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The Folding Knife (& Switchblade) Forum The materials, techniques and the designing of folding knives. |
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#1
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newbie auto design
Hi guys,
recent lurker, first time poster here. I'm a 3rd year (of 4) Industrial Design student in New Zealand. Just getting interested in knife making as my pocketknife just broke on me, so I looked at replacing it. Then I ended up looking at the most expensive ones and figured I might be able to make my own. Long story short, I'm here. I was looking originally at a liner-locker, because I like the slimness of the design. My pocketknife was a currey-lockspike, which was nice and thin and sits in your pocket easily. I figure if its nice and thin the more likely I am to have it on me. The best knife is the one you have with you! (sorry, this is a long backstory!) Being a bit of a nerd for mechanical moving parts I was also interested in autos, but wasnt happy with the thickness required for a button type mechanism. So, I did some sketches and some fiddling and came up with this; It appeals to me because it is only three layers (liner, blade, liner) thick, and can afford to have relatively thin liners. Today I found some acrylic and some free time on the laser cutter. A quick and dirty spring from piano-wire and some nuts and bolts and I made a prototype... I didnt really pay attention to the background noise, you might be better off muting it! also, the acrylic is clear so the details will be easier to see in the HQ version... youtube video of prototype action I'm interested to hear your thoughts on the design - some things that I'm aware of are; - made a rough and ready spring for the locking mechanism out of some speargun rubber, it would be better to limit this movement somehow and use a metal spring - I didnt account for the tolerance of the laser cutter, so the prototype doesnt close all the way that it should - The spring pivots are poorly placed and so the blade isnt under tension the whole way through the movement - this shouldnt be too tricky to fiddle though. I have planned to recess the spring into one of the liners. So thats it, i guess. Sorry for the long post! Looking forward to some critique. Regards Rich |
#2
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Because of my very slow 21k dial up connection I can't see the video so forgive me if I must ask questions that would have been answered in the film clip.
From the sketch, it looks like you have designed a modified slip joint knife. Doesn't this knife require two hands to open it and to close it? Nothing wrong with that but the market trend has been towards one handed knives for a few decades now. What is the purpose of the slot at the rear of the spring? I'm all for building prototypes but I usually use aluminum. Speargun rubber is a surprise, doubt I would have thought of that. Seems like you might have tried the acrylic as a spring. That would have more closely simulated a metal spring and it should have enough flex to survive the application for a while....... |
#3
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That's an innovative design. I'd like to see a photo of the model. The video is over so fast and because it's acrylic I can't see the spring.
If you actually make one of these there is some tweaking you may want to do with the locking mechanism. |
#4
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The spring is extremely primitive at the moment. It would really make more sense if the spring coiled around the main pivot.. I'll do some more thinking here and have a play. Don, what do you suggest as far as improvements to the locking mechanism go? Thanks for your input, I really appreciate it! |
#5
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Obviously you've resolved any problems with the lock notches.
Looking at your sketches the locks are square with no angles for a lead-in, but your model works fine. Thanks for the photos. |
#6
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You may have to do some tweaking with the actual design, but I think you are on to something. I'd like to see it if you do a knife with this. (I've just gotten into making folding knives so I"m no expert, but the model works)
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#7
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Very interesting design and seems to work fairly well based on your video. I'm certainly no folder expert (no expert in anythig really) but I suspect you'll have to beef up your spring a bit if you make a metal prototype. Nicely done!
-Dave __________________ www.ruhligknives.com "The choice isn't between success and failure; it's between choosing risk and striving for greatness, or risking nothing and being certain of mediocrity." - Keith Ferrazi |
#8
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I have just been speaking to a man here in Wellington who reckons he has some HSS that is 18% tungsten that he thinks would be suitable for the blade - I couldnt get any more detail from him from that, other than he said it wouldnt need heat treating (?), I could just grind it into shape. Is it worth looking at? |
#9
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That sounds like M2 HSS. He may have a planer blade or some other tool that has already been heat treated.
M2 would make a very good blade. |
#10
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That's a very intriguing design. I like it! I'd definitely like to see this made into a knife.
Or even just a metal prototype. |
#11
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Great work. I'm impressed, too.
Parts for the knife, including auto coil springs, are easily available at www.knifekits.com. Keep us posted! Coop |
#12
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I have made that mechanism for years and call it a toggle lockback.
I have heard it called a French folder too (probably why I quit making it) If you use a kick spring, they work great. Coil springs can work too. They are a good ambidextrious carry design.(either hand auto) Have fun and hollar if you need help. God bless, Geno |
#13
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hi,im in wellington too.ive made that same style knife too,id be keen to have a chat with you about it if you want.heres the one i made.it uses a leaf spring though.
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Tags |
blade, knife, knife making, knives, pocketknife |
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