YES!! I've successfully salvaged seven machines in this situation and seen maybe a dozen that were botched resulting in cracked knee or column casting.
Stop. Ignore all conflicting advice especially if it seems easier. The only safe solution for a stuck knee gib is a heroic remedy.
You've described a classic stuck knee gib. You are very close to permanently damaging the machine's knee or the column. By permanently damaging I mean cracking the column or knee at the interior angle of the dovetail. Further movement of the knee or the gib in the wrong direction has to be avoided at all cost.
Tear down the machine removing the table, saddle and turret (leaving the ram and head in place if you can handle them safely assembled). Remove the elevating screw, gears, elevating shaft and gears, and internal lube fittings from the knee. The knee gib adjustors have laready been removed you say. Obtain a piece of plate about 10" wide x 3/4 or more thick by long enough to bridge the turret diameter plus 5". Use thin cardboard to protect the scraped surface from the rough plate. Drill four 9/16 holes on 2" centers along a radius to pass the turret clamping bolts through about 6" back from the front edge. Make a piece of 1/2 thick x 10" wide steel plate long enough to span from the turret to the knee. Position it to clear the gib. Fit this plate carefully so it gets good bearing between its ends and the knee and the turret plate. Do not use wood.
Assemble the plate over the turret opening and attach with the turret clamping bolts using lengths of pipe to make up the difference in bolt grip. Install the other plate between the turret face and the top of the knee where the felt wiper would go. Apply some downward force but do not try too shift the knee at this time. Merely snug up the nuts. The object of the turret face plate and the peice down the from its to keep the knee from rising with the gib as it's tested.
Lay the column on its back, blocking it with timber so it does not roll. Drill a hole in the base casting in line with the knee gib and excavate with a die grinder to pass through a punch in line with the gib. Make a 1" dia steel punch about 2 ft long and make the end a parallelogram slightly smaller than the gib. Place it in the excavated hole and position it against the small end of the gib. Bump it firmly but not vigorously with the largest hammer available. If the gib does not move it's time for heat inside the knee.
Secure a large oxy-acetylene outfit with a rosebud tip. Heat inside the knee only the whole of the casting between the dovetails. Do not heat the column. I refer to the clearance metal of the knee between the docetails and not the masses that include the dovetails. Keep the torch moving and avoid localized heating. This will expand the knee casting without harm. The expansion will release the tension on the dovetail and relax the force on the gib. Have your helper test the gib by bumping with the hammer from time to time. As the knee warms and the metal expaands sooner or later the gib will become free.
This is a job that takes hours or days to set up but only minutes to execute. It has low surgcal risk when done correctly.
Work over all parts paying close attention to the knee and its gib. clean up and inspect the divertail interior angles for inspection under magnification. Dies check for cracks. If there are cracks present there is no permanent repair possible that does not involve replacemet or welding of a major casting. A repair of a sort may be made using IronTite repair technique perpendicular to the crack plane. This keeps the crack from spreading. Google "IronTite."
Remedy all defects particularly those having to do with the gib adjustors. If the gib will not adjust correctly use a brass shim behind it to compensate for wear. Clean and reassenble in the usual way noteing condition and wear as you go unless there is cause for immediate re-scraping and reconditioning.
Any solution that involves hydraulic jacks, heavy hammering, or avoids machine disassembly may damage or complicate the fix.
Beause of the gravity of the original poster's sutuation, I ask others to not contribute to this thread unless they have actual experience as a machine tool mechanic in a remedy of this particular problem. A single lucky break or "a guy told me" does not qualify as experience.
Please forgive my arrogance but this situation warrants careful procedure. Conflicting advise will jeapordize an expensive and hard to replace machine tool.
[ 05-20-2007, 08:17 AM: Message edited by: Forrest Addy ]