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Just Purchased Colchester Triumph Round Head - Plan to Add VFD


Mar 24, 2017
I just purchased a Colchester Triumph Roundhead Lathe this morning - 15 inch Swing over bed. Purchased it from a large machine shop that primarily does CNC work for customers. They used this lathe for some one off projects and misc. shop maintenance requirements. Very clean and well maintained machine with newer 3 jaw chuck. Was able to see it running through all the gears and cutting. Ran real quiet and smooth. All the slide are tight and minimal backlash on the leadscrews and half-nuts. Bed ways are hardened and in good condition. See pics attached of the lathe I purchased.

It is currently a 5 HP 1750 RPM motor - 3 phase 575 volt. I only have single phase 240 volt in my shop so planning to install a 5 HP 1750 RPM 3 phase 240 volt motor and power it with a VFD. I have been looking at the VFD's sold by Vevor - thinking I will get their model A2-8075 - 7.5kw 10HP 240 volt - single phase input - 3 phase output.

I have a few questions on doing this conversion as follows
  1. The lathe is currently started using a lever with a red knob on the side of the head stock. See picture with arrow pointing to the lever. I assume that lever engages a switch inside the housing. The same lever is also use for braking. I have read that it is better to start and stop the motor using the buttons on the VFD itself. The Vevor VFD has a removeable control panel that I could mount remotely on the headstock and not use the lever on the lathe. Would it be better to do that or alternatively I could rewire the start switch on the lathe to provide an input to the VFD and tell it to start.
  2. Similar for reversing the motor - there is a small lever near the start / brake lever that is switched to reverse the motor direction. Should I use the VFD controls panel only for reversing or alternatively rewire the reversing switch on the lathe to provide a signal to the VFD ?
  3. This is my first VFD conversion - I have read that some people add an inline filter on the input side also some install a braking resistor. I wasn't planning to add a filter unless I ran into interference problems and since the lathe already has a hand brake wasn't planning to add a resistor
  4. If anyone has an electronic version of the manual for this model of Colchester lathe it would be great to get a copy, especially the wiring diagram and section that describe control lever functions and lubrication recommendations.
  5. If anyone has any other suggestion on converting, maintaining and operating this lathe your input will be appreciated.
Start Lever.jpgUntitled.jpgPic 2.jpgPic 3.jpg
I have a very similar Clausing Colchester round head. It is 13x36. Controls look identical to your 15" lathe.
Mine has a 2 speed constant torque motor. 3 hp / 1.5 hp
The 2 speed motor makes phase conversion more difficult. When I got the machine I built a autotransformer phase converter which is in the base of the machine. It, thru relays adds cpacitance to the start circuit if you are starting in high speed. I later added a VFD for getting lower speeds than the gearing allowed. It will start and run with either method. The box on the upper left of the headstock is the remote for the VFD.

The manual below is for my lathe but may have info applicable to yours.



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That sure looks like a little smaller sister to mine. All the controls look the same. Mine is 15 inch with a single speed 5HP motor. Haven't measured center distance yet but it is 94 inches overall length. I am picking it up tomorrow.
Thanks a lot for the copy of the manual. I had a quick look through it and has some useful information for sure that looks like it will be applicable to mine.
I'm not sure I would mess with a cheap chinese VFD.
Pony up and get a name brand like Fuji, Hitachi etc. with good support and manuals, they're not expensive.
I've installed 8 Fuji's on various machines.
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I may be going against style, but I’d only vfd the lathe if that will be your only 3ph machine. If you plan more, a mill, drill, something else, I’d get a rotary phase converter. Esp if you get multi speed motors. Or machines with multiple motors.
All "VFDs" are NOT the same.

Vevor is often much more "not the same" than others. I didn't know they had VFDs, but they are a candidate for banning here. The brand in general is known for being cheaper not better, somewhat like the others, such as "Bang-Good" and so on. IMO it would have to get better to reach the degree of badness of some brands already banned on this site.

Absolutely I would go for Hitach, Fuji, Invertek, Teco, etc instead. It would be cheaper in the long run to buy good to begin with rather than be forced into buying twice.
I think it's likely that's the 575V motor could be wired for 440V.
I would request to supplied that, no serious shop should be without three phase.
That will save you from messing with motors, VFD, or even transformee a that would be the other way to do it.
Not much need for a VFD in a geared head lathe.
I also second the recommendation of not buying on price.
Let thr lathe run a it was initial conceived and focus on making good use of it.
I also think the rotary phase converter is the best approach here, much easier than reworking the machine and changing all of the controls.

FWIW My decision parameters these days revolve mainly around practicality. If the original wiring was wrecked by previous users then I will swap to a VFD since it is marginally more expensive at that point and it prevents me from forgetting to turn on the rotary. If the original wiring is in good shape, then I use the rotary.

I run five machines on a rotary.