lathe doesnt spin with back gear engaged.

pipehack

pipehack

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First of all please excuse my ignorance as I'm new to this and have never owned a lathe. I have a Craftsman 101.21400 6" lathe. The only instructions I have are a 6 page pamphlet ( for the most part). When I engage the back gear the lathe locks up... Am I missing a step somewhere or am I some kind of idiot? I apologize for such a lame question, but I don't want to destroy this thing only having it a week.
 
No problem- and welcome to the forum! And machining!

Open the belt cover on the headstock, and look at the gear nearest the chuck (of the two inside there, it is the bigger one with the holes for indexing). This is the bull gear. There is a button on the front of that gear. If you turn the gear all around, you will see it come around.

There is a set screw sort of in the teeth of the gear, lined up with that button.
You have to loosen the set screw, and pop the button out until the bull gear can spin separately from the belt pulley, and turn that set screw back in where it was (approximately) :).
You might have to use a little flathead screwdriver or something to get behind it and pop it out if it hasn't been popped in a while. It should pop out 1/4 inch or so.

You have to do this any time you use the backgear, and reverse to disengage.

It will make much more sense when you see it moving now.

Bernie
 
Awesome.. Thank you. Turning that set screw back in won't lock anything up? I really have no personal money in this lathe , but have wanted one for 20 years. I used to shoot smallbore prone rifle competitively and could have made 100 projects with it. Like all other hobbies shooting competitively has tons of little gadgets. Now it's British bobber motorcycles and the desire to build something for the salt flats.
 
Just turn it in enough to be flush, so the gears won't chew it, and you'll be fine.

What kinds of gadgets did you have to make? And you used this Atlas for it? Cool


Bernie
 
Pipehack,

I can't speak to what's actually in the bull gear on your 101.21400 as wierd things have turned up. But in the bull gear should be two set screws. An 8-32x3.8" socket head set screw should be in the hub near the spindle, and locks the gear to the spindle with the proper running clearance between it and the step pulley. Running through the teeth should be an 8-32x3/16" slotted headless set screw. Under this screw is a 1/8" dia spring and under the spring is a 1/8" dia. steel ball. Under the ball is the lock pin. The lock pin has two detent grooves, one for locked and one for free. Although the pin may be stiff or stuck from disuse, you should not have to touch the set screw in order to pull it out and disengage the bull gear and step pully.

As a suggestion, with the pin locked, mark the pulley in line with the pin. This will save time getting the pin back in the lock hole after using back gears. The late 12" has two holes in the pulley 180 deg. apart. Someone wrote a while back that the 6" pulley has three holes but I haven't confirmed that.

Robert D.
 
Robert nailed it there too. The oil fill hole on the pulley aligns with the lock pin when it is engaged.


Bernie
 
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