Thread: hone lapping troubles

So, I started to lap my Chinese 12K with sandpaper... well, the paper quality wasn't very good, the finer grits kept falling apart/wearing through! But the courser grits were a little better. Anyways, now I don't know if my stone is lapped (I ran out of paper) and there are very shallow (hardly noticeable) semi-circular scratches. Looks like I'll have to try to find some better quality paper (the stuff I used was the best the store had) or even bite the bullet and pick up a lapping plate (DMT).

Were you using wet/dry sandpaper? Regular (dry) sandpaper won't work. Lapping is complete when pencil grid-lines drawn on the stone have been completely removed by the sanding.

I'm fairly certain it was wet/dry paper; albeit the labeling of the sandpaper section wasn't the greatest; I'll try another hardware store and ask next time.

stone you are trying to lap is hard stone will eat up couple more sandpapers. dmt will be better option.
good luck

If you want to try the sandpaper rout again, go to the auto store, they will have wet/dry sandpaper (auto body work).

circular movements may not be the best for lapping

If you want to check your stone you could rub some pencil over your sub-plate. Rub the stone over that to reveal any high spots

Most hardware stores in my experience do not carry wet/dry sandpaper. +1 on virtually any auto parts store carrying them. A store in my area will sell by the sheet rather than having to buy a pack. I would recommend getting even a few sheets of the closest to 100 grit, then 220, then a few sheets of 400 to finish it off.

Chris L

Originally Posted by kevint

circular movements may not be the best for lapping

If you want to check your stone you could rub some pencil over your sub-plate. Rub the stone over that to reveal any high spots

I draw a grid kind of like the old tic-tac-toe kid's game. I do sort of an X pattern in each direction alternately and then turn the stone every so often. Talking in the kitchen sink with water running to wash away the swarf and help prevent stiction. Here is tutorial by Josh Earl, a guy who used to post here a lot.

Originally Posted by JimmyHAD

I draw a grid kind of like the old tic-tac-toe kid's game. I do sort of an X pattern in each direction alternately and then turn the stone every so often. Talking in the kitchen sink with water running to wash away the swarf and help prevent stiction. Here is tutorial by Josh Earl, a guy who used to post here a lot.

Yeah, OK.

I do not use it, but understand the grid.
I do not need Josh's tutorial but thank you all the same.

The OP said he did not know if his stone was flat, and had no more sandpaper to do more lapping. My suggestion is a method to check for flatness

Quick update: well, I finally got around to properly lapping my stone! I've had a bit of extra time and thought now would be perfect. I went out and found some Norton 400 grit wet/dry (it was the lowest grit they had) as well as a piece of granite tile to be sure the surface was flat. It took about 30-40 minutes, and I redrew and lapped of a pencil grid a few times to be sure (it's hard to see the grid sometimes with the colour of the stone). I'm really happy with the surface the 400 grit paper leaves! Only went through 5 pieces (I think I could have gotten more use out of them too). Easier than I had expected (I pray it's flat!).