Single Phase 2HP Motor
 

Hello,

Am after a Single Phase, 2HP Motor (to be used for a lathe)
Can anyone help? :)

Many thanks!
Nao

Machine mart

Thank you, David..... This would be the one I am after
https://www.machinemart.co.uk/p/2hp-...-4-pole-motor/

Have also looked on the Brook-Crompton site, too..... Am trying to get as much info as I can :)

Naomi - you need to say what rpm you want - 1450 ish or 2900 ish (4 pole or 2 pole motor respectively) - my guess is it will be a 4 pole - I would advise you to get a good brand name second hand British one off e bay rather than a modern one from the far east. The British ones will be well made and stand a bit of abuse. If your lathe doesn't have a clutch you will be stopping, starting and reversing the motor quite frequently which single phase motors are less tolerant of than 3 phase motors, so you need something that will cope with a bit more than steady running.

Last time I was looking for one, I discovered the local scrap yard had quite a stock of them. They were taking them off whatever was in the yard, and when there were too many on the shelf, stripping them for the copper windings. It was much less hassle for them intact to sell than strip down! If it didn't work, they'd swap it for another. It sounds worth a try if nothing turns up cheaply on fleabay.

Simon.

I agree that I'd rather have something British and robust.... The lathe is a Harrison, and has a clutch.
I'm after 1420rpm(ish) 4 pole.
Brook-Crompton have the 'Capacitor start capacitor run' version No. 2-TDA 90 LT 4-pole, with foot mounting, which would be ideal....... their website typically doesn't list prices, but if the Clarke motor is £132, then we could probably guess the B-C price.

I have checked eBay but nothing on there as yet..... will keep hunting around.... and if anyone has one, then please let me know :)

Naomi

I have the same lathe and I too needed to fit a single phase motor as it came with a two speed three phase one.
The one I fitted was a good old British 2HP motor as you are asking for, this lasted about 20 years before it gave up the ghost and all I could find at the time was a 1.5HP replacement. This was never really up to the job and would stall if the lathe was very cold.

I recently needed to turn a 12" cast iron flywheel for my model mill engine, the lathe was really too fast for this so I decided to fit a 2HP three phase motor and run it from an inverter.
This is the best decision I ever made, it runs much smoother with hardly any vibration at all, and I can go down to about 10 RPM spindle speed with it.

The brand new motor was then only £76 on ebay, and I already had the inverter, but these can be bought relatively cheaply for a similar price to the motor these days.

http://www.ebay.co.uk/itm/172195074657

http://www.ebay.co.uk/itm/2HP-1-5KW-...cAAOSwYmZXJGmR

Would I ever consider a single phase again ?...........No Chance
Phil

I'd be cautious of the specific inverter in that link. The fleabay location is given as 'Portsmouth' but the seller has an address in China. The description is in broken English which suggests the location is incorrect, possibly just put there to make sure it pops up even if the 'UK only' option is selected.
If the details aren't 100% then the product is always in some doubt, for me. I'd much prefer to buy something from a British company (manufacturer or importer) to be confident of meeting most UK standards and have some sort of come back if needed.

Simon.

I forget the name of the suppliers of my two inverters , but they are the people in Nottinghamshire and have given me excellent service . The flexibility with an inverter is a great convenience . It is worth reading the small print and programming the thing right , soft start and quick stop , and 50% overspeed does me nicely .

Best place to buy inverters https://inverterdrive.com/

Thank you, all! This is very helpful.

Story with this lathe, is, that where it came from, the guy fitted a single phase motor to it..... but it is a 1/2 or 3/4 HP.... something like that..... greatly under powered..... (and for some reason it is running in reverse...... but that is meant to be getting sorted out before it is delivered to me).... It still has the original 3 phase motor and panel, too, so I could easily get that refitted, and buy an inverter/converter....

Hmm, talking of which..... Some people use inverters... others converters..... I know what the visual differences are, and know someone who uses a transwave converter, which is pretty good..... but are inverters the better option? They certainly seem a lot cheaper.... I am happy to do that option if a suitable single phase motor doesn't appear....

