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2020, the year of the slipjoint


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Epoxy doesn't flex, it lets go when heated, it takes a while to set up, and it's finicky to mix properly in the small quantities you use for folder scales.  And it's a pain to clean up. An overnight s

Time to share. The way I was taught was to drill the blade pivot and center spring holes in both liners. Assemble the knife with both liners stacked and the blade/spring on top. Put the blade in

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11 hours ago, Alan Longmire said:

The way I was taught o do it is to not drill the center pin hole until everything else is done.  Fit it up, mark where the hole will be with everything tight, then drill the hole slightly further down the scale.  Ideally, that pin will slip in when you compress the spine with the knife assembled. 

Time to share.

The way I was taught was to drill the blade pivot and center spring holes in both liners. Assemble the knife with both liners stacked and the blade/spring on top. Put the blade in the open position. Now scribe the line of the bottom edge of the spring. Now move the back end of the spring upward 1/32" away from the line by the back hole in the spring. Clamp in place and drill the hole.

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I was waiting for the 1070 to start with folders, while I had 14C28N used in the first kit, and I have some O1 that would be suitable as well.

I have one more hunting knife to give a handle, ditto for 3 kitchen knives and 4 cleavers, then I'm cleaning my shop a bit and seriously getting into folders, might never make a fixed blade again!

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16 hours ago, Alan Longmire said:

I think I'll try Joshua's method next time. B)

The method explained in the fewest number of words B):D

I bought some materials yesterday, I think the liners of the first knife were 1.2mm engravers brass, was a gift from my supplier to try out first.  He doesn't have 1.2mm and I feel the first knife is too heavy, so I got 0.5mm brass and 3mm brass plate for the bolsters.  3mm stainless rod for the pins.

We have a whatsapp group with most of the local makers, at least one group that's not irritating, but I digress.
I've shared some of the folder photos on the group, and one of the guys, a retiree currently on a fishing holiday at the coast (far away from his workshop) made a function wood lock-back folder from wood using his Leatherman.
He in turn inspired me with the lock-back idea, for sure worth a try.  
I suspect I'll cheat and take apart one of my Spydercos, use pin locations and the lock design, change the handle and the blade shape.:ph34r:

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@Brian Dougherty I printed out your design landscape and portrait to get different sizes.
My biggest concern is accurate drilling, so I drill all holes before roughing out the parts.  I noticed your design is missing the 2nd hole on the spring, from the advice above I now understand why, hope I can pull it off.

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2 hours ago, Gerhard Gerber said:

@Brian Dougherty I printed out your design landscape and portrait to get different sizes.
My biggest concern is accurate drilling, so I drill all holes before roughing out the parts.  I noticed your design is missing the 2nd hole on the spring, from the advice above I now understand why, hope I can pull it off.

Hmm, I should have had the hole in the spring, but not in the liners.  If that isn't the case, let me know and I'll correct the drawing.

 

I do as you plan to, and drill the holes first.  However, if you grind a little short of the lines (leave excess material), and adjust in the following order, you'll find that the hole placement isn't beyond what is easily achieved with a drill press.  (That's all I use)

 

  1. Grind the tip of the spring until you get the tip of the blade where you want it with the blade open
  2. Adjust the top of the tang to get the open spring height where it needs to be
  3. Adjust the half-stop flat on the tang to get the same spring height as fully open
  4. Adjust the kick and the closed flat of the tang to get the proper closed angle on the blade.  (The kick and corner of the tang form a  line at this point that is hinted at by the shaded area on my drawing)
  5. Slowly push the line above backwards until the closed height of the spring matches the half-stop and open height. (This gives you a flush spring in all 3 positions)

This is actually the first time I have listed these steps out like that.  I haven't made a folder for a few months, but I think that is what I do.

 

 

 

 

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Been a bit busy but I'll post some photos.
Hole is definitely not marked om the template, but that's not a problem with how I've been doing it till now.

 

Thanks for providing your steps, the issues I've run into with the springs(s) I believe can only be eliminated by changing my process.

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Oh, you must be doing the "Coke Bottle" one:

 

IMG_7515.jpg

 

I forgot about how I did the pins on that one.  Since I felt it was important for the two pins in the middle of the handle to be symmetrically spaced, I put the holes in the liner first, and then use them to locate the hole in the spring after adjusting it's position for pre-load.

 

(Now that I look back on a pic of this knife, the pins are too big :rolleyes:)

 

 

Edited by Brian Dougherty
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I'm busy with your Coke bottle yes :D

Mine will be worse, best I have is 3mm SS en 4mm brass 

What thickness are your liners generally?

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My liners are too thick.  I keep using 0.062" steel.  (~1.5mm)

I know a lot of people use liners that are half that thickness, and brass to boot.  

