Precision Ground Toolroom Stones

[4GSR]

One of my Chinese diamond cup wheels has this problem. After passing a couple of carbide end mills thru the wheel sharpening the flutes, it started straightening up. Not perfect, but does the job. Might try surface grinding a piece of carbide and see if it takes some of the high spots out of the wheel.

 

[Bob Korves]

just a heads up for anyone considering buying the Shars 505-2233 wheel, I just received one. It looks like it was made by drunken chimpanseses , bad chatter marks, 8 thou runout. With 1018 steel for sacrificial grinding and 150 grit A/O grinding sticks I am making progress but I am an hour later only down to 5 thou runout. This is going to be a long project just to get the wheel true. If I had it do over I would have sucked it up and bought a Norton wheel. The Shars wheel qualifies as barely better than junk IMO and is on par with the quality of smaller HF wheels I have purchased. More chinese garbage is my view.

I finally took my Shars 505-2233 wheel out of the box and actually mounted it on a surface grinder hub. It fit snug on the wheel adapter, and only had about .001" runout. That jazzed me up after all the bad feedback from others who have bought it. It was also reasonably flat, just a few striations at the surface. The wheel was very close to flat across the face. It only took me about half an hour to prepare it for grinding flat stones. Just lucky, I guess...

 

[Bob Korves]

I also FINALLY got the precision ground flat stones (Robin Renzetti style) done today. Here are a couple 'after the fact' pics of the setups for grinding the large faces and the sides. If you look carefully, the thin protruding ledges for stoning relief slots are visible along one side corner of each stone, one fine, one coarse. They were ground together in the same setup in the grinding vise, with the ledges matched against each other for more support. Also shown is the old mist coolant setup that came with my first Millrite. It was pretty sad, leaked at every corner, was full of nasty dried coolant, and the nozzle and hose were messed up. It works good now. Grinding with mist coolant is wonderful compared to grinding dry, better results and perhaps less mess than doing it dry and having grit all over the area. Not one drop of coolant left the table, and this was my first try. The stones are magical. When you start to rub them together, at first is some resistance, which quickly changes to totally friction less, like glass on ice. Same on nice looking ground parts and tools. A little rubbing and it goes friction less -- done! I spent the entire afternoon rubbing down everything I could find for candidates. How did I get along without these stones all this time???

Edit: the stones are great for deburring the mag chuck. Quick, effortless, beautifully smooth and flat. Also good for the grinding vise. The mill table will be the next candidate.

 

[Bob Korves]

I helped a friend with making some flat stones. He is a gunsmith, GunMonkey on HM. Here are some pics of what we have done:
Instead of doing the "standard" 6" x 2" Renzetti flat stones, he wanted to have some larger and some smaller ones for his gunsmithing work. We did a 8x2" set for use mostly as bench stones with the work moving, a ~4" by ~2" all fine grit India set, and a tiny set as well, ground on all surfaces including the ends to be able to get into tight places. He did all the hands on grinding, a raw beginner grinder hand, slightly behind me.... They all turned out very nice, way better finish than my first ones, which do work just fine. The diamond wheel has settled into flat and square after using it in ways to promote that shape. I will be giving my stones an additional finish cut or two to make them as nice.

I would also like to ask any REAL grinder hands out there what they think of the setup for grinding the ends of the small stones. Does it look safe enough? It worked fine, but I want to know if I am doing dumb stuff...

And before anyone asks, I do not do this stuff for money, only for fun. A real hobby machinist! Please do not ask for me to make you some for compensation, not going there.

Edit: I finally got a vertical format photo to post correctly!!!

 

[EmilioG]

I suppose anything can flex if it's sticking out too far, so if it were me, (I don't know squat about grinding), I would think that more support
would give a more precise finish. Putting taller blocks on the opposite side of the vise with clamps, sandwhiching the entire stone up to
the last 1/2" or so. More rigidity?? You know more than I do Bob.
Q: Would a better Norton wheel produce a better finish? Would it make a big difference?

 

[Bob Korves]

I suppose anything can flex if it's sticking out too far, so if it were me, (I don't know squat about grinding), I would think that more support
would give a more precise finish. Putting taller blocks on the opposite side of the vise with clamps, sandwhiching the entire stone up to
the last 1/2" or so. More rigidity?? You know more than I do Bob.
Q: Would a better Norton wheel produce a better finish? Would it make a big difference?

Thanks, Emelio. Yes, that would be a good idea. Perhaps something like a 1-2-3 block. Didn't even come to mind at the time. The friction loads when grinding this stuff are pretty minimal unless you make a mistake with the depth of cut, but the results of something tall and narrow tipping into the wheel can be catastrophic. Even more so with a hard part tipping into a spinning standard grinding wheel. Instant explosion.

 

[Doubleeboy]

Bob, in your photo you have a lot of metal on the back side of the part with that vise, I think it would be fine as long as you are taking light cuts of a tenth or so. When I did my stones my last 3 passes were 25millionths, I think the force of the flood coolant was more than the force of the grinding wheel. Not being Robben or a REAL grinding hand I don't know how well they came out, but on my near new chuck on surface grinder the stones skate across the surface with very little force and no lube or any kind. In my view it was a worthy project. I sure wish I could find those Norton 4 x 2 combo India stones that use to be prevalent in every hardware store. I have only one and would love to have more , they are a handy size for stoning mills and tools in general. Nice photos!!

michael

 

[Bob Korves]

Q: Would a better Norton wheel produce a better finish? Would it make a big difference?

The cheap Shars wheel is now doing a fine job. It was only off about .001" radially when new and had a few striations in the face. I dressed those out pretty easily. The wheel has been if beautiful balance from the beginning. Others who have purchased them have been a lot less happy with what they received. It took about half an hour to dress out the .001" runout and most of the other imperfections. Grinding the first two stones pretty much cleaned up the rest, and has been getting better with use. The wheel needs to be used by plunge cutting the entire wheel face as much as possible to help the final truing of the wheel diameter and face. For getting the stones really flat it helps a lot to use a small step over on the final couple light passes.

A Norton wheel would be a big help out of the gate. It will likely be truer and better in every way. It is just the cost of it... There are additional issues that can come up from the wheel adapter and the grinder spindle that can and will cause problems no matter how good the wheel is.

 

[Dabbler]

A Norton wheel would be a big help out of the gate. It will likely be truer and better in every way. It is just the cost of it...

yeah. the corresponding Norton stone here is over $500, for a 6 incher. I didn't even inquire about the 7 inch wheel...

 

[Bob Korves]

Here is how to dress and true a diamond wheel: