by jpboyt on Fri Mar 11, 2011 6:10 pm
If one takes a close look at a new set of burrs you will see the grind marks that run in a straight line from one edge to the other. These are left from the final manufacturing process that grinds the hardened burr parallel top to bottom. If you see any circular marks interposed on the straight lines you have an indication, used burrs, that the upper and lower burrs are touching. You use the contact patches as a witness. Isolated marks on the rotating burr mean that the rotating holder is not perpendicular to the motor axis. Isolated marks on the stationary means that the adjuster is not perpendicular to the motor axis. To determine total lack of parallelism, adjust top holder down to the point where the lower starts rubbing. Mark lower and then rotate 180 deg. Mount a dial indicator on upper and gently adjust down till lower won't turn at all. The number is the total lack of parallelism. If you don't have a dial indicator you can use the thread pitch to calculate. Many of the grinders use a 1mm pitch which equates to approx .039" per revolution. Watch how much of a revolution of the adjuster to calculate. 1/8 turn would equal .039/8, which would be around .0048". anyhow you get my drift. I commented on another post as I have an Azkoyen grinder that ended up with, memory at work, about .004" to .006" of out of parallelism.
James
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