Thread: How did barbers hone a wedge in the olden days?

you are probably right John

I don't know what to tell ya Ivan

You have decided that all those recommendations for this 3 surface method are wrong and you're right,, this method is all over the place it has a long track record with Tool guys.. It doesn't seem logical that the method would be used for so many years when it requires 3 stones instead of 2 if it wasn't needed..

Reading about using hand lapping methods even using a Reference Plate warns of the problem of creating convex and concave surfaces and that the Reference Plate needs to be re-flattened over time.. Pretty much flies in the face of your two stone method

Now in practical terms I am in agreement and so is most of the reference material that two surfaces can be used to get both surfaces smooth but it often comes with warnings about the flatness of those two surfaces...





Here is what I know for a fact, using the Norton Lapping stone and the Norton 1-4-8 for a few years resulted a very uneven lapping plate, I chalked it up to human error.. Then I bought a DMT 325 and moved on

Originally Posted by gugi

A recommendation is only as good as the recommender. When guys on military missions in the jungle have been both trained and successful in lapping two stones flat it doesn't really matter to me that a desk jockey insists three is the minimum number needed.

We've all heard plenty of 'old wisdom' that is pure garbage and plenty that isn't.
In my book understanding is always better than not understanding but I have zero interest convincing people they're wrong. Everybody is free to do things any way they like - the dumb way may just as well get you to the same place as the smart way would.


This isn't the process of lapping hones by rubbing them together, but rather something completely different. It is a process for verification that a flatness is achieved You keep one surface as 'reference' and remove material from the other by some means, then you check against the reference if there are any 'gaps'.
There is no motion whatsoever between any two surfaces he is looking at. If you allow motion you'll clearly see the gaps even with two surfaces and you don't need three:
Attachment 201383


Three surfaces are absolutely necessary for verifying flatness (i.e. zero curvature) by static matching, but they are not necessary for achieving it.

First things first, I had nothing to do with the straight edge link. I think that says something right there about your concern for accuracy. The link I posted describes lapping the items against each other, which I guess you didn't bother to read again, because you are convinced that you simply can't be wrong. That said, you are still not correct, no matter how much you want to argue the point. Military guys out in the field do things all the time that are "field expedient." What this means is that they make do with what they've got, whether it gets the job done optimally or not. They are concerned with getting what needs to be done, done. Regardless of whether it works as well as the correct, optimal or better way to do things. I can see that no matter what is said and by whom, that you think you will always be correct, so it's pointless to continue this discussion. Good day.

Originally Posted by eKretz

What I take issue with is the blatant misinformation being spread around. Rubbing two stones together will NOT result in flat surfaces. As they are rubbed together, one will take on a concave spherical surface and the other a convex spherical surface. This is a fact, not an opinion, despite all the pecking by you and the guys that are like old mother hens around here.

This is where you are wrong - it is not a fact, it is a false assertion. You can certainly rub two spherical surfaces together around their center and keep them spherical, but only as long as the only motion is rotation around their common center. That doesn't resemble even remotely the process of lapping. The moment you move the centers of the two spheres apart you begin to flatten the surfaces.

Originally Posted by eKretz

Try reading a factual reference book, like "Foundations of Mechanical Accuracy" by Wayne R. Moore. Or even search for it yourself. Since you are such a tinfoil hat conspiracy theorist regarding Google (oops, found it with Google!) and I know you won't be buying the book, try this link written by a CWU scholar. Section 4.3 is the pertinent information to 3 stone or item flattening, but the rest is good reading for anyone interested in lapping.

https://www.google.com/url?sa=t&sour...KB5GGRbS4v_DRA

Reading a book is not the same as understanding it, and so far you seem to be missing the later part.

4.3 Refinement of Form
Principle 6: If two surfaces are rubbed together with abrasive between them, they will eventually be in contact over their entire areas. The nature of the resulting surface depends on the path of the rubbing motion.
Principle 7: Two surfaces in contact at all relative positions and orientations must be spherical.
Principle 8: Three surfaces, each in contact with the other two in all relative positions and orientations, must be flat.

