Hand grinding/shaping tungsten carbide on an 8" bench grinder?

[Sparky961]

Presently my work uses silicon carbide (green) wheels and even a small amount of grinding leaves gouges in the wheel, you covered in grit, and the room looking like a day at the beach.

This is what's currently being used:
Norton Abrasives
66253044087
Gemini Crystolon Bench or Pedestal Grinding Wheel - Grade: Medium, Grit Number: 60, Wheel Diameter: 8

Typical uses are adding clearance to small boring bars, putting flats on end mills, and modifying OD and ID grooving tools/inserts.

I've seen quite a few people say here that diamond is the way to go, but I'm not seeing many options that are economic, mount on an 8" bench grinder, and have a similar form (or at least a useful one).

Can anyone point to some specific recommendations? Or perhaps mount on a 6" grinder, as I see more options in that size.

 

[sfriedberg]

If you are just roughing/reshaping, you can probably find a plated diamond wheel that's more economic that the typical resin bond diamond wheel. For one thing, there's a whole lot less diamond! The finish will not be good for cutting edges, but should be OK for clearances, flats, and so on.
Thing is, there are relatively few "stock" plated wheels. Much of that business is made-to-order. Give a diamond wheel maker a call. It will probably help if you have the wheel nomenclature ready when you get in touch, especially the bits that describe where you want the diamond. Check out pages 6-10 of this catalog from Norton/Saint Gobain. I think that's all resin bond wheels, but the wheel shape and abrasive location bits are the same. If you want to use just the circumference of the wheel, bench-grinder style, that would be a 1A1.

 

[eKretz]

I can feel your pain. The first shop I worked in had big green wheels out in the shop for carbide. I learned pretty quickly not to use them for much besides roughing in the tools. Also that you'd better head straight to an air gun right after doing so, that way you could blow all the grit off your arms, shirt, pants, boots, hair etc. After a bit of experience developed, I started sneaking into the tool room to use the diamond wheels and a proper T&C grinder.

If you want to stick to the bench grinder and a normal wheel for that, you can get a Poltava (Ukrainian) resin bond wheel that will fit for under $200. They're pretty decent quality. I have several and they work well.

 

[???]

The cost of green wheels will probably add to more than the diamond wheel when you factor in longevity of the diamond wheel over the green wheel. Add in the sub optimal job of the green wheel and it's a no brainer.

 

[michiganbuck]

Going to a too-fine-grit diamond wheel can jeopardize the cost efficiency of using diamond wheels. A 120-grit wheel run wet can be the lower-cost method and gives an Ok finish for such as flats and tickling boring bar ODs.
At first use, it is best to indicate the wheel OD to .002 or better so at the end of life, you don't run out of diamond on one side.

A simple aquarium pump can be attached to a bench grinder setting in a homemade plastic tub for a mock Tc grinder... you might even consider attaching a bargain tilt table.

 

[stephen thomas]

You don't need an 8" wheel.
5" or 6" which are cheap would be fine.
Get the common wheels for T & C or surface grinders with 1-1/4" holes, and make yourself an arbor adaptor to run it on the grinding spindle you want to use.
Resin bond.
Some say 50% grinds cooler, i always went for 75% or mostly 100%
A lot of what you do would easily be done with a 120 grit.
Or 180 grit.
For offhand shaping with coarser cooler wheels, if you want sharp edges you would best hone with hand held hones after grinding.
220 would be good general purpose if you use it on a T & C. It's good offhand, too, but a little slower for shaping.
Get a cleaning stick and use it. Keeps the heat down and actually makes the wheel last longer.
Mist coolant will help keep the dust from traveling if you wear rubber gloves and supplied air hood or full cartridge respirator while grinding.
Don't dip and grind with carbide, it shocks the edges and makes them weak/micro cracks. Better to just grind dry (for the carbide) than intermittant coolant.

FWIW i've bought large diamond wheels cheap on eBay for my 10" wheel surface grinder because no one uses them

I'm old enough to be thankful for the bullets i dodged so far to this age, back when i thought i was indomitable and breathing would always be easy.
Do yourself a very big favor and read up on the risks of breathing carbide dust, and the risks even of absorbing it (cobalt) through your skin as you grind. Then take adequate personal protection, and be sure to confine the detritus to areas your kids and wife won't be exposed to.

smt

 

[jccaclimber]

The only advantage I see to a green wheel in this application is that you can't ruin them through abuse as quickly as you can a diamond if run dry. That said, some basic education and the diamond, especially if you can run it at a low speed, will last longer and do a better job than the green wheel.
Running wet also has the advantage of catching the carbide dust, that stuff isn't great for you.

 

[eKretz]

Good tips from the guys. I would stick to 120-150'ish grit and hand hone the finish, just like Stephen mentioned. Also a coolant mist is good, and if possible a vacuum. If not, a mask.

