Build Log | Caractacus - Any Tips?

Hello everyone!

Ive taken the plunge and decided that im going to start work on my Featherweight robot "Caractacus", named after Caractacus Potts from Chitty Chitty Bang Bang because of the mad inventor scenario xD

http://i.imgur.com/I11vjgX.jpg

I have bought a Spektrum DX6i transmitter after asking a few questions down at Robot Wars Live Gloucester as well as some research online.

I was just wondering if you guys could give me a few tips based on your experience?

A few main questions I have is:
- Would you recommend a Spektrum receiver and if so/not which would you recommend?
- Im looking at a steam punk look but would iron/steel be too heavy as armor?
- Im looking at using the BotBitz 85AMP Electronic Speed Control (v2) as I looking at cordless drill motors. Thoughts?
- Is CAD design worth doing? and if so, what software would you recommend?
- Any other general tips?

Any information at this stage is very much appreciated! I eagerly await your responses!

Thanks a lot

Will :-)

Edit: Forgot to ask something ¬_¬ lol. I have been looking into batteries and chargers and I hear Turnigy are good. Any recommendations for both? Thanks xD


Build Log Videos! :)

http://i.imgur.com/BolTxP6.jpg

Hahah! Well that's an interesting name, it's been a long time since I watched Chitty Chitty Bang Bang. Let's get to these questions:

-Spektrum receivers seem fine, I have an AR610 to go with my DX6i and it seems perfectly adequate. There was a discussion not long ago, have a look: http://www.fightingrobots.co.uk/thre...obotwars-arena

-You don't want pure iron, I think barely anything's made out of iron these days, too heavy and brittle. Hardox (a form of steel used as a wearplate) is commonly used in most robots. It's heavier than plastics or Aluminium, but very very hard. You'll want to keep weight in mind when deciding how much you want on your robot and at what thickness, but quite a few people use Hardox on their featherweights, like Omega, but keep in mind that's a rambot with no weight taken up by a weapon mechanism. Actually, check out Team PP3D's 'Getting Started' guide for a really good rundown of different armour and chassis materials: http://pp3d.weebly.com/getting-started

-Yes Ranglebox's 85A ESCs will do fine for a featherweight, as will drill motors. Just be prepared to find a wheel that'll fit on the 3/8 UNF thread.

-If you can use CAD programs, go for it! I find it helps get a much better visualisation of your robot before you go buying up all the parts you need, or ordering waterjet-cut steel. I used Sketchup, but if you're experienced with more advanced CAD programs like Solidworks or Autodesk, they'll probably help you estimate weight as well, among other things.

-As for general tips, I'd say just make sure you plan stuff out before you buy. The less money you waste on unneeded or incompatible parts, the better. Also personally, I'd advise doing your wiring last. I wired my electronics up before I finished the chassis, and all the moving about has played hell with my soldering. Though I did use quite stiff wire, so that has undoubtedly contributed. I'll be doing a rewire once I'm finished with nice flexible AWG silicone-coated wire. Others will have plenty more tips for you, they'll probably know more than I. :P

Best of luck!

Thanks a lot for the reply! Some awesome feedback :-) Also glad you like the name ha ha!

Out of interest, what is your robot? I'm always interested in seeing other peoples projects!

Thanks again! :-)

I want to see how the commentator copes in a three way meleé with Caractacus, Carcinus and Cerastes :proud:

YES! That will be amazing xD

Here's my build diary thread since you asked, I haven't updated in a while but I've been quietly working on it these last few months - it's getting near to completion. :)

http://www.fightingrobots.co.uk/thre...d-lifter-aegis

Quote:

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Originally Posted by R9000

Here's my build diary thread since you asked, I haven't updated in a while but I've been quietly working on it these last few months - it's getting near to completion. :)

http://www.fightingrobots.co.uk/thre...d-lifter-aegis

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Mate, that looks sweet! :-) Cant wait to see it in action!

I forgot to ask before -_- but what would you recommend battery and charger wise? I have been looking at the Turnigy LiPo battery's. Any thoughts?

Thanks xD

Team RCC has a few Turnigy's in use. If the mAh and C rating is chosen well, no problem.

Wireless Madness have a bunch of batteries that I haven't seen anywhere else. Not heard of the brands, but they were good for my rc gear the batteries have the connectors for balance chargers too which I didn't spot on the cheaper ones.

