myford ml2 / ml4 motor

[les peacockParticipant @lespeacock91391]

After a little research I think my lathe is an ml2 and not a ml4 as it is 15ins between centres, any way the motor I got with it is a non runner, what motor would people recommend, 1/4hp or 1/3hp single phase or three phase

[les peacockParticipant @lespeacock91391]

[RedsetterParticipant @redsetter]

Either 1/4 or 1/3 hp, single phase, running at around 1400 rpm will be fine, assuming you have a countershaft and the back gears. That is what it would have originally, and is all you need.

[David TParticipant @davidt96864]

An ML2 has a centre height of 3-1/8", an ML4 is 3-1/2". If I recall correctly, the recommended size motor is 1/3hp to 1/2hp.

Edited to add: The usual advice is that if you need to buy a new motor, it may be beneficial to buy a 3-phase motor + VFD. 

Edited By David T on 02/07/2018 14:32:31

[GeorgineerParticipant @georgineer]

I have a 1960s letter from Myford to my father stating that the biggest recommended motor for the ML4 is 1/3 hp. No mention of the ML2, but 1/4 or 1/3 hp should be right.

George

[les peacockParticipant @lespeacock91391]

The centre height is 3-1/8in and what does a VHD cost

[SillyOldDufferModerator @sillyoldduffer]

Should be able to get one for between £40 and £100 from ebay. The cheaper units tend to be shipped from China which might get sticky if it doesn't work.

You might prefer to buy a VFD and motor together like this kit from a UK supplier (£131) I have no experience of the company myself. Note you may also need a potentiometer, switch (on same page), and box to keep the wiring safe and the electronics clean. (The box and switch are also needed for single phase.)

Single phase is acceptable but 3-phase with VFD adds speed control, a smoother motor, higher reliability and improved stop-start performance. I've yet to find anyone who would go back to single phase once they've upgraded.

Dave

[NigeParticipant @nige81730]

Les, be careful if you go down the VFD route with any motor. You will very likely find you can drive the main shaft at speeds it and the bearings were never designed for which can lead to places you may not want to go with an old Myford

[les peacockParticipant @lespeacock91391]

Thanks for the advice very much appreciated

[les peacockParticipant @lespeacock91391]

Does any one know the maximum speed you could run a ml2 without damaging bearings, does a vfd allow you to adjust the rpm

[Mike PooleParticipant @mikepoole82104]

As the speed of the motor used with a Variable Frequency Drive (VFD) is dependent on the frequency then as the VFD Can vary the frequency, the speed of the motor can be varied. As usual there are limitations, as you slow the motor you will have less power even if you use a drive that can maintain good torque at low rpm. When you slow a machine by pulley and gear systems the torque will be increased and this may be useful if taking a heavy cut on large diameter work. A VFD will give a wide range of useful speed control but the laws of mechanics and electrics still apply. I doubt that anyone who has converted to a VFD would not recommend the conversion. I think I would stick to an upper limit of 1000rpm on a ML2 which is a bit above the range of the original factory drive setup.

Mike

[les peacockParticipant @lespeacock91391]

Ive decided to go with a single phase 1/4hp or 1/3hp and work on max revs of 1000rpm any recommendations for suppliers for motors

[Clive Brown 1Participant @clivebrown1]

I bought my motor and VFD from Inverter Drive Supermarket, (Google them). Next day delivery, wide range of motors, mainly TEC. No connection other than as a satisfied customer.

[RedsetterParticipant @redsetter]

I would be inclined to look for a secondhand 1/4 or 1/3 hp, it should not be expensive, and you will have more to spend on tooling. These motors are quite robust, and if it works it will probably go on working for a long time. It might even come with a suitable pulley!

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