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Build your first slip-joint - Tutorial


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Now we need to get some holes in the scales for the rivets to hold them on, and for the through pins.  The surface of the bone is far from flat, so we can't just set them on the table and drill through from the liner side and expect the holes to be lined up.  However, this no longer really matters for the holes that just have rivets.  The 4 rivet holes are just for rivets to hold the scales to the liners, so lets just drill for those by simply eye-balling the assembly to be level and drilling as straight as we can:  

IMG_7951.JPG

 

The other holes do matter.  If we eye-ball them like I did for the rivets, we will have problems getting the pins to pas through both sides.  My approach is to use the spring as a drill bushing to help keep things in line.  First I clean the adhesive out of the holes in the liners, and use dowel pins to line the spring up with those holes. (The very tips of the pins are sticking into the holes in the liners)  Then I temporarily super glue the spring in place.

IMG_7952.JPG

 

Then using the spring as a hardened drill guide, I carefully drill through the first side.

IMG_7953.JPG

 

Then I put the pivot pin through both sides to maintain the alignment at the pivot and drill back through the other direction.  We want to hit the hole in the second liner as we drill back through.  The pivot pin will constrain the parts in the right location except rotationally.  However, I have found that you can see through the holes well enough to get the holes pretty well lined up, and then rely on the drill bit to center the second liner up "perfectly" as it passes through the hole.

IMG_7954.JPG

 

Ream all the holes while both sides of the knife are still held together, and then you should be able to pass the dowel pins though.  If you are using bone, you may find that they are a little harder to press through now.  The reamer produces a tighter hole in bone that it does in metal, but you shouldn't need much force to get them through.

IMG_7955.JPG

 

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Time to bring this build to an end!  Where I last left off, we had peened the main pivot pin.  The next step is to get the nickel silver spring pins in place.  Below you can see how long I leave the s

OK, let's make some liners so we can get into fine tuning the action.  I'm trying something new here and using brass for the liners.  I had some 0.050" (~1.25mm) thick brass sheet lying around so I su

Now you can carefully grind away most of the excess bolster material.  You need to go slow here.  Nickel silver heats up quickly, and you can get it so hot that you melt the solder.  

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How are you liking the Loctite so far?  I've learned when applying the adhesive to squeegee most of it off before sticking the scales on the liners.  It's thick enough you can't get it all, and it saves some sticky fingers later. 

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1 hour ago, Alan Longmire said:

How are you liking the Loctite so far?  

I've only used it the one time, and haven't really tested it for durability.  However, I like the application process much more than Gflex.  What really sold me was the ideal glue thickness is 0.002" as opposed to 0.004"to 0.006" for epoxy, with tensile and shear strength that is comparable.

 

I bought a coupe of single use kits at $6 each to give it a try.  As you say, the stuff is on the expensive side...

Edited by Brian Dougherty
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I considered for a brief moment finding out who the Loctite agent is, but I decided to learn from past experience and avoid the disappointment.

Eagerly waiting for the next installment, that's where I have the most questions.  

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12 hours ago, Gerhard Gerber said:

who the Loctite agent is

 

Over there the brand is owned by Henkel, here's the ZA page from them: https://www.henkel-adhesives.com/za/en/product/structural-adhesives/loctite_aa_330.html I can't imagine why they don't have a presence in Namibia... :rolleyes:

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16 hours ago, Gerhard Gerber said:

Eagerly waiting for the next installment, that's where I have the most questions.  

I suspect you are eager to hear about adjusting the spring tension.  It will be a bit before I can post that part.  The photos I took during this build don't tell the story very well on their own, so I need to draw up some diagrams to go along with the pics.

 

However, before we can adjust the spring tension, we need to clean up the profile on the back side (spring side) of the handle.  At this point all the parts, including the spring, have some extra material on them.  If we adjust the spring tension now, and then clean up the profile, we run the risk of weakening the spring during the clean-up process.

 

What I do at this point is assemble the knife in the closed position.  Do not be tempted into trying to open the knife at this point.  You'll probably break the spring.

 

I use a combination of the 2x72 and a spindle sander to clean up the profile.

 

IMG_7957.JPG

 

IMG_7958.JPG

 

Once the back side and end are cleaned up, take the knife apart, and reassemble it in the open position so we can clean up the inside profile and blend in the spine of the blade into the handle.

IMG_7959.JPG

 

You can see in the previous picture that the spine of the blade is a bit proud of the handle.  The goal is to blend that into a fair curve without removing much if any more material from the back side of the handle.

 

 

 

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Now is a good time to rivet the scales to the liners.  Before we can do that, we need to get them closer to the final shape.  To do this, I disassemble the knife again, and pin the two handle halves together.

