On Tue, 05 Apr 2016 12:15:48 -0700, wrote:

On Tue, 05 Apr 2016 14:23:59 -0400, Ed Huntress
wrote:

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.
Eric

Hmm. You're looking for Mikron or Kugler accuracy from a Fadal. I'm
surprised you're getting it that close. Don't sneeze! g

The model I have has the linear ways. Though not as heavy duty as box
ways they don't wear the way box ways do. Since the mill is back in
pruduction it has probably changed already and I am going to resist
checking it again unless I see another problem. Unbelievably the 4th
axis that came with the machine is out of square. This is the stock
Fadal 4th axis. I bought the machine used so I expected some error
somewhere but the amount of out of squareness in the 4th axis is huge
for this kind of machine. When used with the rotary table surface
parallel to the Z axis I have to put .006" shims under one edge of the
thing in order for the table to be square to the mill table. The back
surface is parallel to the table surface. I thought that maybe the
table spindle is adjustable in the casting that holds it but there is
no adjustment. The holes machined in the casting for the spindle are
off. Too bad the rotary axis spindle can't be trammed like the main
machine spindle can. One of these days I am going to set the 4th axis
on the surface grinder and square it up after I rough it in on the
mill.
Eric

Thats ALL you can do. And its surprisingly common. There is a reason
Fadal went out of business. They had too many bad days amongst all
their good days.

Gunner