Changing a 3 phase drill to single-how practical is it?

[mart]

What would be entailed in changing a 3 phase machine (pillar drill in this case) to single phase? Would it be a case of changing the motor and some/most of the wiring?

It has been suggested on here (and I am in favour of the suggestions) to look on flea bay for an old well-made brand as opposed to a new (wobbly) budget DIY brand. A lot of these machines seem to be 3 phase.

 

[storm monkey]

I have the same problem. I (hopefully) have a lathe and pillar drill on their way, from a school workshop clear out, and need to decide if I replace motors or get a 1-3 phase converter.

Phil

 

[bigdavesproule]

replace motors is easiest or buy a convertor, i have plans for making your own convertor using dual voltage welder transformer, 240/415 volt and a three phase motot to create a 3 phase supply from single phase, very interesting stuff. if the motors have 230/415 stamped on the rating plate the short bars can be changed and a capacitor added to make it run on single phase, very easy to do but needs to be 230/415 on the plate, i can possibly send you the information if anyone interested.

 

[mart]

That is interesting stuff big Dave. I have a spare SIP set in the garage with 240/415 selector switch-maybe I could utilise the bits that you refer to. Is it really that simple though? Yes I would be interested in the information that you are offering to send.

Willing to keep it a “two way street thing” if you need any help facilitating the shipping of the rods that you are trying to source. Happy to ship something over if you locate any supplier in the South Yorks area.

 

[bigdavesproule]

thats exactly the kind of welder, how will i send the file over the internet???? pm me and ill get ur emailaddress. i got the details for nothin so im not looking for anything in return. the capicitor idea would be easier if the motor is compatable, the welder type is identical to the convertors you can buy, using the transformer to create 415volts and a capicator to generate a 3rd phase, this then runs a 3phase idler motor and using the start circuitry it will increase the output when the drill is started, the idler motor needs to be a bigger hp than the drill. i have everthing sitting for a 3phase convertor of my own but never get round to finishing it.

 

[^neo^]

Best way is to get a single phase motor for it. May have to bugger around and get a new pulley or modify the one you have to fit the motor shaft.
Just look for one with roughly the same HP and speed. Think machine mart do them new, but don't know how much they are.

 

[mart]

You could attach a file and email it or maybe upload a file to photo-bucket and post the link here. PM Sent.

ps
I acknowledge that you are not wanting anything. I just picked up on a way to help you, and would would be glad to do so regardless.

Thanks

 

[bigdavesproule]

email sent, pleasure doin business with you lol

 

[steve238]

Mart your right to get an old pillar drill rather than the cheaper new ones.
If you are in Yorks there are plenty of used machine dealers not to far away.
I would search on thier websites and then go and have a look when you find something suitable.
When i got my Viceroy pillar drill i changed the motor to single phase.
When you look at old drills have a look at how the motor is mounted because if you choose one like mine that is held on with four bolts (one in each corner of the motor) you could change the motor in about 2 minuets.
Also check the spin speed of the motor on the drill and replace with one simaler,usually about 1425 rpm.
You are probably better off getting an older motor so as the shaft size is more likely to match,my one had a 16mm shaft and machine mart don't do that size so i got one from a used machinery dealer for £20.
Also there are 2 pole and 4 pole motors and the 2 pole spins half the speed and is usually about 1450 so thats the sort of thing your looking for,about 1/3 or 1/2 a horsepower motor should do the job.
Another thing to think about is are you going to get a morse taper drill,cos then you have the option of a chuck fitted with a taper shank and also you can use morse taper drill bits,i reckon a 2 morse taper is probably the best for most home users?.
The drill on the left is my 2 morse viceroy and i paid £50 for the drill and £20 for the motor and the other drill is an old ajax and that was a freebie.

 

[mart]

Thanks for the pointers Steve. I did not know about the 2 pole & 4 pole differences. I have noted what you have explained about the motor size and speed.

Yes there are a couple of used machine dealers in Sheffield. It will be interesting to look around them and see what is available.

Together with Big Dave`s input there are a few options available-thanks.

I have been watching this item on flea bay
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=160233066859

I asked how the 9 speeds are changed and the seller explained that it is by changing the belt on the pulley (or cogs as he refers to them).

I would imgine that on the modern drills the speed would be changed by turning a potentiometer. Is this a disadvantage with the older machines?

 

[fingers99]

On the modern, cheap ones at least, it's changed by moving the belt.

