Thread: Bridgeport Style Turret Mill Motor

Electrical Motors,3 Phase Motor,Gear Motor,Industrial Electric Motors by Royce Cross

Never dealt with them myself.

Mechtric - Mechtric. I purchased my replacement lathe motor from these guys. Foot mounted, Y2 100L frame, 2.2kW 3 phase 240/415V IP55 for AU$260+ GST. WA based.

I have contacted a couple of motor suppliers without any luck.
One even asked me to ring back if I find a supply as they do get the occasional request.

A realistic option is to use a standard metric frame flange mount and make an intermediate mounting plate, probably about $450.

Drives Direct in the UK are now offering on ebay their voltage doubling 3 HP inverter, 240 Vac 1-phase // 415 Vac 3-phase, at a cost landed something like $800.
I am a bit cheesed-off with this as I requested a quote from them about 3 weeks ago, and got no reply.
Be aware that the voltage doubling technology does have some concerns about EMC (electromagnetic compatibility), but I suspect that 3 HP in a residential environment will be OK as there are listings in the US for the same devices.

In the end, I elected to go with a commercial motor re-wind, about $400, as I had already committed to purchase a 240/240 inverter.
The rating and motor operation will be unchanged, just 240 Vac 3-phase instead of 415 Vac 3-phase.

If anyone else is in a similar situation, I would recommend you consider the standard motor with adapter flange option as you can then select a single speed 1500 RPM motor at 2.5 HP, instead of two speed at 1.5 HP/1500 and 2.5 HP/3000.
The inverter will easily over speed to 3000 RPM, if you need it, and the turn-down ratio would give you probably 500 RPM without motor heating problems (but be careful).
This gives a 6:1 range without pulley adjustment.
The back gear selector would then give you all the lower speeds.

Happy machining,
John.

You really don't need 3hp... The original Bridgeport's were only 1.5hp... I doubt you would stall a 1.5hp let alone a 3hp.

Originally Posted by electrosteam

I


The inverter will easily over speed to 3000 RPM, if you need it,

that maybe so, as most inverter drives can go to 200hz, and above, makes the theoretical speed of a 4pole motor on a 200hz VSD at 6000RPM...the motor is not going to like that, and I am not talking about the bearings

if your going to drive a standard motor more than say 10-15% above rated full load speed with a VSD dont expect it to last very long if I were you.

It should be a purpose built motor to do that type of duty

Putting a fan above the motor will help keep it cool during low speed operation

dont those milling motors have to have a longer shaft? i just remember elsewhere on the net of people turning a sort of spigot, fitting an oversize extension shaft, welding them together and then truing them back to size

.RC.,
You are probably correct on the motor rating for a hobby workshop, but, my Kondia is fitted with a factory original motor of 2.5 HP (at 3000 rpm), presumably required for reliable industrial applications.

eskimo,
My use of 'standard' was a bit of a simplification.
Any motor purchase should be on the basis of the supplier understanding the application.
Standard frame motors capable of over speeding to double the 50 Hz rating are available.

new_guy90,
The Kondia motor appears to have a non-standard shaft, compared to current metric frames, greater diameter and longer.
Another challenge to fit the multiple-step pulley if one goes down that path.

Note that I believe a well selected standard motor on an adapter plate would not need the multiple pulley selection in the existing design.
A single pulley on the motor to a single pulley on the head input gears might be all you need for hobby use, especially if the base motor rating was higher power at a lower speed.
The full speed/load range of applications would have to be considered.

Happy machining,
John.