Kosmos Build Diary

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Rocketeer13
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Kosmos Build Diary

Post by Rocketeer13 » Mon Sep 18, 2017 12:22 pm

I thought I should start one of these, despite having already begun the robot's chassis. It's my first ever build, so please feel free to comment and critique as much as you like! My plan is to have the robot ready for the next AWS, whenever that is organised, but it will certainly be done by the end of the year. I'll post some photos this evening!

Kosmos is a front-hinged flipper, as after watching footage from several AWS events, I decided that this would be a very effective way of making good use of the low walls and open areas in the arena. The shell is 2mm Polycarbonate, and will have 1.5mm polycarb as internal supports. The drive motors are speed modified servos, and the Tx and Rx are the HobbyKing T6A. I'm still in the process of choosing the weapon servo, but I'll link the most likely option, a 2.5kg Goteck Metal Gear Servo, below, while I'm planning to try 3 AAA batteries as a power source, but will change to lipos if necessary. The name and colour scheme came from an early Russian space rocket, an idea that I think was partially inspired by bots such as Apollo, or the antweight Vostok. The aim has been to keep it relatively low budget, and I'm very pleased with the results so far!
Kosmos CAD.jpg
Kosmos CAD.jpg (41.9 KiB) Viewed 2244 times
NB: The computer I'm currently on doesn't have CAD software. The current version of the chassis has a small 45° angle at the rear, like many similarly styled flippers, to allow it to roll back onto it's wheels.
More pictures of the build so far will follow this evening. :)

http://www.robotshop.com/uk/25kg-goteck ... servo.html
Crossblow [BW] - Bugglebots Entry - Four Bar Lifter (Under Construction)
Knighthood [AW] - Lifter/Rambot (Under Construction)
Kosmos [AW] - Front Hinged Flipper (Retired)

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ShootyMcExplosion
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Re: Kosmos Build Diary

Post by ShootyMcExplosion » Tue Sep 19, 2017 7:44 am

Nice to see more front hinged flippers! Just be careful when designing the flipper that you leave enough room for the servo to fit and to allow the machine to self right, for my ant it was a very small window indeed!

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Rocketeer13
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Re: Kosmos Build Diary

Post by Rocketeer13 » Tue Sep 19, 2017 11:39 am

ShootyMcExplosion wrote:Nice to see more front hinged flippers! Just be careful when designing the flipper that you leave enough room for the servo to fit and to allow the machine to self right, for my ant it was a very small window indeed!
I was very impressed with Sioc! It was nice to see someone else with a similar idea! Yeah, self-righting is definitely an important feature, and slightly more difficult with front-hinged designs! (hence the fins on top, to keep the flipper flat to the floor when it's overturned, which should hopefully make s/r easier - that's the plan, anyway! :P )

There's a bit of a delay with the photos, as I've had to order a slightly bigger battery holder: once that's sorted, I'll post them on here!
Crossblow [BW] - Bugglebots Entry - Four Bar Lifter (Under Construction)
Knighthood [AW] - Lifter/Rambot (Under Construction)
Kosmos [AW] - Front Hinged Flipper (Retired)

Team Page:
https://www.facebook.com/MotteAndBaileyRobotics/

AntRoboteer
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Re: Kosmos Build Diary

Post by AntRoboteer » Tue Sep 19, 2017 4:13 pm

I've tried going with AAA batteries before and trust me, you will want to go with a lighter battery for sure. :D The AAAs are really heavy and restrict the design so much due to their size and weight. Also, with 3 AAAs, you will only be at 4.5V with alkaline cells or 3.6V with NiMH cells which is way lower than the specification for the servo.

I've used these batteries for quite a while: http://www.componentshop.co.uk/6v-1-4aa ... -pack.html

They are 6V, 120mAh batteries which are small, quite inexpensive and have a resonable current specification. That should do the trick nicely.

