Edge is hitting the backspring and dulling?

Danbo

Danbo

Joined
Nov 28, 1999
Messages
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Just got myself a new pearl handled slipjoint gents folder, made by a guy named Ohta. Gorgeous little knife, but the edge is hitting the backspring when you close the knife. This leaves a small area of the edge that is dulled by a flattening of the edge. Other than that, I love the knife. My question is, should this be a deal killer or will it simply sharpen out? I'd hate to send the knife back, since it's so freaking gorgeous.
 
Danbo said:
Just got myself a new pearl handled slipjoint gents folder, made by a guy named Ohta. Gorgeous little knife, but the edge is hitting the backspring when you close the knife. This leaves a small area of the edge that is dulled by a flattening of the edge. Other than that, I love the knife. My question is, should this be a deal killer or will it simply sharpen out? I'd hate to send the knife back, since it's so freaking gorgeous.
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Question: Are you letting the blade snape closed, or does it just touch the backspring while resting?

Sometimes snaping the blade closed will alow the blade to swing down hard enough to hit the backspring and then come to rest. This can be kept in check by making sure to close it slowly.

If it just touches the backspring while closed though, definately you should send it back.
-Kevin
 
Give Otha a call. I have talked with him in chat over the years - Great guy.

He may say it is ok change the blade profile slowly so that it does not contact the spring or he may want to get the knife back from you to refit or replace the blade.
 
Bastid said:
Give Otha a call. I have talked with him in chat over the years - Great guy.

He may say it is ok change the blade profile slowly so that it does not contact the spring or he may want to get the knife back from you to refit or replace the blade.
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I'm not sure this guy even speaks English; or he speaks very little of it. Doesn't he live in Japan?

I will try to sharpen the small flat area on the edge, and be more careful when closing it.
 
No, this guy is Japanese and his last name is Ohta. Makes really finely finished Loveless style reproductions.
 
Danbo,
The other thing you can do is place something like a small piece of cork in the blade channel -- apparently this is traditionally done by Laguiole owners, to prevent the blade from touching the backspring when the knife is closed.

I use a short piece of waxed thread with my AG Russell Ultimate Pen Knife.
 
I have a gorgeous stag-handled Case Trapper that has the same problem.

The blade doesn't actually touch the backspring when closed slowly, but it does when snapped to closing, due to dynamic inertia of the long blades when snapped shut.

About the only practical solution is to simply close the folder gently.
 
Its called overtravel. Even if the blade isnt actually touching at rest, if you let the blade drop when closing it, there is a chance it will hit and create the dull spot. The answer has three parts... 1) the blade has to be resharpened to get rid of the dull spot. Often that takes away enough material to fix the problem. 2) Close your custom slipjoint knifes carefully; dont let the blade drop. (And for that matter, open them carefully to prevent blade rubbing on multiblades.) 3) If it is touching at rest, or the nick is too deep to sharpen out, the knife has to go back to the maker. A few minutes on a belt grinder and the problem is solved forever.
 
Danbo said:
No, this guy is Japanese and his last name is Ohta.....
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Hiroaki Ohta. A very quiet, reserved gentleman. Doesn't seem to have any problems answering emails in English (or perhaps someone else does it for him?) I'm certainly looking forward to spending a bit more time with him at next year's Blade Show.

email: ohtaknives@nifty.com

BTW, I have three rather expensive slipjoints that also suffer from this "bounceback" problem. I gently took out the flat spots with the white ceramic stone and will now close the blades gently, instead of allowing them to snap shut.

(But I am going to miss that wonderful "clack" sound when I just let them snap shut! :( )
 
Hey guys, It sounds like the kick on these knives is too short, it can be stretched a little, unless the spring is way too thick, for the length of the kick. Stretching should only be done by a qualified knife repairman, (or someone handy with tools) it involves striking the kick with a peening hammer, while kick is resting on a hard knife anvil, it then has to be buffed out a little. Sometimes a few "hard" hits is all it takes to stretch one enough, and there is a slight risk involved, it could break the blade off at kick (seldom happens if kick is lying on anvil).
Try this.... cut a small peice of thin paper, like a post card, or a little slimmer, and super glue it to the bottom "point" of kick, make sure it is small enough to fit in between liners when blade is shut (use tweezers to glue).
Sharpen ding out of blade with a ceramic rod, then shut blade as normal, open and you should not see a ding in blade, this means you stretch the kick this much, if you have to double the thickness of paper, then kick may be a problem to stretch this much unless heated. Sharpening the blade down enough to compensate sometimes can be bad, may take a lot of edge removal before it helps, sometimes not, you can usually tell how bad it is by the deepness of the ding. Hope this helps.
Robbie Roberson ;)
 
gud4u said:
I have a gorgeous stag-handled Case Trapper that has the same problem.

The blade doesn't actually touch the backspring when closed slowly, but it does when snapped to closing, due to dynamic inertia of the long blades when snapped shut.