It is absolutely correct and has nothing to do with creating flat surfaces. Reread section 3.3. and add the part that he missed about the 'high spots of the work' that are in contact with the reference surface are the same but the contact counterparts on the reference surface are distributed.

Just to clarify

We all agree that the 3 surfaces work

Ivan you just don't think 3 surfaces are needed and that 2 will work also

We all agree that nobody needs this method for SR honing in 2015 because we have referenced Diamond Lapping plates


Yep that is something to argue about alright

Wait and we also have Alex who thinks we need a concave hone anyway to hone wedges correctly like they did in the old days
Which we also don't need regardless because we have Electrical tape in 2015

Whooooo hooooo yep real minutia here in this thread alright

Originally Posted by gssixgun

Just to clarify

We all agree that the 3 surfaces work

Ivan you just don't think 3 surfaces are needed and that 2 will work also

We all agree that nobody needs this method for SR honing in 2015


Yep that is something to argue about alright

That is correct. Somebody is insisting that I am spreading misinformation but so far nobody is able to defend the need for this more complicated way. The best argument presented is "we don't really know, but lots of people are into it so they must be right" which doesn't quite cut it for me because (1) there is no theoretical justification (2) people have been successful in practice without the complication (yes they have to know what they're doing and avoid a particular pitfall that the complication is trying to fix).

Originally Posted by gssixgun

I don't know what to tell ya Ivan

You have decided that all those recommendations for this 3 surface method are wrong and you're right,, this method is all over the place it has a long track record with Tool guys.. It doesn't seem logical that the method would be used for so many years when it requires 3 stones instead of 2 if it wasn't needed..

Reading about using hand lapping methods even using a Reference Plate warns of the problem of creating convex and concave surfaces and that the Reference Plate needs to be re-flattened over time.. Pretty much flies in the face of your two stone method

Now in practical terms I am in agreement and so is most of the reference material that two surfaces can be used to get both surfaces smooth but it often comes with warnings about the flatness of those two surfaces...





Here is what I know for a fact, using the Norton Lapping stone and the Norton 1-4-8 for a few years resulted a very uneven lapping plate, I chalked it up to human error.. Then I bought a DMT 325 and moved on

I actually know what is the problem they are trying to solve and why they have it - unless one puts in conscious effort hand lapping is largely anisotropic so it leaves curvature in one direction. To a degree that is due to hones being rectangular and not circular or at least square (ergonomics) and figure-8 lapping is an attempt to compensate a bit, but it's not perfect.
Still if one is aware about the potential issue and makes sure to rub the hones in 'all directions' they will end up flat.

Originally Posted by gugi

Still if one is aware about the potential issue and makes sure to rub the hones in 'all directions' they will end up flat.

Prove it... See this is where the info out there disagrees with you, yet you simply keep claiming it anyway

So prove it,,, Smooth yes, Flat no.. especially over time the surfaces will go out of true flat, so show me a reference to what you claim...

Originally Posted by gssixgun

Prove it... See this is where the info out there disagrees with you, yet you simply keep claiming it anyway

So prove it,,, Smooth yes, Flat no.. especially over time the surfaces will go out of true flat

Define 'proof'. Go back to 2007-2008 and find the thread where lapping in the south american jungle was posted about.

If you want the mathematical proof I already pointed out the important point, but I can write it up in details as well. But if you're gonna make me do that work you have to accept/refute it based on its merit not on some irrelevant and unverifiable argument about 'experience'.

Originally Posted by eKretz

That said, you are still not correct, no matter how much you want to argue the point. Military guys out in the field do things all the time that are "field expedient." What this means is that they make do with what they've got, whether it gets the job done optimally or not. They are concerned with getting what needs to be done, done. Regardless of whether it works as well as the correct, optimal or better way to do things.

Up until now your disagreement was that rubbing together two surfaces only can never work to make them flat, not that three is better. That's the whole reason you picked this tangent in post 68.

And yes, the job gets done, that was the whole point of the guy posting about it - knowing how to use what you have as most people are long on tools and short on the ability to handle them.

Who gives a sh*t. Honestly it doesn't matter how they get flat. I thought this thread was how did barbers hone a wedge back in the day not how to get a stone flat...