My first multiblade slip joint

R

Randy3000

Joined
Jun 3, 2017
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I've made about 15 single blade slip joints now, and my last 2 were the only ones i felt were close to good (still far from perfect). The whole point in making slip joints for me is to overcome the challenges in all the thousands of different designs and make useful multi function tools. I feel like I'm starting to get the basics a little and want to attempt to make my first multi blade. I wanted to do a double ended spring, and I've started whittling again, so it made sense to me to make a whittling knife. I just finished the spring and fitting the blades.
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It's a big knife. It's 4" long, the pen blade is 1.25" and the coping blade is 1.5" edge length. I made it slightly offset on purpose, but i realize now that was a mistake because it resulted in that coping blade's kick being way too exaggerated.

I'm thinking about redoing the coping blade and move the kick closer to the pivot. The concern i have is it being too easy for the blade to then smack the spring when closing. In my short experience, i think the kick hitting the spring more than a third of the way down provides a pretty abrupt stop and also makes it pretty hard to squeeze the blade to where it hits the spring.

Assuming i was dead set on using this spring, would you redo the coping blade or not?
 
To me, it would be a better knife if you made a standard two blade setup with overlapping blades and separate springs. That would cut the length down significantly. You could even do a single spring and by-pass the blades with a left and a right grinding placement.
Your build is essentially two separate folders sharing one set of scales and liners.
 
Well, the idea is to have a long enough handle i can get a full grip and rest my thumb along the back of the handle instead of on the blade. Kind of like the fixed blade whittlers. I also wanted some experience on the double ended spring as i plan to make a traditional whittler and half whit designs soon. We'll see how it goes.
 
I was wondering how difficult it would be to fit the blades to the spring using only a single pin. I guess you would have to work on both blades at the same time. If you take some off of one blade it will affect the other blade's fit. I'll try it next time.
 
What Stacy and Bill both said, single center pin
and definitely make it so the blades bypass each other.
Ken.
 
Look fine to me, for what you want (long handle, short carving blades).
I would use a single pin for the spring, but see nothing wrong with two. Give it a go.
 
be careful, your pivots locations look like they'll give you different spring heights in opened vs closed positions
 
After wasting 3 liners due to not being able to get both pivot holes drilled right, i threw the spring away and am going to go with a single pin. I will probably have to redo the blades to so i can fit it properly again. If i have to redo the blades, I'll think awfully hard about making one a wharncliff style...
 
I just scrapped the whole thing. I started a traditional dogleg half whit design. I already made the spring and it's tempering now. Here is a bad drawing of what I'm going for. The spring is 3/32", the wharncliff blade will end up around 1/16" and the pen blade around 1/32". Is 1/32" too thin?
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So i always try to learn from my mistakes, and i keep notes on each design i develop so I don't repeat mistakes and look for ways to minimize impacts of errors. I cut and drilled the liners before fitting the blades this time. I started with a finished spring, it's 3/32" thick and 0.060" tall. I made the spring longer for the small blade so it'll counter balance the mechanical advantage the longer blade has when opening (i want them to open with about the same force). I completely fitted the pen blade to the spring before working on the wharncliff blade, which I'm in the middle of fitting. I had started plunging into the side of the pen blade before i realized i could fit the wharncliff blade with the pen blade open since it was already fitted (equal when open and closed). I should have fitted the wharncliff blade first, so if i messed up fitting the second blade i would of only needed to of remade the smaller blade.

But anyway, i think it's coming along. I plan on wharncliff thickness 1/16" to 3/64" and pen blade thickness 3/64" to 1/32" where they overlap, so together they make up 3/32" throughout. Then i hope the actual beveling will give them some breathing room.
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It might help you if you scribe a circle around the pivot. This will be a guide for where the high and low spots should be in the tang ends.

Generally, the rest spot on the blade (kick), which determines how far it seats when closed, starts as a flat area and not a projection like you have on the Wharncliffe blade. As in your pen blade, in shaping the bevels, the edge will drop back from the starting point. The kick then can be relieved in a convex between it and the heel to make it easier to adjust the exact seating.
 
The circle makes sense. The distance from the pivot hole to the spring when open, half open, and closed defines a unique circle, which is the circumcircle of the triangle of those three points. Being that the circle is unique, and the pivot has to be at the center of the circle means it is really hard to do by eyeballing. I have been making it even when open and closed, and leaving the end of the tang about 1/32" long. I've kind of been content with this because it makes the action a little snappier, which i do like. But I'm curious how you actually scribe the circle, and if the pivot hole is drilled or not before scribing.

As far as the projection on the wharncliffe blade, it'll get smoothed out a bit.

Edit
I just thought about how to scribe the circle. I could drill the pivot hole first, then take a piece of scrap metal and drill a hole for the pivot pin, then drill a small 1/16" hole about 1/8" or so from the pivot hole. This small hole will hold a drill bit and i could swing that scrap bar around and get a decent circle.
 
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I started the tapered plunge and i have about 0.015-0.020 left to take off each blade, and the angles on each blade are the same. Have to break here. Tomorrow I'll start the beveling. It's a little tricky because I'm using a filing jig and anytime i loosen the vise grips to check my progress, i have to readjust everything for several minutes until i match the angle I've been working on. I use a sharpie so i can see where the file is cutting, very helpful.

I'm very happy that each blade opens/closes with about the same force, those spring lengths are just right. Once the blades are finished I'll shape the liners very close to their final shape. I'm hoping i can use a piece of antler i have, but if not I'm going to try doing jigged cowbone. I really hope this turns out good.
 
Finally bevelled the blades! They overlap with a thickness 0.085"-0.090" throughout, and the wharncliffe blade is 0.090" at it's thickest near the base. Man that's a lot of filing! The 3 dimensional filing isn't too difficult, just a lot of sharpie to see where it's hitting. I still need to round off the edges and clean it up.
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Coming along nicely.

"I'm curious how you actually scribe the circle, and if the pivot hole is drilled or not before scribing........"

When you do the lay out the blade stock, it is always best to peck the pivot hole location with a small drill bit first, and drill the pivot size hole later on. This centers the pivot size drill. No need to drill the pilot hole all the way through, just a little starter divot is all you need. Once you have the divot drilled, scribe a series of circles around it with a compass. These will help you shape the open/closed contact points as well as place the ricasso.
 
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I got it together for the first time! I have a lot of shaping to do on the handle and polish the blades. I may file some grooves on the bolsters, i need to try it first on some scrap. No blade rub at all!

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Randy once you have it shaped and the scales contoured to the bolsters you could "jig" the ends of
the antler and then use potassium permanganate to color the antler. I've had good luck doing it this
way.
Ken.
 
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