Critique our lathe choice

[Jared]

Personally, I'd go for an old south bend or other older American lathe. We have a Grizzly lathe that's pretty terrible, and a smaller south bend that's pretty good. The Grizzly is less than ten years old and has over 1 entire turn of backlash on the cross slide.

Both of the lathes have 1.5" spindle bores, which is nice to have.
Cory's lathe has a quick change tool post with 5 holders.

Originally Posted by Cory

I have heard good things about this lathe.

971 has it and I believe they are happy with it.

I have no experience with this lathe, but I wouldn't recommend it because of the bizarre motor setup.

You can find an... interesting comparison chart on their website:




More seriously, the thing that's really weird about this lathe is that it gets you from 110-1800 rpm (or 50-850 rpm in low gear) without a gear change on a DC motor.

It's not a 3 phase with a VFD like in CNC machines - it's just varying the voltage of the DC motor to go slower. This means that you won't get torque multiplication through a gear reduction as you slow down, like you normally would. You also are changing your motor curve as you decrease voltage so that your torque at any given rpm decreases. You might actually get less torque at 110 rpm than at a much higher speed. Your 1.5 hp motor will act like a 0.1 horsepower motor if you set the speed to 110 rpm. You'll really notice this loss in power if you use a larger drill in steel, or if you're power tapping in the lathe. A slightly dangerous workaround is to set the rpm much higher than it should be, and let the load of the cutting slow down the spindle, but you'll end up tripping fuses/breakers quite often.

It also doesn't have a back gear. For FRC uses, where we're mostly turning aluminum, 850 rpm will work in most turning/parting operation, and it's where you'll get the most power from the lathe. However, there are definitely cases where you'll want to go faster.

My other concerns with this lathe would be quality/customer service. Some quick google searches show that precision matthews isn't well known for timely deliveries or assistance. People on the internet have had trouble with the motor/speed control burning out, which is hinted at in the manual:
"We suggest selecting the low speed. It provides stronger torque while operation."

It's not that big of a deal, but having to remove a bunch of screws to go switch pulleys, and no quick change gearbox might be annoying if you're used to having one.