Featherweight first build

Welcome to my build log

After 20 years of saying I’m going to build my own robot, I’ve finally got round to doing something about it. Thanks for the nudge Mr Manuva27 and Diddlydodger


To start with, I’m just going to build a simple pushbot and try to get it to move before developing it any further.


After reading through some of the other build logs, I have managed to get transmitter, receiver, drills, wheels, Escs and have found some wood in the garage for the frame, so now it’s just a case of finding the time to get on with it.


Once I’ve managed to get that working then I’ll look to upgrade the armour to hdpe and think about adding a weapon.


First task was to strip the drills down however I managed to break my screwdriver trying to undo the reverse threaded screw (off to a good start!) I have ordered a new one so whilst I wait for that to arrive I’m hoping to get the nuts inserted into the nylon wheels with the help of a blowtorch and pillar drill. Then it will be on to learning how to solder up the connections and figure out the wiring.


Most importantly I still need to come up with a name for my robot!

Hey there, welcome to the forum!

Sounds like a good start, just getting your robot to survive a 3 minute bout is an achievement in of itself (which I confess not a lot my robots are able to do but we don't talk about that.. :P).

Yes to the HDPE definitely but wood does still work if used right. The Honey Badger, even to this day, uses wood as part of the main chassis and has held up OK though the BW variant definitely does better. Get the basics right first and then add a weapon methinks.

Soldering is one of those things that I personally have a love/hate relationship with. When it works, it works but I've been known to spend an hour soldering one XT90 plug into a wire because it just won't take so I wish you with that. ;) Connections are quite easy, I am sure I made a diagram a while ago showing how that looks.

And here is the diagram, both in theory and a working "in build" one using 10AWG wiring and XT90 connectors (I was building it for a MW but the principle for a FW one is the same).

Attachment 9524 Attachment 9525

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Thanks for the nudge Mr Manuva27 and Diddlydodger

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It took more effort than that! Better late than never! :lol:

Welcome to the forum. If I remember correctly, you have the old Argos 12v drills. Which ESCs do you have?

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Originally Posted by Ocracoke

Hey there, welcome to the forum!

Sounds like a good start, just getting your robot to survive a 3 minute bout is an achievement in of itself (which I confess not a lot my robots are able to do but we don't talk about that.. :P).

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Thank you. I’m assuming survival is more down to reliability of the robot more than anything else. Just wondering what the most common causes of failure are?

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Originally Posted by Ocracoke

Yes to the HDPE definitely but wood does still work if used right. The Honey Badger, even to this day, uses wood as part of the main chassis and has held up OK though the BW variant definitely does better. Get the basics right first and then add a weapon methinks.

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Good to know that wood is usable to start with at least. I’ll make sure to check out The Honey Badger build diary

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Originally Posted by Ocracoke

Soldering is one of those things that I personally have a love/hate relationship with. When it works, it works but I've been known to spend an hour soldering one XT90 plug into a wire because it just won't take so I wish you with that. ;) Connections are quite easy, I am sure I made a diagram a while ago showing how that looks.

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Yes I'm not looking forward to soldering the plugs but hopefully will get a bit of practice in first with the connections. Plenty of YouTube videos to watch first. Many thanks for the wiring diagram too :)

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Originally Posted by Mr Manuva27

If I remember correctly, you have the old Argos 12v drills. Which ESCs do you have?

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Cheers Andy. Yes I have the old Argos drills with 2 x Botbitz 30a ESCs

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Just wondering what the most common causes of failure are? [...] I’ll make sure to check out The Honey Badger build diary

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The original build diary: http://www.fightingrobots.co.uk/thre...e-honey-badger (2017 - 2019) and the current one mixed in with all the other robots I've done: https://www.fightingrobots.co.uk/thr...en-build-diary (2019 - )

In no particular order, based on my experience, here is the incomplete list of failures I've had in my robots:

• Wheels falling off (The Honey Badger)
• Motors burning out due to insane overvolting or overdrawing (Kaizen)
• Batteries puffing up because they were overdrawn and exhausted (The Honey Badger)
• Wiring popping free from a terminal block (The Honey Badger, Jibril, Kaizen, Azriel)
• Ground clearance issues due to design (The Honey Badger, Jibril)
• RC Receiver failure (Jibril - that was a short leading to a oh so minor fire, Kaizen)
• RC Transmitter failure (Jibril - I dropped the transmitter whilst loading the robot up into the loading pen)
• Gear pinion screws slipping off (Jibril - That was right before a championship quarter final)
• Bad solders (The Honey Badger, Jibril, Kaizen)
• Speed controller burnout (The Honey Badger, Jibril, Ikari)
• Removable link failure (The Honey Badger, Osu, Shu!, Jibril)
• Insufficient sized bolts leading to mass breakages on the first ram (Kaizen - that was mighty spectacular)
• Stripping gearboxes (Shu!)

