Solution for fixing overly strong spring?

[Cory Hess]

I wish you could make a short video of this or at a series of pics to show what you mean by this.

Watch your spring as you open your blade to figure out where the spring is at it's highest. When it's at this point stick a small screwdriver under the spring. Put your knife, springs up, on a table and push the handle of the knife down to put pressure on the springs. Hold the knife steady and use the screwdriver as a lever to push the springs past their normal full extension. I don't know if this helps, but here is a picture of my knife with the screwdriver inserted:

 

[yatsunil]

I went through this dilemma recently with a GEC 78. Got it from a 9 to about a 6/7 in the course of an afternoon. The key was . . . flexing the spring BEYOND it's maximum extension. Leaving the knife open for a while will have a similar effect, but not as quickly and not to the same extent.

In a thread on this very topic a while back, Ken Coats demonstrated that you can either add or subtraction tension from a backspring by flexing it in a special vice. That, of course, required taking the knife apart. But another forumite pointed out that you can do this without taking a knife apart: open the knife roughly 3/4 of the way and insert a small pry bar or similar tool into the space between the tang and the spring. Next, place the butt of the handle and the tip of the blade on a flat surface. Simultaneously torque the pry bar and but down on the knife; the blade will not move, but the pry bar with flex the spring. You only need to flex it an eighth or a quarter of an inch at most past its point of maximal flex to reduce the tension. More than that, and you risk snapping the spring.

I was worried about this at first. I didn't want to damage the knife. But I went ahead with it, and now I can easily open the knife, having done no damage to the spring. I've followed up with WD-40 and a 3-in-1 oil. My American Jack is a nailbreaker no more, about on par with my 71.

Anyway, that's one way to tackle the problem. I can understand if others were hesitant to do this, but I'd happily do it again.

I just tried this on a really stiff Rough Rider that I wasn't too worried about breaking. It made it significantly easier to open with about 5 minutes worth of work. Thank you so much for sharing this.

Watch your spring as you open your blade to figure out where the spring is at it's highest. When it's at this point stick a small screwdriver under the spring. Put your knife, springs up, on a table and push the handle of the knife down to put pressure on the springs. Hold the knife steady and use the screwdriver as a lever to push the springs past their normal full extension. I don't know if this helps, but here is a picture of my knife with the screwdriver inserted:

Thanks to everyone for your comments. Especially Stencil, Jr and Cory Hess for the description and picture of how to overstress the backspring. I'm a tinkerer at heart so I might give this a shot. Not gonna let a knife get the better of me

At least now I won't have wasted my time leaving it 3/4 open without getting any improvements.

Linus

 

[Stencil Jr.]

Cory's got it exactly right. Just go slow, don't pry too far, and don't let the screw driver/prying tool slip out. It made a world of difference for me.

 

[Bigfattyt]

Lots of opening and closing has significantly lightened many of my pulls.


I absolutely love a hard pull.


Thew thought of a large coke bottle S&M with a hard pull just made my fingers tingle! I almost ordered one, but the springs on my S&M grandad barlow were softer, so I did not order one.

 

[colubrid]

Watch your spring as you open your blade to figure out where the spring is at it's highest. When it's at this point stick a small screwdriver under the spring. Put your knife, springs up, on a table and push the handle of the knife down to put pressure on the springs. Hold the knife steady and use the screwdriver as a lever to push the springs past their normal full extension. I don't know if this helps, but here is a picture of my knife with the screwdriver inserted:

Thanks for that! Much appreciated

I will give this a try.

 

[colubrid]

Okay I tried it and it worked. But be forewarned-now both blades have side to side play. Somehow by relieving the springs creates some side to side play.

 

[yatsunil]

Update : The solution provided above WORKS! I tried it out. Going gently at first but gaining confidence as I went along. Torqued it just a little at a time and tested the pull repeatedly. After 10 minutes, the pull on my knife has gone from a nail tearing 8-9 to maybe a 7+. Still strong but manageable. I'll let time and usage do the rest.

You just need a quality screwdriver that's the width of the backspring and maybe cover the edge of the blade with tape to prevent mishaps. Don't overdo the torquing and check often.

I did not any side play after torquing.

My thumbnail and I owe you one Stencil and Cory!
Linus

 

[colubrid]

Yes, I used a very small jewelers screwdriver which was the perfect size and sharp edges.. It worked perfect and I hardly torqued it. It went from about a 9 to an 7.5 . But both the blades have side to side play now whereas before they were tight as a vault

 

[yatsunil]

Yes, I used a very small jewelers screwdriver which was the perfect size and sharp edges.. It worked perfect and I hardly torqued it. It went from about a 9 to an 7.5 . But both the blades have side to side play now whereas before they were tight as a vault

Oh no. Did you by any chance happen to apply some sideways pressure that opened up the pivot?
Linus

 

[Cory Hess]

Okay I tried it and it worked. But be forewarned-now both blades have side to side play. Somehow by relieving the springs creates some side to side play.

I did all three blades on that knife and have no side play.

 

[yatsunil]

How does one measure the pull weight?

I don't know the difference between a 5, 7 or 9 except from what I read here and my guess is what a 7 is to one person might be a 8-9 to another?

If you're still curious about measuring pull weight, this old thread might help :-
http://www.bladeforums.com/forums/showthread.php/992550-The-Grand-Unified-Traditional-Pull-Scale

I think the common concensus is that the pull on a Vic SAK is rated a 5 and you can work out the rest from there.

Linus

 

[davek14]

Yes, I used a very small jewelers screwdriver which was the perfect size and sharp edges.. It worked perfect and I hardly torqued it. It went from about a 9 to an 7.5 . But both the blades have side to side play now whereas before they were tight as a vault

Good stuff. I have not liked that I have rounded tang corners to ease a pull. Now I have to wait till I get a "not perfect" knife with a hard pull to try this on.

