myford motor

[michael chalmersParticipant @michaelchalmers19148]

would some of you nowledgeable people please advise on the motor pulley size of a ML7.

Thanks

[michael chalmersParticipant @michaelchalmers19148]

[Neil GreenawayParticipant @neilgreenaway71611]

Hi Michael,

1-7/8" is the standard size for 35 to 640 rpm however they did supply a larger 2-1/2" pulley for 47 to 870rpm with a 50hz motor.

If you need a manual with the info in it I might be able to email you one.

thanks,

Neil

[michael chalmersParticipant @michaelchalmers19148]

Neil

Thanks for the info, wil putting a larger pulley on have a detrementail effect on the white metal bearings, higher speeds wont be used that often, and only for short periods.

Mick

[David Clark 13Participant @davidclark13]

Hi There

I put a 2800 RPM motor onto an ML7 and ran it for a couple of yours before I sold it with no bearing problems.

regards David

[Neil GreenawayParticipant @neilgreenaway71611]

Hi,

On the Myford pages on http://www.lathes.co.uk it is noted that "it is wise to bear in mind that the maximum recommended speed of the original white-metal bearing spindle is 1000 r.p.m", however the author also notes having seen many lathes run above this speed – I suppose good lubrication and careful adjustment of the bearings is important.

I have an ML7 which I fitted with a 3ph 1400rpm motor and have only run it on the normal speed range, however I have it in mind to open up the max frequency on the inverter to 100hz – for short running periods speeds using up to 100hz are acceptable providing cooling is adequate. I am considering setting the normal frequency to 60hz as per the USA myford spec to give a slightly higher speed range. If you used a 2800rpm motor on an inverter you could safely run it at 25hz to provide the normal speed range, however motor cooling would need careful attention, and perhaps an auxiliary fan.

Thanks,

Neil.

[JonParticipant @jon]

Its going back quite a bit but used a driller pulley, smallest around 2 1/2" dia using a Brook Crompton 1hp 240v. It transformed the machine in to something quite useable. Chalk and cheese.

Before hand i did make up and scrape in some phosphur bronze bearings with deep oil ways, just a constant top up.

[michael chalmersParticipant @michaelchalmers19148]

Thanks to all the replies. will try a 21/2 pulley.

Mike

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Be prepared to ease off the thrust bearing just a little for running at higher than designed speed . There is a well known problem with ML7 of spindle going tight in the bearings after running too long at even normal top speed . It is actually caused by the spindle getting warm and expanding too much endwise .

The main bearings are ok by design for at least 1500 rpm given good lubrication . The actual practical top speed may come down to problems with vibration etc .

Edited By MICHAEL WILLIAMS on 08/05/2012 11:37:34

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