MetalworkingFun Forum

(10-17-2012, 07:15 PM)Highpower Wrote: [ -> ]So what happened to the quarter?

the real one I put back in my pocket the one on the casting the lathe ate it.

here is my mill with a new three Phase motor and Teco VFD. motor is a Leeson Metric motor that was a direct replacement for the single phase motor that was on it, the shaft is a half inch longer then the original motor so I had to use the spacer that I made when I replaced the burned out motor with one I got from Ed.

I still have a couple things to do like a remote panel so I don't wear out the little touch buttons on the from and to make it more convenient for operation.

[attachment=4526]

Looks great! So, is the 3 phase drive as much an improvement over single phase as touted to be?

(02-18-2013, 07:08 PM)stevec Wrote: [ -> ]So, is the 3 phase drive as much an improvement over single phase as touted to be?

I think it is. I converted my mill to a VFD shortly after I bought it and it's great to be able to change the speed on the fly depending on how the tool is cutting. It's even more useful on a lathe.

Ed

Steve

the thing is with the VFD you have infinite speed control from 0 to the full RPM of the motor, not just 6 speeds like I had with the single phase motor. Plus the new motor is a 3450 motor versus the old one at 1750. Now when it got one of them little tiny carbide endmills or small drill bits in the collet, I can run that much faster and hopefully not break em as fast,

dallen, I'm quite aware of the variable speed feature and suggest that speed control down toward 0 rpm would be next to useless, you need the torque increase of the mechanical advantage obtained by pulley or gear changes.
I was inquiring about the smoothness(is that a word?) with 3 phase motor equipped machines.
I have read that finish is greatly improved, at least on a lathe that is.

(02-19-2013, 07:44 AM)stevec Wrote: [ -> ]dallen, I'm quite aware of the variable speed feature and suggest that speed control down toward 0 rpm would be next to useless, you need the torque increase of the mechanical advantage obtained by pulley or gear changes.

I think it depends on the VFD Steve. Sensorless vector control models often have 200% of the normal starting torque down to 1Hz. I do know that in low gear, running at 2 RPM, I can't stall my lathe chuck. How much of that is the SVC or the gearing I don't know.

I also know my lathe is a lot smoother and quieter since the conversion. All the vibration and rattling I used to get out of the geartrain is gone now. I'm a believer.

Willie, have you any idea what speed the motor is turning at 2 RPM? Just curious.
And thanks for your input regarding the smoothness.

You know Steve, I don't have a clue. But it's easy enough to go downstairs and check. I'll be back....

... and the survey says:

2.4 Hz = 72.2 motor rpm = 2 spindle rpm at my lowest gear setting. (Normally 60 rpm spindle speed)

I'll let you do the math, because I suck at it.

[attachment=4531]

[attachment=4532]

OK, at a ratio of 36.1 to 1, no wonder you can't stall the chuck. Mind you even single point threading to a shoulder would be possible
if you didn't fall asleep in the first inch of thread.