Thread: My lapping experience

Ok, that does sound rather obscene...but here goes.

Short and sweet, bought several Nortons used, multiple sides, thought aht the surfaces which was using had been lapped - and with all due rtespect to previous owner, I think several had - so I decided to go ahead and lap with 600 grit wet/dry sand paper that I had - First the 8000 grit- drawn grid, circular motions with paper (dry) on a flat marble tile. too a little time, grid comes off- all is good, stone very smooth, but some of the grey color form the paper stays on stone.

Then I did the same with the 4000k, new paper but my grid, in the very center of the stone, will *not* disappear. Spent some 10 minutes dry and then wet the paper, because the grit was clogged and the grid still doesn't leave in the dead center! No wonder I have been having problems getting a useable edge! Man, was I annoyed - and relieved.

Now went to hone, put tape on spine, and went to town setting bevel on 4k - now I rinsed the 4k to get the grit off, but I could *not* get all the grey color off the white stone - is this going to be a problem?

What I noticed later is that there must have been some other grit on the paper, because I have several, not a lot but a few, noticeable scratches on the surface of the stone - will this kill my honing until removed?

Now I have read hat I can use one Norton stone to lap the other, how do I do this and how do I keep them flat?

Thanks,

K

Some small scratches are not a problem, bumps would be, but a small depression isn't.

Lap two stone by rubbing them together, moving one over the other in figure of eights or circles or a combination of both.

Draw a grid or diagonal lines on the stone, when five or so rubs removes all the lines the stone is flat.

Scrub the stone with a green scrubbing pad to remove sandpaper grit.

Gross alignment is no big deal with rubbing stones together but I would get a plate of glass, initially, and test it for cohesion with the stone. Then add some more lapping on the glass with wet/dry sandpaper, until you attain strong cohesion.

I'm concerned about lapping a stone with dry "wet/dry" sandpaper. Although I'm not expert on any of this, perhaps that isn't the best way to do it. I've certainly never done that. Did you read about doing that here?

Make sure you remove all the grit now embedded in the stone.

I agree that the lower grit cuts will not be a big problem. But good lapping wouldn't yield them, to me they seem to be an indicator that the dry lapping isn't such a good idea.

The norton should be soaked for ~30 minutes before lapping, and the wet/dry sandpaper should be used wet.

Thanks for the replies.

I used a marble tile for the lapping (ala Home Depot) because I could not find a pane of glass. But I know where I can get one...the marble tile seemd pretty falt to me, and cost a whole 3 bucks.

I used wet/dry sandpaper dry for the first pass (after soaking the stones) because once I wet it, it not only turns into a soup but sticks to the stone, drowns the tape holding it to the tile, and starts moving, making the lapping process end pretty quickly. The water does unclog the sand paper pretty quickly, but keeping it still becomes a major chore.

The scratches are pretty prounounced, so I think I am just going to have the lap them out - the indentation in teh 4k was very pronounced, and I think it really was the reason why I was getting what appeared to be uneven swarf marks on the stones - I am washing these things after every honing session, but water alone was not getting the swarf off the stones, so I had some foaming dial hand soap (which is pretty mild) on the sink and decided try and use the foam to lift out the discoloration, and it seems to work well - my luck it will be that I am somehow screwing the stone up doing that - any suggestions?

HOWEVER, all said and done, I took the razor to the 1m and .5m pasted paddle and test shaved last night - and it was ... amazing. I don't know if it was just that I finally had a sharp enough razor by my own hand to shave with or what, but it was the best shave I have ever had - I only did one side of my face, and then ran to the wife to have her feel the results - and even she was amazed. I will be posting picts soon.

K

Well your lapping application still needs work honestly, but your shaving sounds pretty good! I think most guys would be happy that!

Kriton,

The marble tile should work well--that's what I use.

If you soak the sandpaper for a minute or two before starting the lapping, the back will be wet. It will form a suction on the smooth marble; you don't need to tape the paper down. If the back is dry it will slide around.

I think you need to get those grooves out. I did that to my stone by trying to lap it with a smaller water hone. Get some coarser paper, maybe 320 or 220 grit. That'll make it go much faster.

The sandpaper shouldn't leave any discoloration on the stone if used wet. My white 4K is brilliant after lapping.

If you get the 1K flat with some coarse paper (220 to 400 grit) it will work very well to lap the 4K and 8K. Just keep the stones wet and rub them together.

Good luck,
Josh

I appreciate the responses - went to the flea market to day and found a 6/8 Goldedge and old square tip Henckel with notch for some serious restoration work at a reasonable price - this truly is getting out of hand.

I will post the Bengall pictures, it is something special.

Thanks for the tips Josh, I will try it again.

K

I lap with a DMT Coarse Continuous Diamond hone. I do about 10 coticules a week and have been doing that for several years. The Coarse stone doesn't clog up and I lap in the kitchen sink under warm running water to wash away the swarf. It's counterintuitive but a Coarse 325 grit stone leaves an 8000 grit coticule purring like velvet. It's quick too! I lap flat in under a minute and that goes for vintage coticules from eBay as well which are almost always dished significantly.

Don't worry about the color in the stone as long as the stone is lapped flat. Hold a straightedge onto the surface of the stone lengthwise with the straightedge on edge. If you can see light between the straightedge and the stone, you've got more work to do. I use a 6" Starrett Machinist's Rule as a straightedge and I'll send you one for $3 if you'd like (plus shipping) which should be about $1 as I could put it in an envelope.

Starrett tools are the most precise in the world and they're made in Athol, MA. I use a lot of their tools. "Flat" is a specification and not a state.

Howard,
I lapp initially with a Norton flattening stone. It make quick work of any belly on the stone and in just minutes I am ready for some finer paper. I'm sure those DMTs work wonders.
Been doing the running water trick myself to keep the grit washed away while lapping

Tony