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Aiden CC

Swiss Army Knife WIP

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I'm sure someone has done something like this, but I didn't see anyone show their progress, so here goes nothing. I have a piece of CPM 154 for the blades/tools and some 410 stainless for the liners. The plan is to get all of the pieces cut out and rough-ground in the next few days while I have some time then heat treat them when I can use my school's materials science lab.

Knife Assembly 2.JPG

Did a 3D model to check for interferences and make sure none of the tangs will poke out of the handle. Some of the hole locations will be informed by the drawings, some will be a result of trial-fits. The order of operations for this knife will matter a lot.

Knife 2 Cut Sheet.JPG

Made a template-sheet with centers marked out so I can get cutting. The sheepsfoot will need to be ground down by the thickness of the liner stock for clearance reasons. The cutouts in the liners and nail-nicks will also be done once everything is put together so I can make sure all the clearances are spot on. There's a lot of interesting mechanical things about this type of knife (like the floating springs) that I'll try to explain as I go, but I'm definitely still learning.

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Looks like a Victorinox "Tinker"

I carried one of those every day for years :)

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I'll be watching this one with interest!  If you look at an actual SAK from the top down you'll see some of the blades are ground off-center, or "krinked" as they call it, to allow a tighter fit between the liners.  That is to say, looking at the one in my hand right now, the short sheepsfoot is on the outside and is ground striaght on the side that touches the liner, and tapered on the side that is towards the main blade, and is also, as you note, ground thinner on the tang by the thickness of the liner.  There's also an added bit of liner on that end to maintain the parallel of the center liner to the outer ones.  The main blade is ground to a taper on the side that abuts the small blade, but it straight on the other side where it meets the liner.  Subtle stuff!

For that matter, mine (a Victorinox explorer model with white scales I got in Switzerland in 1992) has three different thicknesses of liners, and 5.5 liners overall.  Complicated little bugger...

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Following. This is something I would probably never do, just because I'm fundamentally a lazy man and this is not cut out for thick fingered clods with facial hair like me. I have to say it Aiden, you have a knack for reaching out there and tackling the tricksy stuff.

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This is about as far as I would get.

danook-shows-off-his-swiss-army-rock-0-29890983.png

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9 hours ago, Brian Dougherty said:

Looks like a Victorinox "Tinker"

I carried one of those every day for years :)

The design is based off of the tinker with a few changes: longer handle and main blade, sheepsfoot instead of the small spear, and no key ring.

9 hours ago, Alan Longmire said:

I'll be watching this one with interest!  If you look at an actual SAK from the top down you'll see some of the blades are ground off-center, or "krinked" as they call it, to allow a tighter fit between the liners.  That is to say, looking at the one in my hand right now, the short sheepsfoot is on the outside and is ground striaght on the side that touches the liner, and tapered on the side that is towards the main blade, and is also, as you note, ground thinner on the tang by the thickness of the liner.  There's also an added bit of liner on that end to maintain the parallel of the center liner to the outer ones.  The main blade is ground to a taper on the side that abuts the small blade, but it straight on the other side where it meets the liner.  Subtle stuff!

For that matter, mine (a Victorinox explorer model with white scales I got in Switzerland in 1992) has three different thicknesses of liners, and 5.5 liners overall.  Complicated little bugger...

I've had a little experience with krinking when I made my stockman, I ground the blades off center and applied a bit of a bend to one of them. In this case I'm going to take the trick of using a half liner with a 1/16" blade sharing a spring with a 3/32" blade to get some extra clearance. I'll try to get some good pictures showing the strange workings of floating springs as well.

4 hours ago, Joshua States said:

Following. This is something I would probably never do, just because I'm fundamentally a lazy man and this is not cut out for thick fingered clods with facial hair like me. I have to say it Aiden, you have a knack for reaching out there and tackling the tricksy stuff.

Yeah, especially when I have a long time I can't work on knives, I get all sorts of big ideas (I'll finish that lock-back some day, I swear!). Definitely had to make sure my beard was trimmed short for this project :P.

