PDA

View Full Version : Grinder Wheels for HSS Tools ?



nc cooter
06-26-2008, 04:28 AM
I am newbie with a new/used JET 9x20 and I need help selecting grinder wheels for my 6" bench grinder. I know the selections for a 6" are limited, so any input will be appreciated.
My main tools will be HSS but I would also like a wheel for touch up on carbide.

Thanks.

Your Old Dog
06-26-2008, 08:22 AM
Sorry you didn't get an answer sooner. ( I am no expert on this topic but here's how I do it. ) I use a "pink" 60 grit wheel for my HSS bits. It cuts the HSS very quickly and with much less heat. I should probably get an 80 or 100 grit wheel to go with it for a nicer finish. These wheels are soft and do not tend to burn the steel. I use these only on my HSS bits because they'd wear out pretty quickly on general shop grinding but for bits the last really well.

I do baby them in handling till I get them on the grinder. I worry about them developing a fracture and of course I always fire up the grinder and then get the hell out of it's way till it comes up to speed for a moment or two.

oldtiffie
06-26-2008, 08:32 AM
It is a wise move to test any grinding wheel for cracks or fractures before mounting the wheel and to stay clear of it as it starts and runs for a minute. It should be OK after that - until you re-mount it.

To test it for cracks etc., just hold it on a bit of steel rod and "tap/rap" it sharply at about 2 or 10 o'clock. If it "rings" it is OK, but if the response is a "thud" or none at all, just toss it out - the risk is not worth it.

Get two similar cups, saucers or plates - one cracked the other not. Tap both (don't hold in your fingers) and you will see the difference immediately.

If you "ding" a wheel even when mounted, test it again.

A flying broken grinding wheel is not something that is easily forgotten - as they can do real damage.

SGW
06-26-2008, 08:48 AM
I use silicon carbide "green" wheels for sharpening. They will grind carbide, sort of. Although the only way to properly sharpen carbide is with a diamond wheel, these do an acceptable job if you can settle for something less than the best possible edge.

The silicon carbide wheels are soft and wear quickly, like the wheels YOD suggested, but they cut HSS well and don't tend to heat up. I think I've got an 80 and a 120 wheel. If I were doing a lot of grinding the rate of wheel wear might be an issue, but for what I do it doesn't matter. I've had these wheels for 10 years or more, and there is still plenty of wheel left.

Richard-TX
06-26-2008, 09:07 AM
I have two grinders and the tool that I use for grinding HSS tool bits is my 12" disc sander. I know it seems odd but it works for me. Large table, adjustable angle, mitre gauge slot, all add up to a pretty good HSS grinder solution. I don't do carbide on it though. Carbide is ground on my carbide grinder. FWIW

miker
06-26-2008, 06:38 PM
Mike, take a look at the article by Harold that Bad Dog posted here:

http://bbs.homeshopmachinist.net/showthread.php?t=25268

Well worth a read and explains in detail how to select a grinding wheel. Explains the Number/Letter code/system used. Also have a look at "NORTON"'s web site for added info.

"If you want to study some a good book that maybe your library might have or might be able to get on interlibrary loan is
Design and Use of Cutting Tools | by Leo J. St. Clair
or like me maybe you could find one on ebay"

I managed to get a copy of this book and it is a goldmine for anyone wishing to understand the WHY and HOW of HSS tool shapes and how to grind the angles.

Good Luck.

Rgds

nc cooter
06-27-2008, 05:27 AM
Thanks for all the input. Looks I have more studying to do .

38_Cal
06-27-2008, 10:26 AM
I rough hss lathe bits on the grinder, finish them on my 1x42" belt sander. I can go down to 600 grit on it, gives an excellent finish, and takes minimum final touch up with a stone.

David
Montezuma, IA

Evan
06-27-2008, 10:45 AM
Soft aluminum oxide wheels work best for HSS. They cut fast and cool.

As for testing wheels for cracks there is a more reliable method than "ringing" the wheel. You need a tuning fork which is easy to make. Strike the tuning fork and hold the stem to the rim of the wheel while supporting the wheel at the centre. If the fork quickly goes dead the wheel is cracked. If the wheel is sound the sound of the fork will telegraph into the wheel and be audible.

dan s
06-27-2008, 12:09 PM
Mike, take a look at the article by Harold that Bad Dog posted here:

http://bbs.homeshopmachinist.net/showthread.php?t=25268


Harold knows his stuff, and gives really good advice.

Don't get a 6" wheel, unless you absolutely have to, because its next to impossible to find a soft one.

Check the diameter of your grinders shields, and the rpm at which it turns, and see if you can't get a 7" wheel on it (I could on my $20 special).

I Personally run these wheels on my grinder.
http://www.use-enco.com/CGI/INSRIT?PARTPG=INSRAR2&PMAKA=422-0279&PMPXNO=7856630