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[monk12]

Have the condensor heat coffee?

Brilliant! Better yet, break out the entire apparatus whenever you want to steam vegetables or clams at parties.

[Moogie]

Also shamelessly posting to follow. <3

[Araph]

Woah, sudden surge of posts. Unfortunately, two things will be delaying a real response: lathe-related problems in my high school's welding shop and the intertubes at my house being clogged. I'll have an update and Internet again by the end of the week.

[rarborman]

I've been reading this, and I have a few questions.

First and most important, what are your plans for your boiler.

What do you plan to use this animunculi for?

Lastly have you worked with steam before?

[Araph]

Okay, response time! The intertubes are back up, the lathe works again, and I bought the wrong sized pipe.



Don't I feel stupid now.

@ Virex
I'm not quite sure if I'm understanding your idea for the shoulder. Do you mean that their would be a ball-and-socket joint with four pistons moving it in any direction? And would it be possible for you to sketch that idea and post it?

I understand your idea for the sealed joint, though. That might work, but I would need each steam bearing joint to have several of those. I'll have to try that once the project is really moving.

The pistons on either side of a joint would have pressure building until they're closed off. Then the limb should stay more or less in the same spot until the opposite piston is fired. If one piston is building up pressure, then its opposite has it's pressure released. That way the limb would be free to move in the other direction. I don't foresee the need for springs to move it back into the correct spots, given how the pistons would be moved closed again by their opposites.

And yeah, exhaust is the way I'm planning on going for controlling the flow of the steam. Condensers would be much to hard as it stands right now.

@ monk12

Have the condensor heat coffee?

Brilliant! Better yet, break out the entire apparatus whenever you want to steam vegetables or clams at parties.

Now THERE'S a good idea! Maybe we could just have a pressure cooker built into the body of the robot! Then when I'm having a party, I show off the steam contraption for a while, and BAM! Dinner is ready, as I whip open the front of the robot! Man, that will TOTALLY supersede all of the other plans for this thing!

@ rarborman

My plans for the boiler are a bit ambiguous as of now. I haven't worked with steam or pressurized air that much before, so I don't now how much force can be gotten from a boiler that would fit in the Centurion. Also, I don't know if there's things regarding the boiler that I'm overlooking, so my (somewhat vague) ideas on this topic may be totally unworkable.

And the Centurion has no practical purpose yet. It would be a cool little doohickey that looks complex and can wave it's arms around.

[rarborman]

Ok, what do you have for the boiler?
I'd say that the amount of work it can do will definetly shape the rest of the centurian because all the nice little steam joints dont mean anything if your boiler cant do work.

[Virex]

@ Virex
I'm not quite sure if I'm understanding your idea for the shoulder. Do you mean that their would be a ball-and-socket joint with four pistons moving it in any direction? And would it be possible for you to sketch that idea and post it?


I understand your idea for the sealed joint, though. That might work, but I would need each steam bearing joint to have several of those. I'll have to try that once the project is really moving.


The pistons on either side of a joint would have pressure building until they're closed off. Then the limb should stay more or less in the same spot until the opposite piston is fired. If one piston is building up pressure, then its opposite has it's pressure released. That way the limb would be free to move in the other direction. I don't foresee the need for springs to move it back into the correct spots, given how the pistons would be moved closed again by their opposites.

And yeah, exhaust is the way I'm planning on going for controlling the flow of the steam. Condensers would be much to hard as it stands right now.

The reason I suggested using springs was that if you have self-resetting pistons, then you can eliminate a piston per joint, because you don't need extra pistons to move the limb back to it's original position. Less pistons == less stuff that can go wrong . Of course, the feasibility of this depends on if you can get springs that can exert enough force without making them excessively heavy.


Also for the shoulder, I meant you'd use 2 disk joints, like this: #0-=|, where # is the body, 0 is a joint in the plane of the body, - is a connector piece, = is a joint perpendicular to the first one and | is the arm. Combined, they'd work similarly to a ball-and-socket joint, but you can just use disk joints, which are simpler to construct.


