90˚ Knife II "The Domestic"

[uhiforgot]

Dedguy, your knife seems like a nice idea. It sure does not look very common. I'd only suggest that you rethink the handle. Otherwise it won't work properly or it would not look very nice when it's closed. To illustrate what I mean, I've attached a little sketch based on your drawing. Not perfect, because I didn't take time to do it perfectly but the measurments are taken from what you've posted, and so are the hole sizes.

Don't get me wrong, designing a folder is hard work and sometimes a little bit difficult - that's one thing I know very well :rolleyes: I Just wanted to add my 2 cents on something that might have been overlooked.

Cheers, Rob

I could see this coming as well. A 90-knife as is materializing here poses many problems in the cartesian plane, and cartesian obstacles must be overcome before moving into the third dimension. At this point, no suggestion is a "bad" one, per-se, impractical as it may be because it might lead to another idea by derailing one's current train of thought. That being said:

What about if the extra necessary handle length were to be retractable or foldable so as to keep it out of the way when the blade is in use?

Do with this as you see fit.

-Jeff

[dedguy]

the way i normally work is i do a drawing for something purly around appearances then slowly work towards functionality. i had yet to figure out how the knife would function when folding and had mearly imagined it as a fixed blade knife. i've just spent some time re-working it to function better when folding in addition to looking nice while folded.



i'm sure more premutations are to come.

[Joe Talmadge]

So - Joe - -you have been around a long while.... got any ideas you can add to a design to make it more marketable?? :o

I have a little trouble visualizing this kind of design in 3-d, so I may not be much help directly. But, I can suggest trolling for ideas from Ray Appleton. Here's a production knife he did that locks in 90 and 180 degrees. http://casiberia.com/cas/product_details.asp?id=KH1004

[dedguy]

also, since scale is so hard to tell on these things i'm aiming for a fairly small knife. 2.5" blade or even smaller.

[smcfalls13]

Personally, I'd prefer the leaf blade on this one, for it's utility value. I can't imagine anything I'd cut with the scimitar blade this version has. The tip of the knife blade is just in the wrong area for me.

Guess it's just a matter of opinion.

[dedguy]

well that's essentially a leaf shaped blade with a curbe cut from the top. the extended under belly is to increase the flat cutting surface of the blade. a regular leaf shape while pretty would only allow the tip to contact the cutting surface (as was kindly pointed out to me by another forumer).

again, thanks everyone for the input, this has been fun.

[LukeC]

Very cool thread going on here guys- awesome work dedguy! Well you got me thinking and I made this little sketch of a 90 knife. Much more modest design, and not nearly as skilled as some of the other pics here, but I thought I'd just post it up here for fun.

[SoCal Operator]

I really like where this is going. I like the idea of calling the knife "the Domestic", but most knife knuts are going to look beyond the name and see a knife that could be well suited for SD, as it is easy to compare this design to the Ayoob. Also, though I am normally a huge fan of :spyder: 's leaf blades, I think that the bullnose design looks, and most likely functions, way better.

[Dannyvi]

I am not into 90 degree knives but I guess you mean a knife that closes only halfway so it points 90 degrees in relation to your closed fist. Can't any knife be made into a 90 degree knife by just changing the position of the stop pin and or the locking mechanism? A lockback would be the easiest one to do, I think. A 45 degree angle might be better. Sorry, I meant this 45 degrees from the open position, 135 from closed. IMO

[smcfalls13]

At 90 degrees, the blade will be perpendicular to whatever it's cutting, which means your edge better be perfectly polished and razor sharp, or you're going to have problems cutting.

Take a knife you have, and try push cutting straight into commercial grade cardboard keep the edge at a perpendicular angle. It's very difficult to do with anything less than a razor edge. You're better off redesigning the blade to open at a larger angle(if a normal blade opens at 180, make this one more like 135, Ayoob was probably about 160, but I'm just guessing) that will put the blade at an angle against the cutting medium, and will allow the material to be sliced as well as push cut.

Just my thoughts on this, from a user perspective. I'm no engineer though, so I could be completely wrong about the physics behind it. In fact, I probably am, so take my advice with a grain of salt.

