angle of diamond when dressing wheel?

[TRX]

I used to see crankshafts from a particular shop that miked out okay, but had a peculiar "threaded" look after they were washed. I did notice the operate swiped the diamond across the wheel pretty fast.

[Harold_V]

I used to see crankshafts from a particular shop that miked out okay, but had a peculiar "threaded" look after they were washed. I did notice the operate swiped the diamond across the wheel pretty fast.

That would be a mistake on a crank grinder, due to the large diameter of the grinding wheel, operating at a relatively slow speed. Diamond feed rate should be in keeping with the speed of the wheel (revolutions per minute, not surface speed).

I expect the operator chose that method because the wheel was likely more aggressive. Not a good compromise for a surface that should have a nice, smooth finish.

H

[TRX]

While we're talking about dressing, is it best to do it with coolant on or coolant off?

[GlennW]

If you are grinding with coolant, dress with coolant.

[Harold_V]

If you choose to dress wet, make sure the diamond is submerged at all times. If, by chance, the diamond goes dry, when it is then hit with water, there's a chance it will shatter. For that reason, I always dress dry, even when operating a centerless, where wheel width is exceptionally large (it can be 8", even wider). Diamond tolerates heat quite well, but it may not tolerate thermal shock.

There's a terrific amount of heat generated at the diamond. Take note that it glows when being used.

H

[GlennW]

Depth of infeed is also a large factor when dressing.

I prefer .001" for normal dressing and .0005" for finish dressing.

Too deep an infeed can fracture the bond and the fractures can subsequently pack with fine swarf which can affect the finish on the part.

[mcostello]

there is a monthly publication out that is called "Cutting tool Engineering." It has articles in it by Jeffrey Badger PHD, and John Webster PHD. They write about problems with grinding and get to answer some questions by Readers. Well worth the read.