Help/Build diary for/of my first antweight.

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Puddle
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Help/Build diary for/of my first antweight.

Postby Puddle » Sat Mar 18, 2017 1:49 am

Hey everyone,
I've been into robot combat since the original robot wars series but I was young back then and didn't know where to begin with trying to build my own but now the new series is back and I found the AWS videos on youtube I decided I wanted to finally give building my own robot a go. I've been lurking around this forum and reddit trying to find stuff out while my account was being approved so I know the basics about Rory's kit being the way to go for beginners and polycarbonate being the holy grail for people who don't have the tools to 3d print or work with metal. I also read through Shakey's build diary and picked up on that one servo that he said he used in all his flippers but I still have some questions that I wanna ask before I buy any bits and turn this question thread into a build diary.

as you probably guessed from me mentioning a servo I'm planning on building a flipper ant as my first robot but wait! before you roll your eyes in shock about a newbie building a two wheel drive servo flipper as their first antweight hear me out. Because this is no ordinary flipper, it's a DOUBLE FLIPPER. I basically had the idea of what if a front hinged flipper went all the way round the robot and had a scoop on it so that when driven in reverse it acted as a rear hinged flipper. And from there I thought about the robots with those two weapons that I found the coolest/were the most successful and I ended up with the drawings you see below. Basically the front of Chaos 2 on the back of firestorm/Cassius 2.(I added some squiggles meant to look like motors and circuit boards but I don't actually know what would fit where) I have no idea if it would work but I like the idea and from watching some of the AWS videos there's quite a lot of 2WD wedges with flippers and I wanna be different.

anyway I've got most of it sorted out I just need help with a few things:

1.I don't know what transmitter to get although I know that Rory's kit's receiver won't work with a certain kind of transmitter?

2.I don't know what kind of battery to get beyond LiPo's being powerful and light

3.how big should my bot be? I know about the 4" cube but should I aim to take up all the space? or atleast the flat areas? or do I want the robot to be as small as possible?

4.How should I attach the flipper to the servo? directly? I read something about having a rod between the servo and the flipper wasting power and gears being the way to go? or would that not work in my design?


That's about it for now but I'm sure I'm forgetting something. I'll pop my drawings of what I had in mind for my bot below so you may see what I'm going on about. the bit near the wheels is what I imagine chaos 2's flipper blade would have looked like nowadays, kinda wrapped around the rear/front of the bot to protect the wheels from any marauding spinners. I thought that maybe if it was only a small bit bent in a couple places I could use metal for that bit and polycarb most everywhere else but I don't know what kind of metal to use or in what thickness.

Thanks again for reading this hideous wall of text and for any advice you may have.
My name's Harry by the way, I forget whether I entered that for my account.

Image
Image
Harry

Occashokka
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Re: Help/Build diary for/of my first antweight.

Postby Occashokka » Sat Mar 18, 2017 8:03 am

One of the most popular lipos is this one: https://hobbyking.com/en_us/turnigy-nan ... tore=en_us and I use it in everything because it only 13g, most people build right up to the cube with wide and length but make it quite low, by doing this you can put it in the cube diagonally to make it fit, for example my spinner is 3.9 inches wide and 1.5 inches high and 4.6inches long.

If im not mistaken your flipper needs the power of the servo on the movement up, but it doesnt need strong torque on the way down, in robots where no such grabby capabilities are required you can literally put the servo arm on the face of the flipper then have an elastic band between it and the flipper to pull it down after the flip, you are more than welcome to play with cool mechanisms as they can change the ark angle or speed for your flip, but that its probably not necessary to make it flip well
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BeligerAnt
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Re: Help/Build diary for/of my first antweight.

Postby BeligerAnt » Sat Mar 18, 2017 4:50 pm

First of all, welcome to the forum!

Rory's kit won't work with DSMX transmitters, only DSM2.This is down to the receiver module that he uses. You can get the speed controller board without the receiver and use your own to avoid compatibility problems but it will probably be bigger and heavier.

The Turnigy nano tech battery that Occashokka suggests will be fine; just make sure you get a proper LiPo charger to charge them with.
The IMAX chargers are popular and come with an adapter to the JST connector used by the Turnigy batteries (and most other batteries of Antweight size): https://hobbyking.com/en_us/imax-b6ac-v ... arger.html

You robot must fit in the 4" cube, but importantly there is no restriction on how it fits in the cube. Wedge-shaped robots often take advantage of the diagonals of the cube, giving a maximum overall length of about 140mm.

For your design the hinge of the flipper is not the same as the axis of the servo so you will need some sort of linkage. You could just rely on the servo arm pushing on the flipper to lift it with an elastic band to pull it back down or you could build a 4-bar linkage. Gears would probably be more difficult to build and align; the simplest solution would be to have the arm pushing the flipper directly, you can always upgrade it later.

Good luck, and have fun!
Gary, Team BeligerAnt

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Shakey
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Re: Help/Build diary for/of my first antweight.

Postby Shakey » Sat Mar 18, 2017 5:10 pm

Puddle wrote:4.How should I attach the flipper to the servo? directly? I read something about having a rod between the servo and the flipper wasting power and gears being the way to go? or would that not work in my design?


Gears are neat and really get the power out but are only needed if maxing out is something you're after. A standard link would be perfectly fine and they look something like this:

Image

In your case just imagine the examples are rotated 90 degrees clockwise. The hinge would be the front, then extend the other end of the flipper arm down so it forms an upside down U over it all.
Nuts And Bots - For all your components and ready built antweights!

