So, do any of you degenerates own an "M" head Bridgeport?
http://www.dkpercussion.com/blog/un...m-head-rebuild-for-the-benchmaster-mill-pt-2/
And the Author reports...
""
NSK 7205 CTYNSUL P4 ABEC7 ($100 on eBay for a matched pair)
Upper spindle bearings:
Nachi 6205 C3
Pulley spindle bearings:
SKF 6206 C3
Why all the different brands? No reason other than price and quality, all purchased on eBay, all US or Japanese made. The matched pair are the only ones that need to be truly precise, where as the others can be electric motor quality or better.""
Note that the author's purpose here was a Bench-Port/Bridge-Master. He is crossing a Benchmaster mill with a Bridgeport "M" head.
The photo is quite large. On one hand going through all that trouble for 3 1/2" on quill travel seems a bit silly. On the other hand the "M" head is better thought out and has somewhat better support of the quill/spindle. On the gripping hand the "M" head does have a 12K RPM option although a bit rare.
It was a good read if just for the thought process and problem solving.