About the only practical solution is to simply close the folder gently.
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This is THE answer. One of the serious problems with traditional pocket knives today is that customers have complained so much about this that the blades are too narrow. By being unwilling to close your knives gently you give up lots of blade. When I make iknives like this I assume that my customers are bright enough to close their knives gently and preserve their edges. Not everybody sees it my way. Their choice. I like full blades.

all the best,

A. G.
 
Robbie Roberson said:
Hey guys, It sounds like the kick on these knives is too short, it can be stretched a little, unless the spring is way too thick, for the length of the kick. Stretching should only be done by a qualified knife repairman, (or someone handy with tools) it involves striking the kick with a peening hammer, while kick is resting on a hard knife anvil, it then has to be buffed out a little. Sometimes a few "hard" hits is all it takes to stretch one enough, and there is a slight risk involved, it could break the blade off at kick (seldom happens if kick is lying on anvil).
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Robbie, does this work on a blade that's heat treated? Also, if you did change the height of the kick, either by stretching or grinding, you would change the position of the backspring in the closed position, because you would be changing the rotation of the blade, and therefore where the tang hits the backspring. I still vote for closing slip joints gently, and so do a number of top makers. If the maker has put in too much blade, back it should go to be put right.
 
I don't know if a blade hitting a backspring is something that should be accepted. I have been told and read that this is a classic flaw to look for in a traditional folding knife. It's sometimes hard to get it right.

I have one good quality MOP production knife from about the 1920s and it does not hit the backspring at all. I also have a current custom mini-trapper, with blades that are not "too thin" that has does not hit the backspring. I've bought three Case (whittler, mini-toothpick and warncliffe copperlock) as presents in the last year and neither had any problems hitting the backspring.

If you have a slipjoint with a good spring and try to close it gently, you may catch a finger or break a nail. The "safe" way to close slipjoints has often been to use your leg, letting it snap close.
 
If you "snap" the blade closed there is a possibility of the edge hitting the backspring, depending on the location of where the edge is hitting. All in all though, a well made knife? This should not happen. I suppose it depends on how much you paid for it, whether you can live with that or not. Me personally? A hand made knife should not do that. Laguiole's are famous for doing this as the heel of the blades tend to be too short on many to keep this from happening.
 
Overall, a VERY well made knife. I can live with this teeny flaw. Who knows? Maybe once I sharpen the little flat spot on the edge out, and start carefully closing it, it might not even be an issue anymore.
 
Fasteddie, Yes, peening or stretching the kick does work on heat treated blades, but again, you have to be careful not to "kink" the blade while hitting it. It is really a simple thing, you just have to hit the kick right on the button to stretch it some. And it needs to be done right on the edge of the kick. With solid support under the kick. This will raise the blade when closed, making the blade edge raise up off of the springs, just enough to not hit. It will not change the backspring at all, it will only cause the blade to pivot upwards and out of the blade track.
I would advise whoever wants to see what messing with the kick will do, get a cheap knife to practice on, softer steel, and easier to stretch. Close knife and mark end of blade where it is level with liners with a magic marker. Then open blade and peen kick, stretch it out pretty good, then close knife and look at mark on blade, you will see it raised the blade quite a bit, therefore raising edge of blade off of spring.
You can also lower blades in knife when closed by cutting a slight amount of kick off with dremel, You do this for old knife blades that have been sharpened so much that the blade point sticks up above the liners and catches on your pants (or fingers).

Robbie Roberson ;)
 
Hey Guys
I have made my share of slipjoints over the years and A.G. Russell is absolutely right. I always try to fill the handles of my knives with as much blade as possible. The wider the blade the longer it can be sharpened before it is worn away. However I try verry hard to not let the blade tag the spring when it is closed. My knife handles are sometimes thicker to allow more room so the blade doesn`t tag the spring. Us multiblade makers work very hard to be sure the backsprings lay flush with the liners with the blades open and closed. Any alteration of the tang will cause the springs not to be flush. Another thing is the longer the blade the worse this problem is. The longer the heavier and when the blade is allowed to snap closed the heavier blade is more likely to overtravel and make contact with the spring. When I finish a knife I let the blade snap closed several times and if there is contact with the spring I grind the edge back a little and try it again until its right. I can`t tell you how many times I have had customers at shows mash down on the blades when the knife is closed, very agrivating to say the least. Oh well now I`m just venting. Hope this helps
Bill Ruple
 
Pknives, I agree with you, and A.G., But I have never stretched a blade kick enough to cause any change in the back springs. I usually change it about 1/32 of an inch, if this much, and it never has caused me any concerns.
Now for a slight change in topic (briefly). Why in the world do people mash down on closed blades ? What is this supposed to prove, or disprove, you mentioned it :D, I have had them do this to mine before. What is the reason for this ?, do they realize they are denting the blade (possibly) ?
And the all time worst thing I hate to see is someone opening a blade and bend it from side to side while open, with enough force that you can see their knuckles turning white (slipjoints only) ! I realize they are just trying to check for blade play, but they can accomplish this by just barely moving it from side to side. Sorry, but I had to ask, thanks.
Robbie Roberson ;)
 
I´ve had similar problems with three knives.

One was an old stockman that had a blade ground at the tip by the previous owner giving it more belly and raising the tip (I assumed trying to sharpen with a grinder), now the tip stuck out over the liners, I filed down the kick to lower it but over did it, the blade was touching the spring, I got it back up a bit by stretching the kick as Robbie Roberson mentions, came out fine and I see no change in the spring backs.

Another was a British Rigging knife, even after stretching the kick it would still touch the spring when closed, I fixed it by carefully cutting a small slot in the inside of the spring with a carbide wheel in a Dremel, now the blade goes a bit into the slot and doesn´t touch the spring.

The third is a Laguiole, obviously unfixable by stretching the kick, I managed to put a strip of duct tape inside on the spring for the edge to rest on and I close it gently.

Like others I don´t like to snap shut my knives.
 
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