Thanks Harold, I usually use them to rough out a shape prior to finish dressing with a diamond. It helps to save on my diamond life.Harold_V wrote:Depending on the wheel, that can be a good use, but consider that aluminum oxide is MUCH softer than silicon carbide, which is not normally used for grinding steel. I make mention because how hard the dressing stick is speaks volumes about the results of dressing a grinding wheel. If you dress with a soft material, the wheel will be dulled by dressing (that isn't normally acceptable). Because dressing sticks are made from harder materials (silicon carbide, or boron carbide), the wheel isn't dulled as badly. That, of course, is based on the assumption that the dressing stick is applied properly. Use a flat surface of the stick and they're no better than using aluminum oxide. A sharp corner, so the dressing stick cuts instead of abrades, is desirable.carlquib wrote:I hope you saved the pieces of the wheels that failed the ring test. I use dead wheels in the same manner you use a dressing stick. They work and you can get a little more use from an otherwise dead wheel.
In regards to storing wheels on edge, yeah, doing so can make a difference, but I contend that if a wheel is subjected to damage, how it's stored isn't going to make a significant difference. It stands to reason that they will withstand a force on edge better than they will from the side, but in either case, the wheel would then be suspect.
Something of interest (or not).
I was assigned to precision grinding for several years. Amongst the machines we used was a Cincinnati #2 centerless grinder. They are rated to grind up to 3" diameter. One part for the missile that required grinding, a part of the guidance system, was a steel piece that was 3½" diameter, and three inches long. That's a recipe for problems, especially being larger than the normal capacity of the machine. Because the part had to be ground well above center, they could be troublesome, as the regulating wheel could lose traction, allowing the grinding wheel to "pick up" the part. When that happens, it is driven at extreme velocity, and has the ability to leave the machine.
While I often heard them rumble as they traversed the blade (which supports the part while being ground), I never lost a part. However, 'ol Musselman (on the opposite shift), wasn't quite as lucky. When I reported to work, the wheel of the grinder (20" diameter and 6" wide) had a divot removed from the center of the wheel, which was still intact, and sound. One of the pieces jumped out of the grinder, and came down sideway, slamming the wheel to a dead stop. No small feat considering the wheel is powered by a large motor, something like seven hp. Because a void eliminates the possibility of using the wheel, it was dressed enough to remove the divot. Lots of grinding life lost, but the wheel was still serviceable.
I make mention only to show that wheels can take serious punishment and still not fail.
I always wondered if Musselman had to change his shorts after that experience.
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