Sb Gibs Coming Loose. Why?

Pinresto

Pinresto

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hi,
I have a 9" SB lathe. I've been making some little items trying to teach myself the in's and out's of lathe work. When I originally set up my lathe I had the compound and cross feed gibs adjusted to what I thought was perfection. Everything moved smoothly and without any play. Now that I've been using the lathe I've noticed the gib screws are coming loose as I work. 3 times now while working I noticed some play and had to tighten the gib screws. The first time I figured i would have to make some adjustments as I first starting using the machine but now it's just keeps happening. Is this a common problem? Is there a good solution? Does this mean I'm doing something wrong?
Thanks in advance:)
 
Gib screws often have nuts on them to maintain their position, are yours without nuts? Were there nuts originally (are there wear spots where the nuts used to be?
 
A pic would help. My 10L has a set screw that locks the adjustment screw. A 9 is probably different.
 
I'll get some pics shortly. I'm not home now. My gib screws have no nuts and no way to lock them. The screws sit near fush with the holes they go in. No room for a nut. Based on pics I've seen online they are as they should be. Pics to come.
 
Many lathes use a brass pin between the adjustment screw and the gib to prevent chewing up the gib. Is it possible that your lathe is missing those? If your adjustment screws are long enough, you can make some pins to expose enough of the thread to put a lock nut on. An 1/8" or 3/16" pin should be enough to allow adding a lock nut.
 
Pinresto said:
hi,
I have a 9" SB lathe. I've been making some little items trying to teach myself the in's and out's of lathe work. When I originally set up my lathe I had the compound and cross feed gibs adjusted to what I thought was perfection. Everything moved smoothly and without any play. Now that I've been using the lathe I've noticed the gib screws are coming loose as I work. 3 times now while working I noticed some play and had to tighten the gib screws. The first time I figured i would have to make some adjustments as I first starting using the machine but now it's just keeps happening. Is this a common problem? Is there a good solution? Does this mean I'm doing something wrong?
Thanks in advance:)
Click to expand...
No, the 9 inch SB doesn't use locknuts. Had the same problem with mine. You can remove the gib screws, clean the screws and the threaded holes with alcohol, coat the screws with silicone gasket sealant, install and adjust them and let the sealant cure 24 hours. This will keep them in place pretty well, and they can still be adjusted when needed.
 
this may or may not help out,
in a couple situations not lathe related, i have used a brass set screw in place of the allen head set screw.
i would modify the brass set screw in 2 ways, i would turn the first 2 threads off the screw on the non driven end to make a crush pad.
secondly i would purposely lightly/moderately deform the threads longitudinally with a small but wide cold chisel , 180* opposition on both sides of the screw.

the crush pad expands slightly upon use, the reason for removing the first couple threads, (you'll thank me upon removal)
the deformed threads will cling to the internal v thread and take up excess clearance. they will move -but only when you want them to move with tools.

we are talking about gib screws so a brass replacement would have sufficient strength,
although you should be more gentle on brass than you would a steel screw
 
"Vibra-Tite" has been on my shopping list for some time now, but I keep forgetting to get some. I've been told that this stuff works great and is made for your situation exactly. It stays slightly pliable, so that adjustments can be made, without breaking the bond (like locktite) but holds the screw from turning on its own. JR49
 
Thanks for the heads-up on the Vibra-tite! I didn't realize something like that existed as a few times it would have been very handy.
 
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