[dedguy]

well i was thinking about this and if you look at the blade almost 50% of the edge is parallele to the handle. i was thinking a PE on the portion front of the curve and a SE on the inside edge of the curve could make for a rather powerful cutting combination... i may be wrong as well as i am not an engineer either, just a graphic designer.

[sierra]

to provide a true utility to the cutting. I wanted this knife to not rely on just the 1/8th of the blade tip. A leaf design would again force the user to bend their wrist to get the the cutting edge of the blade (not just using the blade tip).

If you look at the first dedguy drawing, or the knife design (of someone who already makes this basic design) provided by Joe, you see that only the tip scratch/cuts. If you look at the second illustration dedguy provided, you can see where the full belly blade design actually provides usefull blade performance. Remember - the intent of this knife is not to be a punch knife -although is certainly can - but to provide many hours of useful cutting to the folks out there who do a lot of cutting; whether factory workers opening freight, or office people opening paperwork.

This 90(degree) Knife has great potential to be the best, most ergonomic working knife ever if all the design ideas come along.

As you can see - there are alot of great minds on this forum - and talented folks here who can put concepts on paper for us to see. Good Job folks - this is developing well indeed. dedguy and rob - thanks for your graphics talent to make this idea come alive for us!!

[dedguy]

so i started into more detailed design. still missing some things (like a pocket clip) and you may notice i went back to the lockback.

[smcfalls13]

Here's the question we need to answer though, exactly what purpose is this blade designed for?

We can't just design a blade because it looks cool, it needs to have a particular job in mind, especially with this kind of unique design. This is definitely not a "general utility" knife, it's going to be fairly specialized, and we need to determine exactly what specialty we're aiming for, because that will affect the design.

I know we've chosen the scimitar design so that we can use more than just the tip of the blade, but in some types of cutting, the tip is all that's necessary.

For example, opening freight was mentioned as a use for this knife. I do this at my job, every time we get a stock order in, and I can tell you that knives with belly like this are poorly suited to opening freight. Opening a box only requires maybe 1/4" of blade, depending on the thickness of the cardboard. You don't want to cut too far into the box, because especially with food items, there is not much room inside the box. Case of cereal for example, are packed extremely tightly, if I used a knife with a lot of belly, I'd very likely cut into the box of cereal while opening the case, and I'd have Cheerios everywhere. Food rarely contains packing material, so for that type of cutting, the blade needs to be designed for shallow intricate cuts, a Hawkbill works best by far, with the Wharnecliffe a close second. There's a reason the Dodo is the most useful knife at work, it's got a short blade which won't damage the products inside the box, and the hawkbill tip allows superior control.

I could go on and on and about knives opening boxes, but I'd like to hear other's opinion as well.

I never use anything other than the last 1/4" of the blade, I have no need to.

Knives with belly like this, in my opinion, are best for food prep, skinning, and other similar activities, not for opening boxes. Also, at the 90 degree angle, you lose a lot of the ability to make a slicing motion, which is what bellied knives do best. The angle needs to be brought up a little.

And we need to figure out WHY we're designing this. What's it going to be used for?

[dedguy]

i was thinking along the lines of packing and things of that sort but you're right. a hawkbill IS best suited for those sorts of tasks (as i know from experience). i am entirely open to changing the blade shape.

so here's the problem... a hawkbill is generally seen by people as very threatening and ment to hurt people, even if we all know this is not true it's what the general public thinks in my experience. so how can you get the utility of the hawkbill without the threat of it?

i do really like this bullnosed scimitar design i got going but i think you're right. it's not the right blade for this knife.

[hrdwrguy]

This is an interesting looking knife, more practical looking than a kerambit.

I occurs to me that this blade might work well with serrations at the tip and a plain edge near the handle. The plain edge would be usefull for pull cuts, i have found that a PE sharpens quicker and touches up faster than SE, this would help keep that razor edge going. The SE tip portion would be useful the way any SE knife is, I can picture the saw like effect of that serrated belly cutting into coarse material.

I have been hoping that Spyderco would release a knife with a serrated tip and plain edge at the back. Victorinox does this on their SE blades and that little bit of PE is useful for detail 'shaving-like' cuts.

