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Old 05-13-2014, 10:52 AM
weldtoride weldtoride is offline
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Join Date: May 2009
Location: Northern Illinois
Posts: 896
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So far in this thread I haven't seen mention of matching disc speeds to the tool, other than these two consequences of NOT matching:

Quote:
Originally Posted by David Gardiner View Post
... American Chopper where they use discs which are far too big for the grinder without any guard....

Quote:
Originally Posted by Phil Minton View Post
.......a work colleague who did ( believe it or not a firefighter) He removed the guard to fit a larger cutting disc. This broke up at high speed and a large chunk went through his chest, knocking him off his feet and putting a cut in his aorta. .....
Forgive me if the old shop teacher inside surfaces for a minute: Every grinder; bench, hand, whatever, has a max no load speed. Larger diameter grinders turn slower. I just glanced at Milwaukee's catalog right now, one of their 7-9" grinders runs 6000 rpm; their 5-6" runs 9000 rpm, and one of their 4 1/2" units runs 11000 rpm, almost twice that of the larger.

Every disc in turn has a maximum safe speed. Putting a disc, even a correct diameter one, on a faster turning arbor than its design limit is asking for trouble.

Putting a larger diameter disc on a smaller grinder than it is designed for is begging for trouble, as the maximum safe speed is likely to be far less on a larger diameter disc.

When I taught shop, I had to keep all the abrasive discs in my office, after I caught a student installing a hard grinding disc rated at 12k max safe rpm on an air sanding tool rated at 20k no load speed. It fit perfectly well, and it was the same diameter, so why not?....

I have mentioned this before, quality abrasives can save money through better wear characteristics. I might add now that they can also save on drama.
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Mark from Illinois

Last edited by weldtoride; 05-15-2014 at 12:45 AM.
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