Winter Mill work

David G

Well-known Member
I think that I will change out the single phase motor on my mill to a 3 phase with VFD this winter, the prices on those components are really not that bad.
 
Good Idea. Coupled with the existing speed changes (I assume a back gear and multiple pulleys) it will be flexible. A student broke off our Renshaw Probe ruby ball (a 2590 dollar wrong direction) Ut was not my student!! Jim
 
I don't think I've ever seen anyone change a single phase motor for a three phase. Even if you have three phase I can't see it worth the expense.
 
(quoted from post at 15:48:07 11/25/18) I don't think I've ever seen anyone change a single phase motor for a three phase. Even if you have three phase I can't see it worth the expense.

He needs the 3 phase motor to make use of the VFD to control speed.
 
There are many advantages of a 3 phase over single phase.

High starting torque, no capacitor or centrifugal start contact to wear out, higher efficiency.

Starting, stopping, and reversing on the fly is a major advantage. Think tapping a hole on a mill.

With a 3 phase and a VFD the motor can be run at a very wide speed range, both under and over driven with little loss of torque.
 
You can easily run a 3 phase motor on single phase, you just have to oversize the VFD by 3X to compensate for the loss of energy in the missing two phases. I have never been a fan of static phase converters because they really do not produce a clean 3 phase.
 
Finish cuts are often at higher spindle speeds with a minimum depth (or step over) cut. Helical entry Spindle speed can also be changed to accomodate the helical offset and plunge rate. When manually programming a simple path, no issue. When making money it matters, and when using a CAM program it is a decision that is built in. Jim
 
If it only broke the ceramic part, $100ish and a few minutes and you're back in business. Takes longer to recalibrate it than to change stylus.

I broke a stylus a few years back. I wrote a routine to probe several features on a casting. It probed the 1st part fine, but the second part on the table was rotated 180? from the 1st so I had coordinate rotation on for the 2nd part.
Something in the Renshaw macro didn't like the G68 and the machine moved with the probe still into a cast opening.
 
Jim,

That is mostly why I want it, the CAM will select the speed and download to the mill, saves me the trouble of changing belts, which is PIA.
 
.....With a 3 phase and a VFD the motor can be run at a very wide speed range, both under and over driven with little loss of torque.

This ^ is really handy. I have my manual mill's 3 phase motor running on single phase with a VFD. Probably only move the belt on the pulleys once or twice a year instead of multiple times a day.

I did the same on my manual lathe too. 250 rpm to 1020 rpm with no gear changing, just twist a knob.

I also run my CNC on single phase despite it originally being designed to run on 3 phase. No rotary or electronic phase converter used. Servo drives and spindle drives are glorified VFDs and happy to run on single phase as long as there is enough power to maintain the DC bus voltage. The CNC control power supply is single phase to begin with. Only thing I really had to do was add a VFD to run the 3 phase coolant pump as that was cheaper than buying a new single phase coolant pump.
 
I worked on cmm machines for years. Mostly Zeiss. We bought our probes from Q mark in California. I think they made them for Zeiss. We used them for many years. We had some wear over time, we replaced tips if the std of the calibration exceeded .001 mm. The tips get very small pits and cracks that are very hard to see, but can affect accuracy. I never had much luck gluing the balls back on. The most expensive we ever used were 50 mm spheres, section in half, made in Sweden. I think $10k? Lead time on delivery was 6 months. Boron probes are supposed to be better for longevity.
 
You also need to get a dual rated VFD because not every drive is rated to handle that. It only needs to be 2x as large as the FLA, HP, or KW, depending on how you like to do your calculations. Humblest of opinions, getting a 480 motor and drive combo seems to be cheaper than 230 and correctly sized vfd.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top