Warp vs Bad Grind

[Doc226]

I got this razor to hone, the member could get it right. It is a new TI.

Took a look under the loupe and could tell the bevel looked good at the toe and heel on both the show and back side. The middle part of the bevel on both sides basically dropped off.

Hone wear mirrors the bevel-heavier at toe and heel

Here are some vids

I think this was a bad grind and it got too thin in the mid portion.


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[global_dev]

I’ve been thinking about this for a minute but never asked anyone. How much of the blade is left to grind after a quench? Is it enough to render warp moot?

 

[bluesman 7]

I’ve been thinking about this for a minute but never asked anyone. How much of the blade is left to grind after a quench? Is it enough to render warp moot?

I think that your thinking is correct here. The term warp suggests that it's something that happens in the heat treat. To my thinking this is always a grind problem. I suppose that the double wheel grinder, since it uses the second wheel as support and grinds both sides at the same time, would tend to follow any warp in the heat treated blank, but there is plenty of stock there for a skilled worker to grind out a warp. The problem that Alfredo shows is fairly common and is the cause of the frown that gets fixed and then re appears.

 

[SliceOfLife]

The "fix" I know is to hone it like you want a smile... Essentially compensate for the recessed middle by pushing toe and heel back.

Fixing it and getting it so it can be honed normally in the future? That means regrinding... And sounds like there's not enough meat for that.


As for meat post hardening... I have nine blanks I bought from a knives store in 2019. They were vintage unhardened blanks (Herder, Solingen, early 20th century I suspect) for hollow ground razors. A member here hardened them for me. They're 1/4 to 1/3mm or so thick for most of the blade... You wouldn't be able to correct any serious warping in grind (post hardening). Minor ones maybe, but as speculated above, the tools would probably default to NOT correcting.

 

[Brianskeet]

I harden and temper a bit of steel from time to time and doing so without dimensional change can be tricky. Lots of internal stresses forming and moving around. I remember a video of a razor maker straightening blades with a hammer, so I could easily believe one slipping through the system not straightened perfectly. At the same time, grinding on an assembly line basis is bound to find a few blades that are not ground perfectly. Tighter tolerances drive prices up exponentially. The time required to go from a part within a couple thousandths of an inch to a part within a ten thousandth of an inch is huge so I bet most razor tolerances are pretty loose.

 

[Steve56]

If it’s overground in the middle you can never fix that if the over grind extends up the blade. But you can hone them with narrow hones or on the corner of a hone.

 

[Doc226]

If it’s overground in the middle you can never fix that if the over grind extends up the blade. But you can hone them with narrow hones or on the corner of a hone.

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I agree Steve, this being a new TI I recommended he get in touch with the seller and try to get a different blade.


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[Steve56]

Yes, if it’s new it needs to go back.

 

[Jnatcat]

This is why I never chased getting a TI, I heard to many stories about wonky grinds....

 

[Frank Shaves]

To close the loop...

OK, so I'm the guy with the TI with the uneven grind. The good news is that I worked out an arrangement with the seller to replace the original razor with a 7/8 inch Basic Black with singing hollow grind, thumb notch and mirror finish, and I am very pleased with the second razor, plus I picked up a second TI while waiting for the seller to receive new stock - see Straight Razor Acquisition Thread - https://www.badgerandblade.com/forum/threads/straight-razor-acquisition-thread.418229/post-11192224.

So it all worked out for the best , and thanks to @Doc226 for his generous help with this one!

 

[Bowmaker]

Not what I consider a warp but a very uneven grind..





I wouldn't be happy if it was a new razor but it really didn't matter with this razor.