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All the parts layed-out on my fancy steel (managed to get my school to reimburse me for it too!). Note that all the parts which require extensive grinding are buddied up. This makes them easier to hold on to and grind.

IMG_5721.JPG

Here's where things get tricky: the spring holding the blades is going to be 0.092", and the other spring is going to be 0.082", to slim down the knife and make the openers less blocky. Finally, the secondary blade gets two layers of liner, so it needs to be 0.033" thinner than the main blade. This means things need to be ground to rough thicknesses which will be lapped down to 0.092", 0.082", and 0.059". Yikes. A surface grinder would be perfect, but I got it to within 0.001" using a disk sander and calipers.

IMG_5722.JPG

Everything's rough ground except the small features, ready for the tangs to be shaped. 

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Posted (edited)
11 hours ago, Aiden CC said:

Definitely had to make sure my beard was trimmed short for this project :P.

I had a little propane incident and now my beard is trimmed short. And my left eye brow and eyelash. I almost posted it in shop safety but didnt because i was kinda embarrassed at the time. Now that i think about it, it is really funny.

Edited by Jeremy Blohm

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Posted (edited)

Ok the propane incident wasnt funny but the burned hair part ended up funny.

I will be following this one for sure! 

Edited by Jeremy Blohm

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Got some work in this morning, get ready for a lot of pictures!

IMG_5723.JPG

If you go gently and don't put too much lateral load on the quill, a drill press can do some "mill like" things. Joshua gave me a tip about doing this for nail nicks, I used the same concept ot make the screwdriver. 

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It's a little hard to see in this picture, but those are two features super-glued together. This is what I generally do for two-spring folders, and it lets you skip a lot of fiddly work. The following operations will be carried out with the spear point glued to the can opener, the sheepsfoot glued to the bottle opener, and the two springs glued together.

 

IMG_5728.JPG

This is the slot that the spring pin will fit in. When the features on the back of the knife are opened, the spring will get pushed down, which is why this is a slot and not a hole. There is extra room on each end so nothing bottoms out. The depth and placement on the spring was determined by checking the motion in CAD. The slot has some clearance to allow for smooth action while still keeping the spring in the knife (wouldn't want it slipping out :wacko:. When I use my dial indicator jig for the fitup, I'll try to show it in action.

 

IMG_5730.JPG

Order of operations: use template to place and drill pivot hole for main blade, put the spring where I want it then drill through the slot to place the spring pin hole, place secondary blade where I want it and drill through the pivot. If this were a normal two bladed knife I would have added the pre-load (the bit of tension in the springs even when the blades are "at rest"),  and been done, but this is a special case. Also, note that to same some time the liners are glued together.

 

IMG_5731.JPG

Adding pre-load starts in a similar way to any other slip joint: put in blades and spring, push the spring down, and trace the blade of it. Next, I placed the awl on the liner such that it would interfere with the spring by the distance of pre-load I want (in this case, 3/64"). Then I drew a line there so I could super-glue on the awl for drilling.

 

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Finally, I drilled the hole and assembled the knife. With un-hardened springs, you can assemble the knife in open/closed positions, but DO NOT try to open or close the blades, you will permanently bend the springs and be sad. The next step is to separate the tools/blades and start doing some of the finer fitting as well as make the spacer for the secondary blade. 

 

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More progress from last night! Today is my last day to work for a while, so these need to be ready for heat treat pretty quick.

IMG_5734.JPG

Primary blade lapped flat.

 

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Next I lapped the secondary so that it's tang and the liner equal the thickness of the primary blade.

 

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I've shown this jig before, basically you zero the indicator with a blade open, then close it and remove material until you zero it.

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Like so.

 

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Things are starting to come together! I still need to taper the blades a bit so they congress a bit better with no rubbing and finalize the bend on the primary.

 

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This is that nail-nick trick I mentioned earlier. The results aren't as quite as crisp they would be with a dovetail cutter or a chisel/die, but they are pretty consistent once you get the hang of it.

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All that's left before heat treat is to polish the tangs and some other stuff up to 400 grit and taper the blades a bit so there's more room inside the blade well.

