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South Bend 9A Apron Worm Gear Collar Pin

sometoyotaguy

Plastic
Joined
Jun 10, 2013
Location
Maine, USA
I'm trying to remove the pin from the worm gear. The rebuild book says to drive it out from the inside using a clamp.



This gets the pin part way out, but doesn't drive it out completely.



Is this just a straight pin? Can I just punch it towards the center, or do I need to do something more to push the pin out the rest of the way from the center?

I found this thread that leads me to believe that this may be the case.

http://www.practicalmachinist.com/v...h-worm-gear-128791/?highlight=lock+collar+pin
 
I was able to remove mine by gently tapping it in towards the center. The key and the pin remained connected so the key came out at the same time. But I was very careful, it goes without saying that it's pretty easy to mess up and render your power feed inoperative forever.
 
Because the pin was installed from the outside at the factory, the head is peined over ever so slightly. If you drive it toward the center, you're pushing that peined over part of the pin through the hole in the fragile edge, risking a blowout in the process. Removal in the reverse of the original install, as advised in the book, is the least risky way to remove it.
 
Because the pin was installed from the outside at the factory, the head is peined over ever so slightly. If you drive it toward the center, you're pushing that peined over part of the pin through the hole in the fragile edge, risking a blowout in the process. Removal in the reverse of the original install, as advised in the book, is the least risky way to remove it.

So, how can I press it the rest of the way out without using a punch? Do I need to install a pin into the clamp or key?

Thanks
 
I used a small pin punch to push it out from the inside right from where you have in the picture now.
Chris
 
I used the key and a mini c clamp to push mine out. I flipped the key around and used the c clamp to push on the pin with the key. Came out the way it got put in. The peening is what got me to do it from inside out. I thought if the pin rode in, it could lead to lead screw damage.
 
Some ideas? Now that you've got the pin out that far, you could probably gently tap it out the rest of the way with a small punch.
Or you could spin the worm gear around and file any burrs off the protruding end and then push it through to the inside without damaging anything?
Or maybe just grab it with a pair of pliers and yank it out the rest of the way? File off any upset metal before putting it back in?

Here's some pics of the associated parts so you know what you're dealing with:

worm1.jpg


worm2.jpg


I modified my worm gear and drive key to allow for adjustment of wear on the gear and the apron casting. There's additional pics and details here:
http://www.practicalmachinist.com/vb/south-bend-lathes/need-obscure-10k-9a-part-dims-make-222673/
 
I'm rebuilding a 9a. I see that the key a step in it. Mine has one too. Is this from wear or is designed to be like this.
Sean
 
The only thing that wear on that key will do is introduce backlash into your power feed drive systems (power cross feed and longitudinal feed). And the only thing that backlash there will do is cause a small momentary delay before all the backlash is taken up and the feed starts to move.

So... When should you replace it? When the backlash in the power feeds are so great and they take so long to start moving that you can't stand it anymore.

In other words, probably never?

I would just clean it up, get all the abrasive swarf off the key and out of the corresponding groove, put it back together, and forget it ever saw the light of day. There's already backlash in all the gears in the train between the spindle and the cutting tool. I doubt you would ever notice wear in that key.
 








 
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