Copied or influenced?

One good thing to do when designing your first folder mechanism is to see what really works vs what you dream up. Many of us think things ,even draw them on CAD design, and when they are transfered into metal we find what we missed. If you don't want to make several trial blades, get a knife with a shape and lock mechanism similar to what you want, and disassemble it. You might even use the tang shape as a template for laying out yours. Once you have several folders under your belt, you can start re-inventing the wheel.

One thing you really want to make is a set-up jig. It is a piece of heavy aluminum plate ( or steel) that you drill out exactly like your liners. The holes should be the same size,too. Using pins inserted into the holes ( instead of screws and pivots), you assemble the knife on this, rotate things to see where more metal needs to come off, fit the locks, etc. Once all is right, you can move to assembling and disassembling the knife with the screws and bolts. Such a jig is almost a requirement for lock back assembly and design.

Stiff cardboard or plastic sheet makes an excellent material for creating a blade template when doing work board design. A plastic blade with a pin/tack through the center of the pivot area can be rotated over a drawing to see what hits where.

While Ron's triangle is hard to visualize, a circle is easy. Start all folder tang design with a circle the size of the pivot. Then draw in a second circle that is the distance from center that the farthest part of the blade from the pivot ( usually the spine). Last, draw a circle where the detent will ride. From these three concentric circles you can place all the lock components and then extend the blade out from that. Once you have this, you can remove parts of the tang to shape it as you wish, as long as any of those circles do not get crossed. Thus you add a flat for the lock, a dip from the outer circle to nearly the detent circle for the stop pin,shape the heel so it still keeps the detent on the tang during close, position the closed stop so the blade rests just proud of the standoffs, etc.
If you add those circles to your drawing, you will instantly see what Ron saw.
 
Thank you Stacy, I use more than CAD software I use true 3D and animation software so I get the the same effect as I would with the cardboard cut outs, and get to save a tree or 2 this way because I will be going through a lot of design changes. Once I get close I will be making cardboard cut outs to do real life testing.
I really like the set-up jig idea, I would have never thought of that one on my own, thank you very much on that. I have cheap Cabelas sawtooth folder here that I have been trying to use to to viualize just how the liner lock works,taking it apart is the next step. That combined with Ron's triangle and this tutorial is really helping. I would like to find a copy of The Tactical Folding Knife by Bob Terzuola. I found it online, but dang its expensive $178 CND new and $68 used, there are a number of downloadable versions but I don't really like that option.

My original drawing was just a conceptual thing with no real thought of the lock, because I have a lot to learn in that area. I figured once I got the actual blade and handle shape done I could play with the tang/lock area to get that working right, knowing full well that I would most likely have to tweak that area of the handle as well. I figure that I have a good month of learning and tweaking on this design before I even put a template, saw, grinder, or file to metal on it.
All the help I am getting in this thread alone is invaluable, and I hope that when I take this off the computer and put on steel that I can do all the help I am receiving justice

George
 
Looks like the one I am building. Don't forget to give credit to Micheal Walker.
He designed the lock that we all use. Bob's book is incredible for anyone building liner or frame locks. Email me. I have some information you might be looking for.
 
send away, any information I can get is appreciated. I tend to be a rabid sponge for things I am interested in, I read text books, spend hours on line looking things up, I love learning new things
 
There are a number of fine resources. However, Bob Terzuola's book should be one of your resources.... just as much as Gene Shadley and Terry Davis's book should be a prime resource if you make slipjoints.
And yes, if it is gonna be a linerlocked folder, Michael Walker deserves credit for that invention.

As to copying vs inspired by, when in doubt acknowledge your inspiration....
 
Well I found Bob Terzualo's book on line for $35 before shipping so I think that I will be ordering that tonight
 
Well with all the great advice I have been getting here I have decided to keep trucking with the design of this knife. I see what was meant by getting the perfect triangle was almost impossible, I have been trying for the last 3.5 hours and I am still not there:o Just how close is close enough? I am with in .2 units ( I haven't set a measurement scale) from largest side to smallest side.
So here is where I am at right now

Open

open.jpg


possible rollout problem at 90*

rollout.jpg


Closed

closed.jpg


Just what sort of tolerances are needed between the stop pin and the blade through its travel and the closed position?

I just ordered Bob Terzuola's book, but it will be a couple of weeks till it gets here, and I have my focus set on this and want to keep going and 2 weeks seems like a life time once I get in this frame of mind.
 
I don't have a measurement for close, I just eyeball it. On the design you just did, I would keep the stop pin at least 1/16" down from the top of the handle. You may need some room to grind there. You could also move the stop pin toward the back of the knife some (right) to avoid the blade bumping while closing. I hope you don't think I am trying to nitpick you ... I know you have put a lot of time and thought into this. I am just trying to help.

