SG grinding wheel

[Bob Quale]

I want to get a new SG grinding wheel for my pedistal grinder, it uses a 6in cupped wheel. I use it for general purpose sharpening of my HSS and T-15 cutters, free hand. Should I get a 46 or 60 grit?

Thanks Bob

[Evan]

Use 60. It will run hotter but the finish will be much better. That's a Norton wheel?

[Bob Quale]

I was going to use the Norton, I have had good luck with them. I am currently using the white wheels and they work well for HHS. I have been using T-15 in my shaper and lathe and boy, is it hard to sharpen! I figured the SG might be a good comprimise. The CNB wheels are a little pricy for me at this time.

Bob

[Evan]

My wife says to use a white aluminum oxide wheel, 46 grit to rough it and the same in a 60 grit for finish grind. I also have a super fine grit double sided wheel designed for grinding on the faces of the wheel, one side is about 100 grit and the other is around 180. It puts on a mirror finish but is not intended for stock removal.

CBN is really nice, I have one and grind all sorts of stuff including cobalt drill bits and it doesn't wear at all.

[Bob Quale]

Evan,

You mean a white wheel and not a SG? I thought the SG was better for the harder T-15?

Bob

[Evan]

The white wheels are pure vitrified aluminum oxide. The SG wheels (grey) are also aluminum oxide but have other fillers and binders and will probably wear faster. BTW, T-15 is supposedly used because it is easy to grind even though it is RC67 or so. It shouldn't be a big problem.

[beckley23]

I have had great success with the Norton SG wheels on my surface grinders, 60 L on one , and 46 I on the other, in grinding production runs of M-2 blades that I manufacture for a pipe cutter. The beauty of the SG wheel is that they are basically self dressing, even when they look loaded up. Production runs are approx 200 pcs and the wheels will last for about 5 runs before they are too small, for effective SFM.
I have tried other wheels, except CBN( and they were not recommended by Norton), in this application, and nothing comes close to matching this performance. Keep in mind that this is a controlled procedure, table speeds, cross feeds and down feeds; something practically impossible to do on a bench grinder.
I have also tried the SG wheels on my cylindrical grinder to do the cutting edges, and they failed miserably, the wheel broke down after about 3 blades and had to be redressed. Went back to using a Radiac ruby wheel, that performs like the SG wheels on the surface grinders.
In both situations I contacted my tool suppliers, and we got on the phone with the respective technical support people for their advice.
Harry

[Koloya]

1

[This message has been edited by Koloya (edited 12-18-2004).]