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bitternboy
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Postby bitternboy » Fri Feb 11, 2011 9:08 am

Yes, I was asking if those motors would do, sorry for being vague. I think 600kg of crush is impressive but it wasn't what I was aiming for. Surely, just to "hold" a robot takes no more than 50kg of force which must be achievable with some form of geared motor. Anymore force than this would put my craftmenship to the test and may cause my robot to rip itself apart. You see, I can't weld, I was planning on using HDPE for the claw with steel teeth and my robot was going to be held together with standard nuts and bolts. Basically, if I use and actuator (which I may still look into) I may be unable to use it effectively. :-?
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Remote-Controlled Dave
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Postby Remote-Controlled Dave » Fri Feb 11, 2011 9:35 am

Jonathan, I don't know if you've seen a featherweight competition recently, but most of the robots are getting towards bomb-proof bullet status. No-one has really been able to make a decent grabbing arm recently because they are just not effective, not even with an actuator. I sincerely doubt you'd get 50kg of hold from a servo anyway, but even this wouldn't be anywhere near enough force to hold a modern featherweight down. I really would listen to Jamie (Terminal Damage) as he has built a featherweight grabber himself and knows what he's talking about.
If you want to build a feather, I would suggest what I would suggest for any weight catagory. Build a simple robot first, no weapons, and get it in the arena. This will give you experience and a base to build upon. If it falls apart, you know you need to build it better. If it doesn't, you know the engineering is ok and you can build upon that. But I really wouldn't spend any money trying to develop that claw, it really won't survive.
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bitternboy
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Postby bitternboy » Fri Feb 11, 2011 12:31 pm

*sigh*, I can't argue. My reasoning was that having a weapon (however ineffective) to start with would give me something to develop. If it's impossible to achieve an effective grabber then I suppose I'll stop trying.
Jonathan
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Remote-Controlled Dave
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Postby Remote-Controlled Dave » Fri Feb 11, 2011 8:48 pm

I know it all sounds a bit harsh matey. It's all in the best intentions though. Take it from me, someone who's had his featherweight torn to bits! lol :D

http://www.youtube.com/watch?v=tYp3wZbP9Zw
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bitternboy
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Postby bitternboy » Fri Feb 11, 2011 11:07 pm

That's fine :) . Spirits not dampened whatsoever.

BTW OUCH! that looks mighty painful.
Last edited by bitternboy on Fri Feb 11, 2011 11:08 pm, edited 1 time in total.
Jonathan
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Postby Remote-Controlled Dave » Fri Feb 11, 2011 11:07 pm

Good man. :D
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maddox
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Postby maddox » Sun Feb 13, 2011 3:08 am

There is a Dutch feather in use, PulveR, that uses a full fledged hydraulic setup that has at least 500 kg on the tip.
And even with that kind of force, there are feathers that just shrug it off without even a dent.
BonX springs to mind.

Even the Soft Skinned Hannibalito's don't care much. The shape and size make it so that the claw can puncture the armor, but to hit something that can't take it, nah.

Model RC servo's are nice stuff for controls or such, but for power applications above beetleweight, forget it.

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bitternboy
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Postby bitternboy » Sun Feb 13, 2011 1:04 pm

Don't worry I gave up on servos a while ago. :)
Jonathan
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haz
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Postby haz » Sun Feb 13, 2011 6:14 pm

i did have a diagram to turn a drill into a big servo (ish) somewhere

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bitternboy
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Postby bitternboy » Thu Apr 07, 2011 8:15 pm

I may have found the solution to the problem mentioned above. I didn't want to use an actuator before because I assumed I had to fabricate one myself but low and behold I've found a range of them made by pololu...
http://www.pololu.com/catalog/category/103
A bit pricey but some to aim towards.
Jonathan
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Jonny
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Postby Jonny » Thu Apr 07, 2011 8:41 pm

check out ebay for cheaper actuators
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bitternboy
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Postby bitternboy » Thu Apr 07, 2011 8:56 pm

Might just do that. Also, would the pololu 37Dx54L motors do for drive or are they a bit weedy?
Jonathan
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Jonny
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Postby Jonny » Thu Apr 07, 2011 9:27 pm

almost definetly too weedy. just go buy 2 12v drills from argos for a tenner each and use the motors from'em. cheaper and they'll definetly be torquey enough aswell as speedy :)
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haz
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Postby haz » Fri Apr 08, 2011 7:34 am

indeed i found they where too fast for me on 12v so i know run them on 8.4v which im happy with

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bitternboy
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Postby bitternboy » Fri Apr 08, 2011 7:51 am

I've already got 2 drills and harvested the motors and batteries, way ahead of you there :) Pololu motors in general are quite tempting though as you can choose the gear box and buy quality wheels and mounting brackets that fit them, both of which I'm a bit short on.
Jonathan
Before you criticize another person, first walk a mile in their shoes. Then, when you critisize them, you'll be a mile away and have their shoes.


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