Don't assume...
 

I fought with my mini lathe for ages trying to get it just right. I was
never happy with it, and when I got the 8.5x18 which was much better I
pretty much quit trying to use the mini lathe at all until one day I needed
to be able to feed right to left. That's one thing the 8.5x18 doesn't do.
That led me to remember that the forward and reverse feed gears were
stripped, etc etc etc... Anyway, I put my little magnetic base halogen
light on the beam next the bench while I was working on the gears and I saw
a sliver of light between the face plate and the adaptor plate. WHAT? That
can't be!!!

I thought about it for a bit, and I know what happened. I always "assumed"
the register and the pocket on the adaptor plate were sized to match. Nope.
The register on the face place turned out to be a smidgeon to large and it
was causing the adaptor to cock ever so slight when it was bolted down. I
turned down the register just a smidgeon. Then I turned down the adaptor
plate face again. I put it all back together and it looks like I have about
..0008 - .001 eccentricity when measuring on the chuck. Since the high point
is pretty abrupt at a very small range of the rotation I think its possible
that's an imperfection in the chuck itself. I did another more practical
test. I threw a piece of square stock in the jaws and turned it about half
way to round over an inch of travel. All four rounds looked to expose the
same amount of clean metal and were uniform in width from end to end.

Maybe I'll put a short piece of precision rod stock in the chuck and see
what it indicates at, but I just improved the accuracy of this lathe by
several hundred percent. Now if only it didn't have some much flex in the
compound that it will jump off the work piece rather than kick off the motor
or bend a work piece under a heavy load.

One negative is if I ever install the original chuck it may not register in
position... although if I recall the original chuck waived metal around a
bit to. Maybe the register was just oversize. Honestly though I will
probably NOT ever install the original chuck since I mounted it on a home
built adaptor plate on a rotary table for a home assembled work piece
indexer. It turned out to be more accurate on the register on the adaptor
plate I made than it ever was on the mini lathe.

Don't assume...
 

"Bob La Londe" wrote in message
...
I fought with my mini lathe for ages trying to get it just right. I was
never happy with it, and when I got the 8.5x18 which was much better I
pretty much quit trying to use the mini lathe at all until one day I
needed to be able to feed right to left. That's one thing the 8.5x18
doesn't do.

Oops. Meant left to right.


That led me to remember that the forward and reverse feed gears were
stripped, etc etc etc... Anyway, I put my little magnetic base halogen
light on the beam next the bench while I was working on the gears and I
saw a sliver of light between the face plate and the adaptor plate. WHAT?
That can't be!!!

I thought about it for a bit, and I know what happened. I always
"assumed" the register and the pocket on the adaptor plate were sized to
match. Nope. The register on the face place turned out to be a smidgeon
to large and it was causing the adaptor to cock ever so slight when it was
bolted down. I turned down the register just a smidgeon. Then I turned
down the adaptor plate face again. I put it all back together and it
looks like I have about .0008 - .001 eccentricity when measuring on the
chuck. Since the high point is pretty abrupt at a very small range of the
rotation I think its possible that's an imperfection in the chuck itself.
I did another more practical test. I threw a piece of square stock in the
jaws and turned it about half way to round over an inch of travel. All
four rounds looked to expose the same amount of clean metal and were
uniform in width from end to end.

Maybe I'll put a short piece of precision rod stock in the chuck and see
what it indicates at, but I just improved the accuracy of this lathe by
several hundred percent. Now if only it didn't have some much flex in the
compound that it will jump off the work piece rather than kick off the
motor or bend a work piece under a heavy load.

One negative is if I ever install the original chuck it may not register
in position... although if I recall the original chuck waived metal
around a bit to. Maybe the register was just oversize. Honestly though I
will probably NOT ever install the original chuck since I mounted it on a
home built adaptor plate on a rotary table for a home assembled work piece
indexer. It turned out to be more accurate on the register on the adaptor
plate I made than it ever was on the mini lathe.

Don't assume...
 

I've never owned anything like this asian machine, but I've heard to
consider them a work in progress. Sounds like you just proved it.

That's not to say old american iron don't need repair. I've had my
Excello CNC mill for 18 years and it wasn't a virgin when I bought it.
I went through the knee and table last year, adding a power knee ball
screw. Right now, I'm rebuilding the spindle with new bearings. I
still need to replace a lower seal in the head to get rid of an
annoying oil leak. When I'm done the old girl will be a prom queen
again.

Karl