 

[CarbideBob]

Do yourself a very big favor and read up on the risks of breathing carbide dust, and the risks even of absorbing it (cobalt) through your skin as you grind.

smt

This is a problem? Someone should have told me. There were some big lawsuits.
Maybe the cobalt skin thing is bigger when grinding wet with the wrong coolants.
Much info out there that is hard to sort though. Big difference in tickling a tool bit and grinding carbide 10 hours a day 6 days a week.
For sure all not good for you. Hence the now a law warning labels on your carbide parts.
Never. ever want to think I have put my employees at risk...
Then they bitch that they do not want to change the coolant tanks or the air filters as it seems fine to them which makes me the butt-hole boss.
I can not win. Should mention that I smoke 2+ packs a day. I would advise all to not do that.

 

[jccaclimber]

This is a problem? Someone should have told me. There were some big lawsuits.
Maybe the cobalt skin thing is bigger when grinding wet with the wrong coolants.
Much info out there that is hard to sort though. Big difference in tickling a tool bit and grinding carbide 10 hours a day 6 days a week.
For sure all not good for you. Hence the now a law warning labels on your carbide parts.
Never. ever want to think I have put my employees at risk...
Then they bitch that they do not want to change the coolant tanks or the air filters as it seems fine to them which makes me the butt-hole boss.
I can not win. Should mention that I smoke 2+ packs a day. I would advise all to not do that.

The CDC says you aren’t supposed to breathe the cobalt dust. I’m not sure about skin exposure. It could well be that coating yourself with dust just results in breathing bits of it later.

 

[stephen thomas]

Carbide - I'm pretty sure it was you, that (thank you!) warned me about reading up on skin contact with coolant + cobalt/carbide many years ago. Someone could probably look it up.



I already knew about breathing it.
FWIW i worked in a carbide tool rebuilding shop part time nights for a while. That had collection on all the machines but probably no where near ideal.

Something that still bothers me; about 30 years ago after first moving to this area, i walked into a basement grind & tool shop that mostly did carbide sawblades and other carbide tipped woodworking tools. As soon as i got near the door let alone open it, i could smell the carrot smell. Back then i "assumed" with limited exposure, i'd pass the dust back out of my lungs soon enough, so went in and followed the signs downstairs. It was almost a fog in the air. No dust collection whatsever. no coolant, no mist. Old guy and a kid probably around 19 or 20 going to town. They stopped and were cheerful and proud of their work & it was a professional shop with good machines. I did not have anything with me to drop off, since i was running other errands and had only seen the sign going past. I wanted to say something about the dust but figured it's none of my business. I mean the old guy probably died from other causes, but the kid was young, breathing that stuff deep, all day long. Reminded me about the stories of the needle grinders in Victorian England except they knew they were trading health & any hope of advanced life for short term (relative) wealth, fast living, and a certain reputation.
I never could bring myself to go back to that shop.

So now days when the subject comes up i say something.
You can do what you want with it.

smt

 

[???]

Carbide - I'm pretty sure it was you, that (thank you!) warned me about reading up on skin contact with coolant + cobalt/carbide many years ago. Someone could probably look it up.



I already knew about breathing it.
FWIW i worked in a carbide tool rebuilding shop part time nights for a while. That had collection on all the machines but probably no where near ideal.

Something that still bothers me; about 30 years ago after first moving to this area, i walked into a basement grind & tool shop that mostly did carbide sawblades and other carbide tipped woodworking tools. As soon as i got near the door let alone open it, i could smell the carrot smell. Back then i "assumed" with limited exposure, i'd pass the dust back out of my lungs soon enough, so went in and followed the signs downstairs. It was almost a fog in the air. No dust collection whatsever. no coolant, no mist. Old guy and a kid probably around 19 or 20 going to town. They stopped and were cheerful and proud of their work & it was a professional shop with good machines. I did not have anything with me to drop off, since i was running other errands and had only seen the sign going past. I wanted to say something about the dust but figured it's none of my business. I mean the old guy probably died from other causes, but the kid was young, breathing that stuff deep, all day long. Reminded me about the stories of the needle grinders in Victorian England except they knew they were trading health & any hope of advanced life for short term (relative) wealth, fast living, and a certain reputation.
I never could bring myself to go back to that shop.

So now days when the subject comes up i say something.
You can do what you want with it.

smt

Good advice, I think there are probably some on this site who like me have disproved the adage "live fast die young" in that we have managed to survive our own stupidity. Whenever young people ask me for advice nowadays I always tell them to remember life is a marathon not a sprint and its definitely more enjoyable in later life if you look after your health. Even in this day and age it is quite rare to find employers that actually care about employee safety because it is the moral thing to do instead of a legal requirement. So when your boss says do something and you think its risky don't do it.

