DC lathe motor upgrade?

[txvwnut]

So I have searched the GJ forum and the results didn't jump out as the answer I needed and an interweb search is just pretty much info overload.
So here's my question. I am needing to change the motor in my metal lathe as it keeps blowing the run capacitor out of it, and being an import motor I know the horsepower rating is not actually what the tag says.

So is there a benefit to changing to a DC motor?
I am looking at going with either a 3/4 or a 1 horse motor.

 

[rsanter]

The benefit is that you can go,to variable,speed.
Often what people,do,is they get an old treadmill and use that motor and the variable speed controller from the treadmill.
The other option is to,go to a three phase motor and a VFD

Bob

 

[454ragtop]

As Bob mentioned, either 3 PH w/VFD or DC would be an upgrade. The treadmill motors are all over the place power and quality wise, and usually aren't std shafts or mounting, although they can be adapted to work if you want to spend the time. Easiest is probably the 3 PH, should be able to find a motor cheap, and a 1 HP VFD is a little over $100. That's what I have on my older Jet 12 X 36.
HTH, Jim

 

[tdkkart]

The Dc motor conversions were the hot ticket for awhile about 15-20 years ago, and then along came affordable VFDs and the DC stuff pretty much went away. Efficiency and economy came out on top.

 

[Packard V8]

But when with a bit of craigslist, one often can get a treadmill motor and controller free for hauling it away, that's a cost-efficiency hard to beat.

jack vines

 

[txvwnut]

Yeah I've heard about going VFD but then we go back to info overload from the interweb. I did discuss his with a friend of mine who used to sell machine equipment and he said to stay away from VFD set ups as you loose torque.
Who all has converted from an AC drive motor to a VFD setup and did you notice any power loss in your machine?

 

[POS Racing]

You may want to check with A-1 Electric Motor Services Co Inc in Fort Worth, TX they should be able to help.

 

[454ragtop]

Well, I have a treadmill motor on a 13" DP, a 1 HP industrial DC motor and control on a band saw, and VFD's on 3 DP's, 2 lathes, a 30" band saw, and a 20" disc sander. My old mill had a VFD on it also, the new to me mill has 3 motors on it, so a little trickier converting to a VFD, but I'm thinking about it. All motors which you are able to slow down lose torque, no way around it. That's why you need to keep the original speed reduction of the machine also, whether it be step pulleys or a gear box, back gears, or whatever. But once you convert to either a VFD or DC variable speed, it will eliminate at least 75% of the manual speed changes, most of the time a simple twist of a knob will do the trick, but you always have the machines gear or belt reduction as a backup if you need more torque. If you change to a 3 PH motor and VFD, at 60 Hz, it is at its rated RPM and torque and HP, same as the single phase motor that is on there now. But if the current motor is say 3/4HP, and you change to a 1 HP, you'll have more power at 60 Hz, and the same power at a lower speed, probably around 45 Hz. On my Jet belt drive lathe, I can't remember the last time I actually moved the belt to a different pulley, if I need more power at a lower speed, I just engage the back gear. No reason to be afraid of a VFD, once you actually use it you'll see what a great thing it is. Embrace it, move into the 21st century.
HTH, Jim

 

[txvwnut]

454ragtop, thanks for the awesome reply. You've given me the simple answer that I couldn't give myself plus some more food for thought.