Common Grinder Wheel Grit Recommendations?

[freudianfloyd]

I recently picked up a really nice Milwaukee 10" bench grinder. I also have a 6" Craftsman that has served me well. Anyway, I am looking to possibly dedicate the 10" to just grinding duties and use the 6" solely for wire brushing. My question is, what two grinding wheels grits would you recommend, and what different types of wire brushes should I invest in? I don't have any particular metals or materials that I will use them on, so just basic grits and types? Besides buffing, which I already have a dedicated buffer for, what other wheels would you recommend if not two different grits or brushes?

 

[Toolmaker51]

Grinding wheel selection depends on what grinding is to be done. A normal combination [one each] is in range 36 and 60. If you are grinding cutters those each could be raised a step, ~46 & 80.
Straight [loose] wire brushes offer decent performance and conform well to contours. I'd avoid knotted variety, unless you have sufficient experience regarding placement and orientation while brushing. They're not only very aggressive, they are absolutely unforgiving. Either way a 6" motor is more accommodating. Anything larger, a 7" or 9" angle grinder is a better start. The trick to brushes is wire diameter; fine wires are dense and leave a nearly imperceptible 'graining'. Coarse wire, used with abandon, will remove material and ruin contours, just as easily it does de-scaling of hot rolled stock or welds.
You'll likely wind up with a bank of brush and grind motors. Here, I use 6" Craftsman, 10" Baldor's and 14" Cincinnati's. Guess which is the beast, I'd think twice before mounting a brush on it. I have used wire wheels on big grinders, but it requires concentration. I won't use any brush or grind wheel without proper guarding and tool rests, buffing is a little different, but can still grab a sharp corner.

Pic is just before rigging it up and out where purchased, not running at my place yet. 14" wheels 440v; just for scale, notice extinguisher. Less apparent, beveled steel plate under pedestal; it's 1-1/2" thick, 36" x 36", 550# on it's own. 1/2 ton chain hoist and gantry close to limited out unloading. Plan is filling pedestal with oil-dampened sand. It runs fine, but will inspect and megger wiring, check bearings, remount switch, drill plate for leveling screws, into 2" x 2" plates with a layer of machinery felt contacting floor, then balance and true wheels. I've used big offhand grinders, never seen one so large.

 

[torqueman2002]

I use Norton wheels.
https://www.nortonabrasives.com/en-us/norton-best-sets#Anchor_Cutting

 

[sqznby]

I'd use what was provided with the grinder if you do not have a specific use for the grinder.
Honestly, I can't remember the last time I used a stone to do any grinding. Belts and discs have become a more popular and efficient choice to remove material.
Grab yourself a belt attachment for that grinder and you'll fall in love with it.

 

[Toolmaker51]

Taking advantage of a captive audience, awaiting USPS shipment. Better to thwart porch-pirates than more positive measures; legally speaking...

Sanding-wise, I have 3 pedestals carrying discs of 6", 12" & 20", the 6" tied to 2" x 42", the 12" with 6" x 48" belts.
Big discs are it on larger drill bits, belts kick azz shaping. Neither much good on lathe tools, for metal or wood.

It's not just the abrasive, primarily it's form of machine used, e.g. preparing lathe bits. The clearance created by a curved wheel [comparatively large radius] creates minimal contact to workpiece, allows very precise honing, plus simplifies the resharp effort, not having to replicate previous angle.
I'll agree 100% that belts are a huge benefit, somewhat restricted to parts small enough to heft and manipulate. Not lots of shaping going on with portable belts.

Grinding is not sanding. Grinding entails material removal along with exposure of fresh abrasive. Same as chop or hot saws and deburring wheels. Pressure determines consumption of wheel and rate of material removal, evidenced by heat generated.
Sanding removes via 'permanent' grains, material released by coatings on those abrasives. Sanding enables far more aggressive grit size than practical in a bonded wheel of same diameter.
Polishing is a sanding operation, finer abrasives suspended in temperature resistant 'adhesive'. The compound cuts surface and the removed material somewhat burnishes workpiece. After period of use the buff is shagged, removing old compound and recharged, commonly with rouge, aluminum oxide, or emery.
Honing and lapping remove even smaller quantities of workpiece. Honing relates to grinding, where material and abrasive are flushed by a flood of liquid.
Lapping relates to sanding; the abrasive is retained in a material softer than workpiece to act on workpiece. That's why thorough cleaning of a valve seat is required, lapping compound remains embedded after cutting much harder valve face.

Now what, still no packages...

 

[boom_bap]

I'd ditch the grinding wheels entirely and go straight to bench grinder attachment.

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On the otherside I'd get a wire wheel.