 

[michiganbuck]

One thing about carbide grinding with a green wheel is that you realize how much pressure it takes to get the abrasive to penetrate the material. Often a rocking motion is advised to allow putting all the pressure on a smaller place.
A wet diamond wheel has way less pressure required.
I am lucky to have good lungs after many years of grinding. Light stuff like drywall and wood sanding is likely very bad, also.
OSHA warns about washing your hands to not to ingest bad stuff.
One fellow I knew got shotgun shot at 16 years old and had pellets that He could feel at over 90 years old... seems that lead does little /no harm unless it gets into stomach acid.

 

[eKretz]

One thing about carbide grinding with a green wheel is that you realize how much pressure it takes to get the abrasive to penetrate the material. Often a rocking motion is advised to allow putting all the pressure on a smaller place.
A wet diamond wheel has way less pressure required.

(Snip)

Yes, agree for sure. Rocking definitely helps with that if taking a lot of material out. Still clouds the area with SiC dust though. Less pressure helps too, but the more that is done to mitigate wheel wear and dust clouds, the longer the grind job takes. Moving to diamond is just plain better all 'round. More controllable, faster cutting, much less dust.

The only thing I ever liked SiC wheels for was roughing out brazed carbide. You can grind the carbide and the steel all at once, and save some wear on the diamond wheel. These days I'll use a plain AlOx wheel for the steel part and diamond for the carbide.

 

[Sparky961]

Thanks for the great input so far! I'm glad to hear I'm not the only one who's been down this road.

 

[CarbideBob]

One thing of note.
Green grind wheels were cheap. Diamond was expensive.
Big change when the patents expired. What was a 1000 dollar wheel went to 300 in six months.
50 cons vs 100 cons. The 50 runs cooler, more open and sometimes faster. The 100 holds a corner better but loads.
I buy a lot of 50s for long contact face wheel work on IC grinders but since the diamond now so cheap there is very little price difference.
If you go from a 50 to 100 one needs to radically change the bond to get the same cutting speed or action.
The off hand grinder, the Blanchards, the Agathons and the Sgs all want very different diamond wheels in grit and bond.

From the very limited info here I'd be in a 6 inch 50 con 220-320 grit SiC filler (green colored) wheel at 1800-3200 rpm with some at least spray bottle coolant.
The copper filled ones (brown) move heat better but do not in general like low coolant flow.
Your mileage may vary.

 

[Sparky961]

One thing of note.
Green grind wheels were cheap. Diamond was expensive.
Big change when the patents expired. What was a 1000 dollar wheel went to 300 in six months.
50 cons vs 100 cons. The 50 runs cooler, more open and sometimes faster. The 100 holds a corner better but loads.
I buy a lot of 50s for long contact face wheel work on IC grinders but since the diamond now so cheap there is very little price difference.
If you go from a 50 to 100 one needs to radically change the bond to get the same cutting speed or action.
The off hand grinder, the Blanchards, the Agathons and the Sgs all want very different diamond wheels in grit and bond.

From the very limited info here I'd be in a 6 inch 50 con 220-320 grit SiC filler (green colored) wheel at 1800-3200 rpm with some at least spray bottle coolant.
The copper filled ones (brown) move heat better but do not in general like low coolant flow.
Your mileage may vary.

It seems clear that diamond is the way to go, but which diamond on a cheap 6 or 8" bench grinder is the million dollar question.

 

[Pete Deal]

I have a resin diamond wheel on a 6” grinder, 1/2” wide or so, that I’ve been using for this purpose for almost 20 years. I’m not sure what grit it is since someone gave it to me. It does a great job though. I too am curious what to buy when it needs to be replaced. I’ve bought a few chicom cheapie diamond resin wheels that I use on my cutter grinder. What’s the consensus on these?

 

[EmGo]

I’ve bought a few chicom cheapie diamond resin wheels that I use on my cutter grinder. What’s the consensus on these?

You want us all to come over and watch you sharpen endmills for a while, so we can give you a score ?

They're on your grinder, how about you tell us ?

 

[michiganbuck]

I never tried an import diamond wheel for sharpening, so can't comment on them. I did use a thin diamond parting wheel and it worked well. Another big change in diamond wheels was manufactured diamonds, they became popular in the 60(or what)and cut the diamond wheel price. I visited the 9-mile road shop where GE/Carbloy was experimenting with manufactured diamonds. There was a rumor that they had to make a deal /Agreement with Debeers to be able to market MFG diamonds.
The true diamond wheels whispered through carbide, and MFG ones made a bit of a rumbling sound. Likely not everybody noticed the difference. Good for an outfit doing a lot of carbide work to try a true diamond wheel to make a cost evaluation. True diamond wheel prices came way down from what they used to be because of competition.
One can use a dry 120 and 220 gt for sharpening, the 500gt will/may heat check some carbide if used dry. the 500gt is about the beginning of near mirror finish, and yes one can sharpen with 1500 grit and finer.