Really nice design, looking forward to seeing another front hinge flipper as they've become much rarer recently. Best of luck with the build!

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peterwaller
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Re: Kosmos Build Diary

Post by peterwaller » Tue Sep 19, 2017 7:13 pm

They do quite a range of cell sizes and you can get them with the JST red connector see them on ebay.
http://www.ebay.co.uk/itm/4-8v-6v-120-4 ... yXTZtwbf9Q

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Rocketeer13
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Re: Kosmos Build Diary

Post by Rocketeer13 » Wed Sep 20, 2017 10:41 am

peterwaller wrote:They do quite a range of cell sizes and you can get them with the JST red connector see them on ebay.
http://www.ebay.co.uk/itm/4-8v-6v-120-4 ... yXTZtwbf9Q
AntRoboteer wrote:I've tried going with AAA batteries before and trust me, you will want to go with a lighter battery for sure. :D The AAAs are really heavy and restrict the design so much due to their size and weight. Also, with 3 AAAs, you will only be at 4.5V with alkaline cells or 3.6V with NiMH cells which is way lower than the specification for the servo.

I've used these batteries for quite a while: http://www.componentshop.co.uk/6v-1-4aa ... -pack.html

They are 6V, 120mAh batteries which are small, quite inexpensive and have a resonable current specification. That should do the trick nicely.

Really nice design, looking forward to seeing another front hinge flipper as they've become much rarer recently. Best of luck with the build!
Thanks for that! Battery weight is definitely a concern I had with the alkaline option, but I was going to finish cutting my body panels, to get a better idea of the overall weight first, and whether or not I could use them. However my receiver arrived at the start of the week, and requires 4x AAA batteries - 6v - minimum to run. Luckily, a larger battery holder is very cheap and should arrive tomorrow, but that will almost certainly have a significant affect on the weight! I'll probably just use it to get the robot up and running for now, then look at those battery packs. I'm guessing 120mAh is all the capacity I'll need? Any idea how long that will last without a recharge?

But thanks for the encouragement! Once I get the new battery holder, I'll post a proper build update for everyone to see, as at least I'll have got the servos running by that point! (fingers crossed!)
Crossblow [BW] - Bugglebots Entry - Four Bar Lifter (Under Construction)
Knighthood [AW] - Lifter/Rambot (Under Construction)
Kosmos [AW] - Front Hinged Flipper (Retired)

Team Page:
https://www.facebook.com/MotteAndBaileyRobotics/

AntRoboteer
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Re: Kosmos Build Diary

Post by AntRoboteer » Wed Sep 20, 2017 2:04 pm

Absolutely, that's great. The AAAs will be more than enough to get you started and then you can easily switch over when you like.

I've found that the 120mAh batteries tend to be good for 5-6 full length fights but with speed hacked servos and weapon probably closer to 3 fights. Of course you can just leave the battery topping up in the pit area during fights so it's no big concern. At AWS 52 one of my machines lasted all through the day (making it to the group final) only on a single 4 cell 120mAh green bar battery. You won't have any problems at all. :D

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Rocketeer13
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Re: Kosmos Build Diary

Post by Rocketeer13 » Thu Sep 21, 2017 5:54 pm

Hi everyone. Here's what I've managed to do so far. Let me know what you think!
IMG_20170921_183149947.jpg
IMG_20170921_183149947.jpg (224.65 KiB) Viewed 2106 times
IMG_20170921_182824754.jpg
IMG_20170921_182824754.jpg (199.5 KiB) Viewed 2106 times
IMG_20170921_182842894.jpg
IMG_20170921_182842894.jpg (196.54 KiB) Viewed 2106 times
I should get the rest of the body panels completed soon. I think they'll probably be mostly super-glued together, if the plastic will stick, with the top panel screwed on. My main issue at the moment is the reciever: I can't get it to power up! It might be that I need new batteries, but I suspect not, as the light has blinked at me while plugging it in, then it died again once it was properly connected. My soldering seems solid, so my guess is it'll either be a dodgy connector or a faulty transmitter (though again, I suspect not for the latter). Please feel free to leave your thoughts!
Crossblow [BW] - Bugglebots Entry - Four Bar Lifter (Under Construction)
Knighthood [AW] - Lifter/Rambot (Under Construction)
Kosmos [AW] - Front Hinged Flipper (Retired)