IMG_7960.JPG

 

Then I blend the scales down into the bolsters, and roughly shape the corners into something more pleasing to hold.  It doesn't need to be finely sanded at this point, but you do want to have the bulk of the unnecessary material removed so that there isn't any risk of filing/grinding away the rivet heads later. 

 

IMG_7961.JPG

 

We can put in 4 rivets now, 2 on each half.  The inside of the liners need to be flat for the knife to function, so lets countersink the liners so the rivet heads have a place to go.  I've tried a lot of countersink options, but what I like the best is to use a center drill for this.  A #2 center drill works well with this size of hole.

IMG_7962.JPG

 

We need a similar countersink on the outside.  The reason I like to use a center drill for this is because the pilot makes it easy to keep the chamfer centered, especially on the textured parts of the scale.

IMG_7964.JPG

 

IMG_7963.JPG

 

Now we need some rivets.  I make them one at a time from nickel silver rod.  First I form a head:

IMG_7966.JPG

 

Run the rod through the scale:

IMG_7967.JPG

 

I clip it off fairly close to the scale:

IMG_7969.JPG

 

...and carefully grind it until about this much sticks out:

IMG_7970.JPG

 

Then I peen it into position with a tiny ball-peen hammer on a miniature anvil.  As someone once said on this forum, peening pins is like death by a thousand cuts.  I probably used >200 hammer "taps" to finish this rivet off.

IMG_7971.JPG

 

 

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I've caught up to where I am on on this build so it'll be a few days before I get to the next update.  However, I have a couple more pics I'll leave you with for now.

 

I like to grind most of the blade bevels in before I do the first assembly with the spring.  I've hollow ground the last few with a 10" wheel, but flat grinding them works well too.  My lazy way to grind these blades is to set the spine on the rest, and just grind straight across.  With a 120-grit ceramic belt running at about half speed, I can grind a heat treated blank in about 10 minutes.

IMG_7956.JPG

 

Here is where I am at right now.  I've made a bit of a mistake at this point.  It's a problem I have had in the past, but it was the process of writing this tutorial that made me realize the cause.  I think I can fix it, but need some time to work through the issue.  It's a minor thing, but I'd be happier with the action if I fixed it.  I'll leave the pic here to see if anyone spots the goof...

 

IMG_7972.JPG

 

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The top part of the spring sits just a hair below the liner when fully closed? 

I am actively considering starting one of these just to have a go at trying to do one. 

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The kick is still a bit big causing the blade tip to lie outside the handle?

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10 hours ago, Brian Dougherty said:

  I'll leave the pic here to see if anyone spots the goof...

 

My money is on that little gap......?

 

Not sure, but I don't think my SS pin material would allow me to use this method, I was waiting with baited breath for the peening.

 

Being a noob I know there's lots of room for improvement in my order of operations, and similarly your approach does not make sense for me because I'm sure I would mess something up(most likely scales), only answer is I'll have to try 

gap.JPG

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2 hours ago, Gerhard Gerber said:

My money is on that little gap......?

 

DIng ding ding ding!  We have a winner :)

Does anyone care to guess why this is a minor issue? (Hint: It has to do with where the centerline of the pivot is in relation to where the spring pushes on the tang)

 

2 hours ago, Gerhard Gerber said:

Not sure, but I don't think my SS pin material would allow me to use this method, I was waiting with baited breath for the peening.

 

Being a noob I know there's lots of room for improvement in my order of operations, and similarly your approach does not make sense for me because I'm sure I would mess something up(most likely scales), only answer is I'll have to try 

 

 

I've used SS pins before.  They are a little harder to deal with, but you can still peen them.  If they are 300 series (304, 316 etc.) you can "anneal" them by heating them up and quenching them. (Yes, just the opposite of what we normally do)  Apologies to Jerrod for a loose use of the term anneal :)

 

I'm not sure which part of the process has got you worried.  If it is shaping the scales, then just think of it like shaping the handle on a fixed blade.  It's the same thing, and has the same level of risk.

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2 hours ago, Brian Dougherty said:

Does anyone care to guess why this is a minor issue?

 

It causes a slight "loose" feeling before the crisp snap of opening to the half-stop position?  Or rather than loose, there is a definite bump on opening?

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Close Alan :)

 

The symptom is that on snapping close, the blade will rebound off the kick, and open back up a few degrees.  You can close it back up, but it feels "mushy".

I've had this happen before, but it wasn't until I spent time with all these pics that I understood why.

 

In the closed position, my spring is pushing on a line that is pretty much centered at the pivot point. (The blue line below)  That means there is no leverage to force the blade to pivot around the pin into the closed position.  What I need to do in the future is to make sure that the spring is always bearing against a point outside the pivot point. 

 

I could correct the problem on this particular knife by removing a little material along the red line in the pic below.  However, that will allow the spring to rest a little bit lower in the closed position than it does in the open position.  To get it perfect, I will have to adjust the tang for all 3 positions again, and I'm not sure I want to remove any more tang material.