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Put in some time this morning lapping tangs, grinding/krinking the blades so they mesh nicely, and lightening the springs. I want to be able to put this together right out of heat treat to check the action. I may cut some swedges after heat treat to give more clearance. 

 

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The small spacer above the sheepsfoot is called a catch-bit and is a very clever thing used in some slip joint designs. It's held in by the pivot pin, and kept from rotating by the spring.

 

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I'm really excited to get the springs hardened so I can see how it works.

 

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All the parts as they are now.

I won't really be able to do much on this for a few months, other than to harden everything

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Wow, very helpful description and photos.  This thread might need to be pinned...

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Dude! This is an outstanding WIP. I second the pin nomination.

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In that case, pinned it is!

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Thanks for the pin! I tried heat treating some CPM 154 fixed blades and something went wrong because the hardness was essentially unchanged from annealed. Glad I tried the test pieces first! I used some firebricks in the furnace to prop them up, which may have prevented them from getting up to temp. The furnace also may not be calibrated properly. I’ll probably try again soon with the test blades (a couple of full tang puukkos). 

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1 hour ago, Aiden CC said:

Thanks for the pin! I tried heat treating some CPM 154 fixed blades and something went wrong because the hardness was essentially unchanged from annealed. Glad I tried the test pieces first! I used some firebricks in the furnace to prop them up, which may have prevented them from getting up to temp. The furnace also may not be calibrated properly. I’ll probably try again soon with the test blades (a couple of full tang puukkos). 

I don't know what HT process you are using, but I posted a .pdf file with the HT info for 440C that works well for CM154 here. If I were home, I would PM you the document.

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3 hours ago, Joshua States said:

I don't know what HT process you are using, but I posted a .pdf file with the HT info for 440C that works well for CM154 here. If I were home, I would PM you the document.

Took a brief look at it, it gives rates which is helpful. My process was: ramp to 760 C (1400 F)  at max rate, then ramp to 1050 C (1922 F) and soak for 45 mins, then quench between two aluminum plates with compressed air. When the foil pouch came out of the furnace, it wasn’t glowing, so I quenched one and tested it. When it came out soft, I let the other soak for 45 more minutes, and tried it with the same result. 

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I think you are taking too much time getting out of the foil and/or the aluminum is not a fast enough quench. Personally, I always quenched this stuff in oil and used the pressure plates to straighten and complete the quench. Do you have any anti-scale compound? 

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12 hours ago, Joshua States said:

I think you are taking too much time getting out of the foil and/or the aluminum is not a fast enough quench. Personally, I always quenched this stuff in oil and used the pressure plates to straighten and complete the quench. Do you have any anti-scale compound? 

I left it in the foil and went straight to the plates, then applied compressed air for a few minutes. My leading theory is that the blades hadn't equalized to the temperature in the furnace wherever its thermocouple is. I don't have anti-scale compound, but I could look into it. Does it prevent decarb too?

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Yes it does.

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44 minutes ago, Alan Longmire said:

Yes it does.

I might have to give that a try. Turns out I had the furnace fan on, which likely causes some of my problems. Doing another run today, total run time 185 mins with a 45 min soak at 760 C (1400 F), then ramp to 1050 C (1922 F) and soak for 45 minutes. Soaks slowed down to 10 C/min (18 F/min).

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Turns out we just got the furnace I used from another college and it was set to Fahrenheit (despite it having “Actual C” printed on it). Doing another try today. 

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Well, that will surely make a difference.  Lol:D

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27 minutes ago, Aiden CC said:

Turns out we just got the furnace I used from another college and it was set to Fahrenheit (despite it having “Actual C” printed on it). Doing another try today. 

That shouldn't have been a problem--you did all your measurements on an inch scale.:blink::P:D

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15 minutes ago, Vern Wimmer said:

That shouldn't have been a problem--you did all your measurements on an inch scale.:blink::P:D

True! I converted all of the temperatures to C so I could enter them...49BE3952-EAB3-47A9-BC60-1DDFE8830BBF.jpeg

You can see why I thought it had to be in Celsius. 

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