New knee mill - advice saught on motor controls - VFD, DC conversion etc

r-mm

Registered
Registered
Joined
Jul 31, 2020
Messages
263
I have a handshake on an Enco Knee Mill that I hope to have home this weekend. I was mostly looking at new bench/mini mills and would very much like the convenience of speed control without belt changes. I'd also be interested in any motor mods that reduce the overall depth of the machine.

I know treadmill motor conversions and VFDs are options. Can anyone suggest a good way forward?

Existing motor is import / 2hp 120/220v.
 

Attachments

  • Photo Nov 15, 10 39 37 AM.jpg
    Photo Nov 15, 10 39 37 AM.jpg
    1.7 MB · Views: 27
  • Photo Nov 16, 6 46 18 PM.jpg
    Photo Nov 16, 6 46 18 PM.jpg
    1.4 MB · Views: 26
3 hp VFD and good control switches.

The belts stay on center range and VFD allows wide speed range.

If higher speed or higher torque needed then move belts as needed.



Sent from my SAMSUNG-SM-G930A using Tapatalk
 
  • Like
Reactions: Z2V
I've been reading up on VFDs and have a dumb question.

I presume the motor in my photo is single phase. It was connected to standard 120v power. The vast majority of VFDs I am reading about concern 3 phase. What is a good search term to find the VFD I am looking for?
 
I converted my mill using a 220v single phase —> 220v 3-phase 1.5 hp motor and Teco VFD rated for 2hp.
I have a box on the mill where I control frequency (speed) with a pot and direction with a switch.
@mksj was a tremendous help in getting the VFD programmed.
I’m very happy with the results


Sent from my iPhone using Tapatalk
 
I used to own that exact mill. 3HP on it is a total waste. Choose a quality 1.5 or 2HP 3PH motor and a good VFD, and you will be very happy. I was.

My conversion was inexpensive, because I had the right 3PH motor available, $300 for a TECO/Westinghouse VFD. I had a spitten-sparken incident early on in use, and the VFD was just fine. I challenge the offshore ones to get severely loaded like that and survive....
 
Yes, to have any other speed control you'll need to change the motor. I haven't done the treadmill motor but I suspect you'll be happiest with a three phase and VFD if you really want that functionality. I also doubt any motor change will reduce the depth of this machine by an appreciable amount but many folks find placing their mill in a corner helpful.

As for costs to do a VFD conversion you're probably looking at around 2 or 3 hundred for the motor and another 1 to 2 for the VFD, then there are any switches, wiring and enclosure you want to use.

I suggest you start using it as/is first and then see how necessary the conversion is for your use. Yes, it's great to be able to just dial the speed up and down but there are lots of other factors in getting your set-ups right that take more time than belt changes.

John
 
Can you give me some idea what that cost?

It was approximately $500 CDN.
I went with all new components because I had a company help assemble the package.


Sent from my iPhone using Tapatalk
 
I've been reading up on VFDs and have a dumb question.

I presume the motor in my photo is single phase. It was connected to standard 120v power. The vast majority of VFDs I am reading about concern 3 phase. What is a good search term to find the VFD I am looking for?

I have the same machine that you show in your OP. I put a 2hp 3ph motor on it with a VFD. I run it on 240v single phase. There are drives available that will output three phase from a single phase input up to 3 maybe 4 hp. TECO, Hitachi are real popular. Mine is a Delta brand that I got off eBay for around $100, works just fine.
The 3ph motor is so much smoother running than the single phase, you can’t go wrong if you want to invest the money for the conversion.
 
Back
Top