Flattening India stone on a cheap granite surface plate

S

ScottEnglish

Joined
Apr 11, 2020
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59
Hello.

I own a Norton IB8 combination stone. I intend flattening it by means of 80 grit silicon carbide powder on a cheap granite surface plate. Has anyone experience of doing this? If so, did it work?

I'll be using the block of granite mainly for leatherwork so am not overly concerned if it wears slightly.

Any relevant shared experience will be appreciated.

Thanks,

Scott
 
It would work fine. Unless you have feet attached to the airy points use the bottom to flatten your stones. No need to trash the good side of your plate.
 
Thanks for the suggestion of glass tiguy7. Diemaker, I did check the bottom of my surface plate for flatness and unfortunately it's far from level. It was my intention to use the underside until I checked it.

Scott
 
Scott, welcome. How far out of level is your IB8? The method you describe should work. The coarse side will go faster. If you're leveling the
fine side, that will go slower. Be sure and use a black marker on the stone, making a few diagonal lines so you can tell where your removing
material. You likely will only have to do it, this one time. Good luck, DM
 
I use granite tiles for this and the granite wears more than you might expect, especially with hard oil stones like an India. If I had a surface plate I would not use it this way.
 
ScottEnglish said:
Thanks for the suggestion of glass tiguy7. Diemaker, I did check the bottom of my surface plate for flatness and unfortunately it's far from level. It was my intention to use the underside until I checked it.

Scott
Click to expand...
You might want to rough in your stone on the bottom and see how it works. You could try leveling your granite while flattening your Norton. I am not sure how important flatness is of the reference surface when lapping your stones flat, I know they don't have to be perfect. Probably the biggest problem is if the granite gets hollowed out in the middle. When I am leveling/dressing stones I like to work on leveling my reference plate vs the sharpening stone.

The problem with glass is it is softer than most granites. Oh, and it is polished. You want a coarse surface that keeps the loose grit from skidding around, you want it to roll. Another reason to use the bottom of the surface plate, or tile.
 
FortyTwoBlades FortyTwoBlades What do you pay per square foot for 3/8" glass? The prices I've seen are several times more than the $7.50 I paid most recently for a 12" square black granite tile. (Interestingly the rough-sawn back side was flatter than the polished front side.)
 
Mr.Wizard said:
FortyTwoBlades FortyTwoBlades What do you pay per square foot for 3/8" glass? The prices I've seen are several times more than the $7.50 I paid most recently for a 12" square black granite tile. (Interestingly the rough-sawn back side was flatter than the polished front side.)
Click to expand...

It doesn't have to be anywhere near that thick. But local glass shops will often have off-cuts available quite inexpensively, which is just fine for the purpose. If you can get stone tile of reasonable flatness that's fine too, but a stone tile isn't the same as a reference plate. The relative softness of the glass doesn't matter much, nor does its polish, as that is almost immediately destroyed. I've got an old glass "cutting board" I was gifted years ago that I've been using continuously for lapping work and it dishing out doesn't seem to matter too much because it only dishes where the stone has been working, and so if I run a stone into a portion that hasn't sunk with the rest of the work surface, the stone cuts it flat. Glass was the traditional plate material of choice for the purpose for over a century and it still works fine. It's not the exclusive surface to use, but it does the job well and can usually be scavenged up easily. I've taken a short straightedge to the worn portion of my particular plate and it's actually nice and level--the only hollow one sees is when spanning a long straightedge across the full breadth of the now-lower flat center. :D
 
Mr.Wizard said:
FortyTwoBlades FortyTwoBlades What do you pay per square foot for 3/8" glass? The prices I've seen are several times more than the $7.50 I paid most recently for a 12" square black granite tile. (Interestingly the rough-sawn back side was flatter than the polished front side.)
Click to expand...

At the box store a ceramic tile at least a foot square can always be had under a dollar, even as low as .29 cents
 
bucketstove said:
Hi,
How flat does it need to be?
Esp if you're gonna use loose grit on top?
Esp coarse 80 grit / 190.00 micron (.19mm)

I'd guesstimate any floor tile is at least as flat as a
spyderco bench stone at 508 microns
Click to expand...

I mean, if it starts off a little out of true, it's gonna' lap itself flat in use. It's kind of the advantage of using the three-body abrasion method with an abrasive that's hard enough to cut the lapping plate.
 
B bucketstove I must have been in the wrong section as most of the ceramic tiles had textures or patterns on them. Nevertheless I want my base to be flat as stones that aren't can cause problems with straight razors and plane blades.

FortyTwoBlades FortyTwoBlades Smoother, sure, but flatter? Maybe it's a technique thing but my previous lapping base became less flat in use. I tried to spread wear but it still became dished. (When I get three dished tiles I'll lap them together to find reference flat again. That's not what you mean, is it?)
 
Thanks to everyone for your input and to David Martin for the welcome. I've decided to follow Diemaker's advice and use the underside of my surface plate which hopefully will be flatter along with the India stone after lapping.

Scott
 
The 3 plate method requires 3 plates that are identical, a big plate and a small stone don't work the same. In leveling a stone your action is more akin to leveling a granite surface plate, if you knew where the high spots are. I find a decent pair of calipers to measure my stone as I flatten it are invaluable. All my stones are mounted on EP blanks so the backs are a great reference.

Porcelain tile is the hardest surface we can get for a reasonable price. The problem is many are textured and even if they are meant to be flat they are probably warped. My favorite flats are Cambria engineered quartz. They develop a nice texture that really enhances the cutting action of the abrasive.
 
Mr.Wizard said:
B bucketstove I must have been in the wrong section as most of the ceramic tiles had textures or patterns on them. Nevertheless I want my base to be flat as stones that aren't can cause problems with straight razors and plane blades.

FortyTwoBlades FortyTwoBlades Smoother, sure, but flatter? Maybe it's a technique thing but my previous lapping base became less flat in use. I tried to spread wear but it still became dished. (When I get three dished tiles I'll lap them together to find reference flat again. That's not what you mean, is it?)
Click to expand...

In my experience with lapping on glass you do dish out the glass, but the dished region is flat-bottomed. Because the abrasive is so much harder than the glass, if the stone brushes up against the slope of the sides of the dished region it's going to mostly just abrade the glass, and it's going to be in the form of two-body abrasion. In the region where the three-body abrasion is occurring it stays well more than flat enough for the purposes of manual sharpening. If I span a straight edge across the full length of the hollow, yeah, it's hollow. But if I use the short end of the straight edge at just about anywhere inside the worn portion there's no visible dishing under the shorter straightedge length. It's like an inverted mesa -- a lowered flat region with a sloped perimeter.
 
Hi
My 12inch non textured tile (wall/floor tile I used on wall)
its flatter than base of my empire rafter square
as in I cant slide one sheet of printer underneath the edge of my rafter square
but I can slide a sheet of printer paper under the base
and I can see sunshine spots coming through
its brand new

I looked at the 3 plate method , its 3 plates that are identical, and you're rubbing the stone front to back, straight line, no figure 8s ...

I've used a textured floor tile (lengthwise wood texture grooves)
I've even used the back of this tile (slanted lines)
I used figure 8s, switched orientations, sides,
I mark a grid on stone with pencil or marker and grind until flat
I check stone corner to corner with a ruler
Looks flat


I repeat my question, how flat does it need to be? Eyeball flat?
How smooth/rough does the surface need to be? How much light under ruler?
I cant imagine this isn't flat enough for any kind of chisel/plane/straightrazor
apparently its as flat or flatter than spyderco benchstones
 
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