Team Page:
https://www.facebook.com/MotteAndBaileyRobotics/

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Rocketeer13
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Re: Kosmos Build Diary

Post by Rocketeer13 » Thu Sep 21, 2017 5:56 pm

IMG_20170921_183052713.jpg
IMG_20170921_183052713.jpg (178.03 KiB) Viewed 2106 times
(Forgot to add a photo!) :roll:
Crossblow [BW] - Bugglebots Entry - Four Bar Lifter (Under Construction)
Knighthood [AW] - Lifter/Rambot (Under Construction)
Kosmos [AW] - Front Hinged Flipper (Retired)

Team Page:
https://www.facebook.com/MotteAndBaileyRobotics/

Occashokka
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Re: Kosmos Build Diary

Post by Occashokka » Fri Sep 22, 2017 12:55 pm

If that's polycarb then I would advise against super glue and go for nuts and bolts
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AntRoboteer
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Re: Kosmos Build Diary

Post by AntRoboteer » Sat Sep 23, 2017 11:38 am

I'd suspect the issue is down to either batteries not making a solid connection in their casings (or being flat of course) or the crimped connections on the servo plug I can see you've used are not tight enough and are therefore not conducting electricity properly. Additionally, a strand of wire could be connecting one of the wires and a pin, causing some kind of short.

I think the plan of action should be:
1) Check connector for any loose strands of wire; if there are any, remove and retest
2) Take out all batteries, put batteries back in and retest
3) Change the batteries for fresh ones
4) Remove the crimped connections from the connector by very carefully levering up the small plastic clip on each wire with a tiny screwdriver, being very careful not to break them. Then while holding the clip up, slide the crimped connection and wire out of the connector. You may want to give the part of the crimp where it clamps over the wire a squeeze with pliers. Just make sure not to clamp down on any of the crimp where the pin from the receiver would enter. Try this for both the red and black and I'd advise removing the white wire entirely using this same process and leaving it out. Then, put wires back in and test.

Hopefully that helps and you can get something going soon; the chassis looks awesome, very nicely cut. Hot glue sticks really well on polycarbonate so that would be the way to do it in my eyes and also gives a bit of flex which is essential against spinners. Superglue apparently causes the polycarbonate to weaken.

I look forward to seeing your progress. Best of luck with the troubleshooting! :D

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Rocketeer13
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Re: Kosmos Build Diary

Post by Rocketeer13 » Mon Sep 25, 2017 10:03 pm

AntRoboteer wrote:I'd suspect the issue is down to either batteries not making a solid connection in their casings (or being flat of course) or the crimped connections on the servo plug I can see you've used are not tight enough and are therefore not conducting electricity properly. Additionally, a strand of wire could be connecting one of the wires and a pin, causing some kind of short.

Hopefully that helps and you can get something going soon; the chassis looks awesome, very nicely cut. Hot glue sticks really well on polycarbonate so that would be the way to do it in my eyes and also gives a bit of flex which is essential against spinners. Superglue apparently causes the polycarbonate to weaken.