Quite a list. :P In short, check everything twice, make sure you have spares and/or able to fix the existing damage and build it like a tank.

Welcome to the forum Ian, good luck with your first build!

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Originally Posted by Ocracoke

Sounds like a good start, just getting your robot to survive a 3 minute bout is an achievement in of itself.

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I'd second that... actually I think just getting to the start of a fight is a good effort, certainly I don't think I've ever felt more elated than when our first robot went into the arena and sort-of successfully moved...

Thanks Sam. Yes just getting a moving robot for now would be great :mrgreen:

Progress update - drills have now been stripped down and are sitting nicely in their motor mounts (thanks Nat for those). Inserts have been put into the nylon wheels and bike tyre is in its way for adding grip. I’m using a Devo 7 transmitter so have managed to link that up to the receiver successfully. Got a few things on order this week and then it’s on to soldering :uhoh: Had a play about connecting up some old bits of wire and that didn’t go too badly so hoping to make some progress next weekend

Managed to get the wiring done and it actually moves! :D As you can see from the picture, much time and expense was spent on mounting to the base sheet!
Attachment 9585
Still a bit of finishing off with the soldering and then it’s on to the weapon. To keep it simple I’m going for a linear actuator powered lifter. Got a few bits on order but was wondering if it’s better to have the weapon on a separate circuit or to have it all powered by one battery?

I assume you are using a 3S battery with the Argos drills? Most Linacs are 12v, so you should be fine to run them on the same battery providing you have a big enough mAh battery capacity.


Edit: You are clearly using the drill battery. I assume you are planning on moving over to LiPos, from conversations we have had in the past?

Cheers Andy. Yes still using the drill batteries for now and looking at a 12v Linac so 3S would work for everything when I get round to upgrading to Lipos. Any ideas on battery capacity required to run everything?

Currently the wiring coming from the fuse spilts to go off to the Escs and light at the same point (with linac wire to be added in) is there an easy way of soldering all these together? Currently this point is held together with electrical tape

Hi Ian, Looking like a good test bed.
Batteries, some people use 2.2amp as a good start with a good high C rating 30 minimum.

I run my 2wd Argos drill bot (with electric axe) from 4s 2.65 turnigy nano-tech 35-70C and it lasts a fight but drops about 70% power. It has since become a bit puffy, so perhaps i over ran that one.Otherwise i use 3.3amp lipo. I have also used a 5s 2.2 amp zippy 40C battery, whjich lasted a 3 minute fight plus half another fight - ran out of time to swap. just depends on how you use it or your driving style.

There is a full calculator online somewhere, but dont know where - perhaps on askaaron?

for joints on big cables, one method - although not the best due to its high resistance, is to use eye crimp terminals and blot them together.
Another way is to use a junction box such as Wago connectors or chocolate blocks- although not designed for battle knocks and bumps as these can come loose. The best method is to use Y connectors using xt60 see here - or for space saving/weight, use a large watt soldering iron, strip the wire ends, hold together and wrap them with some copper wire. The copper wire helps get heat around the wires and solder them together, then add heatshrink over the join.

links as examples available. other stores/prices are about, i just chose a random link :)

https://wheelspinmodels.co.uk/i/2631...CABEgJJm_D_BwE

https://www.youtube.com/watch?v=4vLqajvCgdI

https://www.youtube.com/watch?v=7t9nT3Hn9b0

Looking good so far, reminds me of my first attempt at building a Beetleweight. That was held together with tape as well! :P

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Got a few bits on order but was wondering if it’s better to have the weapon on a separate circuit or to have it all powered by one battery?

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As alluded to, provided you have sufficient capacity, you can run it off of one battery unit but it is worth considering, in my opinion anyway, how resilient that will be. Kaizen used to use separate circuits for its weapon and drive but that was largely down to it having the weight to run it. Jibril doesn't and so uses a common circuit.

Thanks all for the helpful comments everyone, they are really appreciated. I’ve got the linac all wired up and successfully working now :) its currently running off two drill batteries but will upgrade to lipos in the future. I found the askaaron site really helpful thanks Nat.

I’m still playing around with the design, so may change the front scoop to more of a wedge shape but here how it looks at the moment ...

Attachment 9624

Looks good, well done so far. How much does it lift?

Thanks. A very crude test with the current drill battery was able to lift around 12kgs (very slowly). Also it couldn’t self right so I need to redesign the shape and positioning of the linac to sort that out