Thread: Lapping Question

I purchased a new set of new Naniwa hones that i will give their first lapping with a DMT 325 over the weekend. I understand that lapping is necessary to give seemingly flat stones a true flatness necessary to optimally sharpen blades. Obviously it would be supremely important that the lapping stone be truly flat. Are lappers such as the DMT 325 built with a higher degree of precision and tolerance so as to guarantee that they are truly flat from the factory?

DMT are supposed to be very flat.
If you have a flat granite plot you can do the lapping on it with sand paper.
You need flat stones but not micron precision flat.

As Stefan said they are very flat, but they do make mistakes. I have checked all of mine with a straight edge and they have all been great. If yours isn't flat contact the company, they have been very helpful with other SRP members in the past.

I use a 325 DMT to lap all my hones and it works great.

Make sure you thoroughly wet the Naniwas before you hone them. They warp as they get wet so you need to saturate them then lap them, and then always resaturate them before use.

Originally Posted by Stubear

I use a 325 DMT to lap all my hones and it works great.

Make sure you thoroughly wet the Naniwas before you hone them. They warp as they get wet so you need to saturate them then lap them, and then always resaturate them before use.

+10 on that! This is why I mostly use my GS's any more....

Besides the flatness issue/non-issue Naniwa's and Nortons have a top layer that just needs to be removed before they start honing their best.. I didn't notice this on my Shapton's but it has been some time since I bought those..
At the Denver meet John brought a new set of Norton's and most of the new guys were amazed at just how much lapping was required to get the 4k/8k flat and that top layer gone...
On the Naniwa's also watch that spot where the sticker was, if you can still see that spot clearly, keep lapping and as noted above WATER is your friend...

Amen to that in regards to the Nani's...

Originally Posted by TopCat

I purchased a new set of new Naniwa hones that i will give their first lapping with a DMT 325 over the weekend. I understand that lapping is necessary to give seemingly flat stones a true flatness necessary to optimally sharpen blades. Obviously it would be supremely important that the lapping stone be truly flat. Are lappers such as the DMT 325 built with a higher degree of precision and tolerance so as to guarantee that they are truly flat from the factory?

Generally, DMT D8C are the ideal compromise between price and function.
They're fairly cheap, and generally very flat.

You can also buy non-diamond lapping stones such as the Norton lapping plate, but they wear down over time and lose their flatness.
There are also much more expensive diamond plates such as the diamond glass lapping plate from shapton, but they are not necessarily flatter or more reliable.
You can also use wet-dry sandpaper on a glass or granite plate. While that works for occasional use, it is just messy.

If you intend to use your hones, then the D8C is in my opinion a very valuable and affordable investment.

Thanks to all for the reassurance and excellent advice! Had a go today, and i very highly recommend the DMT 325 (DC8) which performed exceptionally as a lapper, making quick work on the Chosera 1k, and Naniwa 5, 8, and 12k. Probably spent an hour total on all four. Now on to the fun part...learning to hone!

Originally Posted by gssixgun

...a new set of Norton's and most of the new guys were amazed at just how much lapping was required to get the 4k/8k flat and that top layer gone...

Speaking of that, is there sort of a red-herring layer, or a "grey zone" in between a new Norton out of the box and a completely lapped one?

I spent a few hours lapping mine flat and the surfaces feel just the way that everyone describes how they should feel (smooth on 4k, silky smooth on 8k), but I see everyone talking about having to lop off as much as an 8th of an inch, and I took off less than a 64th from each side. Never noticed any grittiness below the original surface.

Did I just get lucky?