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On 1/22/2021 at 3:16 PM, Brian Dougherty said:

My liners are too thick.  I keep using 0.062" steel.  (~1.5mm)

I know a lot of people use liners that are half that thickness, and brass to boot.  

My first one used 1.2mm brass, but I'm afraid the 0.5mm brass I bought (not cheap) is too thin.

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2 hours ago, Gerhard Gerber said:

My first one used 1.2mm brass, but I'm afraid the 0.5mm brass I bought (not cheap) is too thin.

Yeah, 0.5mm is ~0.020" which would seem awfully thin for brass unless you're making a very small knife.  I think Alan has been using thinner liner material than me.  I seem to remember Joshua had a post about the material he uses and it was closer to 1mm.    They'll probably chime in.

 

I've heard it said that the bolster and the spring take the brunt of the force on a slip-joint, but I don't really buy that.  Between the pivot pin, and the center pin on the spring, the liners and scales are the main structural element.  I actually grind the free end of my springs to be half a thou thinner than my blade.  It wouldn't take much bending to distort the knife that much.

 

I use bone scales most of the time which add a lot of rigidity to the liner, so maybe I am being too conservative about it.

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Well, I had a choice between 0.5mm or nothing, maybe should've bought less and tried first, didn't even think about getting SS.

But I think you raised a very valid point, I only thought about the pivot that would be reinforced by the bolster, did not consider the spring pin.....or how I've been assembling up to now, if I do the same that will most likely crush those 0.5mm liners.

*face-palm*

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I've been using 0.025" / 0.64mm brass liners with no problems.  I used 0.040" / 1.06 mm on one large folder and it's way too thick.  I use 3/32" pins and 1/8" bolsters, and it's more than strong enough.  

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Thanks Alan.
So far (technically 2.5 knives) I've been adding extra pins for the scales because I was not willing to peen on the scale material.

I peen the spring pin, grind it down a bit and a small divot on the bottom of the scale to accommodate it.

Does that pin have to be peened, will glue maybe been enough? 

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If the spring pin is captured in place by the scales on either side, I don't see why it would need to be peened.  It will be there as long as the sales don't fall off.

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Sure, but I want to get away from extra pins just for the scales.
I've only completed two and and made every single order of operation mistake I could! :lol: 
Need some KISS :D

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Oh, I misunderstood where you were trying to go :lol:  I wouldn't want to add any more pins to the process either.

 

If you want to use one pin all the way through the spring, liners and scales, then I think you will want something more permanent than epoxy holding them in.  IMNSHO, I think the epoxy would fail on such a small pin in a "carry it around in your pocket every day" scenario.

Edited by Brian Dougherty
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Exactly.  You need at least one scale-only pin.  And it has to be slightly peened.  It doesn't take much.  Or there's spun pins.  I always screw that up, though, so I don't do it.  Which means I can't do fragile things like pearl scales.  Oh, well.

 

Also, I've stopped using epoxy or cyanoacrylics for folder scales.  Loctite 330 speedbond.  Pretty much the same glue that hold your rearview mirror on your windshield.  Does not fail.  Ever.  Or at least for the next 60 years, whichever comes first.  It does stain bone, though.

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Why the 330 over epoxy Alan?

 

I'm probably going to put together one of these "Coke Bottle" designs over the next few weeks.  I'll try to document the process I go through.  Maybe I'll learn something by trying to document it :)

 

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1 hour ago, Brian Dougherty said:

Why the 330 over epoxy Alan?

 

Epoxy doesn't flex, it lets go when heated, it takes a while to set up, and it's finicky to mix properly in the small quantities you use for folder scales.  And it's a pain to clean up. An overnight soak in acetone will remove it. 

 

The speedbonder is nearly instant, cleanup is easier than epoxy because it relies on the 330 on one part and the activator on the other.  If the activator and the bonder don't touch, a quick wipe removes it. It is not a gap filler, it has to be a tightly clamped joint to get the full 4500 psi shear strength.  350 hours in acetone reduces the bond to 450psi. Does not soften with heat.  Flexible. 

 

To minimize the mess, spread a little 330 on the liner and squeegee it off with an old credit card or something.  Wipe the edges off with a paper towel dipped in acetone.  Spray a little blast of activator (it's an aerosol) on the back of the scale, and wipe off the excess with a clean paper towel. Within 15 minutes of applying the activator, stick the scale to the liner, make sure it hasn't shifted, and carefully clamp.  Check again to ensure it hasn't shifted.  You have about 30 seconds before it can't be moved. 100% strength in 6 hours, but strong enough (50%) to start working on after maybe 15 minutes.

 

The downsides: It's expensive, the bonder has a relatively short shelf life, and it stinks like you wouldn't believe. If you get the mixed bonder and activator on your skin, it has to wear off over about a week or so.  

 

I really think that with the speedbond no mechanical fasteners are required for any reason.  It's amazing stuff.

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