Thread: Lapping? What exactly is it, etc...?

What exactly is lapping? I have read some posts where someone put up a picture of a stone and was told that it needed lapping. What do you need to perform "lapping?" How do you know when you need to lap? Thanks

Originally Posted by wireless00

What exactly is lapping? I have read some posts where someone put up a picture of a stone and was told that it needed lapping. What do you need to perform "lapping?" How do you know when you need to lap? Thanks

It's pretty much the process of making the surface of your hone a flat plane. If it's not perfectly (or near-perfectly) flat then parts of your edge won't touch when honing.

There's a wiki article about it here:
Hone Lapping 101 - Straight Razor Place Wiki

My first intro to lapping was to improve contact between electrical components and a heatsink for cooling purposes.

Basically you want the two surfaces to both be as flat as possible. This is done by taking a surface you know to be flat (Back in the day I used a small but very thick windowpane (real glass)). Put a sheet of rough sandpaper on it. Sand until the scratch pattern is uniform on the surface. Then grab a finer paper, repeat. Continue going finer until you are happy. On heatsinks we usually went up to 1600grit. Most people here are happy anywhere from 120-1.2k grit. And many use a diamond hone in place of a flat surface and sandpaper. Keep in mind DMT only recommends the XX (120grit) for lapping waterstones.

Also since most stones wont show a scratch pattern very well, we draw a grid in good ol' pencil on the entire surface, and lap until it's entirely removed.

If your stone is badly uneven or very hard, prepare to spend 30mins+ rubbing it back and forth.

It just dawned on me how much money I could have saved if I'd owned a DMT set back in the day. I probably spent $300+ on sandpaper (I lapped a LOT of components and heatsinks). I wasn't even aware these things existed back then.

I just got a couple of used stones. I will go out and get some paper and lap them before I try using them. Thanks for the info.