Alex Shakespeare - Team Shakey / Nuts And Bots:
AWS 44, 45, 49 & 51 Winner - Far too many robots!

Puddle
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Re: Help/Build diary for/of my first antweight.

Postby Puddle » Sat Mar 18, 2017 5:43 pm

Ok so I found this Battery charger: https://hobbyking.com/en_us/turnigy-12v-2-3s-basic-balance-charger.html would this be suitable for now or should I go directly for the one Gary posted to save upgrading in the future?

I found this Transmitter on the googledocs about the kit https://www.amazon.co.uk/gp/product/B00OBB7WU0/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1 is this still the one to go for for DSM2? I think you have to upload a bit of firmware to it or something but that looks simple enough, Just downloading a couple files and extracting them into the transmitter.

For the flipper link if using a rod is ok would I just have the servo attached to the rear hinged bit of the wedge from the bottom to get the 90 degrees at the top? here's a hastily done MS-paint Diagram to help you see what I'm getting at:

Image
Harry

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Shakey
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Re: Help/Build diary for/of my first antweight.

Postby Shakey » Sat Mar 18, 2017 6:03 pm

That battery charger is fine, basic but it works well enough for our needs.

The walkera works but needs a slight tinkering, see here: viewtopic.php?f=5&t=2387

And remember the length of the purple bit and the length of the orange bit between the two hinges forms a ratio that adjusts speed, torque and travel. The way you show there has a very small travel in the flipper. Especially with a front hinge you need to get it quite steep.
Nuts And Bots - For all your components and ready built antweights!

Alex Shakespeare - Team Shakey / Nuts And Bots:
AWS 44, 45, 49 & 51 Winner - Far too many robots!

Puddle
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Re: Help/Build diary for/of my first antweight.

Postby Puddle » Sat Mar 18, 2017 6:26 pm

so I want to make the purple bit longer and move the green one with the end of the purple to keep it 90 Degrees? when you say I need it quite steep do you mean the wedge itself of the servo?
Harry

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BeligerAnt
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Re: Help/Build diary for/of my first antweight.

Postby BeligerAnt » Sat Mar 18, 2017 7:23 pm

You can figure out the movement your linkage will give using some fairly basic geometry, remember that a servo doesn't move much more than 90 degrees without some tweaking. Figuring out the speed can be a bit more complex as it's not always constant.

This tool http://blog.rectorsquid.com/linkage-mec ... simulator/ can be used to simulate linkages if you don't want to do it all by hand. Your linkage has two fixed points, the servo axle and the flipper hinge.
You can turn the servo over (to put the output on the left in your picture) which will help to equalise the lengths of the orange and purple links.
Gary, Team BeligerAnt

Puddle
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Re: Help/Build diary for/of my first antweight.

Postby Puddle » Sat Mar 18, 2017 7:43 pm

Ok thanks, I'll have a play around with this and find the best point to have it all attached
Harry

Puddle
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Re: Help/Build diary for/of my first antweight.

Postby Puddle » Sun Mar 19, 2017 12:50 am

I couldn't really figure out how to use linkage in the end so I just resorted to doing it on paper but I still can't quite figure out how to get the best position out of my chassis. I know it's a bit much to ask but could someone who knows their way around servo flippers have a crack at finding a good setup for this? or is it something that's easier to figure out once you have a cardboard mockup to use as a reference?

Below is an image of what I was working with on MS paint for anyone interested

Image
Harry

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BeligerAnt
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Re: Help/Build diary for/of my first antweight.

Postby BeligerAnt » Mon Mar 20, 2017 8:09 pm

What are the dimensions? Without some dimensions you could have any arbitrary answer but the angles wouldn't necessarily be what you wanted!
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Puddle
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Re: Help/Build diary for/of my first antweight.

Postby Puddle » Mon Mar 20, 2017 8:18 pm

Yeah I realized that. I'm building a cardboard mockup to figure out the dimensions now. I just dived straight into the interesting weapons bit without knowing what size it was gonna be :oops: once I've got that and know where I'm gonna fit the motors and wheels I'll come back to the servo.
Harry

Occashokka
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Re: Help/Build diary for/of my first antweight.

Postby Occashokka » Mon Mar 20, 2017 9:46 pm

I really like the concept! , one thing I warn you of most as someone who has owned a front hinged flipper is that the if it is too shallow then the servo being the fattest thing has to end up right near the back, which means harder linkages and also having the servo where you want to drive motors to be, so you will have to carefully plan the angle and the placement of electronics inside. Good luck tho I really want to see this do well!
Team Badger
Has a 3d printer now yay
-£4.82+VAT (intact)
-cool modulated printed thingy
-not yet built nasty mean spinnt thingy

I'm gonna build something huge and stupid, try and stop me :P

Puddle
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Re: Help/Build diary for/of my first antweight.

Postby Puddle » Mon Mar 20, 2017 10:09 pm

Ok so I've hit a semi snag in that I don't know how big the motors are. http://www.robotshop.com/uk/pololu-30-to-1-metal-gear-hp.html I found these which are the ones Rory's kit has right? but does the listed dimensions include the shaft or just the body of the motor?
Harry

Occashokka
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Re: Help/Build diary for/of my first antweight.

Postby Occashokka » Mon Mar 20, 2017 11:08 pm

I know they are 10mm x 12mm width and height and roughly 25mm long without shaft so that measurement includes the shaft which I believe to be 10mm long same as the wheel width
Team Badger
Has a 3d printer now yay
-£4.82+VAT (intact)
-cool modulated printed thingy
-not yet built nasty mean spinnt thingy

I'm gonna build something huge and stupid, try and stop me :P


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