HI Group:

I was goofing off trying to figure out rollie dad's method of headstock
alignment and see if my headstock is REALLY aligned or not. .

Lathe is an Emco (not enco) V10 Maximat. Bed has been leveled using a
precision .0005 /ft level

I measured not quite 3 thou total indicator runnout (TIR) at the
headstock end with my old Union 6" 3 jaw chuck , and 15 thou TIR at the end
of a 14" long ejector pin (ground, 3/4" dia).

Following the formula, I think you divide both readings by two to get the
"near and far end average"-- I get 1.5 and 7.5. Subracting as per Rollie
method, does this mean my headstock is out 7.5 - 1.5 = 6 thou over the 14"
length?

And in which direction is the headstock misagligned--- away from the
operator or toward the operator? I am not sure how to tell with the dial
indicator reading...

I can cut a 4" inch straight piece of steel chucked at one end with almost
no taper, and with tailstock support, can easily cut 12".

Am I "twisting" the lathe with the tailstock to turn with almost no taper,
or am I doing something wrong in measuring the alignment???

Steve

Your goal is to bring the 2 averages as close to be identical as possible.
Regarding if the work piece is away or towards the operator, the easiest way
to tell is chuck up your indicating stock and zero out the indicator. The
slowly move the carriage down towards the tailstock. If the movement of the
carriage moves to the negative side, then the work piece is away from you,
and if the indicator moves towards the plus side, then the work is closer to
you. I went through this process on a 7x12 import and learned quite a bit.
It may be that your tailstock is pulling your work piece closer to
alignment, so little or no taper would result.


"Steve Koschmann" wrote in message
news
HI Group:

I was goofing off trying to figure out rollie dad's method of headstock
alignment and see if my headstock is REALLY aligned or not. .

Lathe is an Emco (not enco) V10 Maximat. Bed has been leveled using a
precision .0005 /ft level

I measured not quite 3 thou total indicator runnout (TIR) at the
headstock end with my old Union 6" 3 jaw chuck , and 15 thou TIR at the
end of a 14" long ejector pin (ground, 3/4" dia).

Following the formula, I think you divide both readings by two to get the
"near and far end average"-- I get 1.5 and 7.5. Subracting as per Rollie
method, does this mean my headstock is out 7.5 - 1.5 = 6 thou over the 14"
length?

And in which direction is the headstock misagligned--- away from the
operator or toward the operator? I am not sure how to tell with the dial
indicator reading...

I can cut a 4" inch straight piece of steel chucked at one end with
almost no taper, and with tailstock support, can easily cut 12".

Am I "twisting" the lathe with the tailstock to turn with almost no taper,
or am I doing something wrong in measuring the alignment???

Steve

Steve Koschmann wrote:
HI Group:

I was goofing off trying to figure out rollie dad's method of headstock
alignment and see if my headstock is REALLY aligned or not. .

Lathe is an Emco (not enco) V10 Maximat. Bed has been leveled using a
precision .0005 /ft level

I measured not quite 3 thou total indicator runnout (TIR) at the
headstock end with my old Union 6" 3 jaw chuck , and 15 thou TIR at the end
of a 14" long ejector pin (ground, 3/4" dia).

Following the formula, I think you divide both readings by two to get the
"near and far end average"-- I get 1.5 and 7.5. Subracting as per Rollie
method, does this mean my headstock is out 7.5 - 1.5 = 6 thou over the 14"
length?

And in which direction is the headstock misagligned--- away from the
operator or toward the operator? I am not sure how to tell with the dial
indicator reading...

Just touch the test bar, and you will see the indicator deflect. Then
you know which way is near/far on the dial.

As for the adjustment, you need to make 3 readings. One at each end
of the bar, and one in the middle. If you get a consistent slope,
ie. the 3 readings would plot out on a straight line, then the headstock
is indeed out of line. if you get a confusing reading that indicates
either a barrel or opposite-to-barrel shape would be cut, then the bed
is twisted (or worn). This is easier to figure out by adjusting the
tailstock setover until the indicator reads the same at both ends.
Then you check the middle. If it reads the same, everything is now
perfect. If it reads different, the bed has twist or wear that is
throwing everything off, and you are compensating as best as possible
with the tailstock offset.
I can cut a 4" inch straight piece of steel chucked at one end with almost
no taper, and with tailstock support, can easily cut 12".

Am I "twisting" the lathe with the tailstock to turn with almost no taper,
or am I doing something wrong in measuring the alignment???
Hard to tell. If you get the indicator to read the same at both
ends of a bar held by the chuck and the tailstock, and then back
out the tailstock ram, the center hole in the bar should stay right in
front of the tailstock center. If it wobbles around the tailstock
center, the bar has a little bend in it, or wasn't held straight by the
chuck, etc. If it orbits consistently to one side of the tailstock
center, then it shows that you ARE forcing it into alignment by the
tailstock center, and the spindle axis does NOT point right to the
tailstock.

Jon