Author Topic: Have a look at my cad - find bugs, weaknesses, etc  (Read 4733 times)

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Offline izuaTopic starter

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Have a look at my cad - find bugs, weaknesses, etc
« on: March 03, 2008, 02:48:15 PM »
It's the first time i'm CADding something so complex (been using SE very little), and it's actually the first time i'm attempting some serious mechanical design.Yesterday, a friend mounted the wheels on the servos, and i've mounted the whole thing with duct tape to the battery. although the wheel spins terribly out of center, the offset from a straight line ain't worrying (yet).. Maybe I'll post some pictures or movies if anyone interested.

Anyway, here are a few images of how the final guy should look (electronics go on top). Let me know of any ideas, bugs, improvements, etc. I'm using two pieces for the main hull since i have some scrap plastic, and two times its height is close to what i want.

http://www.flickr.com/photos/14530888@N05/sets/72157604039561623/

« Last Edit: March 03, 2008, 02:52:47 PM by izua »
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Offline Steve Joblin

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Re: Have a look at my cad - find bugs, weaknesses, etc
« Reply #1 on: March 03, 2008, 03:18:57 PM »
How will it balance?  Do you need a third castor wheel?

Offline izuaTopic starter

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Re: Have a look at my cad - find bugs, weaknesses, etc
« Reply #2 on: March 03, 2008, 03:21:02 PM »
Yep. I'll put a castor wheel at some point, but i haven't found any yet, and i'm not sure i can design one.
*thinking of using a roller for chairs*
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Offline frank26080115

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Re: Have a look at my cad - find bugs, weaknesses, etc
« Reply #3 on: March 03, 2008, 04:44:48 PM »
PLEASE use rechargeable battery packs and not AA batteries.
I like the design, reminds me of http://www.recon-scout.com/products/index.cfm

Offline airman00

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Re: Have a look at my cad - find bugs, weaknesses, etc
« Reply #4 on: March 03, 2008, 08:10:15 PM »
PLEASE use rechargeable battery packs and not AA batteries.
I like the design, reminds me of http://www.recon-scout.com/products/index.cfm


why?

AAs are fine .

battery packs do look more professional though --- BUT they cost lot of $$$ compared to AAs
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Offline frank26080115

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Re: Have a look at my cad - find bugs, weaknesses, etc
« Reply #5 on: March 03, 2008, 08:18:05 PM »
PLEASE use rechargeable battery packs and not AA batteries.
I like the design, reminds me of http://www.recon-scout.com/products/index.cfm


why?

AAs are fine .

battery packs do look more professional though --- BUT they cost lot of $$$ compared to AAs


A 4 pack of alkaline AA batteries will cost you at least $3 replace that 15 times and you can get a 7.2V 3000mAh Ni-MH battery that will last longer and let you draw more current, plus a charger. And you can use it for all your other robots since it doesn't need a specific holder (a connector is only $2).

Offline airman00

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Re: Have a look at my cad - find bugs, weaknesses, etc
« Reply #6 on: March 03, 2008, 08:22:11 PM »
good point

I usually use rechargeable AA batteries (1.2V each)

Occasionally I use battery packs on some projects( but only if I get a spare battery pack from a r/c toy)
Check out the Roboduino, Arduino-compatible board!


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Offline Admin

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Re: Have a look at my cad - find bugs, weaknesses, etc
« Reply #7 on: March 03, 2008, 08:22:56 PM »
You will have serious difficulty drilling holes into the sides of those plates for the servos.

(assuming you don't have a good vice and drill press)

At 1" thick total, those two plates look rather heavy, too.

Offline izuaTopic starter

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Re: Have a look at my cad - find bugs, weaknesses, etc
« Reply #8 on: March 04, 2008, 06:28:37 AM »
i am using 4 nimh accus in series, to create a 4.8V battery. for the moment, i'm not thinking anything fancy like self charging, but maybe, i'll use individual holders for batteries, so I can charge them separately, put them in series via electronic command and monitor them individually, and so on :)

the plates are 2 cm high (both), barely under an inch. the material is light, though, (i've been told it's comatex or expanded plastic, iirc) - one uncut plate is just a tad heavier than one nimh accu (plate is 22x8, robot 13x8). about processing them, well, i'm not really worried - for now, i might be able to cut them on a cnc and i can drill the lateral mounting holes with a tap&t wrench (they call it "tarod" here). i'm pretty sure i'll find a drill press (although i preffer drilling a thread hole than a simple hole)

edit: do suggest where i can find some small castor wheels (with mounting, preferably)
« Last Edit: March 04, 2008, 06:30:09 AM by izua »
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Offline Centaur

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Re: Have a look at my cad - find bugs, weaknesses, etc
« Reply #9 on: March 04, 2008, 04:03:55 PM »
Those plates really are overkill.  You could probably get away with a much lighter design, which means it could accelerate much faster with less battery drain. 
Any intelligent fool can make things bigger, more complex, and more violent.  It takes a touch of genius - and a lot of courage - to move in the opposite direction.  ~E.F. Schumacker

Offline Mcrich113

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Re: Have a look at my cad - find bugs, weaknesses, etc
« Reply #10 on: March 04, 2008, 08:00:58 PM »
Hey guy!
     Ok look, everyone says to use rechargable batteries, I agree wit them too, well the reality is, all bateries are! When two bateries or more are in a device, they are placed oposite end with opposite end, but when the two side are the same, energy from the youger or less used battery recharge the other, just use electricle tape and put them together. I got this from a website called infinite soulutions.The results may vary though.

Thanks!Mcrich113 ;D

Offline ed1380

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Re: Have a look at my cad - find bugs, weaknesses, etc
« Reply #11 on: March 04, 2008, 08:38:47 PM »
so in the end you take a good batteries power and instead of sending it to the motors you send it to a bad battery. it'll work, but not as good.
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click here. http://www.societyofrobots.com/robotforum/index.php?topic=3292.msg25198#msg25198

Offline Mcrich113

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Re: Have a look at my cad - find bugs, weaknesses, etc
« Reply #12 on: March 04, 2008, 11:55:19 PM »
Hey guys!
     Ed1380, I dont think u understand, u can just do it normaly with electircal tape, To do it better, try putting on lemon juice, it will speed up the process.

Thanks!Mcrich113  ;D

Offline izuaTopic starter

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Re: Have a look at my cad - find bugs, weaknesses, etc
« Reply #13 on: March 05, 2008, 12:49:53 AM »
dude, if i put them in parralel, there's still no mcu or motor that will run on 1.2 V.
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Offline izuaTopic starter

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Re: Have a look at my cad - find bugs, weaknesses, etc
« Reply #14 on: March 05, 2008, 05:27:04 AM »
I've done some case modding, basically, just adding a cutout.
Do you think it might help?

http://www.flickr.com/photos/14530888@N05/?saved=1

edit: i found out the comatex thing - it's expanded pvc. also, the new chassis piece is (in SE20's opinion) 70g heavy.
« Last Edit: March 05, 2008, 05:32:05 AM by izua »
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Offline Mcrich113

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Re: Have a look at my cad - find bugs, weaknesses, etc
« Reply #15 on: March 05, 2008, 05:02:04 PM »
U JUST TAPE THEM TOGETHER! I NEVER SAID PUT IT IN TO THE ROBOT >:(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 


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