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Rapture - Team Dyrodium - NSW
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dyrodium
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Rapture - Team Dyrodium - NSW

Refrained from posting up a build thread on this... but need to get some opinions on a new version so here it goes, the build thread of the rw08 champ. Laughing


I would post a pic of how it looks now if our digital camera didn't pack it in, but basicaly its current problems are:
Not invertable (but not yet caused an issue...)
Weapon motor mount sucks
Weapon shaft screw would unscrew, causing chaos and weapon loss.
Frame warped and twisted...

Merits are its extremely large disk and the power of the GPB/EV's so I want to keep that, but a redesign will hopefully see a fix of the above issues without making the robot too large (I HATE large designs...)

I can't really see how to fit the EV down without making the frame overly long or wide, so we might see a vertical spinner rapture for next event... Need more high tensile steel to avoid frame damage like happened to the mild steel components of the old frame. Cool
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Post Wed Feb 27, 2008 9:30 pm 
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Nick
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Weapon shaft screw is easy; we drill it out and tap the shaft for a left-hand tread. You could also flip the blade over and spin in reverse...

For the frame warp, more triangulation would help. Easier said than done though. I would look at building the frame from 4130 alloy tube; weight for weight tube is far stronger and stiffer than rod, which is why everything from bike to racing car frames use round tube. Welding it will be harder, but worth the effort.
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Post Wed Feb 27, 2008 9:47 pm 
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dyrodium
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Spinning the blade in reverse wouldn't work, then it'd unscrew the other end Razz
Left hand thread is a neat idea, but I can't imagine how hard one would be to get... My thoughts are to lock the thread that is prone to unscrew with superstrength locktite and simply use the one that auto tightens to get the shaft off. That's another point I forgot to mention... the bushing in raptures weapon worked its way loose last event, regardless of the super bushing locktite we used...!!! I'm not sure how, but it was actualy moving up into the blade, not just stopping level with the blade once the load was gone. Russel suggested some pointed grub screws to grab into the bushing and it's so thick I think it'd work well.
I can't say how happy I am with the high tensile, at only $6 for two metres, it produced a frame ending up around 3kg which is quite light, indeed with the A123s rapture only weighed in at 12.4kg. The mild rod which I used once I ran out of high tensile is what let me down, bending out of shape. And I don't fancy my stick weld job on tube. Very Happy
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Post Wed Feb 27, 2008 10:00 pm 
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DumHed
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weld a flat plate on one end of the shaft, and remove it from the other end Smile
You could even just bolt it up as normal and then weld the bolt in - or what about running one bolt all the way through the shaft, and using lock nuts on it?
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Post Thu Feb 28, 2008 7:31 am 
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dyrodium
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Welding wouldn't be such a great idea, the shaft cost a load because it's precision and case hardened, which welding would destroy Laughing
One big hole through the center might be an option though, but might just try the locktite for now which would save lots of problems. Was just checking out the hobbyweight fiasco, and was getting ideas... shame the EV's are so massive, making that shape not exactly efficient... Confused
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Post Thu Feb 28, 2008 7:35 am 
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Glen
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i actually think that would be a good idea to bore a hole all the way through it then just put a big shoulder hex head bolt through. you could really torque it up good then and put a nyloc on the other end.

conversly you could make a plan g style hub design that would weigh next to nothing Razz

also dumheds idea is a keeper. one end needs to be properly captured. so maybe get some 25mm rod or something, lathe most of it down to 20mm or whatever you use so the end cant pull through the end plate. then put a big long through bolt through the thing to stop it coming out (i imagine thatd be way stronger than a tapped bolt.
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Post Thu Feb 28, 2008 8:15 am 
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DumHed
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if you welded a bolt in you could do it without overheating the shaft I think.
Serious welding could be a problem though.
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Post Thu Feb 28, 2008 10:28 am 
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Russell



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Just did a chase up on Nicks 4130 tube and got a price on 12.7mm by 3mm wall at about $20 per meter from a local source, Performance Metals P/L

Post Thu Feb 28, 2008 11:46 am 
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dyrodium
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Shocked Jeez that's better than expected!
Methinks I might be trying that stuff out then. Smile
Only thing with that though, i'm pretty sure it comes tempered and needs hardening before use?
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Post Thu Feb 28, 2008 12:09 pm 
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Knightrous
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The stuff you bought last time Anguz, did it have light blue paint on the end or green?

www.matweb.com is a good place to chase up information on metals, check it out and compare metals against each other and pick what suits your needs
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Post Thu Feb 28, 2008 12:35 pm 
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Valen
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generally when used for making planes and cars etc its welded with a specific rod that is softer than the base metal. The strength winds up being the same because you make the weld larger with a phat bead and gusseting.
Advantage you get then is 50% elongation before break. Your structure winds up being tougher, when filled and heat treated again you wind up with a stiffer structure but its brittle. Generally though the gains of heat treating it are pretty minimal and the stuff comes un-treated as a rule.
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Post Thu Feb 28, 2008 1:12 pm 
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Glen
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wow thats a good price russell, i called them up a few months ago to get some chromoly box section for visceral and it was a huge amount more than that, like $60.

good deal Surprised
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Post Thu Feb 28, 2008 8:58 pm 
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Nick
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That performance metals place is about the best for small quantities of 3140. It works out at the same price in the USA, which is good going for an Aussie retailer.

EDIT: Jake's comment about gussets is probably the key to stopping your frame from bending. gussets will help triangulate the frame and reinforce the joints at the same time.
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Post Thu Feb 28, 2008 9:02 pm 
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Valen
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box section would be much rarer than tube, generally your going to use this stuff when strength for weight is the overriding concern, the corners on box are weak points.
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Post Thu Feb 28, 2008 11:12 pm 
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dyrodium
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The thing is, raptures frame hasn't actualy bent... Laughing
All the high tensile components are as straight as ever, it's the mild steel and... printer shafts (ok, but they're stainless!) which are no longer straight, the 10mm bunnings shitemetal has been the worst and its totaly bowed in. So all high tensile/tube section frame will be a decent fix, with gussets only really needed for a few supports I would think.
I'm getting ideas, if a tube section frame was lighter, a vish brushless could allow weight for a 5kg disk... Rolling Eyes
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Post Fri Feb 29, 2008 7:18 am 
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