Clausing 8520 Quill Deflection & Noise Concern (Video Attached)

Just wanted to give an update and let everyone know I was able to fix the noise issue. Here's what I did for those that may have a similar problem:

I chucked up and turned down the shoulder that locates the plate the pulley seats onto by ~.005. This gave me a loose fit in the casting so I could center it around the spindle. Then I drilled the 3 mounting holes oversized and enlarged the counterbore. This gave me rest of the adjustability I needed so the socket head cap screws wouldn't interfere with the fit.. Then it was just a matter of using feeler gauges around the spindle and centering everything while the quill was locked in the bottom position.

I'll do an update video so you guys can hear the difference. I'm quite happy. Now I just need to drill/tap the drive plate for the brass plungers to quiet it further.

What's the vintage of your 8520? Mine was built in 1968 (serial #7720 IIRC) according to Clausing, and as I mentioned earlier has no shoulder on the plate, so I shimmed around the spindle before tightening it down, just like you did. I'm wondering whether Clausing added or removed the shoulder.
 
I own two machines. One serial number in the 270's and one in the 470s's. Both have a shoulder that is a tight slip fit into the head casting. The 270 machine is the one in the video (total rebuild). I rebuilt the head on the 470 machine (total tear down/new bearings, etc. - but not a cosmetic refurb) and it exhibits the same problem. I'll be doing the same modification to that machine as well. Video to come.
 
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