Build Diary for a new antweight

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Fenrir
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Build Diary for a new antweight

Postby Fenrir » Mon Jul 18, 2016 11:18 pm

I haven't got any plans to complete this quickly, but I figured I'd make a thread early as a motivation. My first antweight is too large to be classed as a legal antweight, and is somewhat fragile, also looking, in passing, like the original Ripper that featured on Robot Wars. My expectations aren't too high for the new one, but I'd like for it to be able to compete at events.

I've settled on a 2 wheel drive wedged grabber using a servo to power the weapon, and a much better construction than superglue on polycarbonate.

Currently, I have two wheels, two gear motors fitted with speed controllers, a weapons servo, NiMh battery, which I believe works but I'm not entirely sure. I've also purchased a few sheets of polycarb, set of M2 nuts and bolts, zip ties and a couple of leads to connect the battery to the receiver making it easier to unplug for charging and as a fail safe; all for under £20. I have no motivation to buy a transmitter and receiver until I have made a chassis and decided where everything will go, so the robot may not be completed for a while.

I do have a question though, regarding the weapon. I was planning to glue, or bolt together a few pieces of polycarb for the grabbing claw but I was wondering if that would A. be strong enough for the job, and B. If there was a more effective material to use, either with multiple sheets or just a single.

bigsi111
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Re: Build Diary for a new antweight

Postby bigsi111 » Tue Jul 19, 2016 7:25 pm

Hi, I'm new myself so will be following this with interest, Best of luck

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BeligerAnt
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Re: Build Diary for a new antweight

Postby BeligerAnt » Tue Jul 19, 2016 9:58 pm

The lifting arm on Make-A-Bot is made of polycarbonate, but it is 10mm thick!
I have also made lifters from 1mm polycarb but you do need to fold the edges to make it stiff.
I think you'd want to aim for around 3mm+ thickness for a weapon arm to ensure that it can transfer the pressure.
Since polycarb is not easy to glue I'm not sure laminating sheets would work well. If you only have thin sheets look at folding it to add stiffness, it might do what you want.
You should be able to find A4 sheets of 3mm polycarb on Ebay for a few quid. You may be able to bolt together a couple of 3mm pieces to give a decent weapon arm.
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Rapidrory
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Re: Build Diary for a new antweight

Postby Rapidrory » Wed Jul 20, 2016 8:30 am

All my grabbers claws have been made from thick paper clips or piano wire... nice and easy, and has the advantage of getting in small holes it the opponents chassis..
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Robots: Too Many...

NanoTwo antweight speed controllers. (viewtopic.php?f=1&t=2128)

Fenrir
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Re: Build Diary for a new antweight

Postby Fenrir » Wed Jul 20, 2016 10:26 pm

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After making a to-scale prototype from paper, made in a similar fashion, albeit using glue instead of bolts, to how I plan to make the robot, I drew the front scoop onto the 1mm polycarb with some non permanent marker before scoring the polycarb.
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I cut it out with scissors and then scored it a little deeper before bending it against the score. The joints felt a little weak but it keeps its shape. It was difficult to bend and it took two failed attempts; one where I bent the polycarb inwards against the scoring and it just snapped, and the other where I didn't score it and so it didn't bend properly.
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Would anyone have any more advice for bending polycarb cold, especially if it comes to a point like that? I've added a tiny amount of superglue just to make sure the fold doesn't break but I can't see it lasting much against a tough opponent.

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Rapidrory
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Re: Build Diary for a new antweight

Postby Rapidrory » Wed Jul 20, 2016 11:07 pm

2 main points with polycarb: Don't score it before folding, and don't use super glue :P

It folds fine without scoring, you just need to clamp it along a straight edge or in a vice.. Even a slight score will weaken it massively and cause it to crack while bending. on a similar note, while heating makes it easier to bend, it also makes the polycarb more brittle, and makes the fold more likely to break under impact.

Superglue reacts with polycarb and weakens it over time. Should be fine for the weekend, but will likely be very weak by the next event.

Keep doing what you're doing with the templates and folded polycarb though; looking good so far. 1mm is a little on the thin side, but should hold up against most things. 1.5mm is about right for the chassis as it's easy to fold but still fairly rigid. Also works for scoops, but better to up to 2mm if you really want to shrug off spinnes.
Rory Mangles - Team Mangler

Robots: Too Many...

NanoTwo antweight speed controllers. (viewtopic.php?f=1&t=2128)

Fenrir
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Re: Build Diary for a new antweight

Postby Fenrir » Wed Jul 20, 2016 11:53 pm

Alrighty. I've only used the tiniest amount of glue so that shouldn't be too much of an issue. I checked around everywhere I could for something to clamp it down with but there wasn't anything worth using. The chassis should be easier as much less folds to a point, but it might a still be a pain. I'll work with what I have and move on from there, I'm not expecting anything super robust for the robot, and should it make it to the arena being destroyed completely would be spectacular to watch haha. Btw would you recommend any SYMA Tx's? I found a few, all around £7-15 and 2.4GHz but Im thinking with such a low price there would have to be a drawback of some kind.

