grinding wheels--when do you replace?

[Australopithecus scobis]

Greetings,

I've had my first grinder for a few months now. (Ugly grey wheels used to chew up metal, not for sharpening...)

I'm wondering how small you let the wheels get before you replace them. Five inches? Down to the label?

I'm asking here instead of the metalworking group, because I think metalworkers would have different tolerances and applications than woodies do.

[robdingnagian1]

What size is the grinder?

Austral> Greetings,

[The Davenport's]

Just as a rule of thumb, I use 15-20% reduction before replacing a white wheel used for sharpening. That means running it down to roughly 6.8" to

6.4" on an 8" wheel. And 5.1" to 4.8" for a 6" wheel.

I also keep one handy that's down to about 50% or so for fine grinding something that I TRUELY don't want to risk burning. The surface speed of these wheels will be low enough that it'll take a long time to sharpen a dull tool without loading up, but for the almost honing effect you get from the small wheels, it can't be beat.

Luck

Mike

[Australopithecus scobis]

6" Delta

[Australopithecus scobis]

Thanks much. That's the info I was looking for.

[Mark and Kim Smith]

What does your manual say?? I was raised in my grinder youth to keep the tool rest 1/8" away from the wheel. As the wheel wore down, you adjust the rest to within an 1/8". When you can no longer do that, the wheel needs to be replaced. Also, if your wheel clogs from aluminum, brass or whatever, best replace it before it shrapnel's on you. It helps to have a wheel dresser.

Whether you are a woodworker or a metalworker, that wheel will spin the same speed. Spending it's life trying to throw it's weight away from center. Taking it down to the "label" the wheel won't care who you are and will throw pieces at you when it fractures. ( Gee! Do you think I've watched too many safety video's that show projectiles piercing peoples faces and eyes and such?? Yup! At least once a year!!)

Reminds me of the Maximum Exposure video where a guy ends up with half of a 10" grinding wheel in his skull. He has it removed and they show him grinding away on a new wheel, big ol' bandage on his head. On the video, he says that he doesn't believe in personal protection and won't ever wear that stuff! I think he could use a Darwin award ( or he'll win one he keeps going the direction he's taking!)

[Ba r r y]

Some people like as small wheels as possible, as it grinds a deeper hollow in a hollow grind.

Barry

[Australopithecus scobis]

Oh. You see, I used to write tech doc for a living. I never read the steenkin' manual. Your point about the tool rest is kinda obvious. Duh. (Finally, a use for the "tool rest" that is otherwise useless!) Thanks.

(The reduction in size is mostly due to my enthusiastic use of a star dresser. Won't get a diamond one until I have a proper rest and some white wheels.)

[Bob G.]

I am in my 60's....and your method is exactly the procedure that my Dad told his "young" son many many years ago.... He was primarly a metal worked BUT I have followed his advice and never ran into problems....

AND I have to THANK YOU

for bringing back memories of my Dad today... I Miss the old Sob ..."Sweet old Bob" ... thats how my Mom used to refer to him .... Unfortunately I think my wife uses the more common meaning when she is refering to me... especially this time of year when I am overly protective of the checkbook...

Bob Griffiths

[J]

Well, not really. RPM may be the same, but the speed at the edge of the wheel will be different. If a 6 inch diameter wheel is spinning at 1000 times a minute, the edge of it will be moving at about 1500 feet per minute. If the wheel wears down to 4 inches then the edge moves at 1000 feet per minute.

-j

[Mark and Kim Smith]

Glad I could bring you some good memories! Happy Holidays!!

[Mark and Kim Smith]

Reread my sentence. If the edge of a 6" wheel is turning at 1500' per minute, it is turning 1500' per minute whether you are a woodworker or whether you are a metal worker ( or an office worker.) If the wheel wears down to 4" and the edge turns at 1000' per minute, then the edge of a woodworkers wheel turns at 1000' per minute and the edge of a metalworkers wheel turns at 1000' per minute. Whether you are a woodworker or a metalworker, that wheel will spin the same speed ( all grinders being equal.) Point to the OP was that it doesn't matter whether you are a metalworker or a woodworker, it is a grinder and manufacturers have specifications on how to operate their product.

[J]

Oh.... Nevermind.