Functional Brick Built Piston

[JackJonespaw]

Hey folks,

Working on a brick-built version of Metal Gear Solid's Metal Gear Rex based off of this 3D model. On the underside of the model, there are two somewhat large pistons, one on either side. They look like this:

Now, I originally thought I'd be able to get away with just using a non-moving brick built thing, something like this:

 

but, with the way the jaw hinges, the piston will need to be able to move. I've scoured the internet and not found anything that'll work at that scale - is there anything brick built that you guys know of or have seen that could work? If there were some kind of hollow pipe I could use for the bottom half having 2x2 round bricks be the upper part of the piston - I think that could work, but I haven't seen any pieces like that.

This pneumatic cylinder could potentially work, but I worry it'll be too stiff for the smooth movement I need. Any thoughts?

[Bartybum]

Your images don't seem to work :S I've tried both Firefox and Chrome and they don't load

[JackJonespaw]

32 minutes ago, Bartybum said:

Your images don't seem to work :S I've tried both Firefox and Chrome and they don't load

Fixed up

[msk6003]

Some of city cerise and 42042 has manual piston thing but it's one stud thick.

[Jurss]

I think hidraulic cilinders will work. 

Even in Your first brick built attepmt, I think that one connection is more like fixed (in one axle)

[allanp]

Are we right to assume that 2 studs is your ideal cylinder thickness? 

[Jundis]

5 hours ago, Jurss said:

I think hidraulic cilinders will work. 

Agreed.

According to the size of the piston, the "jar" of the Robot will be quite big (about 15 studs long?), therefor not that light weight, especially when built by system bricks. According to the little lever between the movable pneumatic arm connection and the fixed part of the jar, you will have easily enough torque to move the pneumatic piston.

[JackJonespaw]

2 hours ago, Jundis said:

Agreed.

According to the size of the piston, the "jar" of the Robot will be quite big (about 15 studs long?), therefor not that light weight, especially when built by system bricks. According to the little lever between the movable pneumatic arm connection and the fixed part of the jar, you will have easily enough torque to move the pneumatic piston.

Okay, cool. So in that case most likely the 2x11 pneumatic cylinder?

[allanp]

31 minutes ago, JackJonespaw said:

Okay, cool. So in that case most likely the 2x11 pneumatic cylinder?

If you don't mind them being yellow (unfortunately they don't come in any other colour) then the small amount of friction two of these provide MIGHT make it somewhat posable, but I doubt the friction alone would hold the weight. Of course there also the possibility that you could hook up some hoses and add just enough air pressure to balance the weight of the jaw, or you could just make the jaw functional and quite fast moving with these pneumatics. Alternatively you could use these:

https://rebrickable.com/parts/75347/support-2-x-2-x-11-solid-pillar/

They are 2x2 round hollow tubes that come in various colours, but might be a but too long depending on the size of your build. You could also use LAs, which come in grey which would be a good colour choice I guess, but you wouldn't be able to pose the jaw directly. Very slow movements is your only option with these!