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BeligerAnt
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Re: Build Diary for a new antweight

Postby BeligerAnt » Thu Jul 21, 2016 7:07 pm

A couple of small, cheap G clamps and a couple of bits of wood will work quite well. Or the edge of the kitchen table if you're desperate! Once you get the bend started you can often remove the clamps and finish the bend by hand, with the help of some big pliers if needed.

You can avoid the "point" problem by initially cutting the polycarb so that the sides are rectangles rather than triangles, then cut them down to the right shape after bending.
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Fenrir
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Re: Build Diary for a new antweight

Postby Fenrir » Thu Jul 21, 2016 7:55 pm

Good idea with the point thing, I never actually thought of that, but I'm thinking of buying a vice that would fit onto the table to spare my fingers the pain of being cut to ribbons haha. I used a piece of metal and a towel in the end to bend out a chassis and tabs for screws, however one of the bends cracked and snapped off but it's not an issue. This is how the main chassis came out, and is a little weak due to being 1mm polycarbonate but I'm sure it will be fine.

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For now I've decided to screw in one panel, the back piece where the fold broke and leave the rest until I can fit some electronics in.

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Since this I've marked on the spot to drill in the motor axles, and where I plan to thread the zip ties through to hold the motors in place. I had a quick look at where the battery could go, and receiver and it looks like the servo will have to go outside the robot, and I don't plan for the robot to be invert only, instead to have he claw right it, or have a srimech attached to the back of the beak through wire, but it's still early days

Fenrir
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Re: Build Diary for a new antweight

Postby Fenrir » Fri Jul 22, 2016 4:40 pm

A lot of progress has been made since the chassis was cut and bent. More holes were drilled in the sides of the chassis, as well as the bottom to allow the motors to poke through and to be held in place by a pair of zip ties.

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I've also settled on a name and aesthetic design. As my forum name would suggest I'm thinking of basing my team upon legendary and mythical creatures, and this robot will be based on the Roc, who's real name is Dwayne Johnson.. No not really, it's an enormous bird which would supposedly pick up elephants in its talons and feed them to its chicks. So to complete this aesthetic, and somewhat protect the wheels, I added a pair of wings on the side and covered them with cardboard "feathers"

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Finally, I drilled some holes in the front scoop and the tabs that will fit it to the chassis. Next onto the top panel and then the weapon.

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botomatic1000
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Re: Build Diary for a new antweight

Postby botomatic1000 » Fri Jul 22, 2016 6:10 pm

It's very nice :) wish I could build something like it.
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Fenrir
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Re: Build Diary for a new antweight

Postby Fenrir » Fri Jul 22, 2016 10:57 pm

botomatic1000 wrote:It's very nice :) wish I could build something like it.

I bet you can you've just got to stick with it. I spent around £220 over the past couple years trying to get something to work and now I've finally got the motivation to do so. I did some more work tonight I'll update tomorrow. Good luck with AWS 50 everyone.

Fenrir
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Re: Build Diary for a new antweight

Postby Fenrir » Sat Jul 23, 2016 3:24 pm

More progress has been made on Roc. The claw was made out of many pieces of polycarb Althouhh some of the smaller ones went missing so I was left with something a little less strong in the long run.

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The beak was bolted together and attached to a servo horn although the bolt to attach it into the servo isn't quite the right size so I might have to glue it in or something but I haven't done anything permanent as of yet. I've also added an articulated arm to the back of the claw to attach a srimech on.

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Finally I found it unfortunate that my zip ties aren't long enough to hold a servo down and so I had to get a little creative with some polycarb and bolt one side to the underside of the top panel and the other to the top of the panel.

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I've done a little more since but I'll update once that becomes substantial enough to do so.

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BeligerAnt
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Re: Build Diary for a new antweight

Postby BeligerAnt » Sat Jul 23, 2016 6:04 pm

Sounds like you've solved the problem of too-short zip ties but for future reference you can "chain" them together. You then get two adjustment points which can be useful. The downside is that you get two lumpy bits that may get in the way a bit...
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Fenrir
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Re: Build Diary for a new antweight

Postby Fenrir » Sun Jul 24, 2016 8:41 pm

I've completed all of Roc that I can until I buy a transmitter and receiver and see what works and what doesn't. I coloured the wings to make them look more aesthetically pleasing, the wings themselves don't really have any use and are just there to make the robot look better, maybe guard the wheels from one or two hits from a spinner.

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Ive also added a piece of cardboard coloured and stylised to the front scoop to be bolted on, agajn for aesthetics more than protection.

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Finally, and most importantly, a cardboard panel has been added to the top plate, but more importantly the feathered tail srimech has been attached to the top panel to hinge it, and the back of the beak to avoid having to add another servo. It is unknown how effective it may be, and I'll have to adjust the claw on the servo to see how far back I should push it to get the tail to right the robot.

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Overall, it looks pretty good, much better than my first attempt which I plan on rebuilding once this project is finished. I can't know for sure how well it will work, but I just hope it ends up looking good and functioning.


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