Does anyone here have directions on how to re-adjust the quill on my friends Bridgeport mill? It's running a bit hot we think that the bearings are to tight, we have tried to loosen the nut but it didn't seam like it wanted to move and we didn't want to force it.
There are a couple of components to this. Lower the quill a coup;e of inches. On the back of the quill is a short 1/4 X 20 set screw. Remove it. NOW, you can back off the quill nose. You may as well remove it and clean it. Use a broom stick to tap out the spindle as an assemblt, tapping from the top. You may have to drop the table of move the ram forward to clear. There are two spacers between the bottom precision bearings, an inner and outer. The top bearing is only to take side loads and prevent the top of the spindle from whipping around. The nut on top of that takes up play in the inner race stack up. Normally when I receive a rebuilt or new spindle the outer race is set up such that the two bottom outer bearings will move in unison, just a bit more snug than free wheeling. Assuming this is all correct and you are certain the bearings are facing each other in the correct direction, slide the spindle back in being careful not to damade the felt strainer at the top of the quill and you may need to rotate it to engage the spline. Spin on the quill nose. I usually use a spanner to tighten it tapping it with the heel of my hand. that is enough pressure. MOST important is that the quill nose puts pressure on the outer races and does not bottom out on the face of the quill. I do not care if you have .005 or .o30 between the face of the quill and the nose. Now spot drill the quill nose for the setscrew, blow out the chip and with very slight pressure tighten the set screw. If you make it too tight, it will egg out the quill and you will have difficulty moving the quill all the way up. It also has to below flush so it does not hit the quill housing. Good luck.