August 2004

After acquiring a headstock spindle dead center & tailstock center, I checked the alignment of the head & tailstocks.  Lo and behold, the tailstock center's point was 3/64" below the headstock's.  Yipe!  I was pretty worried for a while, for the reasons you might expect.

But, it turns out this situation is not infrequently found on lathes of a certain vintage.  In my case, there were two problems;

- The leading edge of the tailstock base pad was heavily worn where it contacts the ways.  The flat is smooth, but is worn such that the tailstock shaft angles downward.  The v way seems in similar condition.  Presumably this is due to chips working themselves under the tailstock pad and scraping back & forth, which is also presumably why some tailstocks have wipers- mine doesn't, unfortunately.  This problem is addressed by shimming the leading edge of the tailstock between the tailstock base pad and upper unit.  Mine needed .020 worth to get the center points right on.

- Near the headstock, the bed ways are somewhat beat up, nicks, gouges, etc..  Nothing deep, but the marks are quite apparent in the photos.  The symptom was the tailstock would bind as it slid from the right end of the bed towards the headstock, about 5" short of the headstock.  At first I thought this was due to wear on the tailstock ways- thankfully they are nice and flat as shown by micrometer.  The cause was the gouges and marks making the surface uneven.  Just a short bit of work with a stone and steel wool improved the binding situation quite a bit.

As I was fooling about with the tailstock, I decided to have a look at the carriage ways.  The simple test of adjusting the carriage lock close with the carriage at the headstock, then feeding the carriage down the ways till it binds showed Gizmo had some bed wear, but I had never measured it.  So, I measured the thickness of the ways with a micrometer at the extreme right end of the bed, then at several points down the bed towards the headstock.  The bed at the headstock is .005 thinner than at the right end, and it looks as if it tapers pretty evenly, but both carriage ways seem to have about the same wear.  Not perfect, but not bad- certainly more than good enough for a newbie like me.

Update 2/5/2005

My buyer did a thorough check-out of the lathe before committing, which included turning a 10" test bar.  By adjusting the tailstock offset, without doing any bed levelling or tweaking of the tailstock center height, we were able to reduce the taper down to approx .005 over 10".


# eof