Printable View
Is it useful, practical or even a good idea to lap 2 identical stones against each other with a little abrasive in between ? Both have been previously lapped using 14 micron diamond polishing compound and I'd like to go up to 7 micron or possibly 3 micron. I'm not talking just sawing back and forth but careful circles, 8's and end swapping , making sure all surfaces are getting contact. My assumption is that finer grits there will be less chance of getting something out of whack.
Sounds like it would work if you could keep the abrasive between them.
That's basically how I polished all of my stones, minus the addition of grit. I used hones that were already flattened and rubbed them against the one I wanted polished in progression. So I imagine using increasingly smaller grit between two flat rocks is the same.
Quote:
Originally Posted by duke762
They will grade each other and both nearly stop cutting, but they will release a small number of particles. I think you'll probably find at this point that you have stones with diamonds embedded in them, but I could be wrong.
For sharpening razors, you only need as flat as a diamond hone will do, and you don't want to lap the finish stones after you get them settled in, anyway. If you only sharpened your razor, your stones only need to be consistent, they don't even need to be flat (which is seen when a barber's favorite escher shows up with a long gradual dip in it - well, we don't see that so often, but I had a 2x10 escher years ago that had half of its thickness worn away and a good amount of dip/sway).
At any rate, I wouldn't rub them on a regular basis unless they are bevel setters. If you find deep scratches in razors with them now, you may need to lap the surface off a little bit to get rid of the diamonds.
They would already need to be flat or very close to it, and you regularly would need to rotate the stones. Even then you are at risk of them becoming less flat.
Imagine if one was perfectly flat and the other was only slightly concaved. As the two are rubbed together, rather than both becoming flat, the formerly flat one could become convexed while the other could remain concaved.
Rubbing them against one another is a bad idea...they tend to push the grit outwards and keep in mind that one area of the hone is in contact more then the oters...the center...
Take for instance rubbing your hands flat togeter...the palm of your hand is seeing more.friction then your fingers because it's the point that always stays in contact... fingers are in contact half of the time.
Translate this into what you want to do...and add the grit...grit should work more on the central area of the stone and less on the ends....and anyway once the stones dont overlap the grit will just be scraped off.
So that's about the technique...
There is a second problem regarding the purpouse of such a fine lapping.
I rarely see people preparing hones with more then 1-2k grit.
If the hone's surface is flat you can burnish it with a rubbing stone/slurry stone...of the same kind...or diffrent but similar grit...that will get your syrface prepared.
Going that high up means costs and extra work and for what bebnefit...
And the thaught that pieces of diamond could remain embeded in my hone kind of scares.me:))
somewhere we had a discussion on this and it was mentioned that granite inspection plates were made perfectly flat by rubbing 3 plates together in a certain order. it seems that using just 2 won't get them perfectly flat.
No, two will just get them to mirror the out of flatness that they have.
I should clarify what I said above about the two stones grading each other and then stopping cutting (i meant stop cutting each other). That much is true, but they will still be a lot more "awake" than they would be if they were just left alone, which is the preferred thing to do with a finish stone.
Any partially awake arkansas stone with loose particles is going to be too coarse to do its best work finishing razors.
I am not sure why you wouldn't just use loose grit on a cookie sheet, glass plate, piece of granite, etc? The loose grit is pretty cheap. What am I missing here?
Also, there is no shortcut or fast 'n easy way to lap arkies :)
No kidding-After doing four this summer, the thought of ever doing it again would fill me with dread. I'm just going to enjoy the ones I've got for now.Quote:
Originally Posted by kelbro
Coarse diamond hone. They are pretty tough on most sandpaper.
If flatness is out more than a little bit, a line of contact on the metal drum on the end of a belt sander is a good way to go, but it must be done outside as I'm sure the dust is terrible for our lungs (don't know if it's the same as silica in effect since it's transformed from silica somewhat, but silica is a known carcinogen and is practically so in more than small quantities).
Cheapest belt you can find for the belt sander if you do it, something in the 80 grit range. It'll smell like fire, even when you do it outside, and you'll see evidence (in terms of a line of light) of extremely high temperatures at the point of contact. It's fast, though, and if you're accurate by checking progress often, it's accurate enough to get you to where you can use a diamond hone.
Not something you do every day, but if you ever pick up a heavily used very thick older hone, you can knock the high ends off of it in a matter of minutes and be ready to finish lap it.
Yes, a specific three stone sequence is the only way to get them flat when you are rubbing two hones together for flattening.Quote:
Originally Posted by tintin
To do the "grunt work" lapping old found Arkansas stones I use a 16 x 8 x 2 concrete block with water and plain ol' sand. Adding water and sand often. Still, it's a lot of work no way around it.
This is relatively effective for getting it close, then I usually use wet/dry sandpaper on a flat surface such as glass for the little bit of finishing up. Though I suspect there is a better method of finishing up than the wet/dry sandpaper, I made do with what I have.
Attachment 270599
Attachment 270600
Attachment 270601
