Thread: Lapping Plates - Glass or Granite or somthing else?

The older members remember Howard at the perfect edge, he had a lapping plate supposedly flat to .0000000000000001 or something like that. It was around the time the Shapton GS's hit, with pond etc...I always thought (IMHO) it was a bit much. As mentioned, It's razors, not rocket science.

Seems like an awful lot of trouble to go through.

Honestly I am pretty OCD about honing razors (I know hard to believe huh )

But honestly anything more than a DMT 325 or a Shapton DGLP or something along those lines is a bit of overkill..
The stones/hones just need to be clean and flat they don't have to be perfect, most of the razors aren't anyway

I am very hesitant about using anything that releases grit to lap with also, you have to be much more conscientious about cleaning your stone's surface to prevent embedding grit... This isn't a big problem in most finishers but it is on the lower grit stuff...

Just like much of what we do it becomes a trade off as to effort-vs-gain, but also they are your hones, so the final decision is ultimately yours...

I lap my hones with wet dry paper on a glass cutting board , I got at Walmart for less than $5 . It works fine for me . As some others have said , a hone doesn't need to be THAT flat . We're lapping hones , not telescope mirrors .

[QUOTE=Brighty83;881192]Thanks Geoff - i will have to see if my local one is too! Also, do you have a new bike?


I have two, Brighty, one K and one R - love them both.
It might be worth PM'ing Pauly to see if he can give you the details of his lapping plate.
He bought it around and lapped my hones for me and it did a fine job - even on the PHIG

So what i don't understand is, I'm told i have destroyed my granite plate that wasn't flat before lapping. I have been using for the last couple of months after lapping it with no troubles.

Through out the thread, the no.1 statement is "it dosnt need to be 100% flat"

I lapped it first with my DMT to get the majority flat and then finished with my glass plate that is much larger then the granite plate, and as noted on here, the glass plate by it self is more then flat enough to lapp a hone (as mentioned previously). The granite plate was noticeably out before lapping it now its, as far as i can tell 100% flat (or 99.9% flat)

Now, this plate will go out and am i supposed to through it out or why isn't it ok to maintain it the way i have, since i seem to be able to get it flat via this method. according to the comments, this plate cant be maintained and once lapped its worthless. I really think that, by saying that, the comments are miss leading people.

I'm very OCD about everything i do and if its not 100% im not happy. I just cant see how it can be decided that its not flat and that i destroyed it when no once has checked it after.

Dose this mean i need to re lapp all my hones now?



If that's the case, i have a lot of work on my hands

Originally Posted by Havachat45

I have two, Brighty, one K and one R - love them both.
It might be worth PM'ing Pauly to see if he can give you the details of his lapping plate.
He bought it around and lapped my hones for me and it did a fine job - even on the PHIG

Thanks, I want a new bike but the fiancee wont allow it..

I have enough lapping stuff to keep me going for a while but if they have a sale on I'm sure there is something else i can pick up from there

Originally Posted by Brighty83

So what i don't understand is, I'm told i have destroyed my granite plate that wasn't flat before lapping. I have been using for the last couple of months after lapping it with no troubles.

Through out the thread, the no.1 statement is "it dosnt need to be 100% flat"

I lapped it first with my DMT to get the majority flat and then finished with my glass plate that is much larger then the granite plate, and as noted on here, the glass plate by it self is more then flat enough to lapp a hone (as mentioned previously). The granite plate was noticeably out before lapping it now its, as far as i can tell 100% flat (or 99.9% flat)

I'm very OCD about everything i do and if its not 100% im not happy. I just cant see how it can be decided that its not flat now when no once has checked it after.

Brighty, the thing is that to check the flatness of the granite plate, you would
need something that is flatter than the plate itself. You used the diaflat as reference
which has a certified flattness of 0.005 whereas the granite plate should be even
flatter than that. It doesn't make sense to use something that is (supposedly) less
flat(Diaflat) to check something that should be flatter(granite plate). What you need
is a certified flat straight edge.

There is a 99.9% chance that you have reduced the flatness of the granite plate. Now from
your post I read that you were going to use abrasive powder with this plate. Well the abrasive
powder would have destroyed the flattness as well. The abrasive would have grinded away
the plate as well. Tiny amounts each time of course. But everytime you would have used it
this way would result in less flattness.

Now you don't need a certified granite plate for your purpose. It's
fun, but overkill. A 10mmthick floatglass plate is all you need. I
would advise you to buy this and also buy the thinnest floatglass
that is available in the same size as the 10mm thick floatglass.
Put the the thin plateon top of the 10mm plate and use the abrasive
powder on the the thin plate. Whenever you seethat the thin plate
has lost its flatness, discard it. There is a chance you might get the the thinfloatglass plate for free.

The 10mm floatglass will cost you about 5-10bucks. The 10mm plate s
upportsthe upper thinner plate so it won't(reduces significanly)
bend/deflect when you put pressure on it.

Not sure how much you payed for the granite plate, but don't
worry about it. It's probably still flat enough for your purpose.
If you still really want to know how flat it is, you can buy a good
certified straightedge and feel gauges. The feeler gauges are very
thin pieces of metal which you push under the ruler and the object
on which the straightedge is put on. The feeler gauges have a
certain thicknes so you can see how much certain areas are
higher or lower than they should be. A set of feeler gauges is cheap
5 bucks or so. A good certified straigtedge costs about 30-300
bucks depending on size, metal, flatness.

As for the OCD you talk about, my advice relax dude. It's all for
the fun. Forget about stones, flattness and concentrate on more
important stuff. It's just not worth it IMHO.

Sharpman

Originally Posted by Brighty83

Thanks, I want a new bike but the fiancee wont allow it..

I have enough lapping stuff to keep me going for a while but if they have a sale on I'm sure there is something else i can pick up from there

Mmmmmmmm My first wife gave me a choice one day "It's me or the bike" and then was dissappointed when I rode away.
Interesting

Those of us who are perfectionists struggle against a world of mediocrity. I use a certified granite slab with 3M 220 grit followed by a finer 400 to get the scratches out. The results are better than what I got with my DMT by hand. However, I will admit that technique trumps technology. I have seen guys sharpen on a hollowed out coticule with excellent results. And the Japanese actually prefer some cupping for sharpening the convex edge of a Samurai sword.