Challenge Cokebottle Challenge

[David Wesner]

BTT I've never made a slipjoint. Now is good a time as any Deker, when you're ready for surface grinding let me know. I'll do it reasonably (free) PM me & I'll give you my addy.

 

[happycat]

This is great and the timing couldn't be better. I've been collecting coke bottle slipjoints on ebay for the past few months. The last two were Henery
Sears with worn blades which I got for relatively cheap and made my own blades. I've been trying my hand at slip joints on and off for the past few weeks and keep gettinh hung up on the springs. Just keep breaking the damm things. I haven't managed to get the temper right yet. I'm using O-1. Anybody got any advise on how to temper to "spring hardness"?
I've printed this out and it'll be my next project. I'll post it if I can get past the tempering issue and actually get one completed.... Since this is pages back I'll post the temper question seperately.
Thanks for the inspiration and the great plans. I Love the symetry of coke bottle designs and can't wait to make myself an EDC thats all my work.
Ed

 

[Patrickknives]

I used 1095 for my blade and spring, I tempered the spring by heating with a propane torch to a bright blue color this which is about 575 f. this would result in a 54Rc for O1 looking at the referance I downloaded from knives.com/heattreat.html.

The first broke when I tried to straigten, second is the final. Good strength and I have been using for about a month with no change is strength.

here is the final product

 

[the possum]

Sorta on topic, I have a question for you slip joint makers. How do you peen the pivot pin so it's tight and blends well with the bolsters, without making the blade too stiff? I realize some use bushings to get around this problem, but would like to know what you guys do if you're not using a bushing? I've had some problems in the past where there's still a dark line around the pivot pin (i.e., it's not invisible).

I've used extremely thin metal spacers while I do the peening, which were removed afterwards. Now I'm thinking about just using a piece of paper or some type of plastic sheeting I can melt out with a solvent as a spacer. Any tricks you can share?

 

[Patrickknives]

Sounds like your countersink may be too deep, I get the bolster very close to finished and put a very shallow countersink. I cut the pin to about 1/16" longer on each side and tap on side turn and tap the other. I also focus on spreading the edges of the pin into the countersink. Once the countersink looks filled the blade is still loose side to side, I tap to get the any play out of the blade. Then one or two more for luck. Even with only 1/16" on each side there is alot of pin to sand but is smashed.

I also sand the liner so the blade will not rub on the edges leaving about a 1/4" circle of material around the pivot hole.

 

[the possum]

Huh. I hadn't thought that the countersink could be too deep. I'm peening around the edges of the pin to fill up the countersink, as well. So you don't use any kind of spacer to control the (miniscule) gap between the tang and bolsters/liners?

 

[Patrickknives]

Not in the two that I have made, this is very limited experience. If your countersink is too deep you may have to hammer too much to fill the countersink. I am guessing that the dark circle around the pin is a small gap between the pin and bolster. On my knife the pin is a very faint shadow you have too look very close to see.

 

[Patrickknives]

On other thought, I have found a drill that gives me a very tight fit for the pin. I keep the drill only for pin material. Is is a little smaller than the pin so I have to tap the pin into place but it goes in easy.

 

[the possum]

Yeah, I'm using a tightly fitting pin, too. And I always upset the pin/rivet enough that it should completely fill the countersink. I just figured somehow I wasn't peening it hard enough to really "bond" with the bolster material to get that invisible seam. I've thought maybe I should be doing something different with the shape or taper of the countersink- maybe making it narrower and deeper rather than shallower... I never seem to have any trouble getting a nice hidden pin with bolsters on fixed blades, or even the rear pins on a folder; just the pivot.

 

[KnifeHead]

This is great and the timing couldn't be better. I've been collecting coke bottle slipjoints on ebay for the past few months. The last two were Henery
Sears with worn blades which I got for relatively cheap and made my own blades. I've been trying my hand at slip joints on and off for the past few weeks and keep gettinh hung up on the springs. Just keep breaking the damm things. I haven't managed to get the temper right yet. I'm using O-1. Anybody got any advise on how to temper to "spring hardness"?
I've printed this out and it'll be my next project. I'll post it if I can get past the tempering issue and actually get one completed.... Since this is pages back I'll post the temper question seperately.
Thanks for the inspiration and the great plans. I Love the symetry of coke bottle designs and can't wait to make myself an EDC thats all my work.
Ed

Getting a spring temper correct is one of the things that can drive even production company engineers insane. They have to be like Goldilocks' porridge, "just right". Too hard and they will break...to soft and they will either loose their "memory" or gald.

I have used A2 so far, and the spring hardness needs to be Rc49-50, 49 being better. You shouldn't have to bend the spring if it is made correctly before prior to HT.

