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

Originally Posted by gssixgun

I am pretty sure that rubbing 2 like stones together will not result in flat, what I am not convinced of is that it will result in Convex and Concave surfaces .. That part I have to see for myself...

And I keep saying it will end up flat no matter what. The problem is the time and effort to get there, so if you want to see it happen you have to work with quickly abrading surfaces and reasonable definition of flatness. This is not a limitation though, only practical means to make it observable.
I never specified a time scale in my statement as it is irrelevant - it's about you what the asymptotic result is not about how long it takes to get there - but I think it is observable with our hones, our requirements for flatness and within a time somebody like us may be willing to spend (we sometimes read about people spending hours to hone a razor).

With specialized equipment that you can measure small changes you could see that rubbing two curved surfaces together the curvature moves towards more flat not towards more curved and you'll know where you end based on the direction you're going in.
However, even with a purely thought experiment if increasing curvature is what happens considering the long-long-long term progress should give you pause as you'll be creating more and more curved hones towards something that resembles piece of a marble:


At some point you will get down to a small enough radius that you clearly know is going to be flattened by rubbing with another piece.

Boy its threads like this that makes me want to leave this place. Such anger and bitterness over a theory.

I am a Toolmaker by trade I've heard and practiced the 3 unit process for squareness of angle plates.
Every time a Toolmaker got the notion to make an angle plate for himself he would make three and disperse the other 2 too other Toolmakers.
Id like believe that the theory is the same for squareness as well as to flatness.

This came out of Practical Machinist.

Scrape one face of each flat, then scrape the other faces by comparing them against each other while the good face sits on the surface plate:-
A-B; B-C; C-A.

If you don't go mad first, you end up with flat and guaranteed square faces. It also taught me that you don't do finish scraping until you've got the rough/alignment scraping done first!

I first did a set of three squares that I'd sawn out of a section of 100mm square cast iron bar and rough machined on the shaper. That kept me occupied for a couple of months, but was a very good training exercise.

Originally Posted by gssixgun

I am pretty sure that rubbing 2 like stones together will not result in flat, what I am not convinced of is that it will result in Convex and Concave surfaces .. That part I have to see for myself...

When I made my granite surface plate with the three stone method and SiC, I would lap until the stones mated with random motion in any direction then switch stones and repeat. It took several iterations of this until all three would mate without lapping. The 2 stone mating and the lack of three stone mating indicated that the interface of the mating pair was not yet flat, but spherical.

Originally Posted by Tarkus

Such anger and bitterness over a theory.

Well, the core of the conflict is over whether the widely used three-plate-lapping method is done out of expediency or out of principle.

I'm trained and work on understanding principles. Most other posters seem to be trained and work in applying them. There is an expertise gap that is hard to bridge (and a bit ridiculous when people get confused about theirs) and the aforementioned Wayne R. Moore who started with strong mathematical training similar to mine and ended in the world of machinists is no longer with us to settle it.

Doing something well doesn't mean you understand what you're doing and why, and understanding how something is done and why doesn't mean you can do it well.

Originally Posted by Neil Miller

I don't want to worry you Bill, but I think you should, especially when the full moon looms large in the heavens, for:

"...Even a man who is pure in heart and says his prayers by night,
may become a wolf when the wolfbane blooms and the autumn moon is bright..."

Attachment 201438

Regards,
Neil

DAD!!!!!!!!!!

Yes such bitterness over differing points of views, there is a lot of very knowledgable folks on here , I do hope that the issue gets resolved with some degree of civility. As to that if the hones are not flat , seeing as this can not be accomplished to the exact degree , we are still getting great edges aren't we? , Now as to theory and practiced , I have prove the mathematics and engineering wrong on several occasions in my field of drilling holes in the ground 2- 2 1/2 miles down then drilling another 2 miles horizontally, and I will agree that the study of this gave me a starting point , but I still had to perfect the mathematics on the job , so maybe that's the common ground here , that even the numbers right as they may be, your personal experience may suggest otherwise , or it didn't matter. As Rodney King said " can't we all just get along?" Tc. Oh and YMMV

I struggle to believe this thread hasn't eaten itself, probably the best thing would be for everyone to agree to disagree seeing as you are all right according to your own assertions and back up documents.
from my point of view this is almost embarrassing now.

"Yeah - mine's a fair bit smaller than yours, he he

Regards,
Neil"

Neil, it takes a huge man to admit something like that on a public forum.

Some things I will take away from this thread:

Google is not always my friend.
I am fearful of my stones collapsing into a black hole if I rub them together for too long.
At least 2 members of SRP are werewolves.
Ed's off topic thread finally has a challenger.
"There ain't no Sanity Clause."

https://www.youtube.com/watch?v=KS2khYJZKwA

That's just it though. We aren't all right according to "backup documents" or references. The person making the inaccurate claims has posted no references other than his own "expertise." (Quotes emphasized).

Rubbing two stones together will NOT result in flat surfaces without constant checking to a flat reference surface and selective material removal to develop the flatness. No matter how many different directions you move the stones relative to one another. For F's sake, you can start with two FLAT stones and rub them together and they will develop sphericity over time. This is NOT a suitable way to maintain stone flatness, period. No question.

Here's what I'd like to see: the guy with the big head go to the meet and put his money where his mouth is. Demonstrate how you take two stones and make them flat by only rubbing them against each other. You work until you say you are done, with no flatness reference during the work. Someone else will check the stones with a straight edge. Do a few iterations of "flattening" then honing some razors, "flattening" then honing some razors. Good lord this is ridiculous. Wayne Moore would B. slap you with his book if he were here in my opinion.