Matt,

On Oct 28, 8:34 am, Bill Schwab wrote:
I do not try to gain ground
during the return pass because I seem to do more harm than good.

Thanks,

Bill

I think that from a conceptual standpoint, there isn't much else
you can do for RT alignment. Getting the spindle center over the
RT center of rotation is the key for sure, and I don't know of any
other mystery techniques to do this other than careful use of an
indicator in the mill spindle.

My hope is that I can make it a little more systematic. For example,
any time I gain by tightening this bolt and loosening that one to bump
in the reverse direction is more than lost by messing with the bolts and
correcting the mistakes I make The return trip is quick, and by
feeling the vise vs. slots, my initial alignment is typically quite
good, so it goes fairly well, and if not, I know to start over. Since I
figured out the "tighten left, just remove slack on the right" trick, I
have had very good results indicating vices.


Your comments bring up the whole question of the sources of
uncertainty in any kind of measurement. The point about dialing
in the vise jaws, for instance: Check everything and figure out all
the sources of error, such as the vise jaw flatness, the travel
straightness of the mill (gibs tight?),

Adjusting the gibs is still a little hit and miss for me. Rather than
constantly fiddle with them, I take note of whether the machine is
"listening to me". If the dials are moving on their own, it is probably
time to check resistance. It is difficult to feel in the x direction
because of the power feed. When the gibs are set correctly (or so I
think), the backlash announces itself with a very subtle sound in
addition to the change in feel. I have tried to control to that, but I
always seem to overshoot and end up backing off. Suppressing rattles
seems to work best???


whether the parts of the vise
might be actually moving relative to each other when you give
the alignment taps, etc. There is a whole lot of stuff that can move
under those conditions.

With the RT, the thing that is moving is the loose screw in my head
I will give myself some credit for having gotten the hang of handling
backlash. I hate to think what this setup would have been like for me a
year ago =:0


Your specific issue about travel direction
difference might be loose gib in X-axis creating different clearance
in one direction vs. the other. I don't know a lot about mill-drill
construction, though. Maybe they don't even HAVE adjustable
gibs. :-)

Only I can say bad things about my mill As I have said, most days I
find it difficult to justify even thinking about spending money on
another mill. I suspect that I will do so after some more mulling about
weight and capacity.

You could easily be correct about the gib, but I suspect the real
difference is that simplification reduces operator error. In truth, by
the time I reverse the tight/loosened bolts, I can be in position for
the next one-way pass. With the setup I just broke down for the RT, I
got it on the second pass, and that is becoming (almost) common. I can
center the RT, but it is not nearly so elegant a procedure

Thanks,

Bill