RE: [CAD_CAM_EDM_DRO]Backlash & Wobbly Spindle on my Bridgeport

Let's see..... how can I start.

I'm drilling 3 (.012" dia.)holes on a .0238"dia. bolt circle 120degrees
apart. I'm using solid micrograin carbide because I'm drilling into
stainless 303. I've got the pecking cycle (G83) figured out and the machine
drills beatifully. The problem comes in when I try to actually get the holes
on the right spot.

Allow me to explain myself. I use a co-ax indicator to center the piece
since it's cylindrical in shape. Once I get the center I actually jog to the
right spot and press the enter key to let the machine due it's pecking
cycle. When that hole is done I jog it to the next hole location and press
enter again, and so on and so forth with the last hole. When the part gets
taken out of the vise it's visually off. The holes are shifted and don't
even look like they are on a bolt circle rather they look like they were
drilled eratically.

So I decided to approach the project in a different manner. Rather then
jogging it from the last hole location I would back the table up a good inch
and a half and jog back to the new position (at this point I was thinking
that the backlash was causing the problem). Unfortunately same problem, the
holes are misplaced.

So then I decided to put some dial indicators on the table. I would move the
"X" .500" and back and I would register "0" backlash. Then I moved the "Y"
.500" and back....same thing, no back lash. So then I moved the table .010"
"X or Y" and before I could move it back I noticed on the dial indicator
that the table only moved .005"!!!!!! It seams like the table is accurate in
distances larger than 1/2" but anything smaller the tolerances are out the
window.

Since I had all the indicators out I also decided to measure the
eccentricity of the spindle. I used a .500" edge finder and put the
indicator on it. It measured .0025"!!!! That's .005" off if I were to mill a
slot the same size of the tool!

I bought this machine used from e-bay for $4000.00 at the beginning of the
year it has the Ahha controller. It's a series I 2hp Bridgeport with a
taper 30 spindle. It's propably 25 to 30 years old. Is this ok? Can it be
fixed? Or am I trying to split hairs with an ax here? Maybe I just got the
wrong machine for the job!

I would appreciate any answers, I'm going mad here!!!!

Thanks,
Alex