Also, I don't really get why you'd need multiple steam streams through a joint? Do you want to have multiple pressures or temperatures throughout your centurion or something? Or would the pressure in the pipes get too high if you use a single pipe? Because if everything is on the same temperature and pressure, you can just split the stream (using 2 smaller pipes) whenever you need to.

[Araph]

I (finally) got the right pipe! I made a piston to see if it works, and once I get an O-ring for it, it should. Slow progress, but at least it's happening!

@ rarborman
Well... I'm not sure how much pressure a boiler the size I'm thinking of can put out, so I'd prefer to test my thoughts on the matter instead of putting my stupidity on display.

@ Virex
The joint system is what I was planning on using; I had the same idea a while back. I'm a little confused as to the reason behind the spring idea though. The limbs aren't supposed to automatically reset, the user is supposed to control that. That's why I was using pistons on both sides instead of springs. As for the multiple streams of steam in a joint, I don't need that now. I thought I would use that to make it so that there could be multiple joints on a limb, but I could do that easier with all the pistons inside the body of the Centurion. They would be connected to the limbs with thin metal bars, instead.

[Virex]

The idea behind the springs is rather simple. Consider the following system:

---X---|==

Where - is piping, X is a valve, | is the piston head and = is the spring.
If the valve is closed, there is no pressure on the piston, so the piston is in it's "rest position". Open the valve slightly and the pressure in the piston will also rise slightly, causing the piston to move to a new equilibrium position. Closing the valve again will set it back to the original position. The advantage of this system (if you can pull it off) is that the piston position is proportional to how far the valve has been opened, which should make things a lot easier to control. Also, if you carefully chose the rest position and the full-pressure position, you can eliminate the need for an extra reverse piston, saving you some work. Note that this would also work with a sealed gas chamber behind the piston, but with springs it's easier to get the right pressure-movement ratio.

[Max White]

If we ever vote for 'dwarfest thread' this one gets my vote.

[Araph]

Ohhhhh! I hadn't thought of that! Wouldn't the springs prevent that much force from being exerted on the arm? I mean, it would be movable, but if you push on the other side of the arm (the side the spring is moving the piston away from) it would be easy to move because the spring is helping you move it.

[Virex]

Well, assuming you push in one direction (doesn't matter which one), you're exerting a force of F_m. A is surface area, P is gauge pressure (abolute pressure - ambient pressure), K is the spring constant and X is how far the spring has been pressed inwards.
F_p = A_piston*P
F_s = K*x
In steady state: F_p=F_s+F_m (taking the push in the same direction as the spring)
A_piston*P - F_m= K*X or
x = (A_piston*P - F_m)/K. Now from this you can see that there is no real preference for any direction in F_m. So whatever way you push, you're always going to move the piston by F_m/K in that direction, meaning how far you can push it is bounded by K. Now a high K would also necessitate a high pressure, or a high piston surface area (but the latter means you're going to need a larger total steam flow and thus you need a higher boiler duty anyway), so to decide if this would work in the first place you'd need to know the desired force and the boiler duty (desired force is the excess force F_e = |F_p-F_s| for a certain value of X)

[NobodyPro]

... and so it was that NobodyPro became convinced that videogames were leaking into reality. He gathered six total strangers, collected several bags of radiation absorbing pump helmets and set off for Africa to fight the killer hippos, hoping that the sphere centurion would be completed before skelephants were discovered.

In other words: posting to watch.

[Araph]

Argh! I hate pistons. Not really, but it's SO FREAKING ANNOYING trying to get a retarded little sliver of rubber to fit right so that it can slide into the other half of the piston. Also, spring break is finally here, which means I'm not able to use the machine shop at my high school. So... nothing really is gonna get made 'till next week.

@ Virex
Ok, I understand all of that except for F_m. I can place all of the respective forces to there origins, except I don't know what you mean when you say that you're pushing in one direction. I thought you meant that steam is doing the pushing, but you already covered steam pressure with P.

And sorry for the lack of updates. I've been kinda distracted lately.

[Virex]

F_m = manual force, the force someone janking on the arm would cause.