Now, the question is can you fix that side to side play.

 

[Jack Black]

I had a very brief meet-up with member ADEE yesterday and he showed me an Arthur Wright Lambsfoot he'd modified as he found the pull a little strong. He'd taken it apart and modified the tang slightly. Perhaps he'll even come along and post some pics.

 

[ADEE]

Thanks for the mention Jack. I did indeed modify an Arthur Wright rosewood lambfoot. The spring action was far too strong for me and to make matters worse the nail nick was very close to the scales and so my nail had to go in at a 90 degree angle and thus was ready to break ! As it was the knife was barely usable so I had to do something. My solution was to dive in with small files and work steadily to reduce the corner of the opening bit of the tang. I did this in situ and did not take the knife apart. It took a lot of patient effort. The knife blade was opened fully and taped for safety. As was mentioned earlier filings get in the works and make the knife feel horrible but careful flushing out solved this. [I used soapy water !] In addition to this I scooped away at the the scales to give a better angle for my nail. I can now squeeze the blade open without using the nail nick at all. The knife has become sweet.Note that this method did not affect the spring tension that holds the blade open and the half stop is preserved. My attempts to modify backsprings have usually ended up with broken backsprings ! I hope this helps.

 

[glennbad]

Thanks for the mention Jack. I did indeed modify an Arthur Wright rosewood lambfoot. The spring action was far too strong for me and to make matters worse the nail nick was very close to the scales and so my nail had to go in at a 90 degree angle and thus was ready to break ! As it was the knife was barely usable so I had to do something. My solution was to dive in with small files and work steadily to reduce the corner of the opening bit of the tang. I did this in situ and did not take the knife apart. It took a lot of patient effort. The knife blade was opened fully and taped for safety. As was mentioned earlier filings get in the works and make the knife feel horrible but careful flushing out solved this. [I used soapy water !] In addition to this I scooped away at the the scales to give a better angle for my nail. I can now squeeze the blade open without using the nail nick at all. The knife has become sweet.Note that this method did not affect the spring tension that holds the blade open and the half stop is preserved. My attempts to modify backsprings have usually ended up with broken backsprings ! I hope this helps.

This is also the method I use, most notably on TL-29 screwdriver blades, which have been known to snap finger bones in two, LOL.

 

[2Dead]

I have had moderate success at this by easing the corners on the tang with jewelers files. You have to be extremely careful though, you can do TOO much and affect the closing snap, or possibly ruin the action altogether. You can also scratch up the liners.

If you bought it from a dealer, like others have said, you should send it back.

Thanks for the mention Jack. I did indeed modify an Arthur Wright rosewood lambfoot. The spring action was far too strong for me and to make matters worse the nail nick was very close to the scales and so my nail had to go in at a 90 degree angle and thus was ready to break ! As it was the knife was barely usable so I had to do something. My solution was to dive in with small files and work steadily to reduce the corner of the opening bit of the tang. I did this in situ and did not take the knife apart. It took a lot of patient effort. The knife blade was opened fully and taped for safety. As was mentioned earlier filings get in the works and make the knife feel horrible but careful flushing out solved this. [I used soapy water !] In addition to this I scooped away at the the scales to give a better angle for my nail. I can now squeeze the blade open without using the nail nick at all. The knife has become sweet.Note that this method did not affect the spring tension that holds the blade open and the half stop is preserved. My attempts to modify backsprings have usually ended up with broken backsprings ! I hope this helps.

I've done this to 2 GEC #73s successfully. I would only do this to a knife that I do not plan on ever selling.

 

[Jack Black]

Thanks for the mention Jack. I did indeed modify an Arthur Wright rosewood lambfoot. The spring action was far too strong for me and to make matters worse the nail nick was very close to the scales and so my nail had to go in at a 90 degree angle and thus was ready to break ! As it was the knife was barely usable so I had to do something. My solution was to dive in with small files and work steadily to reduce the corner of the opening bit of the tang. I did this in situ and did not take the knife apart. It took a lot of patient effort. The knife blade was opened fully and taped for safety. As was mentioned earlier filings get in the works and make the knife feel horrible but careful flushing out solved this. [I used soapy water !] In addition to this I scooped away at the the scales to give a better angle for my nail. I can now squeeze the blade open without using the nail nick at all. The knife has become sweet.Note that this method did not affect the spring tension that holds the blade open and the half stop is preserved. My attempts to modify backsprings have usually ended up with broken backsprings ! I hope this helps.

Thanks ADEE, nice job, I had thought you had taken the knife apart. We need pics!

 

[davek14]

I did a combination of methods to lighten up a Brown Mule some years back. They used to be known as Bear Traps, I dunno about the new ones.

Started with a small jeweler's file on the tang, which wasn't particularly well finished to start with. By keeping away from the liners and filing only in the middle I left thin shoulders on the tang. Took them off with the work, rinse, repeat trick.

 

[Beard&Owl]

Wow fellas, thanks for the tips on the heavy pull. I just got a GEC 73 in a trade with some pretty serious pull on it and used the method of putting a little pry bar under the backspring and torqueing it a bit. The pull must have gone down at least two points and is just perfect now. I've been hearing about GEC's heavy pull for a longtime now and have never owned one that was like that until now. Great advice on that and I can see where it could hurt the knife but as long as you take your time and don't over do it, it shouldn't be a problem. I definitely wont be afraid to try it out in the future.

 

[blademan 13]

I will be giving this a shot tomorrow on an old black box Winchester stockman, the main is literally a nail ripper. Very stiff spring combined with poor crescent pull placement and access. Thanks for the tip!