I was going to string 2 x 7.4v (for a 15V motor) together, but they have some 14.8 V ones that look tasty. What do people think of this one?

https://www.wirelessmadness.com/peak...ector-pek00554

Quote:

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Originally Posted by maddox10

Team RCC has a few Turnigy's in use. If the mAh and C rating is chosen well, no problem.

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Thanks a lot :-)

Quote:

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Originally Posted by lowndsy

Wireless Madness have a bunch of batteries that I haven't seen anywhere else. Not heard of the brands, but they were good for my rc gear the batteries have the connectors for balance chargers too which I didn't spot on the cheaper ones.

I was going to string 2 x 7.4v (for a 15V motor) together, but they have some 14.8 V ones that look tasty. What do people think of this one?

https://www.wirelessmadness.com/peak...ector-pek00554

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Thanks xD

Just as a side note so im not doing anything dense lol but if you run 18v drill motors then the machine runs at 18v right? As apposed to doubling it to 36v (2 x 18v drills). I think I know the answer but just making sure ha ha!

Thanks again for all your help :-)

Did a bit of concept art while I am waiting for parts to arrive xD

Its not to scale or anything xD but let me know what you think and any suggestions :-)

http://i.imgur.com/VHl2Vxjl.jpg

Thanks again xD

Yep, 18v

Hey guys,

Did a video of the first step of the build!

I intend to go on to speed controllers next.

https://youtu.be/aT_fAvAjVGw

Let me know what you think!

Just a quick question, do you think the BotBitz 30a Brushed ESCs would be good enough for a featherweight robot like this or do you think bite the bullet and go for the BotBitz 85a Brushed ESCs?

Thanks a lot :)

Will :)

The 30 amp ESC's will do the job for a 2WD machine with batterydrills.
But once you go for more power,like using Ranglebox Saturns, or the old style Groupner Speed 900 it will get iffy.

The Tz85's have proven to be rock solid, so I would suggest to bite the bullet.

It's also easier to find replacements during life events, as a lot of UK feathers use the 85's.

Hello again everyone,

Quote:

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Originally Posted by maddox10

The 30 amp ESC's will do the job for a 2WD machine with batterydrills.
But once you go for more power,like using Ranglebox Saturns, or the old style Groupner Speed 900 it will get iffy.

The Tz85's have proven to be rock solid, so I would suggest to bite the bullet.

It's also easier to find replacements during life events, as a lot of UK feathers use the 85's.

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Thanks a lot for your reply! Sorry I have only just replied, I forgot at the time like a pleb ¬_¬


Its been a little while because of christmas and stuff but I would just like to ask some advice on the Turnigy ESC's.

I saw this post about reprogramming the Turnigy 85a ESC's to work with the Spektrum DS6i. Being as It is taking a little while to get the BotBitz 85a ones I was wondering if this is a worth while thing to do to save time and money or is it better in the long run to wait and get the BotBitz purpose made ones? Also if so could these be reprogrammed again to work with brushless again if the need arises?

I'm eager to get started thats all but just wondering if its worth being patient and getting them off of Ranglebox.com or should I go for the reprograming option with the Turnigy ones?

Hope that all makes sense xD

Thanks a lot for your help in advance.

Will :)

Absolutely. I bought the TZ85s straight from Hobby king along with an Atmega programming tool, which means you don't have to solder the programming wires on. Just make sure you leave all three output wires on when you convert to brushed, and you should be able to revert back to brushless just fine, so long as you have a hex file for it.

Quote:

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Originally Posted by R9000

Absolutely. I bought the TZ85s straight from Hobby king along with an Atmega programming tool, which means you don't have to solder the programming wires on. Just make sure you leave all three output wires on when you convert to brushed, and you should be able to revert back to brushless just fine, so long as you have a hex file for it.

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Oh, awesome thank you xD I didnt even know something like this existed!

Just to make sure its this speed controller and this programmer isnt it?

Also what usb AVR flashing tool would you recommend?

Thanks again

Will :)

That's the one. Make sure you get a suitable LiPo and connectors.

Quote:

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Originally Posted by R9000

That's the one. Make sure you get a suitable LiPo and connectors.

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Thanks mate, I will do :)

An interesting thought occurred to me while looking up clutches for my old nitro car. Would a nitro engine be:

A) allowed in robot wars
B) powerful enough

My reasoning is that unless you have a 2 stroke engine you are liable to stall if flipped upside down. Would a little nitro engine with its extra power from the fuel type be a worthwhile thing? Sounds like a cool idea thats all even if its not a good idea ha ha

Whats your thoughts?

