Denford Software & Machines

I recently bought a Viceroy 280 synchro which was fitted with a 3-phase motor and pump. Since I don't have 3-phase power and didn't want to run a 3-phase converter and lose the stock buttons I decided to convert the machine to single phase.

Before you start, make sure you take photos and notes of all the wiring for triggering the contactors, because you need this to rebuild them and it's no mean feat for a novice. I took many photos and still struggled.

Firstly I found that the pull-in coils in the contactors would not work on 240V. After searching for 240V coils then researching the cost of new contactors I set-about seeing if I could convert my coils to work the contactors on 240V. I figured if I could remove a good number of turns from the coils they should pull about the same current on the lower voltage and hopefully work the contactors ok. I tried this, and found it worked. The pictures below show exactly what I did.

Now I un-wound the contactor. I didn't count the turns I removed but there must have been a thousand or more. I then reinforced the tail for soldering by making half a dozen loops and twisting them together.

I twisted the wire, turned it around the coil a couple of turns and scraped the insulation off it for soldering:

Now all is left is to re-wind the tape over the coil that you initially removed and re-build the contactor. You should do all three contactors if you want to use all the stock buttons and use a 240V coolant pump too.

The wiring also has to be changed. You cannot use the overload feature on the stop button any more because the single-phase motor will make it trip right away as it draws more current. What I did was to put the supply in the other side and run the motor directly out of the contactor and just use the stop button as, well a stop button.

My single phase motor has a start winding with a capacitor on it and a centrifugal switch, and a run winding wired in parallel with the start winding. In order to reverse the motor I needed to simply reverse the connections of the run winding. To do this I made the fllowing diagram. Note that not all single phase motors will reverse using this method and you should do some research if you plan to do this yourself.

Just to help anyone here is how I wired the contactors for single-phase.

Hi very good post!!!! but i just want to know if it works ??? as am doing my viceroy one right now.

Hi Graham.

Yes it works perfectly, including the coolant pump. I do have some spare 240V contactors I'd sell if you or anyone else needs them. I got them in case the conversion was less than satisfactory and have no use for them now.

Pete.

HI mate thats good to know! I may want one off you as i snapped the wire but i think i have got the end but how much we talking??? can you tell me how i upload a photo? as i have something for you to look at! thanks

HI mate will i need to unwind some off this as well?

This is the cover off my lathe

The set up of my lathe

any one know whats this for the little black thing with two wires and a tube coming out of it???

On my lathe that transformer only powered the light. I ripped mine out and use an angle-poise lamp instead.

Your switching system is different to mine - my buttons push directly on the contactors and then they latch themselves down. Looks like you have a drum switch in your machine. How many contactors in it?

just the one contacted on it. my lathe's a tds11gb!! metric and yes the switch is a drum for f and r

Does the green button press directly on the contactor top?

Hi look at the photo see the black line the green button hits that!

has your lathe got this on? its some sort of air switch?

Yes, I had no idea what it's purpose was and it wasn't conneced so I binned that too

HI i know what its for now. its like a dead mans kick switch. right i have everything put back now and it works but when i turn the drum switch left of right it make's contacted what have i got messed up as i think you turn the switch then press the button and it come's on ?

Aah right, my safety kick-bar has been wired with an electrical contact.