Question(s) Concerning BLADE RAP On Traditional Knives ... (possibly Dremel related too)

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BrotherJim

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Own enough knives and you may deal with a few that have blade rap. That is, when the blade is snapped closed, the cutting edge contacts the backspring.
Some patterns are more notorious for blade rap than others and some knife owners may experience blade rap with a particular pattern while most others do not. Sometimes it's luck of the draw I guess.

Two often mentioned remedies are:
1) Walk the blade down/closed
2) Keep sharpening the blade until it no longer contacts the backspring

Alternative I've read of that may help alleviate the problem:
1) Wedge flat toothpick bits down into the blade well, against the backspring and in the area beneath the blade stop

QUESTION: Is anyone aware of a Dremel bit that will reach down into the blade well and gently grind the hump (on some patterns) over the backspring center pin?

Maybe someone may have other suggestions for dealing with blade rap and sharing of those ideas and suggestions is greatly appreciated !!!
*** For the sake of discussion please consider at this point, return of knife to factory for 'repair' IS NOT an option ***
THANKS !!! :)
 
I'm a worrier, so I would dread to grind away any of the backspring, for fear of weakening it.
I don't know a suitable Dremel bit.
My preferred fiddle of those you mentioned would be a bit of wood under the tang, if that won't raise the point out of the well.
 
scrteened porch said:
I would dread to grind away any of the backspring, for fear of weakening it.
Click to expand...
This would be a real danger!! The ping of a broken backspring is like the sound of DOOM!!
I have peened the kick to great effect!!
Either hammer it out, or dent it with a broad, hardened punch,on each side, to stretch it toward the spring!!
Make sure you don't raise the point of the blade too much!!
 
GREAT responses !!! AWESOME guys !!!
I hadn't given proper consideration to possible weakening of the backspring D'OH !!!
I think I'll just forget about the Dremel idea ...

That said, I have used a thin flat Jeweler's hand file with cutting lines (don't know what they're called) around the thin edges only, to gently massage the 'hump' in the blade well.
Because the cutting lines are only around the edges of the file, it doesn't damage the blade well walls.

But with possible back spring weakening NOW in my mind ... think I'll just forget about the Jeweler's file idea too :D

XKcn3CI.jpg
 
waynorth said:
This would be a real danger!! The ping of a broken backspring is like the sound of DOOM!!
I have peened the kick to great effect!!
Either hammer it out, or dent it with a broad, hardened punch,on each side, to stretch it toward the spring!!
Make sure you don't raise the point of the blade too much!!
Click to expand...
I had said 'blade stop' and that isn't correct. Thank you Charlie for using the correct knife terminology !!!
(bolded and increased font size in quote for emphasis)
 
I have found that most tang/kick areas are tempered somewhat by the cutler, to increase durability and resistance to cracking, so peening or punching will upset or deform the metal slightly, which is what you want!!!! It is easy to overdo it so go slow!!
 
mcc850 said:
How many times have you sharpened the knife? I received a gec 23 with blade rap, and it was gone after maybe 2 or 3 sharpenings. Never came back after that. Good luck with it, as it’s a beauty of a knife!
Click to expand...
Only not quite enough LOL. Blade rap isn't terrible and the 73 is indeed a favorite. Thank you :)
 
waynorth said:
I have found that most tang/kick areas are tempered somewhat by the cutler, to increase durability and resistance to cracking, so peening or punching will upset or deform the metal slightly, which is what you want!!!! It is easy to overdo it so go slow!!
Click to expand...
GREAT idea Charlie !!! I like it.
Problem is that like most problems, there is no one size fits all.

In the case of my 73, the blade tip is already in an ideal position in the blade well. In fact, any further raised and the blade tip would be outside of the blade well. So peening is not an option in this case.

Best choice in the case of my 73 is just to keep walking the blade down/closed until sharpened to the point of not making contact with the backspring when snapped closed.