 

[KnifeHead]

Sorta on topic, I have a question for you slip joint makers. How do you peen the pivot pin so it's tight and blends well with the bolsters, without making the blade too stiff? I realize some use bushings to get around this problem, but would like to know what you guys do if you're not using a bushing? I've had some problems in the past where there's still a dark line around the pivot pin (i.e., it's not invisible).

I've used extremely thin metal spacers while I do the peening, which were removed afterwards. Now I'm thinking about just using a piece of paper or some type of plastic sheeting I can melt out with a solvent as a spacer. Any tricks you can share?

To keep from having a visible line around the pin after it's peened, you need to clean the pin up with light sanding. Any dirt around the pin will cause it to show up after peening. The pivot hole in the bolsters should be tapered with a 10 degree reamer so that the pin spreads out into that and gets a good grip on the bolsters. Those two things, and using the same material for pin and bolsters, should solve the visible pin issues.

You can relieve any over-pressure on the blade after peening by taping on the corner of the blade at the tang while holding the knife handle at 45 degree angle. I have heard of making very thin shims(.001-.002" thick) with a slot in it to go past the pivot pin. That is slipped into place for peening.

I use bushings..solves lots of problems and makes a better knife.

 

[the possum]

To keep from having a visible line around the pin after it's peened, you need to clean the pin up with light sanding. Any dirt around the pin will cause it to show up after peening. The pivot hole in the bolsters should be tapered with a 10 degree reamer so that the pin spreads out into that and gets a good grip on the bolsters.

Yeah, I sand the pins... But the countersink should only be 10 degrees? That may be my problem then- I think the bit I was using is probably closer to 20 degrees. (making the countersink deeper, as PCR said.)

You can relieve any over-pressure on the blade after peening by taping on the corner of the blade at the tang while holding the knife handle at 45 degree angle.

Not quite following you there, man. You're tapping with side pressure on the spine, or kick, or something? Any pictures of the process?

I have heard of making very thin shims(.001-.002" thick) with a slot in it to go past the pivot pin. That is slipped into place for peening.

Yeah, that's what I was doing. My feeble possum brain couldn't remember the word "shim", so I wrote "spacer" earlier. I have no experience with the bushing method, but am pretty sure I wouldn't be able to make them work very well for my application. And, after all, some darn fine pocketknives were made for centuries without 'em.

 

[KnifeHead]

Yeah, I sand the pins... But the countersink should only be 10 degrees? That may be my problem then- I think the bit I was using is probably closer to 20 degrees. (making the countersink deeper, as PCR said.)

The wider you make the countersink, the bigger your "peenage" needs to be. Maybe your peenage isn't big enough

Not quite following you there, man. You're tapping with side pressure on the spine, or kick, or something? Any pictures of the process?

I just took this image(below) and is the best I could come up with. This is called "slackening the pivot" and is just an easy way to spread the bolsters away from the blade. Something more solid than a book would be under the kick as you tap the opposite edge of the blade with non-marring hammer of some kind.

Yeah, that's what I was doing. My feeble possum brain couldn't remember the word "shim", so I wrote "spacer" earlier. I have no experience with the bushing method, but am pretty sure I wouldn't be able to make them work very well for my application. And, after all, some darn fine pocketknives were made for centuries without 'em.

I agree with that part about good knives being made without bushings. You can look this over to see how it's done, http://boseknives.com/pvtbushing(I did that series btw ) , and see what Tony Bose thinks about them and their advantages. It does add a certain level of complexity to the knife building process that some will not want to pursue. All of my folders will have them though because he says it's the best way to do it. It's all up to you in what direction you go. Many fine knives are made today with and without bushings.

 

[the possum]

The wider you make the countersink, the bigger your "peenage" needs to be. Maybe your peenage isn't big enough

Nah, like I already said, I pound it pretty good. It completely fills the hole.

The problem is after I file things over and work the blade back and forth a few times, then the seam shows. Maybe my shim was too thick too...

I just took this image(below) and is the best I could come up with. This is called "slackening the pivot" and is just an easy way to spread the bolsters away from the blade. Something more solid than a book would be under the kick as you tap the opposite edge of the blade with non-marring hammer of some kind.

OK, thanks. That really helps explain it.

 

[Tony Bose]

If you are not going to use a bushing the spring needs to be 1 or 2 thousands thicker than the blade. This gives the blade room to work. If they are the same you have full bearing on the blade and spring and the blade will be lazy .

 

[the possum]

Thanks Tony. You've certainly given me something to think about and try with that tip. I've been "into" knives for about 20 years now, and have never heard that before. Learn somethin' new every day.

 

[John L]

Kerry: How do you and Tony cut the nail knicks(knocks)? Looks like one is cut with dremel abrasive wheel or thin kerf saw and the other with fly cutter. Is this correct or??? Thanks. Am going to have a go at it this weekend. It is a huge folder. Was the same size bushing used on this folder as the smaller ones? If not..what size? Thanks.

 

[Patrickknives]

wrong