View Full Version : Mechanical Engineering Help...
03-06-2009, 01:50 PM
I attended a convention in Las Vegas las year, and was amazed by the large (in some cases HUGE) animatronic displays that they have. But, what amazed me even more was the simple designs they were constructed from. A couple of pneumatic cylinders here and there, a costume, and maybe a BOO Box to control it. The only thing that I seem to be having trouble with is the mechanical portion of the design. Figuring out how long to make a metal bar and where to have it pivot, things like that. The closest textbook thing that I could find to this was a college physics book that didn't really help me at all. And I haven't really found anything online either. If anyone has any suggestions, I would greatly apprieciate the help. Thank you all in advance!
03-06-2009, 02:44 PM
This book is an excellent place to start
Animatronics: Guide to Holiday Displays (Paperback)
by Edwin Wise (Author) (http://www.amazon.com/Animatronics-Holiday-Displays-Edwin-Wise/dp/0790612194)
And then there is the Flying Pig (http://http://www.flying-pig.co.uk/mechanisms/index.html)
This site is for making animated paper toys, but the section I linked to takes you to the area that describes the different types of mechanical movement and the mechanisms that can achieve the movement.
Hope those help a little.
03-16-2009, 04:16 PM
A college level physics book is a good start, you'll probably want one that is not calculus based. If you want to go more advanced than that you can pickup a statics book, and a dynamics book. Both of those are going to be heavily based on calculus, so if you don't have that background they aren't going to do much good.
The basics for what you are going to need are a good bit of trig, some force calculation abilities, some fluids background, and an understanding of moments and circular motion.
OR you can do what most people do and that is just roll with it and figure it out as you go. Sometimes it ends up costing a bit more, and takes more time, because you do make mistakes. However it's not like you're dealing with something that is going to kill someone if it goes wrong, and you only have one chance to get right, like a crane, or a bridge. No this is silly little haunted house props, you can bs your way through these, I promise.
03-19-2009, 05:19 PM
Thanks, that was the kind of info that I was looking for. Those are the topics that I will need to study then. Sounds like fun in the long run!
03-20-2009, 08:53 PM
Even aerospace engineers will make small models to support their calculations and assumptions before building something really expensive. Practical uses for even these models of moving props could be for the actors trophies or other appreciation awards or locking them up like a secret receipe.
Then chose hardware that has known pre engineered loads and safety factors that are known. Use wooden links to mock up what you want then convert it to metal with proper bearings and such. Even poster board cut outs become useful with pins like childrens pocket puppets. With little marks it is a ruler of something larger.
Center of gravity and weights of materials require a little research. You could also befriend an Engineering student of even a whole class to check your work and suggest improvements. They like to show off.
Industrial manufacturers of cylinders love handing out engineering data as it means you might buy their products. Some of the best basic charts come from manufacturers of materials and devices and are way more specific and worked out compared to any text book.
You can become and immediate genius just by reading the instructions.
03-21-2009, 12:14 PM
Thank for the help Greg! BTW, just got done ROFL after I read your signiture. I have probably read it about 10 times by now, and just noticed the part that says,"You read this again,didn't you." Too funny! :))
06-14-2010, 12:37 PM
I've done robotics for a while, but my schooling and the early part of my career had been the computer / control. So a few years ago - when I decided to get into building animatronics - I was up to the same challenge as you, Gary.
I'd had a few ME courses but it really was hard to apply all that math to something like designing a mechanism. I came up with a way to fix this hole in my skillset that worked very well, so here it is...
Bought these two books (Amazon groups one other with these. and it's probably good, too):
http://ecx.images-amazon.com/images/I/51EcNVSn7LL._SL500_AA300_.jpg (http://www.amazon.com/507-Mechanical-Movements-Mechanisms-Devices/dp/1603863117/ref=sr_1_2?ie=UTF8&s=books&qid=1276534975&sr=8-2) http://ecx.images-amazon.com/images/I/51-w1GcvWVL._BO2,204,203,200_PIsitb-sticker-arrow-click,TopRight,35,-76_AA300_SH20_OU01_.jpg (http://www.amazon.com/Mechanisms-Mechanical-Devices-Sourcebook-Fourth/dp/0071467610/ref=sr_1_1?ie=UTF8&s=books&qid=1276534945&sr=8-1)
Then, every day I would crack one of them open and stare at a mechanism until I thought I understood how it worked. I might come up with an application for the mechanism as well. Then I'd read the description and see how close I was, paying special attention to parts and purposes of the mechanism I overlooked.
Sometimes I would try to come up with an alternative mechanism that could perform the same function or movements. The mechanisms are usually in functional groups, so I would soon see if my made-up mechanism was considered worthy of printing - in which case I would mentally high-five myself.
Then Repeat. After enough iterations, you get a good feel for the relationship between mechanism and functional movement.
The first book is from 1906, which is cool because you see ideas that have fallen out of usage because something else does a better job - but it's fun to explore different approaches. And it's just impressive how advanced mechanisms were even back then.
This won't get past the other mechanical hurdles like the weight and strength of materials, dynamics topics like the other posters said, and so on, but it's a good way to learn how to make things move the way you want - and do so within the constraints of the prop.
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