Thread: Single phase and adding a reversing switch

I only just today turned something in reverse that I couldn't have reached any other way.
Get the sparky to fit a reversing switch - you'll regret the bill if you have to call him back in a couple of months....

Originally Posted by NoobHercusOwner

I cant think of many turning operations that require the machine to run in reverse.

One use of the reverse switch is when using transposing gears to cut threads, for example to make imperial threads with a metric leadscrew.
Then, you can't use the threading dial, which lets you disengage the half nuts from the leadscrew. You have to leave the half nuts engaged when returning to the start position for progressive cuts, and powered reverse is handy for that.

I wouldn't be game to do any cutting in reverse with a threaded chuck mount, because it could get ugly if it unscrewed.

I once had to figure out how to install a reverse switch to a new single phase induction motor with capacitor start. It wasn't straightforward as I imagined, not just a matter of permanently changing direction, which is usually just a matter of changing the position of some links in the terminal box. You need to identify some of the internal wiring connections and how they connect to the capacitor and centrifugal switch. Without documentation, it was a bit of a puzzle. The bloke at Teco who I rang to ask for guidance wasn't able to advise, and when I rang back to tell him I figured it out, he asked me if I could give him the details! Basically, you need to arrange for the start and run windings to be reversed with respect to each other when switching over. Note that the motor should be allowed to stop, as a quick switchover will just keep the motor going in the same direction. Actually not such a bad thing, as a sudden reverse could end up unscrewing the chuck.
Note also that the above applies to a simple reversible switch. A safer solution is to use a contactor type switch that has a "no volt release" feature. I don't know how to wire those - job for an electrician.

Jordan

Hi,

I converted my 260 to single phase a couple of years ago. It's a easy job for a sparkie.

I would suggest investigated using a VFD on your 3phase motor though. I find the single phase is a bit too hard on the lathe. I converted my Hercus mill last to run a VFD on the 3phase motor, I bought a cheap VFD from ebay and had the motor rewound/wired (what ever the cheapest option was) to Delta (?). It works much better, soft start and variable speeds. Sorry about the vagueness regarding the electrical jargon, I've got a good mate who's a electrician who does all my stuff for me.

Ben.

If you decide to stick with the 240 volt motor ,it may be a little time consuming for the electrician to sort the wiring using the existing switch gear for reverse.

You may be better off using a Drum switch for for/rev.

In regards to needing reverse it will depend on what you intend to do.( Probably the most common as already stated would be thread cutting.)

If you are careful there shouldn't be to much concern with the chuck or any other work holding/driving device unscrewing from the spindle if run in reverse.

Hi All and thanks for your posts.

I have decided to stick with the single phase option as I had already committed to purchasing a motor.

I had an electrician try and get this going for about 90 mins yesterday, he was stumped and couldn't get it to go. He could manualy push the relay contactor in but the switches wouldn't work. I had to leave and he will be coming back next week to continue to problem solve.

Just wordering for those who have done this did you replace the relay (I think that's what its called, black box) and the fuses? This is what has been proposed. Were you able to keep the micro switch that cuts out the power when the guards are open?

I will post the pics of the wiring. If you see anything that is obviously wrong I would appreciate a heads up.

The electrcian does good work on my house and has done the right thing time and time again over the years. He did warn that this wasn't his area but he did say that it shouldn't be too hard if he had some time with it.

Fingers crossed I can actually use it soonIMG_20140925_082611.jpgIMG_20140925_082634.jpgIMG_20140925_082645.jpg

A drum switch would be easier, and with a little time the interlock and travel stop switches should be able to be done,wouldnt worry to much about the interlock and traverse switch.

G'day Noob,
If you are using the original contactor (relay) it will have a 415v coil which your 240v supply will not be able to actuate properly.
Given the age of the contactor I doubt you will be able to get a 240v coil for it so a replacement is probably your easiest option.
You can get contactors fairly cheap on ebay, something like this one:

http://www.ebay.com.au/itm/Schneider...item3395c726db

With this example you would only need to use two of the four poles but it will do the job.

If you are feeling adventurous you can take the coil out of your old contactor and remove a couple of hundred windings which will allow it to act at 240v.

Lastly you could run the lathe without a contactor. The contactor is a safety device that prevents the machine from restarting automatically after a power outage so this is probably not recommended.
Cheers,
Greg.

id scrap all of the switching
check to see if the original 3 phase motor can be reconfigured to delta ( usually inside the connection box to motor)
get a vfd to run 240 to 3 phase
with this you have variable speed/ forward reverse and lots of different ramp up ramp down etc
do a google or a search on this forum for vfd
john

G'day Noob

My 260 still has the original 3ph switchgear installed & works fine of 240vac. Didn't have to change coils, you just have to make sure the Active & Neutral are connected to the correct phase inputs on the relay. I have the cct drawn up but will not be able to scan until next week. I known Allterrain50 (Mal's) 260 is running like this. He may be able to send you the cct before me.

If you have the end-stop/pulley lid safety switch in cct, have your electrician check to make sure it is working ok.

Regards
JohnQ

Thanks all for sharing your knowledge around this subject. This is the only forum that I have ever asked a question on and I am very grateful for the amount of responses and suggestions. I am going to persist with the 240v option as I have invested money and time to get it going. I still have the 3 phase motor so I can look into the VFD option later down the track if I find I get some use out of the lathe.

The electrician called back today and was keen for it 'not to beat him.' I have told him to hold off until I get some more info or the parts that I need.

JohnQ (or anyone else) if you get around to scanning the wiring diagram for us the try can you please email it to [email protected]

Thanks again, Paul