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SB 9A gear cover

500mpxlcameraguy

Aluminum
Joined
Feb 14, 2018
Location
Iowa USA
Anybody heated up the pin on a sb 9 lathe gear cover to melt the babit and straighten up the pin successfully? I have a loose pin and the cover hangs making the collet closer difficult to set up. Any suggestions would be greatly appreciated. Thanks.
 
Yes you can heat it up to tighten the fit of the pin. You can also pound the lead with a drift pin to squash the lead and tighten it up. Heat takes a little patience. Don't be too aggressive with the heat. If so you will have it running out on the floor.
 
Yup, wire it/block it up in the position you need, find "something" to dam it up so it doesn't run out(as mentioned) go easy and slow with the heat.
 
Its been 4 or 5 yrs but I remember thinking, "surely that hole doesn't go all the way thru, I'll just
soften it up a tad to tighten up my pin" - Wrong. Next thing I knew I had a slug of hot lead down tween my flip flops. Don't recall what I used but dam up the bottom and heat slowly.
 
On my 9B I had the same problem. The first thing I turned on the lathe was a bushing to replace the lead/babbit material. I made the bushing with a fair amount of clearance on the outer side and epoxied it in place. If you do this have some white vinigar on hand for clean up. It works just as well as acetone and is easier on the skin. It has been working perfectly for a few years now. If I ever want to remove it a little heat will cause the epoxy to release.
 
I heated the babbit to remove what was left of it. Then I machined a simple bushing with a loose fit into the casting. I epoxied that in place with the cover properly aligned. It worked perfectly and has continued to for a few years now. A simple fix.
 
I'm late to the game but for what it's worth, I had the same problem of the cover rubbing on the gearing because of a loose hinge pin. I read this post and some of the other posts on this problem, bought a small ingot of babbit, researched pouring babbit bearings, etc. Just now I decided just to try reheating the existing babbit, and it worked fine. As an attempt to contain the babbit metal if it ran out, I put a little piece of tinfoil on top of the hinge pin "receiver" and pushed the pin/cover through it. I had coated the tinfoil with soot from the acetylene torch [oxygen off], but I don't think I really needed to do all that. Then I just heated the babbit on the top of the cover with the acetylene torch until it looked melted, maybe a few seconds longer. It seems to have solved the problem for now. I positioned the cover--with great precision, dont you know-- by shoving a red rag between it and the gearing. Earlier I had tried displacing the babbit metal with a punch from under the cover, as did the previous owner of the lathe, to no avail (that technique is suggested in other threads). If the pin is as loose as mine was, you would have to displace a lot of metal for that to ever work. Anyway, it's worth trying this first before you commit to a full-on melt-out and babbit replacement, especially given the price of the material. Actually I was interested in trying out the full replacement, and if this fix fails some day I guess I'll give it a try.
 
BTW the downside to this is that it buggers up the paint on the cover, but really, not that as much as I thought it would. You'll only be applying the torch for a few seconds.
 
Another Option

One other option, if it's purely an issue of alignment, is to drill and install an indexing
pin. This way, the cover will always stay in its correct place. (That is if you don't mind a couple of "unauthorized" holes). Use a long, partially threaded bolt and use a couple of nuts on each side of the cover,
then saw off the bolt head and round on the grinder. You could even grind a notch in the pin where
it lands on the banjo cover so it won't vibrate out.

This pin was already installed on my lathe when I inherited it, so I just left it alone.
Works good for me.
(And yes, the original pin in the back cover is a bit loose on mine too.)

PMc

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