Thread: Lapping a lapping stone - ceramic tile?

So maybe I should just pick up a piece of glass, rather than using the ceramic tile? The key here is, I'm going to lap it, just to put my mind at ease, but on what surface?

My Dad was a tool and die maker most of his adult life. In an age where CAD-CAM and EDM machining was just coming into vogue in the late 80's and early 90's he was still much sought after for techniques he'd perfected over decades of sheer skull-sweat and improvisation.

He had this lump of granite about 2 ft square and maybe 8 inches thick he kept at his bench for setting up projects and I remember him handing me a surface dial indicator to run over the surface of that stone. From end to end, any direction, it varied in height by a few thousandths of an inch or less. Big "wow" factor there. He said the stone was his most expensive piece of equipment.

So how flat is flat?

Years later I took glider piloting lessons from a UH physicist in Honolulu, optics guy name of "Buzz" (who worked on the problem of "what happened to Hubble's mirrors") who explained to me that the surface of the mirror on the Hubble space telescope was so finely ground and polished, that if you were to expand it to the size of the USA, coast to coast, it wouldn't vary in height by more than an inch. (kind of like Nebraska is now if you've ever driven it).

I don't' think we need precision on either scale to hone razors. At least I say that now. I'm sure flatter is better, but I think a thick enough piece of glass (or ceramic tile) will work fine. Seemed to work okay for me today, I'll test it out soon enough.

Norm

Dammit, I chipped the 1k side of my Norton . I dinged it against the handle of my espresso machine as I finished rinsing it. Piss me off.

I guess it probably won't affect honing, but still annoying!

Anyway, to update, I lapped the 1k on 400 grit paper on the ceramic tile and it came out quite smooth (apart from the chip). I also hit the 4k Norton on the 400 Grit for a while, after giving it a good working-over with the flattening stone. The 400 grit sandpaper worked faster than the 220-grit flattening stone. The 4k side of my hone looks like it still needs more lapping, as it has areas that aren't smooth. I've been told I need to lap a good 1/8" from both the 4k and the 8k, so I think I have quite a bit more to go.

Originally Posted by jdto

Anyway, to update, I lapped the 1k on 400 grit paper on the ceramic tile and it came out quite smooth (apart from the chip). I also hit the 4k Norton on the 400 Grit for a while, after giving it a good working-over with the flattening stone. The 400 grit sandpaper worked faster than the 220-grit flattening stone. The 4k side of my hone looks like it still needs more lapping, as it has areas that aren't smooth. I've been told I need to lap a good 1/8" from both the 4k and the 8k, so I think I have quite a bit more to go.

Especially the 4k (at least mine)

Make a pencil grid on the surface to be flattened, when it's all gone your hone is flat.

Ceramic tile isn't flat enough.

Granite tile, or marble tile, is much flatter. I got a piece of granite tile at Home Depot for about $10, and it seems to work OK.

Charles

Ok, thanks for that. I guess I'll try to swing by Home Depot, then.

Originally Posted by cpcohen1945

Ceramic tile isn't flat enough.

Granite tile, or marble tile, is much flatter. I got a piece of granite tile at Home Depot for about $10, and it seems to work OK.

I agree. Ceramic tile can have lots of variance, including a domed center.

Years ago, I found a piece of glass next to a trash bin. It looked to be a wall shelf or part of a table top. It's flat and about a 3/8" thick. It now sits in my workshop for lapping and other uses.

The grid method mentioned above is a easily and true way to find out the flatness of the stone. The pencil lead won't harm it.