Chips&More (Dave)'s comment earlier in the thread and yours puzzled me until I started reading about gage block stones.Usually a granite rubbing block is used to detect burrs
Yes Rex, I have been using a granite surface plate for a very long time for such purposes. I didn’t mention it earlier, sorry, but I also apply some Starrett granite cleaner as I’m doing the deburring. It really helps keep the shiners/skid marks off the surface of the stone if nothing else. The stone I use is about 9” X 12”. That kind of real estate is another big advantage over the smaller examples. I’m seeing on fleaBay that a replacement, if I bought new, would be about 50 bucks. Both the surface plate and sharpening stone are a good solution to deburr. I’m not deburring every day in my shop. It’s not a priority. But, it is a needed capability in my shop from time to time…DaveChips&More (Dave)'s comment earlier in the thread and yours puzzled me until I started reading about gage block stones.
Starrett still sells stones expressly for removing burrs from gage blocks, which is simply amazing to me. See page 408 of their current catalog:
View attachment 237871
The cheapest of them (for steel) appears to just be a small piece of granite that is precision ground. For ceramic or carbide they recommend their aluminum oxide stones (the larger one has serrations which apparently helps with the "feel" per Starrett). The granite stone is what has my attention, though.
I think Dave may have it exactly right. The cheapest option for a "precision ground stone" may be simply a small, cheap granite surface plate.
I'd be willing to bet that rubbing a hardened and ground part on a surface plate would burnish and identify high spots identically to what you see in Robin's video.
Anyone here ever used any of those Starrett stones?
Hi Bob, after a surface has been blemished it can no longer be the same. So then what? Do you remove the high spot(s)? Or do you try and push them back to where they were? When I recondition my Bridgeport mill table, I DO NOT RUN A FILE OVER ITS SURFACE. Instead, I have a large flat and heavy piece of cast iron that I slide all over the top of the table. This method burnishes the table. I dislike the thought of filing metal off. That will only change the landscape forever. If my precision whatever has a blemish and I’m concerned about it. I’m not that eager to try and remove it. I would rather burnish it. This of course depends on many factors. But I would try and burnish first…DaveThat could be difficult to take to the work, depending on size, shape, and location. I also agree with Jon that it would only burnish, not remove burs.
If you are ever down in Montebello, go to Standridge Granite and talk them out of some cutoffs from making surface plates. Or any other surface plate maker, or tombstone maker, counter top maker or installer, or whatever. They should be free or dirt cheap. I would certainly not try cutting up granite myself. You will still need something like a surface grinder or similar to get the material flat enough so it will not damage the precision hardened steel surfaces when they are rubbed. I think the flattened India stones make the most sense over all, and the cost of the stones is negligible in the big picture. It is like the guys who want to make their own surface plates. By the time you get together all the stuff needed to make, calibrate, and qualify one, and work the learning curve, the couple/few hundred dollars one costs factory made pales when Standridge can whip out in a short time in a factory to a known and tested quantity. Why reinvent the wheel? At some point we should make the parts that all the fancy tooling is designed to help achieve. I know, life is a journey. Enjoy the ride. But, along the road, don't forget to also savor the fruits...Intuitively, I'd also think that a granite surface plate would be terrible for removing a burr after dinging a precision ground surface. My intuition says a granite plate would only be good for burnishing and not for removing a burr.
Yet Starrett sells a granite stone expressly for removing such burrs. Dave also reports success doing the same on a surface plate.
I'm inclined to believe (especially with my humiliating lack of a surface grinder) that a precision ground 2" wide granite parallel might make a passable replacement for a precision ground stone like Robin shows in his video. Robin's stones might work better or faster due to the porosity of an India stone, but a shop grade granite surface plate might actually be cheaper than the commercial $500 stones that Robin mentions (for those of us that can't make our own).
It might take some time and effort with an abrasive stone cutter or chisel, but a $30 surface plate could make a a half dozen or more small hand stones. I'm tempted to try it.
This sounds truly outrageous, but I'm also wondering if a granite plate couldn't also be used as the final step to make a "precision ground" India stone. I want to try flattening an India stone on a diamond plate to get it relatively flat, then lapping it on a granite surface plate directly! I'm probably missing something, but I just don't understand why a stone lapped like that would have a substantially different surface than an India stone ground with a diamond wheel.
This is all just a gedanken experiment for me at this point though. I have no experience at all with any of this.
Sorry, Bob. I seem to have riled you.By the time you get together all the stuff needed to make, calibrate, and qualify one, and work the learning curve, the couple/few hundred dollars one costs factory made pales when Standridge can whip out in a short time in a factory to a known and tested quantity.
Sorry if it sounded like I was riled, I often write more passionately than I actually feel. A remnant of strict schooling...Sorry, Bob. I seem to have riled you.
I'm talking (out of at least one orifice) about breaking a cheap $30 or $40 surface plate into a few pieces to play with, not attempting to flatten granite to surface plate standards in my garage! I'm pretty sure those pieces will have a surface as flat as anything I could make with my (nonexistent) surface grinder and an India stone.
I wouldn't take a piece of hardened steel to anyone's expensive certified plate.
Those cheap offshore granite plates aren't up to standridge standards, but they are pretty flat and surely flatter than a surface ground piece of soft aluminum oxide, aren't they? They are also cheap enough to use as a stone to remove burrs.
Until you shut me up by sending me a couple of the stones you're making I'll keep thinking out loud since I don't have the means of making my own. ;-)
Most stone counter tops are polished. That might defeat the purpose. Some stone counter tops are honed leaving a dull finish which might be more appropriate. I would be skeptical of the flatness.Sorry if it sounded like I was riled, I often write more passionately than I actually feel. A remnant of strict schooling...
I think I would leave any surface plate intact, even if it is destined for rubbing and lapping. A small cheap one would be fine for rubbing pieces on. Then I would find some granite remnants from a counter top installer for hand held stones for rubbing the parts. They should be flat enough for that (?)
7" O.D., 150 grit, 1-1/4" bore, 1/2" wide, 1/8" thick resin bonded media, 100% concentration. I just ordered one of that description from Shars, p/n 505-2233. $81.00 plus freight from Shars, $91.00 and free shipping on eBay. I went with the eBay order, saved about five bucks. I also ordered the stones today, Norton 6 x 2 x 1" combination aluminum oxide, part number 05108568. $15.99 each.
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...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.
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.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?
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.Q: Would a better Norton wheel produce a better finish? Would it make a big difference?
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