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M-head quill pull lever - detent function?

leeko

Stainless
Joined
Jun 30, 2012
Location
Chicago, USA
Hi all,

I have a bridgeport M-head mounted on my hardinge TM, and I like it enough to keep it. I'm working on the few small niggles I have with it. One of those is the quill pull handle. There is a ball bearing detent in the end of it, which is supposed to interact with 2 grooves in the mating pinion shaft.

The ball bearing in mine is present, but it doesn't seem to do anything - I can slide the handle off without resistance (and often do, which is frustrating).

I'm thinking I could replace the spring behind the ball bearing, as that's more likely the problem rather than wear in the bearing or the groove, which looks ok.

I don't see any way to get the bearing out, in order to change the spring. Has anyone here done similar and can advise?

Also, why are there 2 grooves rather than one?

Thanks,

Lee

Sent from my SM-N960U using Tapatalk
 
I suspect the lever hub has a pin that engages one of a set of holes (or serrations) in a hub on the pinion shaft. That feature allows you to select an angular position of the lever to suit the job being done. The inner groove would keep the lever pin engaged with the shaft. The outer groove would keep the lever from being pulled completely off the shaft while moving the lever to a different angular position.

Can you get some penetrating oil into the ball hole? Can you push the ball deeper into the hole and feel spring resistance? That hole must have an outer end, perhaps plugged or covered with a sleeve?

Hardinge has a spring-loaded detent sort of thing where the spring is inserted in a blind hole, then a plunger is inserted and the plunger is prevented from escaping by a tiny pin that intersects the spring hole and partly protrudes into it, trapping the plunger.

Larry
 
I looked at my older M-head and it looks like the ball is held by a crimped area around about half the circumference of the opening. I didn't see anything else holding the ball in place. I took a picture and here's what it looks like. So I guess your best bet is to do like Larry suggests and try to get some oil into the ball hole to free it. Maybe try some gasoline first to clean out any goop, then the oil. Also, there are two grooves so the outer one just lets the handle sit there and do nothing - to store it.

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Irby
 

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I had luck with a similar spring loaded piece on a collet closer that was frozen, and not accessible for replacement. Penetrating oil did the trick and I just worked it in and out until it moved freely. You may need to tap it from one or more sides to get it to spring back the first time.

Clever how they hid the ball plunger in the end of the handle, but it makes replacing it a pain.
 
Hi, thanks for everyone's suggestions - busy week at work, sorry I haven't been back here to respond


My ball detent looks similar to the photos posted. It's not frozen, though - it just doesn't seem to have much spring force behind it. Not sure of the spring is broken, or just worn out. The ball does return, just not very forcefully.

For some reason my picture uploads keep failing, will try again once I get home.

Thanks again

Lee

Sent from my SM-N960U using Tapatalk
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