Purchased a bridgeport mill as a plan to fix it up. The Gib-strip between the knee / column has broken around the adjustment screw, and because of it's tapered design has locked the knee and column up quite well.
We did believe that the knee is was at the bottom of it's travel, but have since un-bolted the 'z-axis leadscrew nut bracket thing' that bolts to the base, and it should have around 1" until the bottom of it's travel.
How to free it???
An initial idea (as there was a small peice of gib-strip underneath) was to lever it up with a big bar. Didn't even move a thou!
Next idea.. Support the bottom of gib-strip with packers, and force knee down with ratchet tie-downs. Nope, no movement again. Now tryed 'swinging-press' techinique. (Sledge hammer). No movment.
Now tried drilling and tapping the top of the gib-strip 1/4 UNC, but broke side of gib-strip out. had to tap it at an angle so I could get the drill in there, but have now thought that I could possibly weld a short length of bar to the tap and drill bit to drill colinear with the gib-strip. Would use a thread around 5/16 or M8 next time.
Next idea which we thought would be perfect, was to lay the mill on it's side, drill through the base, and hit the gib strip out with a long punch. Nope, not going to happen. There's a huge cast rib running right along behind and under the dovetail (in the coolant sump).
We're about to get hold of a mini 4 ton hydraulic ram, and try push the gib-strip up from the bottom, Hopefully this works.
Has anyone else been in this situation? Would like to know some more possible solutions if the hydraulic ram doesn't work!
Details from mill:
Serial Number 9548-M
Order Number 39018
12/69 (Manufacture Date?)
Thanks heaps.
Nigel,
New Zealand.