 

[gavuk]

i have that pillar drill bought new from screwfix some time ago ,its not nearly as sturdy as i thought it would be, payed £35-40 brand new ,vice plate deflects when dilling hard ,i use an old scissor jack under front to stop unwanted movement ,original drill came with 3 year warranty so don't pay too much for it 2nd hand .does compare well to b&q own brand (power tools) that i had looked at also,more powerful motor if memory serves me right

 

[piman]

Hello Mart,

if you look at the motor plate it will give the speed (most common is 1470 ish), voltage, power (kw or hp on older motors, 746 watts = 1 hp) and phase i.e single or three. Also there is the frame size, a combination of numbers and letters, this is what you need to compare motor dimensions, so look for a single phase motor of the same frame size, this covers all important dimensions and saves having to modify a motor base to fit.
There is no reference on the plate to poles, by the way, actually the correct description is pole pairs and a single pole pair is 2,940 ish rpm (it can vary slightly), 2 pole pairs is 1470, 3 pole pairs 980 etc for 50Hz supply.

Alec

 

[snowcat]

I have the same problem. I (hopefully) have a lathe and pillar drill on their way, from a school workshop clear out, and need to decide if I replace motors or get a 1-3 phase converter.

Phil

If you change the motor on the lathe your get involved in a complete rewire, contractors, suds, even the transformer for the low volt......

just something I thought of....proberbly better with a rotary converter for that......

 

[storm monkey]

If you change the motor on the lathe your get involved in a complete rewire, contractors, suds, even the transformer for the low volt......

just something I thought of....probably better with a rotary converter for that......

Thanks, as I suspected. Now I'm getting confused by converter types. Speed controllers, digital inverters, static converters, rotary converters. The only info that I can find is from manufacturers, and obviously, whichever one they sill is the best!

I think I'd ruled out static, and speed controller ones seem to need a lot of rewiring, so I guess its rotary. Shame, as they ain't cheap.

Anybody know if one of these or similar (suitably rated of course) would do the job? I'm guessing its a static converter, so will only run motor based equipment (e.g. no good if I ever ended up with a 3 phase welder).

Regards,

Phil

 

[piman]

Hello Phil,

yes it would do the job, but it is more economic generally to get an inverter to suit the motor size, search on e-bay and you will see a whole range of them. (Inverters will normally give speed control as well, rotaries do not)
If you have several bits of machinery you want to run together then a rotary is more suited but more expensive.

Re welders, although they say 3 phase are often really single phase 415 volts i.e. using two of the three phases. In which case a transformer of suitable size to match the welder load, will do the job.

Alec

 

[big_d]

3 phase drill conversion

guys,
Sorry to say but it is unlikely that you can convert a 3 phase drill to single phase by using bits of an old welder; you are almost certainly will need to change the motor as several others suggest.

However... there may be another solution to the problem. If you can lay your hands on a similar 3 phase motor to the one installed on the drill, and also find a single phase motor of similar power rating, it is perfectly possible to connect the motors back-to-back and by applying 240V to the single phase motor, to get 415V, 3 phase out of the 3 phase motor. I think they used to be called rotary transformers. Note that the speed ratings need to be the same (i.e. both need to be 1450rpm or 2900rpm motors)

this will also give you access to a cheap single phase / 3 phase converter if you don't want to splash out on a box from ebay.

 

[piman]

Hello Big D,

the application you refer to is, or probably nowadays done electronically, was a frequency changer and was a three phase motor driving a wound rotor three phase motor and the output was taken from the rotor. Not a common type of motor and likely to be expensive.

Alec

 

[big_d]

3 phase drill conversion

Alec,
Agree that you can use these to frequency change but this is not needed here. In the general case, a mot ro and generator are basically the same thing; if you drive a motor it will become a generator.

I would also agree that modern way to generate 3 phase is to use an electronic inverter; preferably based upon a
PWM technique to generate a more smooth waveform (to trade I'm a electonic's guy; I've designed several for differing applications) however that is not a particularly cheap solution.

For home workshop applications, the peak power capability of a more simple mechanical solution ( 2 motors) would be easier.

 

[piman]

Hello Big D,

a squirrel cage motor will not generate if driven as there is no rotor field current to generate a voltage in the stator windings. With a frequency changer voltage is applied to the stator of the driven machine and the output taken from the wound rotor windings, i.e. this is a brush machine.

Alec