myford super 7 motor problem

I'm in Greenock, I'll do as you suggest and see how it heats up, see if its warm or really hot, how long do you suggest letting just the motor run on its own?

A'm still afraid of burning it out! it cost a small fortune and i dont want to go looking for an original motor to replace this one.

10 minutes, you can keep your hand on it and feel the temperature increase if you want to. (I presume you have it earthed for safety as required)

Laughing! you got in while i was typing

1 question, how hot should the motor go with no load whatsoever? should it go warm after 5 minutes continuous or?

or should it stay cold?

thanks

I just plugged it in, i did see an earth on the actual motor itself if i remember its at the back of the housing.

there should hardly be any heat at all from it

certainly not too hot to touch

I have the myford book i had a look in that but it doesnt tell you much about the motor and i found this link to one being stripped and cleaned: **LINK**

It will not stay cold, but if there is not a problem with the motor it certainly should not be hot (whatever that is), Let us know when you have run it for 5 minutes, if not warm then, leave it longer. Ignore the link for the time being. If you have the Myford manual you should know not to use grease.

Edited By KWIL on 16/09/2013 14:41:28

I'll go out and try it now without anything attached to the motor

Right i let it running for 10 minutes without belts on, the casing on the motor does go hot but the pulley stays cold and the shaft goes hot but no where near how hot it was with the leed screw, you can actually feel hot air coming out the motor vents as it spins.

Duff motor, I suggest you find a local motor repairer and have them look at it at this stage. They should be able to advise you about it and then you can consider what next.

Where near greenock will i be able to get it checked? any ideas?

Hugh,

The motor should not get hot or even too warm when it is idling.

Just a point you say you greased the lead srew bearings but this is not the correct thing to do. You should be using the proper H32 hydraulic oil which is approx SAE 20 grade on all the oiling points on a myford lathe where things rotate and SAE 30 on the slde ways. If you like I can email you a lubrication chart. I use "3 in one oil " for the front headstock bearing. I dont recommend the use of slideway oil as is rather sticky an swarf etc sticks to it too readily.

Best regards

Eric

Hi Hugh!

Some thoughts on possible causes of motor over heating.

Have you put light oil (say SAE 30 or so) into the bearings on the motor? If the lathe has not been used for 30 years the motor bearings will be dry. You should be able to see the oil caps.

A little while ago I was involved with a similar motor that stopped after ten minutes light use. The front bush was seizing to the shaft. There were no oil caps, just plugs screwed into the bearing housings. Fortunately the shaft was undamaged, so a new bush and topping up the oil to the felts feeding the front and rear bearings resulted in the motor running quietly without fuss.

30 year old oil will be just about solid (grease will solidify even earlier - do NOT use grease on plain bearings on your lathe!)

Oil every bearing and ensure that every bearing has fresh oil seeping out it.

Once you have a motor that runs without over heating (If its too hot to touch, then it is at least at 80C, and even hotter inside!), then as advised, connect the primary belt, but without the secondary belt from the countershaft, and run it to check for hot countershaft bearings. If this is OK after about 30 minutes, refit the secondary belt, and start to check for headstock bearings heating up. When you find that it starts to heat up again, the last item put into motion is the thing causing excessive load. That will be running hot as it disposes frictional load on the motor in the form of heat.

Page 29 of Ian Bradley's book, the Myford Series 7 Manual shows the Super 7 to have a tapered bearing in the Headstock, immediately behind the chuck. Ensure that the adjusting collar for Mandrel end float is not set so that there is zero endfloat, to preload this bush, If it is the bush/mandrel will bind. You want minimum endfloat, but not preloading!

Once all is well as far as the headstock, engage the tumbler gears, but with no change gears in mesh.

If all is well, fit one change gear and run. When that is all O.K. then mesh the change gear with another on the leadscrew and run (Does not matter what gears you use (unless one or more have the teeth excentric to the bore)

The right bearing for the leadscrew (tailstock end) might be tight. There is a collar than sets end float. If it is set too tight, that will cause the leadscrew to bind.

Once it is running reasonably well, I would suggest running for an hour so without trying to cut metal, keeping oil well supplied. (Set the drip oilers, if you have them, for the headstock bearings to one drop about every minute)

Above all, use plenty of oil in the early stages, it is not just to lubricate, (In pressure fed bearings the main duty of the oil is to cool. In Marine engines bearing temperatures are constantly monitored).

Hope that you soon get things up and running satisfactorily.

Howard

I assumed grease nipples were for grease not oil thats why i used the grease gun with castral grease. i'll need to do some reading thats for sure!

Internet search "motor rewinds greenock" showed several firms.

what they all said....................

sounds like you have abearing/lubrication problem

if you have lubrication points on the motor, try squirting some wd40 down in them to try to loosen up anything that may have gone solid over the years
squirt it in and leave for 5 minutes then give a top up with oil and give a light running for 5 minutes. see whaat happens. may be all thats needed, to loosen up the solidified oil

I used aeroshell flued 3 (its all i had lying arround) for the motor on the back end i didnt notice one at the front. All good advice and suggestions and comments thanks guys i'll keep you posted and up to date on progress!

At one time the fan inside the crompton parkinson motor on my ml7 super came loose It appeared to be made of plastic I managed to get a metal one and it's been ok since Must be twenty five or thirty years ago

Roy

Glad that someone said "Check that the centrifugal switch is operating, by listening for click as it runs down"

Several years ago, afternoon of New Years Eve, the motor on my Myford started with a flash, bang and cloud of smoke.

Fearing the worst, phoned a local electric motor repairer, and JOY, they were still open!

Removed motor and took it in. Just under two hours later, call to say it was working. Went over and they told me that swarf had got into the switch and arced. Not having a replacemnt, they cleaned up everything and got it going again. Since it had not been booked in as a job, it only cost a drink for the two chaps.

Went home and refitted motor with a guard to keep swarf away from the motor vents. No more trouble, right upto the day that I sold the lathe, and never had any come back from the colleague who bought it, so they did a good job.

Howard

Hugh, you say you don't want to change the motor for an orrigional type, is the motor perhaps under powered, what horse power is it rated? Ian S C