"DoN. Nichols" wrote in message
...
On 2016-11-28, Bob La Londe wrote:
Well, I just had my first failure with my PM 1440. The cam-lock on the
tailstock broke. This lathe has been just so amazing compared to my
other
Chinese lathes that I got my feelings hurt. LOL.
[ ... ]
This brings us to failure number two. After I put it back together I
threw
a piece of stock in the chuck and turned a point to align the tailstock
to.
Then I threw a dead center in the tail stock and started lining up the
points. When I got out my loupe I found the center was blunt. Looked
like
maybe it was dropped. I couldn't see it with just my glasses on, but it
was
clear to see with the loupe. Thinking maybe I dropped it and didn't
remember I got one out of the tool cart that had never been used before.
It
was also blunt. It was a nice tiny dome, but it was blunt. Orders of
magnitude bigger than the tip on my turned point. Atleast it seemed
uniform
so I dialed it in as best I could. I realize even with hardened and
ground
steel handling is coming to take off needle tips from an object that
heavy,
so maybe that's the norm. I don't know. Both centers came with the lathe
so
perhaps they are just lower grade Chinese parts. Do all dead centers
have a
domed tip when looked at under a glass?
Well ... there are hardened centers, designed to go in the
tailstock, and mild centers, designed to go in the headstock and be
trued up before use. The hardened centers are more likely to have good
sharp tips.
I don't think eaither dead center I have is hardened. I may just have to go
out and spend a 3 dollars on one. There are times when I really need a dead
decenter rather than a live center for turning.
But remember -- the center drills are designed to drill a small
hole followed by a 60 degree countersink so the point normally floats in
air -- or in whatever lubricant you may have put in the center hole. :-)
But... But... But... I might forget.
As an alternative way to center the tailstock -- do you have a
Blake Coax or one of the import clones thereof?
Crap clone. And a couple Last Words and an inspection mirror as an
alternative.
If so, put the shank of
the coax in a collet or in the chuck (collet is better, if you have
them), and set the finger to either trace the ID of the Morse taper
socket in the tailstock ram -- or put the center in and trace on the OD
of it. Set the spindle to a slow speed (back gear) and adjust the
tailstock to minimize the wiggle of the needle. Note that some lathes
when new come with the tailstock just a little above center, so as the
tailstock wears, it first gets closer to center before it starts getting
worse, so you proably won't be able to find a truly wiggle free position.
I may try the pinched plate method just to see how it compares for results.
Good Luck,
DoN.
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