Twitter
Facebook
Flickr
RSSWell, hopefully not. :)
So, here begins my build-a-bridge-in-two-weeks-because-you-didn't-get-around-to-starting-it-sooner marathon. I am such a procrastinator.
Ben, here is what I'm thinking about right now. If you could let me know your thoughts on the design, I would really love it. (I'll even make some more cookies for you when you come home again. :D)
You can click on the picture to enlarge it.
Basically I'm thinking that I'm going to go for a big, heavy (and hopefully strong) bridge this year. Fortunately, the weight limit is 30 grams instead of 25 grams. It'll help, but this is still going to be a scale-full.
I'm thinking of doing members 1, 2, 3, and 4 with fours (four wood pieces laminated together). Member 5, I'm thinking I can get away with using a two (two pieces laminated together), especially since it will only be in tension. That'll give me some good surface area at the top corner joint as well. Member 6 I think will probably be ok just being a single piece of wood (?), but I might want to beef up the corners where the bridge touches the support surfaces. Those two corners are going to be under a lot of stress. First of all, you have the tension from member 6 and then the forces trying to push outward from the big members coming down. So basically, pretty much all the force exerted on the bridge is going into those two corner joints. It makes me scared. Another thing that's scaring me is members 3 and 4; they just seem so likely to snap off where the load is being applied (the red box and arrow). Do you think they'll be ok without any other support from elsewhere? I don't really know a logical place to even support it. I suppose I could put something between members 1 and 3, but I'm really not sure if it's essential.
Anyway, just some of what I've been thinking about. Ben, if you could give me some feedback (unless, of course, you're too busy :D), that would be totally awesome.
Anyone else can comment too. :D Especially if you notice something I didn't!
Comments? Suggestions?
Cellphone Pictures 2011
12 years ago
8 comments: (+add yours?)
Will you make me some cookies if I share my thoughts on your design?
If so, here goes...
..."Gee, that looks really cool!"
How's that? Will that suffice for some of your righteous Pumpkin Chocolate Chip Cookies?
GGM
CHROME dip it!!!!
That would make it really strong!
Hey, pretty cool design.
Could you glue blocks in the corners to spread out the weight? or does the glue do about the same amount of work?
Can you miter the corners? or do you have enough room to make a dovetail joint? Some sort of Mortise and Tenon?
Or you can forgo all that extra junk and just chrome dip it.
http://www.plantfloor.com/states/co/co_metalworking_plating.htm
AHAHAHAHAHAHAHAHAHAHAHAHAHAHAAHAHA
HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA
HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA
HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Now I have your design so I can beat you!
AHAHAHAHAHAHAHAHAHAHAHAHAHAHAAHAHA
HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA
HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA
HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Sorry, GGM, I was talking to Ben about the cookies. :)
Sorry, Steve, but I'm pretty sure that chrome would be classified as a foreign substance. Hopefully you aren't too disappointed.
As for the corners, I'm guessing my best ally will be the friction of a sheering force. In other words, I'm not going to glue the corner by putting members end to end, but I'm going to overlap the member ends as much as possible to maximize the friction between the members. I might add small blocks of wood somewhere in there to make the whole joint more solid...
If that didn't make any sense, just disregard it.
Wow, bridgecontestenemy! You even made a whole profile for yourself!
I think I understand the sheering force you are talking about.. (Maybe I have something in my mind that is just insanity, in which case, please stop reading here)
I know that the pieces you are working on are really small, but...
In respect to your sheering force, could you file groves in support pieces #2 and #3 at the ends, so they actually fit together one on top of the other and then glue em?
I should just draw a picture.
Or for the corners perhaps the basic idea of Figure #7
http://www.dixieline.com/woodjoint/woodjoints.htm
I don't have the rules, but I would wonder if you could encase the ends of the bridge in a formed piece of glue. I.E. make each end of the bridge a solid mass of glue around the joint. :)
Man, you're making me want to try to build one of these things. I've looked into it before, but I never really thought I could build a good one. (Now that I see your design, I know that ANYONE could do it) (kidding) :)
Sorry for not posting sooner, Beck. I've been a grouch recently, so I haven't bothered with looking at blogs. (I'm sure you understand. :-)
Anyway, you always ask the questions I don't know :-)
I have a question, though... Have you built a bridge "completely above the loading plane" with member 6 being a single? I seem to remember you did and the glue joint failed even though you glued extra blocks on the end...
Yeah, the thing is, if member 6 dies, you're doomed. I don't want to disagree with Steve, but I kinda think messing with the integrity of your laminated 1 and 2 members might be a bad idea... It's hard to say because I guess you're filling the gap you cut, but still... Huh... HEY!
I just thought...
Instead of gluing member 6 on the sides of the bridge, why not put it underneath the whole bridge? Have members 1 and 2 sit on 6. (Then he can be squished to a jelly! YAHOO!) That way, the downward force would help hold the joint on member 6, and if things aren't quite perfect, it won't put stress on the glue joint. Of course you'd still have to add some blocks to make it wide enough, but, knock on wood,*knock* *knock*, that seems like it might work! Maybe?
As far as 3 and 4 go... You know, at first I was thinking you should just forget 3 and 4, but you know what? I bet it could add a lot more strength... (thinking out loud here...)
One more comment... I guess I've always thought "go as high as possible," but I'm wondering if that's a little too high. True, the higher you go, the more you're pushing on the length of the members, but I bet the happy medium is a little shorter. I'd take the peak down a big square, but it's up to you. You might as Dad about that one... I'm kida thinking a 90 degree angle might be ideal...
Well... I guess that's all the babbling I have for now. Let me know if you want further blabbering. :-)
And thanks, Beck, for the cookies you sent with me :-D Believe it or not, they actually made it here in one piece... I've been enjoying them thoroughly. I seem to have landed with a bunch of really great sisters, and you're definitely no exception. :-)
Oh, and "BridgeContestEnemy," if you really don't want people to know who you are, you should stop using words like "nemeses."
Thanks for the comments, everyone. I'm thinking...
Ben, I have used a single member 6 without having many problems except for the glue joint. I think that's what failed on last year's bridge. So, I don't think the single member is a problem, but the glue joint...
That's an interesting idea about putting members 1 and 2 on top of member 6, but I doubt I'd want to put members 3 and 4 on top of it. Their angle is so small, I probably am going to want to maximize it as much as possible. (?)
And if I glued those members to the sides of member 6, I'm going to have the same friction/sheering joint problem.
I was kind of wondering about the height just because it seems soo high. I'll ask Dad about the 90 degree thing. That would definitely the weight of the bridge, and I'll have to think about how that will affect the vertical and horizontal components of the applied force. The fact that the loading plate is offset doesn't help either...
Ahhh!! I have too much to think about now. :D
Steve, you really could build a bridge, you know. The rules are at
http://www.pec.org/BBContestRules.html
If you built a bridge in two weeks, you could test it at the contest as an unofficial entry! Yippee! :)
Oh, Ben, Dad was looking at flat-screen TVs at Best Buy last night. I think he's going to get several for the bridge contest. The only thing he isn't sure about is what the standard size video will do on a widescreen TV.
I imagine that you'd better not plan to go to any roller coasters on the day of the bridge contest. I have a feeling that you'd better stick close to your phone. :D
Ok, I'm done rambling, too. I'm just starting to get overwhelmed with school and the bridge contest. I'd better leave before I go crazy.
Yeah... I see what you mean.
Maybe you could glue 3 and 4 to the outside of 1 and 2 stacked on 6?
Still, though, doesn't seem like a single would raise it enough to make that much angle difference, but maybe it would.
Post a Comment