Your advise would be very much appreciated :) :)

Standard AC motors are 415V 3 phase, however most modern motors have six terminal so can be wired for 240V AC 3 phase.
To use an inverter which is single phase 240V AC in gives out 240V AC 3 phase, so for best results you need a motor that can be converted.
I believe the transwave converter capacitors and inductors to give out 415V AC 3 phase.
I don't want to diss somebodies produced, but believe me the inverter is the best way of doing it.

You can make a 3 phase motor to run on single phase, the trick is knowing the capacitor value

http://www.steamscenes.org.uk/tti/14/157_0289.jpg

You will find that the original motor is a two speed one and that will possibly cause problems when trying to run from an inverter.
Also you would need to make sure that any motor you choose can be connected in Delta, ie the windings form a triangle and each phase of the inverter is connected to a corner of the triangle.
Some motors are only connected in Star, ie the windings have one common centre connection, this is OK when used on a normal 3 phase supply at 415V, but for inverter use it needs to be Delta when driven from a household 240V supply.

Don't be put off by all this, most motors can be used but it is just something to be aware of
The inverter link I sent on ebay was just a random example, I agree with the comments about buying from a reputable source.

A converter will give you an artificial 3 phase supply, but they will not give any speed control so have only a limited use and tend to be fairly expensive.
An inverter gives an artificial 3 phase supply, but it's frequency can be adjusted to give a good range of variable speed.
At work we tend to work on approx half or double the rated speed of the motor, if you go too slow the motor fan will not push enough cooling air through, too fast and you can exceed the speed that the bearings are happy at

I only have one machine in my workshop (pillar drill) that is not on an inverter, but I have the parts ready to convert it very soon.

My dad used to run his three phase machines using the capacitor method, but this was long before inverters became affordable.

Phil

I got an inverter and would never want anything else.

I used these guys:-

https://www.inverterdrive.com/

Hmm, yes this inverter option is looking more and more appealing...... will continue to research and will ask an electrician friend for some advise, too.....

Julia / David - which inverter did you get? (same question to anyone else who has an inverter, too) :)

Ring them up, or email them tell them what you are trying to do, and let them specify it,
that way if there are any problems you can go back to them.
David

This is just some observations.

I haven’t used an inverter but I used to have a 415V phase converter, if I needed one I would have an inverter.

I used to work in the Machine tool industry and the Motors that we used on our CNC machines were much bigger HP than those on conventional machines, this is because the power advantage of a mechanical speed reduction is lost.

For example a 1HP motor with a 4 to 1 mechanical speed reduction would give 4HP at the output. (losses not considered)

With electronic speed control a 1HP motor running at ¼ speed would have an output of less than 1HP taking internal losses into consideration.


See Phil Procter’s post above regarding motor speeds and cooling.

You would need to avoid running the motor too slow, a Pulley change might have to be considered to keep the speed up and the motor cool.

Someone with a two speed motor would be able to run their motor on the low speed at double the rated speed, it is better running fast than slow.

The motors that we used on our CNC machines had an independent motor driven cooling Fan allowing the main motor to have a wider speed range.

I would be interested to hear if anyone using inverters has overheating or lack of power at low motor speeds?

I run a little Boley & Leinen (BCA) jig borer with a 0.55 kW motor on a Jaguar inverter. Parameters are normally set to run at an absolute minimum of 15Hz and a maximum of 70Hz

As an experiment I set it to run at 5Hz to see if it warmed up, it ran like that for over an hour with no issues at all, and it is almost impossible to stall it either.
I think the trick is to have a motor that is more than man enough for the job then amount of metal in the casing can keep it cool even without the effects of its fan.

I ran the Harrison lathe for a good few hours at 10Hz when turning my big flywheel, again no problems were apparent.

Phil

Yes, that's a good call.....

Am also interested to know about brands.... Some names I've heard of, others not.... Be interesting to know if people are going for a specific brand - why - any known issues, etc etc.... :) What's hot? What's not?