I look forward to seeing your progress. Best of luck with the troubleshooting! :D
Thank you! That's very very helpful! However, I have since completely disassembled and reassembled the servo plug, with little improvement, though I think I've determined that it's the red positive wire that is most likely the problem. It would certainly seem to be the plug that is the issue, but short of removing then reattaching the connectors, which would be a very fiddly task, I can't quite see how to progress.
I don't really think it's worth getting a replacement cable either, for a likely temporary power source, when the alternative is actually very affordable. So I think the next step, electronics wise, will be to purchase a rechargeable battery pack. Which reminds me: how exactly do you recharge them? :lol:

Thanks for the chassis tips too. That definitely makes things easier, as I'm pretty good with hot glue! I'll have to see how strong it is though, as I was worried it wouldn't be sturdy enough? But if that works out, expect to see some significant chassis progress soon! :D
Crossblow [BW] - Bugglebots Entry - Four Bar Lifter (Under Construction)
Knighthood [AW] - Lifter/Rambot (Under Construction)
Kosmos [AW] - Front Hinged Flipper (Retired)

Team Page:
https://www.facebook.com/MotteAndBaileyRobotics/

Occashokka
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Re: Kosmos Build Diary

Post by Occashokka » Tue Sep 26, 2017 6:24 am

Bolted panels will be stronger than hot glue generally speaking but bolts are much chunkier and can get in the way of your design, if you just try and put a line of hot glue between 2 perpendicular pieces it probably won't be strong enough but u can add some tabs/brackets to your pieces to increase the area for the glue making it much stronger
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-£4.82+VAT (intact)
-cool modulated printed thingy
-not yet built nasty mean spinnt thingy

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Re: Kosmos Build Diary

Post by AntRoboteer » Wed Sep 27, 2017 7:27 am

I've always used a bit of tape to join the pieces, put some glue in the corner between them, adjust the pieces to the right angle and then leave to cool. That approach is more than strong enough and the flex helps fend off spinners as the energy of the impact is absorbed in deforming the chassis.

For the charger, we've always used these: http://www.ebay.co.uk/itm/UNIVERSAL-NI- ... 100623.m-1

And you shall need an adapter so if you get the JST version of the batteries, this would be the adapter: http://www.ebay.co.uk/itm/Tamiya-JST-BE ... SwD0lUkbTi

Else if you get the Futaba version of the batteries which I've always personally used (but you need to remove the casing on the receiver to use): http://www.ebay.co.uk/itm/Tamiya-Futaba ... Swg3FUkbJ8

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Re: Kosmos Build Diary

Post by Rocketeer13 » Sat Oct 07, 2017 9:18 pm

First, a very brief update, but no photos this time. The body is progressing fantastically well, with all the panels cut, save for the internal supports. I can really see it coming together, and that part at least will be complete in the next few days.
AntRoboteer wrote:I've always used a bit of tape to join the pieces, put some glue in the corner between them, adjust the pieces to the right angle and then leave to cool. That approach is more than strong enough and the flex helps fend off spinners as the energy of the impact is absorbed in deforming the chassis.

For the charger, we've always used these: http://www.ebay.co.uk/itm/UNIVERSAL-NI- ... 100623.m-1

And you shall need an adapter so if you get the JST version of the batteries, this would be the adapter: http://www.ebay.co.uk/itm/Tamiya-JST-BE ... SwD0lUkbTi

Else if you get the Futaba version of the batteries which I've always personally used (but you need to remove the casing on the receiver to use): http://www.ebay.co.uk/itm/Tamiya-Futaba ... Swg3FUkbJ8
However, I've given up with getting AAAs to work, and they're far too weighty now anyway. So this is really another quick question about batteries! I'm a little confused by the connectors, and which ones will fit my transmitter. Hitec/JR obviously matches the servos I'm using, but so far only futuba and JST have been mentioned here. Does it matter what I choose? What's the difference (if at all!)?

It looks like we've got less than a month to AWS 53, which seems like a good deadline, and hopefully I'll be able to make it to Southampton for the day. Thank you everyone for your help so far! :)
Crossblow [BW] - Bugglebots Entry - Four Bar Lifter (Under Construction)
Knighthood [AW] - Lifter/Rambot (Under Construction)
Kosmos [AW] - Front Hinged Flipper (Retired)

Team Page:
https://www.facebook.com/MotteAndBaileyRobotics/

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