bench grinder wheels (sorry for asking!)

[myredracer]

Grinder wheels must have been talked about to death here and elsewhere but am not quite sure what to do based on what I've read on the internet.

Have had my 6"x3/4" bench grinder for something like 30+ years and have hardly used it in that time. Has survived a divorce and many moves. It's def. a survivor... Last winter I finally started restoring one of my 2 vintage cars (that have also survived a divorce & many moves). Wow, I can't believe how much I use that bench grinder now. Built a stand for it too which makes it pretty handy to use.

The wheels both need replacing now. Not sure what to get. Should I install one coarse and one medium grit or...? I use it for grinding mild steel only. I want an AO wheel? Is a premium blue AO wheel better?

Is there such a thing as an adapter so I can use a 1" wheel or is that not a good idea?

I bought an old Craftsman drill bit sharpening jig so I can sharpen bits instead of buying new ones all the time. I have HSS and cobalt bits. What wheels do these need? Easy to swap a wheel for doing drill bits if and when needed.

Up until this past winter I also had a second bench grinder and sold it on CL thinking I didn't need two of them. Now I am kicking myself for doing that because I could have used it for a wire wheel and buffing wheel. Sigh. If I go and buy another, should I get a 6" one or larger or one for 1" wide wheels?

 

[Lelandwelds]

Six inchers are for homeowners. Get the largest you can fit in your space. Mine is a 12 inch Baldor. Two inch wide always needs dressing after somebody else uses it. Put your favorite grit on both sides.

The green ones are for drill bits. Buy the fine grit.

 

[Zeke]

I think Norton and others have a complete rundown of what wheel for each job on their sites.

 

[Lelandwelds]

Scotchbrite wheels are nice but expensive. No more stabbings from loose wires. I like the EXL.

I think the ultimate grinding is a 2 x 72 variable speed used for knife making. The back wheel belt grinders the boat prop people use is even more impressive. Still gotta have a bench grinder.

 

[Thumper68]

IME buy name brand wheels and ring test them before mounting, I have had good quality wheels fail the ring test a few times.

As far as a 3/4 or 1 inch take the old wheel off and see if it is long enough to mount a 1 inch, I have a grinder or 2 that will take up to 1 inch and down to 1/2 inch.

 

[MoonRise]

The wheels both need replacing now. Not sure what to get. Should I install one coarse and one medium grit or...? I use it for grinding mild steel only. I want an AO wheel? Is a premium blue AO wheel better?

And then later you say:

I bought an old Craftsman drill bit sharpening jig so I can sharpen bits instead of buying new ones all the time. I have HSS and cobalt bits. What wheels do these need? Easy to swap a wheel for doing drill bits if and when needed.

Up until this past winter I also had a second bench grinder and sold it on CL thinking I didn't need two of them. Now I am kicking myself for doing that because I could have used it for a wire wheel and buffing wheel. Sigh. If I go and buy another, should I get a 6" one or larger or one for 1" wide wheels?

First you say you are grinding mild steel, then you talk about grinding drill bits.

Which are not made of mild steel (well, they aren't supposed to be made of mild steel )

What are you actually grinding? That determines what wheel (grit, hardness, material of the wheel, etc) to use.

Size? Bigger is generally better.

 

[2oolhound]

Get a bigger one, you'll quickly be stalling the 6" with wider stones. I hate changing wheels but I love bench grinders so I have 6. I also have 3 belt grinders, an 8" buffer and more than 10 hand held angle grinders. This way one is usually ready for you to do anything you walk up to it to do, no muss no fuss just get on it.

 

[myredracer]

What I meant is that I will have some drill bits to grind at some point (haven't before). It's time to stop buying new ones and sharpen them myself. Don't know what type and grit of wheel to use for them and if the same wheel can be used? I'll always stay set up for grinding mild steel and only swap out a wheel if and when needed for drill bits (which I know aren't mild steel).

For mild steel, do I want the same grit and type on both wheels? Not sure what I have on there now but looks like coarse grit and they're dark grey.

Larger dia. wheel will mean higher surface speed and I assume more friction/heat. Does that matter at all?

I'm normally grinding 1/8" - 3/16" flat, angle & square steel tubing and 12 - 16 ga. sheet steel.

Some brands are cheaper like CGW and K-T Industries and don't know if they're to be avoided or not. As far as ebay goes, SAIT seems to be the higher priced brand and internet says is decent quality. Not sure what the local industrial suppliers stock.

And then later you say:



First you say you are grinding mild steel, then you talk about grinding drill bits.

Which are not made of mild steel (well, they aren't supposed to be made of mild steel )

What are you actually grinding? That determines what wheel (grit, hardness, material of the wheel, etc) to use.

Size? Bigger is generally better.

 

[myredracer]

Get a bigger one, you'll quickly be stalling the 6" with wider stones. I hate changing wheels but I love bench grinders so I have 6. I also have 3 belt grinders, an 8" buffer and more than 10 hand held angle grinders. This way one is usually ready for you to do anything you walk up to it to do, no muss no fuss just get on it.

I'd love to have a nice HD comb. disc/belt sander but the good ones ain't cheap and can't justify one for the amount it'd get used. Have a few angle grinders & air die. grinders and couldn't do without them.

 

[Zeke]

I bought this for sharpening my TIG tungstens. I think it would do drill bits nicely. It uses a 3" wheel.

 

[exmaxima1]

Larger dia. wheel will mean higher surface speed and I assume more friction/heat. Does that matter at all?

Yes, it does. The optimum surface speed for ferrous metals is with a 6-inch wheel at 3450 rpm. An 8-inch wheel (at 3450 rpm) runs too fast, and the typical 10-inch wheel running at 1750 rpm is too slow.

BTW, a friable white or pink wheel will do a great job of sharpening without taking the temper out of the drill bits. They wear faster, but cut with very little heat.

 

[cheechi]

a few things

sharpening drills with a grinder is a great skill to have. but I think you should look at either a set of bigger, cheap drills to practice or get a tormek or drill doctor rather than expect you're going to get usable drills without a machinist there to show you or a lot of ruined drills along the way.

coarser wheels I find do best with bigger diameters. I have two grinders with grinding wheels, 36 & 60 SiC on an 8" and 100 & 150 (whatever the Norton white compound is) on a 6". I also have wire wheels & flap disc on 6" and a separate buffer with longer arms.

a belt grinder/sander may also complement what you're doing and may be useful either with different sizes, or to reduce the amount of machines you need.