I will have to remember the peening idea though, as it would be quite appropriate in some other cases. Thank you !!!

vFwAM5c.jpg
 
Heartbreaker!! 😲 Backspring 1.jpgBackspring 2.jpg
Broken Backspring - Flawless old pickbone!! Very old curved Schrade stamp!!
Boo Hoo!! Risky repair job!! It broke due to a historic flaw. Not often occuring on these!! Protect the backspring at all costs!!
 
waynorth said:
Heartbreaker!! 😲 View attachment 1582274View attachment 1582275
Broken Backspring - Flawless old pickbone!! Very old curved Schrade stamp!!
Boo Hoo!! Risky repair job!! It broke due to a historic flaw. Not often occuring on these!! Protect the backspring at all costs!!
Click to expand...
OH MAN !!! ... I'd cry and likely scream like a little girl LOL
I've yet to hear of a broken backspring on a GEC but anything's possible I guess.
I'd be doing any and everything possible, up to and including trying to buy a decrepit copy for a backspring donor to fix that gorgeous old knife.
 
Sharpening will gradually raise the tip but it will be a slow process.

You might reach a point where you’ll want to file the kick to lower the tip. At that point there will be a very fine line between tip protrusion and blade rap.
 
Railsplitter said:
Sharpening will gradually raise the tip but it will be a slow process.

You might reach a point where you’ll want to file the kick to lower the tip. At that point there will be a very fine line between tip protrusion and blade rap.
Click to expand...
'Zactly my thoughts too Rick. I can't remember for sure but I MAY have created this problem with the 73.
All I remember is that when brand spanking new out of the tube, I could rub my finger across the end of the handle and slightly catch my fingertip on the blade tip.
I can't remember (it's been 6yrs), if I 'massaged' the kick a bit or not.
Regardless, the blade is near perfectly centered and at an ideal position in the blade well when closed and I just need to keep carefully sharpening until it doesn't contact the backspring when snapped closed.
When I walk the blade down/closed there is no apparent problem ... only when the blade is snapped closed. So there isn't much contact and a few more sharpening sessions should help. Thanks !!! :)
 
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Knives can be a bit like people, animals and cars - temperamental :p Individual knives if they are Traditional are likely to have quirks- what's OK on one is not on another seemingly identical pattern- the side-effect of being often hand made etc. Never had any blade rap on any CASE knife so far, I enjoy the childish inanity of letting multi-blade knives smack shut with satisfying 'talk' But it's not on with some types, a GEC 85 I had needed a fair bit of sharpening down before Rap disappeared. Most Laguioles should not be snapped shut as they will rap the spring unless like Fontaneille-Pataud, they have a stop pin. I use wine cork in my Lags just in case I forget to walk it down.

As for mods, I was going to suggest asking your dentist to lend a micro drill :D they smooth down sharp teeth and fillings very nicely...but perhaps not!
 
Will Power said:
Knives can be a bit like people, animals and cars - temperamental :p Individual knives if they are Traditional are likely to have quirks- what's OK on one is not on another seemingly identical pattern- the side-effect of being often hand made etc. Never had any blade rap on any CASE knife so far, I enjoy the childish inanity of letting multi-blade knives smack shut with satisfying 'talk' But it's not on with some types, a GEC 85 I had needed a fair bit of sharpening down before Rap disappeared. Most Laguioles should not be snapped shut as they will rap the spring unless like Fontaneille-Pataud, they have a stop pin. I use wine cork in my Lags just in case I forget to walk it down.

As for mods, I was going to suggest asking your dentist to lend a micro drill :D they smooth down sharp teeth and fillings very nicely...but perhaps not!
Click to expand...
Will, I'm carrying (one of) my Fontenille-Patauds today and noticed I shouldn't snap it shut either D'OH. The F-Ps are MUCH better than some others but as you stated, individual knives can have some quirks.
... and I think some knife makers must have my address on their 'Do not ship a perfect knife to' list :D
 
Jim, Fontenille-Patauds have a stop-pin so it doesn't matter if you snap them shut they can't hit the backspring. Most other Lags don't have this, it's not a design fault as such but most French knife enthusiasts just won't let them snap shut out of knowledge and if you like, 'tradition' ;)

As for peening the kick, I don't know if I'd dare do it (no peening hammer either) but I'd fear actually shattering the blade......:eek::poop:
 
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