Thanks again

Will :)

I would add two small spikes or protrusions on each side so that you can ram opponents while the axe won't be obstructed by them driving right up to it. I mean spikes as in the spikes on tornado's scoop, something that size.

Hello everyone,

Been a little while since the last update because money hasn't been kind to me lately! But I have managed to lock the motor gearboxes off so they are turning as one now. Once I have the money I will be picking up a pair of botbitz 85a brushed esc's from ranglebox. In the mean time I am going to have a go at some cad designs and maybe a cardboard or wood prototype so I can gage the size's of things. Let me know if you have any suggestions!

Here is the video I made for it: https://youtu.be/-oQ7Z5hIcBI

Thanks xD

Hey everyone!

I finally managed to get my speed controllers so I have started to sketch all of the parts I am going to use in Google SketchUp. I don't know how many of you guys will find it useful but as I'm making them I'm uploading them to the 3D Warehouse. I have made a collection and will be adding to it over the next few weeks I hope!

Here is the link to the collection: https://goo.gl/n62Z8m

And here is my first every model: https://goo.gl/NyhMD9

Attachment 6691

Thanks guys as always!

Will :)

Im on a roll now xD I have managed to attach the wheels to the motors, draw up some sketches in Google SketchUp for what i want it to look like, hack a PC power supply to power the Turnigy Accucell 6 LiPo charger i have got and mounted the motors to a chopping board for a test bench! Just one more video to go and it will be up and running as far as the electronics xD

Here are the videos :)

https://youtu.be/ARI8lT62TXE

https://youtu.be/CVemeKzKmGw

https://youtu.be/FQTJtObznQM

https://youtu.be/p0ur9bYeL0g

I like the build progress videos, wish more people did those. Keep going!

Quote:

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Originally Posted by Giles

I like the build progress videos, wish more people did those. Keep going!

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Thank you! Means a lot that you enjoy them :)

Hello everyone!

Again apologies for the massive gap in posts! I ran out of money again lol I have a new job now so im getting back into building and 3D Printing parts xD Here is the latest few video updates! It actually works now and i have created some 3D Printed parts to mount different parts of the robot. I plan to make these out of Polymaker PC Max when i get a enclosure built :)

https://youtu.be/ezHUsyQd9_w

https://youtu.be/fst5TBajKHk

https://youtu.be/LVHLuZKOexk

Let me know what you guys think! :)

If anyone has any tips on building the chassis and armour out of HDPE and the best sources then please let me know!

Also if ya'll can poke Sam from Team Hatchet and direct him to this thread that would be much appreciated lol I need all the help i can get with the axe mechanism! :)

As always thanks for all your help! I hope i can be ready for one of the live events soon! :)

Hey Will

Best source that I found, and a bunch of other people have lead me to, is directplastics, which does a bunch of HDPE in various thicknesses and sizes, depending on how big you want the sheet to be.

As for the axe mechanism, I wish I could help but I'm doing my own trial and error testing with my own axe mechanism, haha.

Best of luck to you!

Quote:

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Originally Posted by Outlaw

Hey Will

Best source that I found, and a bunch of other people have lead me to, is directplastics, which does a bunch of HDPE in various thicknesses and sizes, depending on how big you want the sheet to be.

As for the axe mechanism, I wish I could help but I'm doing my own trial and error testing with my own axe mechanism, haha.

Best of luck to you!

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Thank you very much for the reply! :) I hope your axe testing goes well! :)

for the axe mech i suggest going for the simple scooter motor chain reduction as it works will

Quote:

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Originally Posted by Maxamuslead

for the axe mech i suggest going for the simple scooter motor chain reduction as it works will

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Thank you very much! :) Would you be able to elaborate a bit because this is a very new thing for me! :)

So it is a scooter motor with a cog that drives a chain connected to another cog connected on a shaft to the axe arm (I am sure Hatchet uses something like this, as does BattleAxe and Blacksmith I seem to recall). Fairly simple and quite effective - I'd go and check their respective build diaries to see the mechanism in action.

Quote:

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Originally Posted by Ocracoke

So it is a scooter motor with a cog that drives a chain connected to another cog connected on a shaft to the axe arm (I am sure Hatchet uses something like this, as does BattleAxe and Blacksmith I seem to recall). Fairly simple and quite effective - I'd go and check their respective build diaries to see the mechanism in action.

