Thread: Did I lap properly?

Originally Posted by jammyman34

hey guys, quick question... I have an 4k/8k norton and I have norton's lapping stone. I've gone through the pencil matrix thing several times and yet my razor still doesn't seem to be lying flat on the surface. So I assume either the hone isn't actually flat, the razor isn't straight or both?

My lapping process is:
1) draw the pencil matrix
2) hold the lapping stone in my left hand, motionless over the sink
3) hold the hone in my right hand
4) place the hone flat against the lapping stone and move it in smallish circles until the pencil matrix is gone, occassionly rinsing the residue off under water.
4.1) repeat if neccessary.

needless to say my razor won't even cut arm hare what am I doing wrong?

I prefer having a small constant flow of water clearing away the slurry during lapping. Assuming that your Norton lapping stone started flat and it has completely removed the grid, then the hone should be flat. You can check it by holding a straight edge up to it and see if you see light in the gap.
As far as the razor being straight, that seems to be rare thing in my experience. That is the reason that the x-stroke, 45 degree stroke, and rolling-x are so frequently recommended around here. They ensure that the entire length of the edge contacts the hone at some point during the stroke.

Thanks Utopian, I tried the straight edge test and it appears that lengthwise it's not flat, when I hold the far sie down there appears to be just about a milliemeters worth of space, maybe half a MM...

So, I gotta tell ya I'm a little ****ed. I've matrixed and lapped that damn thing maybe 15 times already using the norton flattening stone. If that stone isn't flat to begin with then why the heck are they selling it that way? I mean if I have to ensure that the flattening stone is flat using the sand paper method as described in the wiki why wouldn't I just do that for the hone?! What's the damn point of buying a flattening stone!!

I suppose using a straight edge on the flattenig stone will work for testing it's flatness as well?

Thanks again, sorry for my complaining...

OK, take a deep breath, chant a mantra, and consider...

It IS possible that your lapping stone is no longer flat.

Over time if you are not using uniform pressure on the entire surface of the lapping stone, it can become distorted. I lap as described previously with the hone in one hand and a DMTXX in the other. While doing that I regularly swap which way I am holding each of them. Say I'll do twenty circles and then swap the hone end for end in my hand. Then I'll do twenty more and swap it again. I also occasionally swap the DMT end for end as well. I do this because the pressure from my hands is not likely creating uniform force between the hone and the plate. By swapping the regions that are coming in contact with each other, I am hoping that the wear is averaged out. Perhaps your lapping stone started flat but uneven pressure has worn one end more? I'm not accusing, I'm speculating!

At this point, it sounds like you do need to lap your lapper with sandpaper. Once you know it is flat, go back and try lapping your 4/8k again, this time occasionally swapping ends. Try to use uniform pressure. Don't use a lot of pressure. Use a light but constant stream of water. Finally, don't use the Norton lapper on anything but the 4/8k, especially don't use it on a natural or barber hone as they are too hard and the wrong size. Once you have the lapper flat and you are diligent about balancing the pressure and contact between the lapper and the hones, they should continually be lapping each other. In other words, I believe if you are using the Norton lapping stone correctly, it should remain perfectly flat. If it is not, then you are likely doing something wrong.

Good luck!

Thanks again Utopian... looks like I'm off to Lowes to get some wet/dry sandpaper and start this party over

Alright, so last week I found some 320 wet/dry grit at home depot and did some major flattening. Took about 45 mins or so to do the 4K side. I must have gotten that thing crazy out of whack with the norton flattening stone.

However, it also appears that my norton flattening stone is indeed flat. I tested this with a straight age, just as was suggested I do for the hone and it appears to be flat. So my guess is that when using the flattening stone it would be best to place the stone on a flat surface and go through the motions just like you would do when using the wet/dry sandpaper technique, though I have yet to try this out myself. Has anyone used the flattening stone with any success? Any comments on the best techinque?

At this point I feel as though I'd recommend the sandpaper route, pretty easy and cheap, but since I have the flattening stone I'm curious...

Thanks all for the tips!

Part of the problem is that even if your flattening stone is truly flat, you can cause uneven wear if the forces aren't evenly distributed. Not just the force you apply, and gravity, but also the forces caused by acceleration as you move the hone around. (Think of how a car's suspension reacts as you speed up/slow down.)

I try to get around this by resting the hone on the flattening stone. I grip the hone very lightly at either side of the middle point, and just use light force to start/keep the hone moving. I also vary between up/down, sideways, and circular strokes. Always using the lightest horizontal force possible, and letting the movement and weight of the stone do the work.

Doing it this way can be slow, but it's the best way to ensure a true flat surface IMO.