 

 pivot feature.JPG

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Brian.......the space in the closed position......sight unseen, I saw the gap in the photo and felt this was what you were referencing.

Thinking.......could this happen after marking the spring tension, as the spring angle has changed ever so slightly? 

 

Really enjoying this WIP Brian!

Gary

 

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5 minutes ago, Gary LT said:

Thinking.......could this happen after marking the spring tension, as the spring angle has changed ever so slightly? 

I don't thinks so, unless it is caused by the slight flex in the spring caused by the pre-load.  I think it is more likely that I simply wasn't thinking about the need to apply force on the out-board side of the pin until last night.  When I ground that area to adjust the closed position, I had a flawed model in mind.

 

As I predicted, I am probably learning as much about this process as anyone else.  My take away on this one will be to shape the kick/tang area so that the spring contacts the two most distant points.

 

I'm good at changing my mind, but I think I'm going to adjust that area slightly to test my hypothesis.  I'll report back once I do :D

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Or using a punch hit the spring flat at that inside corner to peen out / upset some material, light taps.

Then look at it and say “dayum I shoulda listen to my own plan!  I dun foobard this thang up now!

:D

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OK, I couldn't let it sit, I had to try my hypothesis out when I got home tonight.

 

Just to remind everyone, here is where I was at.  I had inadvertently ground the contact point on the closed facet of the tang so that the spring was touching in a line right at the pivot.  The result was a "Mushy" feeling on closing.  It closed fine, but didn't really want to snap the last few degrees, and there wasn't any spring force holding it closed the last few degrees.  It sort of floated a little at the very end of its rotation.

 

pivot feature.JPG

 

Here is the after pic.  Unfortunately, I took it of the other side of the knife, so I mirrored it to make it easier to see the difference. (Didn't want you all to think I was being shady :) )

 

I removed just enough material to bump that contact point out beyond the pivot.  The result is just what I hoped.  Now the blade snaps closed all the way, and there is positive force keeping the blade up against the stop when closed.  Problem solved.  It didn't even move the spring position enough to worry about readjusting the other positions.

IMG_7978m.jpg

 

 

 

I hope y'all are learnin' something, because I am :)

Edited by Brian Dougherty
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This worked perfect Brian, as it was supposed to.
I’ve gotten a lot from this WIP.

Do you have more to finish?

Gary LT

 

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Yeah Gary, I've caught up with where I'm at on the build so the updates will be in real time from here on out.  The hard stuff is done, but I have all the final sanding and polishing to do.  I also need to make and size the final bushing as the one I am using is just for all the trial fitting.  I'll need to make nickel silver pins to replace the dowel pins as well.

 

The only scary step left is peening the pivot pin.  That still makes me clench my cheeks a bit.

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Brian, as you can get it.^_^.... many will be watching including myself.

Gary LT

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On 2/10/2021 at 8:48 PM, Alan Longmire said:

 

Over there the brand is owned by Henkel, here's the ZA page from them: https://www.henkel-adhesives.com/za/en/product/structural-adhesives/loctite_aa_330.html I can't imagine why they don't have a presence in Namibia... :rolleyes:

Alan, SA has a population of about 60 million, Namibia at a stretch 3 million.......small and ignored market.
You can buy Loctite locally, as long as it's thread locker :lol:
On a less funny note, with the lockdown and closed borders lot's of things have become unavailable or take months to get here. 

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18 hours ago, Brian Dougherty said:

 

I'm not sure which part of the process has got you worried.  If it is shaping the scales, then just think of it like shaping the handle on a fixed blade.  It's the same thing, and has the same level of risk.

Well I guess I can't say "I usually" because I've only made two, but thus far I've followed the same procedure so scales are last.
You touched on my problem, I have been hesitant to peen even on micarta scales, nevermind bone, guess I'll need to get a new peening hammer and give it a go.

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I can't claim any expertise at it Gerhard, but I have never cracked a bone scale by peening yet.  I have chipped them in other parts of the process, and usually hold my breath a bit when it comes time to peen things over, but that hasn't given me any trouble.

 

I think that hammer I used here is 1.5oz.  It is tiny, and may be why I don't crack the scales.  When I do stainless pins, I have another hammer that is about twice that size that I use.  It feels giant in comparison, but hasn't given me any problems.

 

I don't feel that this thread is "My show", so you folks that use bone should feel free to jump in here if you want.

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One thing I've seen elsewhere is sticking tape around the pin that you are busy with.

No knife making this weekend, going to my cousin's farm, but I need to make a gutthook from SS so I'm to make two more sets of blades and springs from stainless as well so I have 4.5 knives to practice on, will try your order of operations and see how far I get.

Thank you again B)

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