Ron
 
Nope don't think you are nitpicking at all I appreciate the tips and help. I am not sure of what my measurements are yet because I haven't ordered any of the hardware yet. Once I do that I will measure up the parts and do some scaling on the drawing and be able to get some true measurements.
I just got my order confirmation on Bob Terzuola's book, latest delivery date is 19/05/2010, I may have actually be started on the knife before that, but I will have it for future reference.
 
I guess my next question on this folding knife project is, how do I decide what hardware to use? Things like pivots, screws, liner thickness, pocket clips, detent balls. Also I work at a bike shop are the ball bearing we get the same as the detent balls I could order on line? sizings are the same and I could walk out with a handful for the same price a single ball from an online dealer.
I think this is my next step to making this knife a reality. Once I have parts in hand and know the sizes I can start setting some of the aspects in stone and know the clearances I need for each part.

Well of to the Doctor to see what he has to say about my elbows, I think I may end up on the opposite side of the knife soon to get this thing fixed. And why do theses shut downs and outages always come when I am starting a project that I need a lot of advice for:( Maybe I will just stop announcing them and the site will stay up for ever:p
 
Here is what I typically use:

  • 3/16" pivot pin & screws
  • 3/16" stop pin
  • Any thumb stud that I like
  • .063" ti liners
  • .015" Nylatron washers (x 2)
  • 1/8" ti or 416 SS bolsters
  • 1/8" handle material
  • .125" blade
  • .155" ti or SS backspacer
  • flat head screws (1-72 or 2-56)
  • pan head or button head screws (1-72 or 2-56)
  • 1/16" detente ball
  • I make my own clips using .050" ti

For the pivot pin, common sizes are 1/8, 3/16, 7/32 & 1/4
For the stop pin, common sizes are 1/8, 3/16, 1/4
For the liners, on a small knife (up to 2.5") you might use .050", a medium knife (up to 3.5") you might use .063" and a large knife might use anything greater than .063". On my larger knives and frame-lock knives I use .100" ti. Remember, the thicker the ti, the harder it is to tap. For the thicker ti (.100) I typically use 2-56 screws, while with the thinner ti (.050 or .063) I use 1-72 screws.

I buy my stuff from the knife supply companies. There are a bunch - Pop's Knife Supplies, USA Knifemakers, KnifeKits.com, Jantz, etc. These are just a few off the top of my head.

Good luck at the doctor's visit.
 
Thanks a lot now I have a shopping list to work on. I was looking around last night at some of the suppliers and got confused because of the selection on them. I am going to have to check the balls at work and give them a little test, stick one in the vice and try crack it and set a few our in the elements to see how well they fair. I am planning to make this knife in the 3.5-4" range just because that is the size blade I like best even though I love my mini grip. You have been a great help with this, thank you for your time and effort.

George
 
So after much tweaking, being off work gives me a crap load of time infront of the computer, this is what I have come up with, with the much appreciated help of rbendele.

open-1.jpg


closed-1.jpg


rollout-1.jpg


detent_path.jpg


3D image
open3D.jpg


So if anything looks off to you speak up, Now it just a thing of collecting materials and getting to work on it. I have actually started to think about going stainless for them instead of the pattern welded steel, because I really want to make a little bird and trout out of that.
 
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Oh yeah! just got the shipping confirmation on Bob Terzuola's book, should be here by the end of the week. Can't wait to get to reading it over.
 
I don't mean to sound overly critical. This is much more advanced than anything I've done, afterall.

Anyway, I think you might want to put a little bit more personality into the profile of the handle. Right now, it looks soft and uncommitted.

All of the sides and corners seem to live apart from one another, without any kind of reference or balance. This gives the handle a kind of "mushy" or "saggy" appearance. Compare that to the clean, pristine profile of the blade and they don't seem to match up well.

Try drawing a few by hand and then scanning your drawing into the computer, then you can retrace it in your cad program and end up with something a little more clean, solid and balanced.
 
Nothing is set in stone yet and I am tweaking the shape all the time. Once I get something close and before I ever start the actual knife I will be making mock ups of it out of wood and other materials to do the final adjustments to the shape of the handle. Right now I have based the handle off of my BM710 but with a more pronounced drop at the back. It's hard to see in the 3D mock up that the top of the handle does arch because of the shadows, and the mushy look I think you are referring to is the bump map I used to give the handle a bit of texture, it just doesn't give a nice transition from the flat to the curve of the chamfer:o

Don't take this as I am rebutting everything that you have mentioned, I will look into every bit of advice I am given. In the long run it will be what ever feels best in my hand for the first one and then when I have a working prototype I will hand it around to others to try out and give opinions on possible improvements. The first prototype will be a lefty too:p
 
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