Manufacturing defect? Misuse? Poor quality metal?
Thanks in advance.
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Manufacturing defect? Misuse? Poor quality metal?
Thanks in advance.
Forging and heat treatment.
It can be a number of things. If the blade is subjected to extreme or uneven changes in heat, poor manufacturing, leaned on (like too much pressure while sanding or otherwise restoring), honed a lot more on one side than another (can affect the temper of the blade, I have been told this by JoeD and he has a solid background in metal working) etc etc. I should probably leave it to those with more knowledge of metal in general to answer, but those are some reasons I know of.
"Wapi" is the Polish word for "warped"
:p
John Crowley of the Shave Shop and I were talking about this awhile back. John told me that when the razors are in heat treatment they warp. Steel has a memory so when they come out a worker hits them with a dead blow hammer and they spring back to their original shape. Apparently some steel has a better memory then other steel. :) You can see this dead blow hammer thing done on the Dovo video .
I don't own hundreds or thousands of razors. I own around 100+/-. I have yet to hold in my hands or use a razor that is what I would consider absolutely flat and even on both sides of the blade. Maybe I'm unlucky, but it's the truth.
Perfectly flat on both sides to me would be a razor where I'd marker the bevels and in ONE PASS for each side of the blade on a moderate grit stone (4k or less let's say) little to no pressure, the marker would be completely GONE. Ok, Ok, to add a little leeway, I'll give you two passes on each side for that to happen. And, the razor would have to exhibit that behavior considently (entire bevel on both sides making complete contact with the stone evenly and during the entire pass). Such a razor would basically hone itself other than me placing it on and drawing it across a stone and would require absolutely positively no modified honing technique.
I will assume such razors exist, but like I said I have never seen one that is virtually effortless in its complete flatness. Don't get me wrong, I have razors that I would consider to be close to this ideal and for practical purposes would probably be considered "flat", but in a very critical sense, nope.
Chris L
Once a razor is warped, there's no "memory" of it's previous shape. The warped shape is it's new shape. You can hammer it back to straight again if it's been tempered well and you do it just right. Hardened steel is pretty brittle, though and there's a lot of waste when hammering a razor blank back into shape after the heat treatement. What causes the warpage in the fist place is the conversion from austenite to martensite during the quench. Martensite has a complex crystalline structure and expands the steel. If one part of the steel tranforms too quickly compared to other parts of the blank, then warping occurs. The beautiful curve of the Samurai sword is caused by this differential heat treatment. The spine is packed with a special clay to retard the quench while the blade is exposed for the quench.. The blade, therefore quickly converts to martensite, making it very hard. The spine, on the other hand, remains soft. The expansion of the martensite formation along the blade bends the steel causing the blade to sweep upward.
Unless you are referring to a Pakistani razor it won't be steel quality that is the problem. What it usually is related to is the hardening process. The razor blanks are quenched after heating which warps most of them. They lay them on a leather pad and whack them with a dead blow hammer which restores their original shape - most of the time. Then they are tempered to remove stress. The ones that obviously don't look right are wastage; however sometimes they are flawed in a way that isn't even noticeable when the grinder does his thing. These get passed on to the customer. Quite unintentionally! Then when it is honed you will notice the flaw. If metal only comes off the tip and heal on one side and only off the middle of the blade on the other - it is slightly bent laterally. If metal comes off the front half on one side of the blade and off the heal half on the other side - the blade is slightly twisted.Quote:
Originally Posted by lawman2