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Author Topic: Tools and materials for a beetleweight?  (Read 275 times)

Caridor

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Tools and materials for a beetleweight?
« on: January 24, 2018, 11:16:15 am »
Hello everyone

I'm planning on starting a beetleweight (in the UK, weight limit is 1.5kg (3.3lb)) and I've never build a robot before. I'm planning on making a crusher, using a rack and pinion drive instead of a pneumatic ram to power a "jaws of life" style crusher, purely because I can't seem to find a small enough cylinder. (http://patentimages.storage.googleapis.com/US7107812B1/US07107812-20060919-D00002.png - Jaws of life, to save you a google search. Part 16 pulls back, bringing the jaws in).

But for this, I'm going to need to shape metal for the actual jaws of the thing, which I'm thinking of modelling on the Trap Jaw Ant (https://pateklab.biology.duke.edu/sites/pateklab.biology.duke.edu/files/imceuploads/bauri2.jpg). I was wondering what kind of tools and materials would be good for this? I'm pretty sure that whatever I make the jaws out of, needs to be stronger than the armour of the other robot, so that the armour breaks, not my jaws, but I have no idea what kind of armour is generally used.

I imagine I'd also need a pretty torquey motor to power the thing.

Thanks
« Last Edit: January 24, 2018, 11:21:44 am by Caridor »

rcjunky

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Re: Tools and materials for a beetleweight?
« Reply #1 on: January 24, 2018, 10:30:58 pm »
Crushers are extremely difficult to build well because of weight. To get enough clamping force your weapon assembly needs to take all that force. Titanium will be your friend as will FEA testing. You're very much in uncharted territory so it'll be very hard to find solid proven advice.
Andrew Burghgraef
Canadian Carnage Robotics

Great Hobbies- Canada's leading retailer of radio controlled models and related hobby supplies

Caridor

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Re: Tools and materials for a beetleweight?
« Reply #2 on: January 25, 2018, 08:10:33 am »
Ah, I see. Maybe something for a future robot then. I must admit, a big part of it was my love for old crushers like Razer.

The other idea was a horizontal spinner, which shouldn't be too hard, once I find the right motor.

I still don't really know what materials are used for the armour in beetleweight though or the tools generally used to shape them.

AmbientChaos

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Re: Tools and materials for a beetleweight?
« Reply #3 on: January 25, 2018, 01:09:23 pm »
American here, so my preferred sources might be different than those across the pond, but here are my thoughts.  If you're looking for armor in the strictest sense (particularly for wedges), grade 5 titanium is what is most commonly used in beetleweights since it is strong/flexy to take impacts while being lighter than steel.  For frames, many people use impact resistant plastics like UHMW polyethylene because it helps to absorb impacts and tends to flex/scratch when hit rather than breaking (one experienced builder recently built a 30 pound bot out of a slab of the similar HDPE that the Brits seem to prefer).  For lids/baseplates there is much wider variety with everything from aluminum to polycarbonate to garolite seeing frequent use.

Weapon motors very commonly come from HobbyKing, with the Propdrive series seeming to be notably popular at the moment.  For drive motors I would recommend Pololu, ServoCity, and FingerTech.

As far as tools go, I've been doing fairly well with basic tools like a drill, jigsaw, dremel, sander, and metal shears supplemented by having a couple more difficult parts cut by waterjet.  You don't have to have a fancy CNC mill or lather to be able to make a cool bot, you just have to be able to design around your tool limitations.

As an aside, this forum has become much less active than it used to be, but there is a very large and active group on Facebook that you could join.
« Last Edit: January 25, 2018, 01:20:20 pm by AmbientChaos »

Pinski1

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Re: Tools and materials for a beetleweight?
« Reply #4 on: January 26, 2018, 04:04:21 am »
This is an American forum, the UK one is http://www.fightingrobots.co.uk which is pretty active. Alos worth checking out the "Beetleweight Robot Combat Discussion" group on Facebook. There's a Beetleweight competition in Bristol UWE on the 10th of Feb which I'd recommend coming along to with a camera. Lots of ideas to steal!

As for Beatles I've tried to keep mine inside the US rules of 1.36kg but has 4mm Hardox and 2mm Ti armour with 6mm 7075 Aluminium chassis. I'm using a Propdrive 28-36 1000kv motor on a 3 cell LiPoly to power my ~100mm long, 1.48" drum with 4 Hardox teeth. The drive is 2x 25mm gearboxes on Quanum MT Series 1806 2300kv Brushless motors which after the gearbox run about 1000rpm. This is connected to the 4 ~40mm wheels by a belt drive. Size wise it's about 200mm wide and 120mm deep, the top of the ears is ~ 70mm high.