700 series carriage lock

rambin

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hey my carriage lock never did seem to lock super tight. then today I noticed it it was just turning...thought I had stripped all the threads out of it... but under better inspection I'm noticing it's only engaging by maybe 2 threads... thinking this isn't the original bolt? can someone verify the length of their bolt? compared to what I have... in the pic20191202_124004.jpg20191202_124004.jpg
 

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hmmm now im really confused. wonder why it wouldn't come right thru the little cast piece so it would have full thread engagement? notice there is about 1/4" on the tip of the bolt that is unthreaded... that part does not stand proud of the cast piece so very few threads are in use... any ideas?
 
Not sure. Mine has full thread engagement. I would just get or make a longer bolt.
Maybe the Wards lathes are different in some way. They were designed early, and Logan did make changes in the
early days to various models.
 
is there somewhere you can buy square head bolts? I don't have the tooling or the know how to make such a beast. its a 3/8 18 thread I believe.... hate having to put a hex head bolt in place of where a square should be....
 
The screw looks like what I would expect the original carriage lock screw to look like after someone had whittled on it. Assuming that the thread is 3/8"-16, it appears to be about 1/16" short and missing the first four threads. Go to Ace or similar and in their nut and bolt assortments area, find and buy a 3/8"-16 x 2 Socket Head Cap Screw for a temporary fix. Then start looking for a replacement original square-head screw. Logan probably carries it, although the shipping may cost more than the screw.

But I cannot think of any good reason for the missing threads. It would just make the screw more expensive.
 
I probably have have 3/8 16 hex in stock but it will be zinced of course... and look like hell... logan will probably have it in stock but I don't really feel like getting raped at the moment... never mind the shipping.. does anyone still sell square head bolts? not sure why or if someone whittled the end of that bolt down.. if it was done on the lathe they polished her good.. looks original
 
So is the bolt not long enough overall or is it just that the threadless end portion is bottoming out so that only 2 threads are able to engage?
 
The tapped hole that it goes into is a through-hole, and if the Logan lathe that it fits is similar to my Atlas (and it probably is), the only things below it that a long enough bolt could hit are the lead screw and the bench or oil pan.

The two things that would make using a hex head bolt in that position are that the spot face is probably too small to clear the points of the hex. And it would be another wrench to have to keep handy on the carriage.

A place like Ace "might" have square head bolts in the proper thread. But there are two types - one with a washer face and one with a smaller square intended for use as a set screw. Unfortunately, the latter type is more common, and won't work.
 
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I probably have have 3/8 16 hex in stock but it will be zinced of course... and look like hell... logan will probably have it in stock but I don't really feel like getting raped at the moment... never mind the shipping.. does anyone still sell square head bolts? not sure why or if someone whittled the end of that bolt down.. if it was done on the lathe they polished her good.. looks original


wa5cab has it right: just buy a socket head cap screw and get your lathe up and running. It may not look original, but
it doesn't look original with a QCTP on it either. Then you can take your time if you really want an original looking part.
Functionally, it won't know the difference.
 
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