Matts Precision Matthews 1236

zoom zoom said:
The heat was coming from the cylindrical motor housing, or something inside it rather, causing the motor housing to get hot. I didn't know these motors were supposed to have a fan.
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This is a Totally Enclosed Fan Cooled (TEFC) motor. That black end bell on the motor is secured by two or three screws, and underneath it is a plastic fan that is attached to the back end of the motor shaft. It pulls air over the motor while it is operating.

If the motor reached that temperature after an hour of breaking-in the lathe, then it is okay. I was more worried about the junction box temperature being high than the motor surface. You can see the article below from Leeson, where they state on-contact readings off 176-212F for a continuous operating induction motor is acceptable.

http://www.leeson.com/TechnicalInformation/hottopic.html

Leeson said:
Another point: for safety's sake, no one should be touching most electric motors in the first place, unless they are specially designed to have safe surface temperatures. Such motors include those used on bench grinders, power saws and the like. For those applications, Underwriters Laboratories sets maximum acceptable surface temperatures for a metal "surface subject to casual contact" at 70° C(158° F) after 30 minutes of operation in a 25° C(77° F) room. Even at that temperature, however, you do not want to touch the surface for long.

The surface temperature of continuously (and correctly) operating general purpose industrial electirc motor will easily be 80° C (176° F) and perhaps as high as 100° C (212° F). You cannot keep your hand on a surface that hot long enough to discern differences, and if you try, you could get a nasty burn.
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Bummer that it broke. Is there a chance that you engaged the feed lever with the half nut engaged?
 
Could you have had the carriage locked?
 
If the carriage is moving freely by the handwheel, then there shouldn't be enough force to pull the lead screw out of the gear box. The lead screw bearing at the tailstock end should have held it anyway. You might take a look at that end to see what happened there. I'm not familiar with the mechanics of that particular lathe, but there should be a drive pin or something there that keeps things together.

BTW, while the long curly chips look cool, they can be dangerous when they wrap around the work and chuck and turn into a rotary razor blade. I normally interrupt the drilling operation by pausing the hand wheel momentarily to allow the chips to break up.;)
 
zoom zoom said:
I don't *think* so, I was only trying to use the leadscrew to make the carriage move toward the headstock.
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Lead-screw is used for threading only. You engage the lead-screw with the knob (right-most knob on the apron) that closes the half nuts on it it.

Carriage feed occurs when you push the feed handle down (central knob on the apron that slides right then down for carriage feed or left than up for cross feed) and the feed rod causes the carriage hand wheel to spin, driving the carriage.

Go get some 5/32" (or whatever size your lathe takes, maybe 3 or 4 mm) brass rod from ace hardware to use as a shear pin. Cut it to size, insert it in the hole, then peen each end to keep it there. Then you don't have to keep worrying about the broken shear pin pieces falling out.

Or you can buy the G0750G shear pin from Grizzly; bet it will fit.
http://www.grizzly.com/parts/p0750g0960
 
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