mech joint how to

I know most flickr builders won't require this kind of detailed description to figure this out, but I wrote it for MOCpages and it was easier to just copy here.


Here is the breakdown of the leg joints. Obviously, that section on the right slides on to the two black bars, and is pushed snugly into the holes in the technic bricks, with the dishes placed on last. There is another, identical section on the other side that is installed in the same fashion. The dishes are mainly aesthetic in nature and not necessary for the joint to function. On the bottom is a simplified breakdown of the pieces used in the actual joint. Of course, any length technic brick can be used and you can replace the 1x1 bricks with studs on two sides with ones with studs on four sides (Travis bricks) for some really interesting possibilities. I also see potential for this joint system for things like fold out wings on spacecraft etc.


Also, apparently LEGO makes two slightly different diameter 4L bars, since the black ones I am using here are significantly tighter than other colors I have tried, and add to the holding power of the joint. The looser fit of the smaller diameter bars still works fine, and could easily have supported a mech this size, but I wanted the centers of the hollow studs on the dishes to be black when the leg was assembled.


One word of warning however…this is a stud friction joint with quite a bit of holding power. It easily holds up this mech in any position, and could potentially support something a good deal larger. But since the joint is so tight, I imagine that over time there could be some issues with parts wear to the studs used in the joint and to the technic brick in the middle, especially when using the slightly larger diameter 4L bars. If you are simply displaying your MOCs as opposed to actively playing with them, I can’t imagine having any problems, and I myself have had no issues yet, but I just wanted to mention it before someone accuses me of conspiring to destroy their laygoes.


EDIT : As Crème-de-la-crème noted, you can do a reverse version of this with the 1x1 brick with side studs on the inside and the technic bricks on the outside. I actually tried that version when first building this mech, with the dishes flipped, slid on to the bars, and their studs inserted into the technic brick holes. This gives about the same holding power as the first version, and the reversed dishes are actually a little more greebly looking, but not quite as “realistic” looking as the outwardly curved version, IMO. But thanks for reminding me CDLC!


  • Creme-de-la-creme 6y

    This is Kinda how I made mine, Except that I made it with the "1x1 brick with studs on opposing sides" INSIDE the joints, so only 1 per joint.
  • Peter Morris 6y

    Actually, since I suck at mecha tech, I do require this. I wondered how you did it. Thanks for sharing!
  • Rodney Bistline 6y

    Even before I saw this, I was blown away by how something relatively simple (parts-wise) could look so visually complex and be so sturdy at the same time. Like, I have hope that I could actually build something with this technique in the near future!
  • Shannon Sproule 6y

    Whoa tl;dr dude.

    JK you rock Brio. You know this.
  • Kevin Huxtable 6y

    Incredible joint tech. Love the mech too.
  • Rod Gillies 6y

    That's an interesting insight, thank you. Might have to give that a go.

    Would also be interested to know how you managed to take the photo on the 25th April then come back in time to post it on the 29th March...
  • Creme-de-la-creme 6y

    ^^ the camera has a date stamp on the image, and you can change it to what ever you want, or in my case, when you turn the camera off the clock fails cause the capacitors suck.
  • Alvaro Gunawan 6y

    Don't you know? He's from the future. ;)
  • Chris "wunztwice" 6y

    That is simply fantastic. Thank you for such a detailed description, because as Mr. Morris has already admitted, I do no more than fumble with mecha.
  • Robo-Knight 5y

    Holy crap, thank you for this diagram.
  • Aidan My last name is none of our business internet pedos 5y

    Thanks! What do u use for the larger mechs
  • Creme-de-la-creme 5y

    He uses a gear system.
    Usually a Worm gear and a toothed gear. (?)

    That's in his really big stuff though.
  • Brian Kescenovitz 5y

    ^ Yeah, worm gear is the strongest, but I also have used AT-AT style click joints. Not as strong, but easier to engineer.
  • nitrobenz 4y

    this gives me some fresh inspiration for linear joints on my mech projects, thanks!
  • Super J Dog 4y

    Beautiful! May I borrow this? (giving credit of course)
  • Super J Dog 4y

    One thing though... how do you keep the 4L bar in place? Seeing as there is nothing holding it in.
  • Joshua 4y

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Taken on April 25, 2009
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