Third Arm knife grinding jig

Discussion in 'Knife Maker Shop Talk' started by patriqq, Oct 12, 2017.

  1. patriqq

    patriqq Active Member

    Video explains it all
     
  2. Smallshop

    Smallshop KNIFE MAKER

    simple and practical! gives you all motion while restricting your grind angle. I like it!
     
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  3. bladegrinder

    bladegrinder Well-Known Member

    Well...........I think I'll add that to my list of "mankinds most ridiculous ideas"
     
  4. Smallshop

    Smallshop KNIFE MAKER

    I don't get the "ridiculousness" of it? It holds a grind angle while giving complete freedom to move in all axis. Much more advanced, yet more "freehand" than the goofy lil jig I made...(or that most of us have made)
     
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  5. KenH

    KenH Well-Known Member

    Interesting idea - Sure seems a bit complex, and not sure it will really hold a good solid angle. I'd sure like to see in action on a 2X72 grinder - isn't that where it would be used?
     
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  6. Smallshop

    Smallshop KNIFE MAKER

    I think so...He's a knife grinder....seeing it in action will prove if it's effective.
     
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  7. patriqq

    patriqq Active Member

    People seem to be under the impression that I am displaying a hypothetical rather than proven device. I'm not sure why. I say the following with respect. I am a professional full-time knifemaker; I raise three kids, pay a mortgage, and make car payments purely with knife sales. I've been in the business for over a decade. I have shipped over 10,000 knives to over 20 countries in the past 10 years. Think of this as a trade secret that I am generously sharing with the community. Your comment is exactly the reason why commercially successful knifemakers such as myself are hesitant to share things like this. I am not currently selling this product, and in the scope of knifemaking tech, I have nothing to prove to anyone except my paying customers, myself, and my family. I gain or lose nothing regardless of your opinion of this device, therefore I have no reason to care for your doubts, and no incentive to spend additional time proving my claims. I'm sure my attitude here is unpopular but I'm just telling it how it is. The knifemaking community has become devoid of innovation - basically 99% of knifemakers are contributing NOTHING to the field and simply here to take a piece of the pie. My hope here is to spark a little creativity in the field. All my best.
     
  8. patriqq

    patriqq Active Member

    Thank you. It is clearly not for everyone - that is ok, because the good news is no one has any obligation to like it or use it.
     
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  9. Smallshop

    Smallshop KNIFE MAKER

    How soon till a using video? I know it will take a bit to get the "feel" down...but can't wait to see it in action!

    Sorry...didn't see the above post...you've already been using it! LOL
     
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  10. patriqq

    patriqq Active Member

    No worries - I have made a career out of throwing knives that have steep scandi-type grinds. I've done (and sold) about 15-20 knives in this jig - knives that are outside my comfort zone with more traditional flat grinds. Because of the freedom of motion, it is quite easy to screw up the grinds - something that is both good and/or bad, depending on your perspective. I'm getting fairly good results now after a small learning curve. Honestly I would like to see what someone who is more skilled than me can do with it. This is one of two knife models I grind on this jig https://www.instagram.com/p/BYyvk5wn2SV/ (the rest I do freehand). Keep in mind that in the market I serve, I stop at 120 grit - i.e. I am aware that what I do is out of the mainstream.
     
  11. Smallshop

    Smallshop KNIFE MAKER

    That's a nice clean grind!
     
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  12. Matthew Gregory

    Matthew Gregory Well-Known Member

    Brilliant, Patrick.
     
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  13. patriqq

    patriqq Active Member

    Why thank you sir, means a lot - especially coming from you. As I mentioned, it all started with Nathan's video from 2014.
     
  14. bladegrinder

    bladegrinder Well-Known Member

    Patriqq, I apologise for my earlier post, but in all of it's simplicity in design it actually appears complicated in use.
    you would have to complete all grinding on one side first, then take the knife out and turn it around. it would seem to me that if it's not put back in that clamp in the exact position in reverse...the grind may not be symmetrical because the angle is dependant on your platen.
    it's also not stationary, it seems that the whole thing could get out of alignment while grinding by just hitting the platform with your foot.
    it just seems like a lot going on verses just free handing them. I've never used a jig so I could be all wrong on this but the couple I've seen were articulating arms that reversed the blade while still in the fixture and were stationary like a rock.
     
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  15. patriqq

    patriqq Active Member

    No worries, it is a goofy looking thing that is awkward, especially because it goes limp when you let go (something I want to address with springs on future versions). As a throwing knife maker, I am often dismissed by the community so I'm sure some of that is coming out as defensiveness on my end. It isn't for everyone and I'm not expecting to please or impress all. I do, however, think it is perhaps/arguably the biggest innovation in knife grinding fixtures/jigs in decades in a world where 99% of knifemakers are making the same basic knife patterns with the same basic methods. There is little to no experimentation or innovation, especially in the area of knife making tech. As I mentioned above, my hope is to spark a little creativity and get some brains churning.

