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precisionworks
02-20-2005, 12:08 AM
Friend just bought a Beaver Milling Machine model VBRP ,here's a link with info:

http://www.lathes.co.uk/beaver/page3.html

Got it set up in his shop and noticed excessive runout when small hole drilling. There was a ER-40 collet chuck mounted in the 40-taper spindle, so I first indicated the inside of the collet chuck - 0.052" TIR. So maybe the collet chuck is bad? Pulled it out and indicated the inside of the 40-taper - 0.0075" at the bottom, 0.0051" at the top (narrow) part of the taper. Preload, maybe? Pulled the spindle/quill assembly and there was almost no preload. Cleaned and relubed the bearings, preloaded til it felt about right (no instruction manual-please tell me if you know the spec) and assembled. Now indicates 0.0035"TIR, which is still 0.003" too much.

The inner surface of the 40-taper looks unusual, sort of blotchy, not uniformly shiny. Maybe it needs finish reaming. Maybe new bearings. I'm out of ideas, so let's hear from you...


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Barry Milton

precisionworks
02-20-2005, 11:46 AM
Come on, readers, someone has to have a suggestion...all input is welcome.

Thrud
02-20-2005, 11:57 AM
The blotcy look is called "frittering" it is caused by never cleaning the socket or shank. It also happens to ER collet and is a form of wear common at extreme speeds - also caused by poor contact of the collet to collet shank.

Spinle Mate has special stones in their taper cleaner (an aluminum taper e cone on a handle with sprial blades on the cone surface. Anyone with NT spindles should have these - thay can prevetn tool damage and wear of the spindle - they should be used EVERY time a shank is inserted in the spindle (this of cousre is not possible with an ATC, but should be a part of daily care of the machine).

If the Spindle-Mate can't clear the excess runout up, the shank may need to be reground.

They make the Spindle-Mates in MT, Jarmo, B&S, NT, and ER tapers (and probably others).

precisionworks
02-20-2005, 06:47 PM
Thrud,

Appreciate the help. I've seen those in the catalogs, but never had because my mill is R-8.

You mention regrinding the taper might be needed. Would a finishing reamer not work?