Blade Rap Remedy: Cutting Groove with Dremel?

AFAustin

AFAustin

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Jun 8, 2004
Messages
2,488
Well, here's my oddball question of the week. I mainly have small traditional folders and more often than I like they suffer from blade rap. That is, the blade will hit the back spring on closing and leave a small ding where the contact was made.

I have 3 methods of addressing this, and will often use a combination---or all 3---to solve the problem. The first is to just sharpen the blade down enough to avoid contact. The problem with this is that it can result in too much metal being lost.

The second is one Gary Graley taught me and that is to insert a small sliver of rubberized cork in the well up next to the tang, which will, in effect, extend the tang and keep the blade from hitting the spring. The problem with this method is that it can result in the tip of the blade (which I like to make very sharp and pointy) sticking up a bit outside the well so that it can poke your finger a little---not good.

The third method is to use a very small diamond file and make a groove in the spring so that the closed blade has a little more clearance. The problem with this method is that it's slow going!

So, here's my question. Could the third method be accelerated by using a Dremel and cutting wheel to make the groove? Obviously, you'd need to use a light hand and be very careful not to cut too deep. I have a Dremel and a couple of the small cutting wheels, but have never used them and am no pro with the Dremel in general, so I'm a little uncertain about charging ahead.

Any advice or experiences would be appreciated. Thanks.

Andrew
 
I'd be inclined to just insert some type of 'insulator' underneath the contact area of the edge. Not under the kick, but directly underneath the part of the edge making contact. A thin sliver of rubberized tape (or nylon, teflon, etc), affixed to the inside face of the spring, might be enough. Others have done this with pieces of leather or wood (toothpick, for example); but, the issue there might be a tendency of the insulator to absorb/hold moisture, which may lead to corrosion issues on the spring or the blade's edge. I remember seeing an old post here on the forum, a long time ago, with a picture of a knife 'fixed' in that manner, and with obvious pitting/corrosion along the blade's edge and on the section of spring where the piece of wood had been.

Grinding a notch into the spring has risks of it's own, possibly decreasing the strength of the spring, or making it structurally weak (prone to breaking/failing). And even if you do that, the issue with the blade's edge contacting it will likely be temporary anyway. As you've mentioned, with a few sharpenings down the road, it may no longer be an issue anyway. But the notch will still be there, ground into the spring.

I've seen another option mentioned on the forum. Some have 'peened' the edges (sides) of the kick itself, using a punch (I think), which effectively stretches or lengthens it a tiny bit, just enough to raise the blade's edge a hair. That may or may not work, depending on how much the blade needs lifting.


David
 
It depends on how good you are with the Dremel!
I suggest you buy a pair of safety glasses and a tube of the cut-off wheels before you start. You'll break quite a few learning to use them.
 
Also, unless you were the Operation champion as a kid, you are likely to scar up your liners on your knife trying to grind the hump on the spring.

Wrap it up good first!
 
Bigfattyt, I wasn't any kind of champion as a kid so, you're right, much care will be taken if I go Dremel.

Hey, Gary, thanks for chiming in. Thanks again for schooling me on the rubberized cork method. It is a helpful tool and I used it on a knife last night. But as for buying a "rap-less" knife, I never know till I've bought it (in this online commerce world)!

Andrew
 
AFAustin said:
I mainly have small traditional folders and more often than I like they suffer from blade rap.
Click to expand...
Sounds to me like you are acquiring the wrong knives.
There are plenty out there that do not do this. Of all the knives I have (traditional folders) only one does this and it is made by/for a company that focuses on making knives that are the farthest thing from a slip joint; think pole axes, swords and lock backs that are demonstrated by ramming them down through the entire thickness of a steel toed boot.
 
Wowbagger said:
Sounds to me like you are acquiring the wrong knives.
There are plenty out there that do not do this. Of all the knives I have (traditional folders) only one does this and it is made by/for a company that focuses on making knives that are the farthest thing from a slip joint; think pole axes, swords and lock backs that are demonstrated by ramming them down through the entire thickness of a steel toed boot.
Click to expand...

