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Brian Dougherty

Culver Inspired (Copied) Slipjoint

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I was going to wait until I got past the quench to start my 2019 KITH WIP, but seeing as how today is apparently the 5th anniversary of me joining the forum, I thought I should do something...

...So here goes :)

I watched a demo on designing and making slip-joint folders by Steve Culver at the Central States Hammer In last fall.  While I was there I bought Steve's book on the subject, and I have decided to just blindly follow along with his procedure for my KITH contribution.  The engineer in me wants to go off and blaze a new path to glory, but since this is my first folder, I decided to cool my jets and do what my elders told me to for once.  (OK, Steve probably isn't that much older than me, but he certainly knows more)

I had a piece of pattern welded material left over from a recent project that was ~1.5" wide and ~0.25" thick.  It had a few weld flaws in it, but I thought I could draw out enough material to get a blade and spring out of it.  The first step was to draw this out to a piece ~1" wide by about 0.125" thick.

 

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I don't have a surface grinder, but I know someone who does, so I cut off a piece of this and ground it to about 0.100" thick.  You can see where some weld flaws were still following me...

 IMG_20190210_132639157.jpg

 

I did a quick test etch so I could try to line up the blade in a way that both missed the weld flaws, and maximized the interesting part of the pattern.  The hole was drilled for a string to hold the bar in my FeCl tank.  (I drilled it through a trouble spot)  I copied the pattern page out of Steve's book, but enlarged it by 25% to get a blade length of 3".

 

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I cut out the paper dolls, and super-glued them to the bar.  Before glueing down the yellow patterns, I used pieces made from tracing paper so I could see the steel below.  Once I like the position, I marked the edges and glued down the yellow paper pieces.  I saturated the paper with the super-glue in hopes that it would waterproof the pattern.  Sure enough, I was able to dunk the pieces in the water while profile grinding without losing the paper pattern.

 

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The next step was to drill and then ream the holes for the pivot and the pins.  I hope I enjoy making folding knives because I splurged $40 on a couple of solid carbide reamers...

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Then it was just a matter of cutting them out.  I don't have a bandsaw that will work for this, so I used a combination of a angle grinder and the belt grinder to get them to shape.  I've hand-filed the critical bits around the tang per Steve's steps.  However, I'll have some more close tolerance work to do with a file before I can call the blade done.

IMG_20190213_201318276.jpg

 

That's all for now...

 

 

 

 

Edited by Brian Dougherty
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Dammit Brian, now I have to make my own pattern :P. I was going to somewhat copy Culver's design as well. 

I've got plenty of time to think about it though, I've got 5 knives to make before I can begin this project. 

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Looking good!  That's going to be sweet when you're finished. 

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2 hours ago, Joël Mercier said:

Dammit Brian, now I have to make my own pattern :P. I was going to somewhat copy Culver's design as well. 

I suspect you (and me) are far from the only ones in that boat! :lol:  I was gonna make the blade a little seaxier, though. The interior geometry is what matters here, there is plenty of room to reshape the blade and handle as long as the tang/pivot/spring area looks like Culver's patterns.

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2 hours ago, Joël Mercier said:

Dammit Brian, now I have to make my own pattern :P. I was going to somewhat copy Culver's design as well. 

I've got plenty of time to think about it though, I've got 5 knives to make before I can begin this project. 

 

16 minutes ago, Alan Longmire said:

I suspect you (and me) are far from the only ones in that boat! :lol:  I was gonna make the blade a little seaxier, though. The interior geometry is what matters here, there is plenty of room to reshape the blade and handle as long as the tang/pivot/spring area looks like Culver's patterns.

Honestly, the three of us will learn more if we see how each other builds the same basic design than if we all did something different.  I day the more the merrier!

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That's gonna be 1 awesome slipey 

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Brian (and anyone else planning a PW folder blade) make sure you have some good acid resist handy for the etch. I prefer nail polish and get a color that is easy to see, do not use clear.

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Nice what did you use to cut them out? Plasma cutter?

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11 hours ago, Joshua States said:

Brian (and anyone else planning a PW folder blade) make sure you have some good acid resist handy for the etch. I prefer nail polish and get a color that is easy to see, do not use clear.

Thanks.  I hadn't thought that far ahead, but I assume you mean to protect the tang area?  I probably would have forgotten and etched the whole thing.

 

11 hours ago, AndrewB said:

Nice what did you use to cut them out? Plasma cutter?

Just an angle grinder, my belt grinder, and some files.

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Just now, Brian Dougherty said:

Thanks.  I hadn't thought that far ahead, but I assume you mean to protect the tang area?  I probably would have forgotten and etched the whole thing.

 

Just an angle grinder, my belt grinder, and some files.

Nice angle grinders and cut off wheels scare me lol.  I wouldn't have done that myself.    What are you planning on using for the handle material?