Mike

[sierra]

My opinion known, I have to respectfully disagree with you smlcfalls13. I greatly prefer the energy transfer advantages provided by a full belly blade because is cuts easier that other shapes. If you read around I am a great fan of hawks, and in the further distant past, the Wharncliffs as well. But physics says that the more perpendicular you bring the blade into contact with what you are cutting - the greater the effort needed to make the cut - multi-axis machine cutters excluded.
When I open things - boes, et all - I slice them - I do not rip them.....such as a hawk opening a box........I never even considered a hawk for a box - more for rope, cloth, etc. I have converted many climber friends to use this in roped accents here in the Cascades. The DoDo has a 2 inch blade that has a very aggresive cutting shape that takes some force. A slicing action to open a box would be less likely to cut deep. Good debate/discussion!!


When making a slicing cut - the blade does more of the labor. Hawks and Wharncliffs take more energy per cut than a full belly blade slice. A fact regardless of our preferences. So if the intent is to make a real tool for hard use cutting - or anything less- I don't see why we have to constrain ourselves to what was designed in the future. Much of our tool designs of the past has been restrained by material and design strengths. We can do so much more now with our metalurgies and the usage of computer models to control the boundaries of stress analysis.

While the scimitar blade can also be perceived as threatening to some - much like any hawk blade - I think the bullnosed scimitar that dedguy has come up with is nearly perfect - if not so already.

hrdwrguy - you are correct this is a draw cutter; draw cutting is more precise that cutting away from yourself ====== except we all know the dangers of cutting towards ourselves.

As far as public (sheeple) opinion - let them become further educated by the community that has the history, interest, knowledge, and appreciate rather than the ignorant (I did not say stupid - there is a difference) dictate what we should improve.

lets keep talking -

dedguy you are rockin me here - I think your bladeshape is perfect for the intent of this knife - great job!!! PS thanks for the backlock!

[smcfalls13]

I'll agree that slicing the box would be better, but in my experience only under ideal circumstances. Ideal being that the edge is perfectly polished and razor sharp, the cutter is familiar with proper cutting techniques, and the cutter is not fatigued in any way.

Bellied knives are better at cutting, but require more effort(skill really) to make the cut. When cutting with a bellied knife, your wrist has to be angled so the blade meets what you're cutting. That angled wrist can fatigue quite quickly. Also if the edge is not perfect, the blade will likely slip and cause injury.

While Hawkbill may not cut as well, it is easier to use overall. A Hawkbill can be held with the wrist perfectly straight, and the blade still curves down to meet the box, Hawkbills can be used for longer periods of time without fatigue. Also, due to the nature of the blade, it's very difficult for a Hawkbill to slip.

I can only speak from my own experience, and it may be purely anecdotal evidence, but between the choice of a Persian or Massad Ayoob and a Dodo or Tasman for box cutting, I choose the Hawkbill every time. It works for me. :cool:

[sierra]

"When cutting with a bellied knife, your wrist has to be angled so the blade meets what you're cutting. That angled wrist can fatigue quite quickly. Also if the edge is not perfect, the blade will likely slip and cause injury."

Your comments here smcfalls13, are exactly why this idea came up. I am sitting here with a mock-up of dedguys latest designs - and true to the purpose of this design 'the wrist is placed in an ergonomically neutral position' (sit with your right arm on a desk - forearm resting on the surface - with your thumb up - wrist and hand vertical. The extension of the thumb forward is only a fraction of a standard inline knife/frame. Make a cardboard mockup of this design - you will find the wrist neutral (and control of the bellied blade) in a very controlled postions - an extention of your forearm. I cannot fathom how this blade configuration would be any more risky...

If you do not agree then - then this is not for you. BUT I am carrying one of my Merlins today with my recent acquistion of a Matriach permanently clipped inside my attache'. Hawks rock.

Ok, what does your acronym/name stand for?? :cool:

[dedguy]

sierra: good to know you find it comfortable. i'm going to try and do the same this weekend. i'm probally going to go as far as making a fairly complete cardboard mockup with a "working" lock and what not. see how well it works in practice.