    Those who freehand grind will never see the virtue of a jig; it is that simple. This includes me - I freehand the vast majority of my knives, and I could grind 3 of my standard knives in the time it takes me to get this jig to the grinder and set it up. I am using this for knives that are outside of my comfort zone (read above comments). I see this as a good way for a new knifemaker to learn how to freehand grind, or at least have a sense of intimacy that is close to the process of freehand grinding.

    Your other points are valid concerns, and they are also directly addressed in the video - did you listen to the audio? It isn't a 10 minute video. In fact, the entire point of the video was to address these concerns. Precision dowel pins with mating precision reamed holes ensure perfect mirrored alignment when swapping sides (as explained in the vid). The time delay required to swap the knife around is no different than any other jig that clamps onto the knife, and the time can be improved by implementing a tool-less swapping method (as mentioned in the vid). Most importantly, the alignment isn't affected by moving the base plate due to the magic of the parallelogram (more info on that below) - again, this is discussed in the vid. There are a million ways one could terminate the bottom of the vertical rods; a base plate is just one. I started with the base plate because I wanted to test/prove the exact doubt you are expressing. The other virtue of the base plate is that the jig can be moved from machine to machine. This could be used in all kinds of machine work, not only knifemaking, and not only metalwork.

    You are just like all of us - same as me before I started going down the road here - we have a pre-conceived notion that a jig must be rigid, when in fact all that matters is rigidity in the one axis that defines the bevel angle. Again, my intention here is to get people to rethink their pre-conceived notions.

    Now it is important to understand that technically there is an error or discrepancy when the base plate is moved, and there is also an error inherent in the radial (as opposed to linear) motion of the jig. However, because the vertical rods are substantially long, the error is not noticeable/measurable. Another way to explain this is - imagine if the vertical rods were only 10" tall. In that case, the discrepancy would be magnified and noticeable. As the rods get longer, the discrepancy minimizes. If you were grinding a 36" sword blade, you would have some problems - which can be solved by either grinding sections of the blade at a time (i.e. moving the base plate) OR using longer vertical rods. Without moving the base plate, the vertical rods should be at least 4x longer than the length of the knife if that gives you and idea of what I mean here.
     
  16. patriqq

    patriqq Active Member

    Thank you! Lets be honest - when you do a full flat grind, where the grind line is "off" the knife, a lot of errors may be hidden. I really wanted to see this jig give me a nice grind line that is parallel to the knife edge, and so far I'm there (or 99% there - close enough for the market I serve).
     
  17. KenH

    KenH Well-Known Member

    @patriqq: I'd still be VERY interested in seeing a video of the jig in operation. I "think" I can see how it works, but does seem fairly complex. While I'd LOVE to be able to totally freehand grind my bevels, I tend to use a simple 1-2-3 block setup as a jig to set my bevels before any freehand grinding.

    Ken H>
     
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  18. patriqq

    patriqq Active Member

    Sure, but not going to happen anytime soon. I grind with a waterspray system so the camera would need to be totally waterproof, which I don't have. I'm a bit confused as to why people are insisting on an action video when there are photos of the result and a video showing the stance, motion, and mechanics. Seems like if I post a video, someone will want plans. If I post plans, someone will want an exact part list. If I post a part list, someone will want a link to every component ... and so on. People in general, and knifemakers in particular, seem to want everything spoonfed to them these days.

    The device starts with the following relatively simple question. What mechanism will hold a steady bevel angle, but allow freedom of motion in all other rotational axes and freedom of motion in the X and Y linear axes? I believe this device is the LEAST complex mechanism that will fit the bill. If it seems complex, it is because 3D geometry (compound angles, etc) is complex. I do appreciate your interest and hope it helps in some way. Down the line I may offer them for sale; at that point I will create more explanatory media.
     
    Matthew Gregory likes this.
  19. C Craft

    C Craft Well-Known Member

    Sure, but not going to happen anytime soon. I grind with a waterspray system so the camera would need to be totally waterproof, which I don't have. I'm a bit confused as to why people are insisting on an action video when there are photos of the result and a video showing the stance, motion, and mechanics. Seems like if I post a video, someone will want plans. If I post plans, someone will want an exact part list. If I post a part list, someone will want a link to every component ... and so on. People in general, and knifemakers in particular, seem to want everything spoonfed to them these days.

    patriqq, Most makers grind freehand and using jigs seems to have a stigma too it!! Folks want to see it in action. When something new hits the market you got to prove it out! No one trying to get the inside track!! If it is good as you say well then the product does its own talking/selling!! If you want to show it off, take a bag and cover the camera, leave just the lens which is sealed open!!
     
  20. Matthew Gregory

    Matthew Gregory Well-Known Member

    Unbelievable.

    Seriously, guys, this ain’t rocket surgery. There is absolutely no proof required. As Patrick has pointed out, find Nathan Carother’s video of HIS jig and make one. It’s two pieces of string and a bar of metal hung from the ceiling!

    Patrick, I know you know I freehand grind, but the simple fact is that this setup could be used for so many other applications, I might consider replicating it, if not doing it Nate’s way. From a production perspective, I could easily see this helping you. Consistency is everything when you’re making hundreds of them.

    Now I want a thrower from you. :D
     
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