Electric Motors

Gents, thank you very much for all the inputs you have shared. I certainly gain more information here than trying to do search the WWW. Not that I'm lazy its just to much information I can filter in and sometimes it confuses me. I'm not at any means an engineer so it takes so much effort and understanding on this field. As I wanted to expand my hobby and skills, I started to accumulate the tools and machinery I need and can afford. Trying to juggle between work, family responsibilities and the hobby proves to be a great challenge and this site never fails me when I need help.

Just to add information, my lathe is a Myford Super 7 with power cross feed and production year is 77'. Got this second hand from a close friend but managed to set all the adjustments just right (thanks to the wealth of info here). My friend told me that the motor might need some fiddling with and so far it was ok until I was reducing a 12 inch long aluminium round bar from 15mm to 12 mm. The cut I was doing is at 30 thou, no issue with the spindle and after following all the advice on how to set it up it can handle up to 40 thou cuts (is this to aggressive?). During the cuts I noticed that half way through the motor "sputter" and "hang" (for the lack of terms to describe) then stalls. I immediately stop the motor, with the lack of knowledge on what to do. The motor is really hot, thought I trip the fuse but all is well other than the "sick" motor. I used a small electric fan and after reducing the motor temp until its comfortable to touch I resume work and all is well.

I was clueless and desperate, I got a second hand single phase 1 hp motor in good condition at a price that fits my budget. I would love to have a 3 phase set up with VFD but not at the moment. This will serve my purpose for now but will definitely get one as the majority speaks of its advantage.

One more thing and this is out of topic, do the counter shaft bearing housing of the S7 near the clutch side do get very hot? Do I need to adjust the belt tension down a bit to ease the tension load and thereby easing the heat generated? There is no "play" or wobble by the way.

Thanks again gents,

Raph

Hi Raph

You seem a little unsure of vee belt tension. You can do a rough check by pushing on a stationary belt with your thumb and be able to deflect the belt about 1 to 1.5 mm for every 100 mm shaft centres.

Eric

Any heat produced may be part of an overload situation of the motor - that energy must be supplied from it and may well increase as it gets hotter.

Bump. Can a Myford S7 owner comment on Raphael's question please? 'Very hot' in that area doesn't sound right to me. Bearing problem?

Dave

My 1974 S7 will get warm on this bearing after extended running, difficult to be precise but I would say only slightly above body temperature ie. can rest my hand on it without saying ouch!

Not very scientific but without further information it would seem that Raphael possibly does have a bearing or maybe an alignment issue here.

Phil

Raphael,
Running with a "slack" belt does have some value. It'll slip if your cut is too agressive and/or you get a dig-in thus reducing stress on your 1ph motor.
What oil are you using in the countershaft oil cups? Mine empty quite quickly when running & need regular topping up. The bearing though does not get hot to the touch.
Another useful and relatively inexpensive modification is to use a multi-link belt in place of the standard V belt. The lathe will run smoother and impose a bit less strain on the counter shaft.

All belts have an efficiency during power transmission. I don’t know whether multi-link belts have a greater or lesser efficieny rating than V-belts. Of course, if one has a marginal surplus of motor power, every Watt can be important.

Raph’s motor appears to the wrong side of the energy equation as it seems to only flake out on longer running, under higher power. I fit linked-belts only when belt changing would otherwise entail a lot of extra work.

Thanks guys. I have slacken the belt tension and its a lot better. Done the whole morning running the S7 and it made a great improvement in the motor temp and the counter shaft bearing near the clutch. The oil consumption (i'm using the ones Myford recommended) on the counter shaft bearing near the clutch lever mechanism is way to much as compared to the left hand side, no idea why. The counter shaft bearings are ok and it has no play (i have disassemble it), the oil is feeding ok from the cup with no obstructions.

I will totally take the motor apart if I have the time and clean it as suggested.

Edited By RAPHAEL VAL GOLEZ 1 on 01/06/2018 14:48:51

Difference in lube could be down to the oilers - swap them over to see if it is one side or one oiler?

But the other possibility of extra clearance on one side is the likely culprit. I would be checking more carefully if the problem stayed with the side on swapping the oilers.

Yes they will get hot within 20 mins giving it some.

Ralph good going on them if removing 1mm off diameter, had to put a 1ph 1hp motor on mine to do that, still got it with pulley.
It really struggled with anything larger than headstock bore and took an eternity to do the simplest of things even with the 1hp motor. Problem is the length of running time generating heat and wear, carry on at that rate 2hrs a night i'll give it till November before it needs a regrind and rebuild. Been there done it but did part own a precision grinding co at the time.

To give a beter idea i would be surprised if it took you sub 48 mins to do that menial 15mm to 12mm x 12" long with 4 passes. Heats generated but do have the better spindle and bearings on that one, mine would seize at 20 mins. Not only that lead screws and the like are under excess strain, if like me dont want to be there all night for simple jobs you would be better selling lathe as is before anything more derives putting the dosh to something more manly for same cost. Nothing to lose everything to gain.

hello all I need some help I am looking for a small 12v electric motor that is strong enough to send some playing cards high up into the air I have some but there not strong enough need something powerful enough to do this any help would be great thank you