making an armature for a human-sized bot

Just when I'm getting a grip on electronics and programming, I realize that my next project has come to a screeching halt due to mechanics. :)
I want to make a human-sized robot, but I'm unsure what to use for the armature (i.e. skeleton or support structure). The problem is that both my tools and my mechanical skills are quite limited; I'm really not going to be welding steel or aluminum, for example. I have a drill, a hacksaw, and a Dremel tool, and I'd be willing to invest another $50 or so in tooling, but much beyond that wouldn't leave me any budget for materials.
I've considered aluminum stock, wood, PVC pipe, Erector set, even Rokenbok beams. But it'd be comforting to hear from somebody who's actually done this, as I'm sure there are pitfalls I'm not even considering yet. I've searched on the net, but haven't found anything useful yet. Any advice?
Thanks, - Joe
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What is the purpose of your robot ? Is it to be a "showbot" for use at trade shows or something like that ? Or just a cool project to work on? Does it need to be able to lift and hold 10 lbs ? Need to be able to lift anything at all? All of that could determine the skeleton's structure & material. Personally, I am a fan of t-slot aluminum extrusions because you can reconfigure it easily once you get used to how things work. You might even want to mix materials - like having a central beam of t-slot aluminum, and hang various other parts made of other materials off of that.
Another thing you might want to consider is using cheap 1x1 or 2x2 lumber wood to prototype everything together. It's available from your local building supply. I suggest wood to start because you can easily drill & cut it with regular DIY power tools that most guys have in their tool box. You might make 100s of changes to it and have 100s of holes drilled in it - but you won't care because once you get your design fleshed out more then you can change to more expensive metal or PVC.
Also, let us know what part of the country (USA ?) or world you live in. Many of the guys on here can give you specific stores and scrap yards to scavenge from in areas they are familiar with.
One more thing, just start Googling like crazy using phrases like "build your own android" and see what others have done. You're sure to get some ideas and discover parts & materials you didn't even know existed. The very first link I found doing just that is this one: http://howtoandroid.com/HowToBuildRobotHead.html - which is a pretty good writeup on building a nice head.
This page is a great jumping off point: http://www.androidworld.com/prod02.htm
My 2 favorite How-To books on hobby robots is Robot Builder's Bonanza (2nd edition) and Robot Builder's Sourcebook. Both have a wealth of info on scavenged parts & things you haven't even thought of yet.
Hope that helps! JCD
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wrote:

Yes, that's the basic idea. I'd like it to be a mascot for our local club, and also a crowd-drawer for local robotics events.

No, mostly it needs to be able to wave its arms around, pan/tilt its head, and generally "do the robot" (i.e. dance and gesticulate). I might have it hand out cards or flyers, if I can think of a reliable way to pick them up, but that's definitely a down-the-road feature.

That sounds good. Where do you get that stuff? And what tools do you use to work it?

That's a point. It also won't matter much if I'm able to make body plates to hide the ugliness. I can certainly make straight cuts (forgot to mention my circular saw -- got that just a month or two ago!), but I don't have anything that could cut shaped pieces. Perhaps I need to invest in a band saw, jig saw, or a milling attachment for my Dremel? What would you recommend? (Now I wish I'd paid more attention in Shop class years ago!)

I'm in northern Colorado, and I do have a good group of guys to help with that sort of thing. But I was looking to cast a wider experience net when it comes to choosing the basic material.

Believe me, I've spent a lot of time surfing those sites. It's surprising how difficult it is to find a good reference for this part of the process, though.

Yeah, that's a neat one, though it starts with a very cool robotic-looking mannequin, which the author found by luck, and he doesn't have any suggestions on where you might find one or what to use instead. (I've looked, and so far haven't had that much luck, but that's a different issue -- I think I have a plan for the head.)

Ah yes, I call this the "rainbow links page" due to the brightly colored link list on the left. There's a lot of fun stuff there, though mostly about things you can buy for $20K, or being built for even more at university or corporate labs. Not much for the home builder, unless I missed it.

Good point, maybe I do need to take another trip to the bookstore. I've got half a dozen robotics books of varying quality, but they all focus on tabletop bots, and don't go into this sort of mechanics at all. I should perhaps be looking up "animatronics" instead for this project. Also, I don't have either of those books you mention, so I'll be sure to look them over.
Thanks, - Joe
--
"Polywell" fusion -- an approach to nuclear fusion that might actually work.
Learn more and discuss via: <http://www.strout.net/info/science/polywell/>
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various
I've been using the 80-20 brand of stuff and am selling that in my line of robot kits. I'll be glad to post a link if you like.
I get some of the stuff from eBay and some of it locally.
But you can get thinner and less expensive aluminum channel from your local DIY super-store. Do they have Home Depot or Lowes in Colorado? If it's going to be hidden eventually, I would recommend that kind of aluminum. The 80-20 stuff is kinda expensive and looks really cool, I think, but why pay for it if it's going to be hidden ?
You can also get aluminum square tube that might be perfect for your needs. The right kind drills almost as easy as wood. You may only need a hack saw if you're not going to cut much of it. If you're going to cut a lot of it, get a $99 mitre saw and a non-ferrous metal cutting blade or a metal cut-off blade (abrasive), depending on the precision you need.
The tools I use are a drill press, mitre saw with metal cutting blade, and a desktop milling machine. Hacksaw, set of files, and standard power drill are also used frequently. I doubt you would need all of these, although the Sherline mill *is* a blast!
Good luck and let us see what you come up with ! JCD
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Joe Strout wrote:

Alumunum channel is pretty good. It's readily available, cheap, and you can cut and drill it with ordinary tools. However, I'd invest in a basic miter saw with aluminum cutoff blade to make the work go faster.
I've built many robot frames out of channel stock over the last 20 years. When done right the frame can support in exceess of 100-150 pounds.
-- Gordon
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Sounds good. Do you have a good online source for this stuff? Or is it one of those find-a-local-supplier type things?
Thanks, - Joe
--
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Learn more and discuss via: <http://www.strout.net/info/science/polywell/>
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