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Awesome, Thank you very much! :) I shall go and have a look now :)

I made an axe mechanism for my robot Onyx a good few years ago. Started off with a drill motor powering it before switching to a scooter motor as the drill motor gearbox was too fragile. Here's a look at the transmission with the drill motor fitted:

Attachment 7932

It's a 5:1 ratio using 8mm 05B chain from Technobots. Think it's a 40T sprocket on the axe and a 8T one on the motor. Just drilled two holes in the axe arm and large sprockect to bolt them together, then drilled a central hole for the shaft, which was 12mm silver steel. It's a live shaft so I used grub screws tapped into the boss of the large sprocket to pin it to the shaft, and then there were 12mm needle roller bearings in either bulkhead (second bulkhead removed for visibility). Made for a very smooth mechanism.

I then switched to the scooter motor:

Attachment 7933 Attachment 7934

It was a bit ungainly sticking out the back but it was a huge improvement. That just bolted to the baseplate with M6 bolts and again used an 8T sprocket. The only difference was that I welded the sprocket onto the shaft and got rid of the idler sprocket from the first picture as I managed to improve the chain tension. The axe arm was a section of hollow steel bar so I ran a steel cable from the axe head down to the shaft, round and back up to act as the tether, as specified by the rules.

And the mechanism in action:
https://www.youtube.com/watch?v=60-9-927nPw

Quote:

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Originally Posted by RogueTwoRobots

I made an axe mechanism for my robot Onyx a good few years ago.

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Two things, 1: That video is absolutely brilliant! Made me lol! xD and 2: Thank you so much! That is really helpful :)

I'm actually just in the middle of printing out the templates for cutting the main part of the robot out of wood so i can test sizes etc so this is perfect timing :)

Will keep you posted how i get on!

Thanks again :)

EDIT: Forgot to ask a couple of things lol. Firstly, when you say the boss of the large sprocket, where do you mean exactly? Not really sure what boss means lol. Secondly, is the tether there in case the fixings fail so it doesn't fly off mid swing?

Thanks again :)

Sorry, just saw your edit.

The boss is the protruding cylindrical part that comes on a lot of sprockets. It's a good wall thickness on the 40T sprocket which made drilling and tapping for grub screws nice and straightforward

Attachment 7944

The tether is in the rules so that if the axe head becomes separated from the arm, it doesn't go flying off, potentially breaching the net roofing of some live arenas and into the crowd. At least, I think that's the main reason. It's more for axe heads that are bolted onto arms where the chances of the bolts shearing is reasonable, but on Onyx the axe head is welded on, so it's a bit redundant, but dems the rules :)

Quote:

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Originally Posted by RogueTwoRobots

I think that's the main reason. It's more for axe heads that are bolted onto arms where the chances of the bolts shearing is reasonable, but on Onyx the axe head is welded on, so it's a bit redundant, but dems the rules :)

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Sorry for hijack but is this required for any axe head evan if the shaft and head are one of the same E.g. Hatchet's ?

It is strictly in the FRA rules but I think that EOs bend them on this one, especially in the age of spinners. A chunk hit off in spinner blow is in my opinion likely to do more damage than an axe head falling off or being thrown.

Battleaxe had a chain tether at Insomnia last year and this was accepted in tech check though it broke in the 722 battle when the head came off anyway :/ It's now on a steel cable tether. Broadax on the other hand is one-piece Hardox so I don't believe it will be required depending on the EOs discretion. Though if in any doubt about the robustness and safety I would add a tether. You are right as far as I know the last Hatchet revision wth the one-piece also did not carry a tether.

It might be the case of still being needed for arenas without a roof I guess.

Hello again everyone :)

Sorry for the really long update on this build. I have had a carpel tunnel operation which has left me unable to do a lot on the robot :( but it is getting better!

I just have a question about the ESC for the axe. If I'm using something like a 300w scooter motor, the first question is probably obvious lol but what ESC would you recommend based on the motor is probably going to do a fair amount of stalling in a battle?

Second, would it be a case of wiring it up the same as the drive motors or is this liable to snap the chain if you go to mad with it? Is a set up similar to a servo what you need? and if so, what would you need to do to add that functionality?

I hope that all makes sense!

Once again a big thank you to you all for taking the time to help me out! I have never known such a wonderful community :)

All the best :)

Will :D

Glad your recovering :)

My axe is run from a 150w? scooter motor through a 2 stage chain gearbox giving 5:1 ratio, so not powerful, however it was rnning from a 30 amp electronize esc - as i didnt have a spare TZ85a esc.

It was stalling allot during my time at ER 3 fights, and didnt suffer, nor did the ESC get warm.
thats my insight into it if its any help.