Thread: Flattening India oilstone

silicon carbide grit loose on glass or a nice flat granite tile. lubricate with water. for flattening an india stone I'd start with the coarsest grit SC you can find. those stones are tough and the SC grit will break down pretty fast.

What grit is it? Coarse, medium, fine, very fine?

Some of my first actions n the 'woodwork' area was flattening a dished old oilstone on a concrete paving slab - that was after trying the driveway.
I don't know that it (the slab) was the worst idea in the world.
I remember it as slow going as it got flatter, but then I knew nothing about what to expect.


A coarse diamond plate maybe?
Another flat, coarser oilstone?

Cheers,
Paul

Thanks for the suggestions. It's a combination coarse/fine and I bought it since it was supposed to be flattened very seldom, but now it has cupped ever so slightly which makes it rather useless for my purposes.

kaf, the quickest way to get your stone back to flat would be with a diamond lapping plate, but one of those might blow the budget. As suggested, some suitable grit and a glass or iron lapping plate is the next best solution, while Paul's concrete slab trick would be fine to get it pretty close

I keep various bits of broken & worn-out stones which I re-shape for special jobs - it's very easy to 'file' them with equivalent stones, so you could just buy another stone & use that to keep them both flat? I've accumulated a small collection of stones over the years, India, Carborundum, & Arkansas. I use them in different permutations to keep them all flat - if you check them on a regular basis it doesn't take much effort to keep them nice & flat. It's easy enough to remove a 'dish' using two stones of similar size, but you do need to be careful you don't cause convexity over the long axis.

It's a pita having to maintain stones, but it has to be done, & it's an unfortunate rule of thumb that the quicker-cutting stones need more frequent attention, so you make your decisions accordingly. I find India stones to be a good compromise between cutting speed & rate of wear, their main limitation is the narrow range of grits that is readily available. If you wish to avoid stone maintenance altogether, the only solution is to lash out on expensive diamond thingies, but even those need checking regularly - I've got a largish plate that has warped a little!

Cheers,

Originally Posted by IanW

expensive diamond thingies, but even those need checking regularly - I've got a largish plate that has warped a little!

Wanna borrow my slab?
Paul

Originally Posted by pmcgee

Wanna borrow my slab?
Paul

Well, polished concrete seems to be the fashion of the day over here, Paul, so if that's what you want, ship your slab over here & I'll see what I can do for you. It may take some time....


There's just nothing you can do about a warped plate, unfortunately. It has developed a very slight convexity across the narrow axis. This is my fault, because it was originally a double-sided plate, with the two bits of steel glued to a plastic core. The glue gave way after a year or so (I don't think it liked the hot tin shed it was stored in), so I thought I'd copy a smaller diamond stone I have & glue them to a piece of wood. I used a good-sized chunk of perfectly quarter-cut, well-seasoned Spotted Gum, & stuck the suckers down real good, with epoxy. Well, I should've used a more forgiving glue, 'cos the wood has moved slightly under one of them, & taken the plate with it (wood always moves, right? How could I forget that!).

Now any blade run long-ways ends up with a slight hollow. It's only a thou' or less across the 3" width, but that really wrecks a smoother blade - about the worst possible result. I still use it, but only cross-wise, which is actually ok. I've always been a freehand sharpener, & using short strokes makes it easier to keep the bevel flat & constant, so it's not a total loss. However, I can't use it for flattening any of my composite stones, which is a nuisance.

Cheers,

Cheers IanW )

I have been considering a diamond stone earlier on, so maybe I will go ahead and buy one. Are you sure it will deal with the india? And hey have a look at http://www.dianova-ab.com/en/sortime...apstone-table/ , the diamonds a glued to a glass surface, so it should keep flat pretty much during it's lifespan. However I don't know anything about the quality.

I was also thinking about one them blue belt sander belts. Has anyone had experience with one of these?

Ive used silica carbide on glass and diamond plates . The silica carbide on a glass plate is most certainly the better, faster way .
Diamond cuts every thing but its slow on something with the surface area of a stone .
When using the SC grit I start with 80 it does not take long for the grit to break down in to finer particles , so if you want to remove a lot you have to keep throwing some more 80 on with a little water, when you get all the hollow out just keep pushing the silica paste back in from the sides of the glass or the flat board that the glass is on, which is where it ends up, being pushed off the glass by the motion of the stone, and add no more of the 80 , the paste just gets finer and finer as you go on it ends up very fine . I just use a small piece of glass 3 or 4 mm thick about 200 x 300 mm and make sure I cover all the glass with the stone .

Rob

Yes, good point, Rob. Unless the diamonds are fairly coarse, they are rather slow, and the coarser the diamonds, the more expensive they are! (kaf, diamonds are the hardest substance on earth - they cut anything!) If you do go with a diamond plate, though, choose carefully! They aren't cheap, & price shoots up exponentially with size of plate & grit size. I hear very different attitudes to diamonds from people who've tried them. My own experience has been that the better quality plates last a very long time, but some people have complained that they got only a year or two's use out of theirs, making them a very expensive proposition! The cutting rates of all diamond plates slows down with use; quickly at first, then slowly fades over the rest of their life.

I reckon I've tried just about every method for lapping metal & stones over the years - each has its advantages & disadvantages. I used to use SC grits for lapping, & for re-habbing chisels & plane blades, not on glass but on a ground iron plate. I bought a kit from Lee Valley, more than 25 years ago. They sold the iron plate along with a selection of grits. I have only used the coarser ones because as Rob points out, they crush & become finer in use, so there is little need for the finer powders in most applications. The iron plate was said to be better than glass because the grains bite into the soft iron, which holds them while they cut the material you are lapping. The good thing about using grits and a backing plate is that it's relatively fast, is the least-cost method, and very versatile, but it's a messy business, & has to be set up/cleaned up each time, especially if you work in as confined a space as I do. Using two stones turned out to be quicker & easier, for me, as long as it's done regularly, so the lapping plate & its grits sit in a drawer & are only used very occasionally nowadays.

I think the message is that you have several choices of ways to flatten stones, each has its pros & cons, so try the method that appeals to you most....

Cheers,

Have had success with a Besser block. The sides are quite flat and you have 4 sides to choose from. Used plenty of water and it flattened my stone quite well. The only downside is that it was quite slow. The Besser block was good for me as it was of sufficient height that I could sit on a small stool and work it over. Move the stone in a figure of 8 pattern rather than just backwards and forwards.

Try this to get it flat and if you want it "better" then move to the more expensive options mentioned above.

Here is a nice video showing how its done

Good video ... but that guy looks like he's in a mocumentary!

I was waiting for something crazy to happen.

I am sure Chris Schwartz has blogged about how he used diamond stones to flatten other stones - and I have used a coarse diamond stone to flatten an India before with good results.