Changing the Motor on a Fobco Drill Press

[jweaver]

Looking at a 3 phase Fobco, and wondering how much work it would be to swap the motor to a single phase..

Found a 1400rpm 1/2hp motor on Ebay for about £60.. But how much work is required.... I guess the key point are

1. Mounting the motor. Shouldn't be too hard to modify the mounting brackets
2. Fitting the pulley to the shaft.. The motor has a 14mm shaft and I find it hard to believe the pulley will fit.. BUT.. I could get a replacement for about £20.
3. Wiring.. Can't be that hard.

Is there anything I am missing?

Jon

 

[chippy1970]

Quite a few people leave the 3 phase on then you can fit a speed controller. 9 fingers (bob) is your man he's very knowledgeable and helpful. You won't find him here anymore he's at www.thewoodhaven.co.uk

 

[wizard]

If converting to single phase i would go for at least a ¾ hp motor.
If you go for an inverter, make sure the 3 phase motor is duel voltage
Also check the motor is working before its connected to the inverter, if you turn the inverter on connected to a faulty or none working motor it will blow up.

 

[Dissolve]

I looked into the practicality of replacing my Medings 3 phase drill and my vote lies with buying an inverter! You can get a decent IMO inverter that I've used before for £65.

Aside from adapting the mounting bracket you'll need to adapt the existing pulley (it'll be a 5/8" bore) or buy the new pulley and cut a new keyway to match. So with the Single phase motor, plus the new pulley and having to cut the keyway if you have means to, You're looking at something like £80/90?

I purchased my inverter for around £70 and it is FAR more pleasing to use the electronic speed control than I first thought. Wizard is right though check it's dual voltage and check the motor works before hooking one up.. But it's certainly how I would choose to run a 3phase drill from now on!

 

[wizard]

Easy way to check a 3 phase motor is working is when wired delta to test with single phase supply buy wiring brown to one phase blue to another phase then brown to a capacitor and from the capacitor to the third phase, you will need to spin the motor to get it started. I have done this lots of times.

 

[jweaver]

If converting to single phase i would go for at least a ¾ hp motor.
If you go for an inverter, make sure the 3 phase motor is duel voltage
Also check the motor is working before its connected to the inverter, if you turn the inverter on connected to a faulty or none working motor it will blow up.

Can you clarify what this means... I dont know much about 3 phase, but all of the pics i have seen for 3P motors shows the voltage as 400v.. What do you mean by "dual voltage"?

Jon

 

[wizard]

Very old 3 phase motors were 415v and a 415v inverter is very expensive, modern 3 phase motors are duel voltage and can be wired up for 200 or 400 volts and a 200v volt inverter is very cheap.

 

[jweaver]

Very old 3 phase motors were 415v and a 415v inverter is very expensive, modern 3 phase motors are duel voltage and can be wired up for 200 or 400 volts and a 200v volt inverter is very cheap.

Ahha.. I didn't know that.. But since we are taking about old machines, how likely is it that they will have dual voltage motors? When you say "very old", how long ago? Will the 3 Phase Meddlings/Fobco/Startrite models I am looking for, have a single or dual phase motor?

Jon

 

[wizard]

Good chance they will be duel voltage it will say on the motor. The other thing using an inverter it must be wired direct to the motor and use the inverter to switch it on and off.