I've been reading this forum for years, but this is my first post. I have to say that this forum has been instrumental in getting my old CNC Bridgeport up and running. Thanks for all the help.
Anyway, the machine is a Series I Bridgeport Boss 8 Rigid Ram machine. I purchased the machine in roughly the 2006 time frame to put in my garage. In order to fit it under the garage door, I had to disassemble the top of the head (vari-disc and such). Since I first reassembled the head (about a year ago), there has always been a noise in the head that is loudest when the quill is fully retracted. The noise lessens as the spindle is extended downward, but is still pretty loud. I ran the mill intermittantly with this noise to make a few parts here and there but have decided that I really need to troubleshoot this problem.
I disassembled the head and during my investigation found that the drawbar was most likely hitting the ID of the spindle pulley hub. What's worse, is that it appears that the top of the splined section of the spindle was also hitting the ID of the pulley hub. It does look like there may be a fair amount of wobble (runout) at the top of the splined section of the spindle.
My mill has the original Kurt pneumatic power drawbar setup that, according to Kurt, was made obsolete 15+ years ago when they stopped making them for Bridgeport. Hence, Kurt did not have much information to offer. The drawbar setup that I have has a spacer between the bottom of the drawbar and the top of the spindle, but I am wondering if I am missing another washer that helps to center the drawbar to the top of the spindle. A couple of pictures of the top of the spindle and the drawbar set up are shown below:
I would be extremely grateful If anyone has any information about the following:
1) Whether I am missing an additional drawbar washer or not
2) Causes/solutions to the apparent runout at the top of the splined section of the spindle (shown in second picture). Man, I hope the spindle isn't bent!
Thanks so much for any and all help - I really enjoy this forum and website.