Well, these days I buy mainly Case folders, and a few others of good quality as well. I don't mean to say that most of them suffer from this malady, or even a large percentage, but simply that it happens "more often than I like". And the sizes of the blade raps I'm talking about are typically very small---visible only under strong light or with a loupe. But I aim for a very good edge and even a very small rap bothers me.

My experience has been that when blade raps do occur, they don't discriminate based on the pedigree of the knife. Back when I bought more GECs, they had their fair share as well.
 
Obsessed with Edges said:
I'd be inclined to just insert some type of 'insulator' underneath the contact area of the edge. Not under the kick, but directly underneath the part of the edge making contact. A thin sliver of rubberized tape (or nylon, teflon, etc), affixed to the inside face of the spring, might be enough. Others have done this with pieces of leather or wood (toothpick, for example); but, the issue there might be a tendency of the insulator to absorb/hold moisture, which may lead to corrosion issues on the spring or the blade's edge. I remember seeing an old post here on the forum, a long time ago, with a picture of a knife 'fixed' in that manner, and with obvious pitting/corrosion along the blade's edge and on the section of spring where the piece of wood had been.

Grinding a notch into the spring has risks of it's own, possibly decreasing the strength of the spring, or making it structurally weak (prone to breaking/failing). And even if you do that, the issue with the blade's edge contacting it will likely be temporary anyway. As you've mentioned, with a few sharpenings down the road, it may no longer be an issue anyway. But the notch will still be there, ground into the spring.

I've seen another option mentioned on the forum. Some have 'peened' the edges (sides) of the kick itself, using a punch (I think), which effectively stretches or lengthens it a tiny bit, just enough to raise the blade's edge a hair. That may or may not work, depending on how much the blade needs lifting.


David
Click to expand...

I have found the best material to line the bottom of the blade channel is actually a cut up little strip of credit card.
 
my kids should do that more often, the cutting up of credit cards that is ;) good idea
G2
 
AFAustin said:
Well, here's my oddball question of the week. I mainly have small traditional folders and more often than I like they suffer from blade rap. That is, the blade will hit the back spring on closing and leave a small ding where the contact was made.

I have 3 methods of addressing this, and will often use a combination---or all 3---to solve the problem. The first is to just sharpen the blade down enough to avoid contact. The problem with this is that it can result in too much metal being lost.

The second is one Gary Graley taught me and that is to insert a small sliver of rubberized cork in the well up next to the tang, which will, in effect, extend the tang and keep the blade from hitting the spring. The problem with this method is that it can result in the tip of the blade (which I like to make very sharp and pointy) sticking up a bit outside the well so that it can poke your finger a little---not good.

The third method is to use a very small diamond file and make a groove in the spring so that the closed blade has a little more clearance. The problem with this method is that it's slow going!

So, here's my question. Could the third method be accelerated by using a Dremel and cutting wheel to make the groove? Obviously, you'd need to use a light hand and be very careful not to cut too deep. I have a Dremel and a couple of the small cutting wheels, but have never used them and am no pro with the Dremel in general, so I'm a little uncertain about charging ahead.

Any advice or experiences would be appreciated. Thanks.

Andrew
Click to expand...

Blade rap is my nemesis. Nthing worse than when i get a nice used knife & go through the trouble of Lansky'ing it up to a perfect edge & first time I close it, get a nice dull flat spot on the edge where the cutting edge hits the backspring. So I have come up with 2 methods - I ordered a bunch of diamond point rotary "burrs" for my dremel - they will work, but you go through alot of them. The best method (as the OP suggests as option 3) is to use the dremel cutting wheel to make a groove in the backspring so that the blade can't contact the backspring. It takes a steady hand to not hit the liner, and the more of these I do, I get a little better at it. Either way with the dremel, it takes a long time - as I usually have to sharpen the blade & try it a bunch of times, and at first it still hits the backspring, and have to remove more material ... last one I did, took me over an hour as I bet I had to sharpen the blade 5 or 6 times and recheck the clearance as I hate to take too much out of the backspring.
 
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