How did barbers hone a wedge in the olden days?

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Originally Posted by eKretz

Nope, not correct. You can rub two stones together in all different directions and they will still develop a curve. Think spherical surface. This is what will happen. Every time. You need 3 stones to get perfectly flat surfaces, as Alex pointed out.

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You have to think about it again. What I posted is correct and you can realize it too if you spend the time to understand what happens in the process (you don't need to understand it on molecular level, just simple newtonian mechanics, but you need to have basic principles of differentials and distributions).

Two pointers to guide you:
(1) what is special with three hones that is different from two? (a: absolutely nothing)
(2) what is special about a flat surface that is different from curved? (a: zero curvature and in any algebra course you learn zero is unique)

My stones always rub together, especially when I run. They still stay, sort of round,,,,,:shrug:

I took the time to read every post and decided this thread went so far down the path of minutia with no real resolve that I knew there was an applicable Calvin and Hobbes strip to put here. In my search for the most ideal one to post I found myself being entertained and realized that I may not be able to find an applicable Calvin and Hobbes comic strip for this particular occasion but I shall search for a future post. A comic strip so enlightening and yet youthful that it may well halt the progress of debate over the proper or improper methods which may or may not have been used as popular method 20 generations ago to flatten stones. I yearn for such an applicable comic strip.

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Originally Posted by gugi

You have to think about it again. What I posted is correct and you can realize it too if you spend the time to understand what happens in the process (you don't need to understand it on molecular level, just simple newtonian mechanics, but you need to have basic principles of differentials and distributions).

Two pointers to guide you:
(1) what is special with three hones that is different from two? (a: absolutely nothing)
(2) what is special about a flat surface that is different from curved? (a: zero curvature and in any algebra course you learn zero is unique)

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I'm not going to argue with you. Google it if you don't believe it.

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Originally Posted by eKretz

I'm not going to argue with you. Google it if you don't believe it.

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That makes sense now. It's ok, I'm in the business of solving problems correctly not in 'googling an answer'.

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Originally Posted by gugi

That makes sense now. It's ok, I'm in the business of solving problems correctly not in 'googling an answer'.

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Sure, guy. Everything on the internet is surely inaccurate, including all the industrial and manufacturing books Google has digitized. Now it makes sense to me also. Those who actually have some knowledge of metrology and good lapping practice will agree that the 3-part method (whether stones or any other material) is the only way to truly get flat parts first time, every time. You and your cronies can go on arguing about it all you want.

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Originally Posted by eKretz

Sure, guy. Everything on the internet is surely inaccurate, including all the industrial and manufacturing books Google has digitized. Now it makes sense to me also. Those who actually have some knowledge of metrology and good lapping practice will agree that the 3-part method (whether stones or any other material) is the only way to truly get flat parts first time, every time. You and your cronies can go on arguing about it all you want.

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Why so defensive? I can prove my point (mathematically) and I can point you to people (senior members here with decades of experience) who have been trained to and successfully used in the field this very simple thing of rubbing two hones together to keep them flat.

All you have been offering on the matter is declarative statements that you're right, an example that makes no sense, and the assertion that your point is proven somewhere on the internet by somebody and google has it in its index.

I don't know why I have to point out that Google indexes good stuff just as it indexes bad stuff. The problem with those who rely on 'googling it' to give them the answer is that they still have to discern between the correct and incorrect one.
If you can't even tell that in this matter three surfaces are qualitatively equivalent to two, you are unlikely to be able to make the correct discernment between the truth and the BS in google's results.

BTW Google first wanted to recruit me and offered me a job over a decade ago. A couple of years back they tried again. So, you can think of what I've offered you as an advancement that Google's search wants to have but doesn't have yet.

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Originally Posted by eKretz

Obviously you didn't bother to read the link posted by Alex above. There's no sense reiterating what's already written there.

BTW, the same method was used in the 1800's to lap gage blocks used in machine shops to size and flatness of somewhere in the neighborhood of .00005" before today's high precision machinery was available.

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Actually I did & he said 'dissimilar stones are the problem not how many you use.
Also when it comes to razors a diamond plate makes 3 stones redundant & a waste of time.

If I ever have to lap a gage block I'll consider my options.

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Originally Posted by Hirlau

My stones always rub together, especially when I run. They still stay, sort of round,,,,,:shrug:

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Old stones are usually round or rounded that's what erosion does for you John, perhaps that also explains your stature :)

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Originally Posted by onimaru55

Actually I did & he said 'dissimilar stones are the problem not how many you use.
Also when it comes to razors a diamond plate makes 3 stones redundant & a waste of time.

If I ever have to lap a gage block I'll consider my options.

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A diamond plate does sort of solve this one doesn't it Os, but what if it is out of true should I use 2 other plates to lap it flat?




Sorry couldn't resist :)