Now, I have no first hand experience with D.C. Speed control. So please let me know if I should plan for different operating conditions. The lathe came without a motor or the old line countershaft assembly! So I am retrofitting the newer SB 9 style tensioning assembly with this DC motor. i can ask the guy to change the set up as needed. Not going to pick it up untill Friday.

Thanks!

Glenn
 
Now, I have no first hand experience with D.C. Speed control. So please let me know if I should plan for different operating conditions

I don't either Glenn, I was just observing and thinking that you would probably setup a lower gearing and speed the motor up to take advantage of more torque. That way you get the most torque and better speed range. And can still go up on higher speed to kill torque if you need to.

But all this was just me over analyzing things as usual.
 
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