On Tue, 05 Apr 2016 11:04:20 -0700, wrote:

My Fadal mill showed me by the cuts it was making that the spindle
needed to be trammed. I have a lot of good machine shop inspection
equipment. I can easily, repeatably, and accurately measure down to 50
millioniths of an inch. Not so easily but accurately and reapatably
down to 20 millionths. I have several standards for lengths. My best
set are the ceramic gauge blocks. The maximum deviation from nominal
size of any of the blocks is +3 millionths of an inch except the 4
inch block which is +4 millionths. Most are only + 2 or less
millionths. I have indirectly seen temperature changes by measuring
lengths. Anyway, back to the Fadal. After leveling the mill according
to the Fadal manual instructions with a precision level to better than
.0005 per foot I checked the table flatness in the six spots
corresponding to the spindle retaining bolt locations, again following
the Fadal instructions. Then, using a tool that Fadal recommends, I
set about to tramming the spindle. The Fadal manual says to tram to
better than .001 in 12 inches and that Fadal Techs usually tram the
spindles to .0005. So I figured I would make mine better. Finally,
after fussing with the damn thing for hours and hours I got the
spindle tram to just slightly better than .0004 in 12. The problem is
that the error is so magnified by the measuring tools that .0004 looks
like a huge amount. And barely touching anything moves the indicator.
I checked and re-checked and so on for the next day just to make sure
the machine wasn't going to settle and change the tram. Since I can
see tiny changes it makes me want to get the machine even closer. But
it's not practical. I am sure that after making some cuts the spindle
tram will change. And I have the tools and knowhow to measure the tram
error. So I have to resist the temptation to check the tram because I
know it will never end. It's the same with parts I make. I check 'em,
see an error, change an offset, see another error, change another
offset, and all the while the parts are within .001 and the tolerance
is + or - .005. It's like a disease. It also affects me when I start
to optimize programs to shave of smaller and smaller increments of
time. At least now that the spindle is in proper tram the cuts look
much better. I am milling some brass door furniture that has large
flat surfaces inside pockets. These surfaces will be polished to a
high shine so the cutter marks must be able to be removed easily. So
it's a purely cosmetic thing but since the pockets can't be sanded on
a surface plate to remove cutter marks the cutter marks must be
removable with only tripoli or E5 emery on a buffing wheel or point.
After tramming the head the parts are now coming out the way I want.

Repeat after me:

Measure with digital calipers.

Mark with chalk.

And cut with an axe.


All better now?

--
If you want to make your dreams come true,
the first thing you have to do is wake up!
--anon