Attention Lathe Turners

flashbacpt · Post by **flashbacpt** » Sat Feb 18, 2012 10:38 am

One can file this under, "Did not know it was Happening!" I was setting myself up to put some final touches on a turning project when I discovered a problem.
I always check the "point to point" relationship with the headstock and tailstock, and if they are off, I simply adjust the center adjustment ring on the tailstock to line up the drive points. This has always been a very quick and easy adjustment to make, something that one does not even think about!!
But.....not this time!!! I would line up the points perfectly, and then start tightening down the set screw on the tail stock (mine only has one set screw), and the center adjustment ring would turn slightly, throwing off the point to point lineup.
After trying a few times, and failing, I decided to take out the center adjustment ring for examination. What I found was a surprise to me! The center adjustment ring had a deep crater, caused by the locking set screw, and was sloped on one side also from the set screw, which explained why the ring would turn when I tighten the set screw! Plus, the center adjustment ring was no longer round, as one side was pushed in, again caused from the locking set screw.
I have to take full blame for this, but was really surprised as I am not the type that normally uses a lot of force to lock down anything.
Checking the parts list for the tailstock on SS, I noted that in their drawing, their tailstock pictured has two set screws, instead of only one, like mine.
Needless to say, I immediately ordered a new center adjustment ring, and was very happy that it was in stock.
In the mean time, I was facing a deadline, and filled the deep crater with fast drying epoxy, and managed to get the point to point adjustment that I needed to finish my project. I don't recommend this but it was something that I had to do.
So....all you lathe turners, take a moment to check your center adjustment ring, and go easy on the tightening of the set screw, or screws!

John
FlashbacPT

reible · Post by **reible** » Sat Feb 18, 2012 10:58 am

And while you have it apart why not add the second set screw?

See

http://www.shopsmith.net/forums/showthread.htm?t=9564

Ed

flashbacpt · Post by **flashbacpt** » Sat Feb 18, 2012 11:41 am

Ed,

Thanks so much for your input, pictures, and no how. I apparently missed your post on this, and most certainly will take advantage of your know how when I return from my pheasant hunt.

You saved me a whole bunch of time by figuring out how to do it!

Thanks Again!

John

JPG · Post by **JPG** » Sat Feb 18, 2012 12:51 pm

flashbacpt wrote:Ed,

Thanks so much for your input, pictures, and no how. I apparently missed your post on this, and most certainly will take advantage of your know how when I return from my pheasant hunt.

You saved me a whole bunch of time by figuring out how to do it!

Thanks Again!

John

Now about the set screw - Flat ended, cup, serated cup, 'domed', pointed?

The 'center ring' is soft(as is the epoxy) so use of a cutting type set screw will damage it and over tightening it will deform it.

Yes this is a catch 22!

IIWY, I would carefully align the old one, use a pointed set screw to gently mark the set screw center, Drill the ring to tightly fit a half dog set screw, and use that for on center work. Use the new one with a flat or domed ended set screw for off setting the center.

I have wondered if fulling that cavity( the whole inside, not the screw ding) with epoxy would prevent future deformation(collapsing).

This is a candidate for a machine shop produced stouter material replacement if your use justifies the $.

Since the ring/tailstock hole is rather sloppy, a shim may prevent the set screw from digging into the soft ring.

Brain fodder!!!

RobertTaylor · Post by **RobertTaylor** » Sat Feb 18, 2012 4:16 pm

a much quicker option (no epoxy needed) is to rotate the ring 180 degrees so that the hole is on the bottom, raise the tailstock and you have a fresh surface for the setscrew. i have never paid any attention to the marks on the ring anyhow. i just look for piont to point contact.

flashbacpt · Post by **flashbacpt** » Sun Feb 19, 2012 3:31 pm

It is my intention, as done and shown by Ed, to tap a second set screw hole. I can see where having two set screws in operation will somewhat prevent what happened from happening again. I definitely will use a set screw that will not dig into the ring.
Yes, the Center adjustment ring apparently is soft, but having two set screws will afford more locking area.
The epoxy was only used to finish what I was turning. I have no intentions of using the damage ring ever again.
I patiently wait for the delivery of the new center adjustment ring.

John

jimthej · Post by **jimthej** » Sun Feb 19, 2012 9:34 pm

When mine was that way I filled it with JB Weld, filed and sanded it smooth. Also did the second set screw.

flashbacpt · Post by **flashbacpt** » Mon Feb 20, 2012 10:58 am

When this all happened, my first thought was JB Weld, but I could not find my tube!!!:( So the epoxy was the second choice, knowing that it probably would not work or last long.
Of course, when I need to find something else, I will, naturally, find my JB Weld!!:D Never fails!

John
FlashbacPT

paulmcohen · Post by **paulmcohen** » Mon Feb 20, 2012 7:41 pm

My points never aligned (at the 0 mark) I think since the day I got my machine new. After reading this I looked and sure enough I have multiple flat spots and the ring is deformed.

I am adding a second screw today and will look for a way to strengthen the ring. Maybe one of the machinist on the forum wants to machine one out of steel and offer it for sale.

paulmcohen · Post by **paulmcohen** » Tue Feb 21, 2012 12:28 am

JB Weld ($4 at Ace) and a new second hole and now I am ready to get back to turning.