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7 hours ago, Brian Dougherty said:

Thanks.  I hadn't thought that far ahead, but I assume you mean to protect the tang area?  I probably would have forgotten and etched the whole thing.

You want to paint the resist inside and around both sides of the pivot holes in the blade tang. This leaves a smooth surface against the liners for the blade to pivot on and also allows for a little relief on the sides of the blade to keep it from rubbing on the liners and getting scratched. painting inside the holes keeps the pin tight in the hole.

You also want to paint the resist inside and around the pin holes in the spring as well as the surface area between the two holes. (but not along the top edge that is exposed to view) This gives you a smooth surface to pin the liners against while leaving the "springy" part with some relief against the liners so it can operate freely.

 

DSCN5216.JPG

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I need to decide how thick to make the liners on this knife.  Does anyone want to chime in how how thick they have made slipjoint liners in the past?

I'm going to use mild steel, or 304 stainless depending on what I have laying around.  I'm leaning towards ~0.060" thick, but that is a guess.  At first I thought that might actually be too heavy, but when you look at how the knife functions, the liners are actually a major structural element so now I'm not sure.  I don't want to go overboard and make this thing too chunky, however.

For reference, the blade and spring are 0.100" thick.

 

 

Edited by Brian Dougherty

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That would bring the handle to around 1/4" thick before the scales. It sounds pretty reasonable to me. 

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I measured the liners on a few Case slipjoints I have, and the ones on knives that size come in at 0.020".  And they're brass.  The spring and bolsters are doing most of the heavy lifting here, the liners are not under that much stress.

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I have used .03-.04 for mine. The only time I went with .06 was on a larger bladed folder

Like 5 inches

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Posted (edited)

I made a little more progress on this over the weekend.  I'd provide more commentary, but I don't really know what I am doing :)  I'm pretty much just following along with Culver's examples.

The next steps are to locate the 2nd pin for the spring, and drill the liners for it.  Then I need to attach the bolsters, and start adjusting the length of the spring and the profile of the tang to get the blade position correct at all 3 stops.

There is a bit of a weld flaw on the spine, but it is very shallow and will get ground out once I put in some distal taper.

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Edited by Brian Dougherty

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Looks like you're getting there.  Nice job.

Something that I  found handy back in the day when I was making folders was to make a jig with all the holes drilled into it so I could pin all the components to it to check  the action of the blade & spring.  It will  also be handy for laying out the holes should you make others the same size.

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Thanks Gary,

I wouldn't mind making more folders.  It fits my machinist mentality.  Once I fumble my way through this one, I may finally sit down and and design my own.

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I have seen that trick referred to more than once and will certainly do it for this build.  Might even get back a little machinist mentality.  My own went out the window during my first smithing class.  We were making tongs and I was trying to get a precision fit by filing the bosses flat.  The instructor (Charlie Orlando, RIP) took a look, said "let me show you something," and gave it one hard whack with a hammer, problem solved. :lol:  I know that doesn't work with folders, of course.

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Posted (edited)

Life has been getting in the way of my shop time lately, but I managed to get a little work done on this folder tonight.  The next major Step in Culver's method is to solder the bolsters in place.  I learned to solder by building my own slot car chassis when I was 12.  That was almost 36 years ago, and I don't hear soldering advice much anymore that I pay any attention to, but Culver's approach is one that I hadn't tried.  I gave it a go, and I have to admit it's better than what I have been doing.

First I used a file guide to scribe matching lines on each liner in order to line up the proximal edges of the bolsters.

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Then the new approach.  Culver recommends tinning the bolsters and the liners with a thin wash of solder.

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Then Carefully line the proximal edge with the scribed lines and hold in place with a spring clamp.  Then heat the parts up gently until the solder re-flows.

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Then I just used the pivot pin holes in the liners to drill through the bolsters and then reamed for the pin diameter.  After that I just pinned everything together and roughed the edges of the bolsters down to the liners.  The overall edges will get profiled later on.

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A couple of days ago I rough ground the blade.  Hopefully I'll get the blade and spring heat treated later this week.

IMG_20190413_105802118.jpg

More to come!

 

Edited by Brian Dougherty
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Posted (edited)

Brian,

Back in my days of making folders I found that Brownell's Comet flux was very handy when soldering stainless.;)

Edited by Gary Mulkey
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Thanks Gary, I'll remember that.  These bolsters are nickel silver primarily because I don't have the best track record with soldering stainless without using real high temp solders.  I didn't like the idea of heating these thin liners up that much, so I went with the NS.

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Way ahead of me!  I just ordered materials Friday...:ph34r:

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I was looking at my friction folder parts the other day wanting to figure out how to do bolsters on them. 

You just gave me an excellent idea to try. Thank you sir.... 

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