Bolts - Featherweight Flail Bot

[callumhoy]

Extreme Robots is in Colchester in September, close enough to me (within 100 miles), that I can justify making it the teams first event.
So because PC Plod won't be ready for heavyweight competition, The Scrappers are making an invertable wooden wedge, driven by Argos drills to enter into the featherweight division. The goal being to keep it as cheap as possible, whilst still being effective.
Due to a lack of experience and time, we've decided to go with two chain flails attached to the back of the bot as our main weapon. We're also considering adding some spikes facing up the wedge, allowing us to hold others on top of the robot (should they drive up it) and drive them around.

Some questions before the build officially begins:
1) What is an average size guide for featherweight bots?
2) Which type of sheet metal and what thickness would you recommend we cover the wood with for armour?
3) Are the spikes on the wedge worth it? Would they help control other bots, or just get in the way when running upside down?

[daveimi]

I've just built a flail bot and the idea was a bit not great. It kept beaching itself on the chains. I'm not sure if more ground clearance would help though. Ended up taking a random metal box lol. Most feathers are about 50cm x 50cm give or take.

[callumhoy]

Looks like I'll have to do a lot of testing to find a way around the beaching issue if it arises. Hopefully it won't be much of an issue, the wheels I'm using should be big enough to keep it moving, even with something underneath it.
Considering the lack of an active weapon, hopefully I'll be able to go a bit bigger, maybe 50cm x 70cm total.

Thanks for the info and the warning.

[daveimi]

Yeah no worries.

It's something I wanted to stick with but it kept beaching itself. I watched Nuts on youtube and it has a ton of ground clearance, so when the chains go all over the place it just sort of rides over them and keeps going. I think if you had like 150mm wheels and a 60mm body etc. It'd be fine. As it was I had a 90mm body and 120mm wheels lol.

[callumhoy]

Drive circuit for Bolts has been roughly put together and tested. Now to build the chassis around it.
Circuit.jpg

[daveimi]

omg you even use the same electrics and motors as me thats so weird! be careful that you have a failsafing receiver, i got stung with that..

[callumhoy]

Well, this must be some pretty good beginner equipment if we're both using it. Thanks for the warning.

[callumhoy]

So, we're having a little trouble with how to attach the wheels.
We're using the new Argos drill motors and some cheap wheels from Homebase.

The motors have a M5 reverse thread internal and a M10 external thread (we think).
Motor.jpg
The wheels have a 13mm bore, not threaded.
Wheel.jpg
Any recommendations on how to attach the wheel to the motor?
If anyone has any links to correct size bolts or other parts to help, they will be really appreciated.

[R9000]

Unfortunately, drill gearboxes have a 3/8 UNF external thread. I don't know why they went with a weird imperial measurement, but they did. Your best bet is to find some 3/8 UNF nuts on eBay and melt them into your wheels. Go look up Ellis of Ranglebox's YouTube channel, there's a very good video there detailing how to do it.

[callumhoy]

Thanks for the quick help, off to eBay I go.

[callumhoy]

Parts ordered and on their way. Here's a preview of what it should look like once the wheels are attached.
First Look.jpg
Once the parts arrive, we'll heat press the nuts into the wheels, attach then to the motors and fix them in place with lock nuts.
Then we'll be able to give Bolts a first test drive before we start shaping the top to make the wedge.

[callumhoy]

So, because we're getting closer to having Bolts in driving condition, we'll very soon be in the place where the wedge is in place and it's technically "battle ready" (in the sense that it could enter an arena and last 3 seconds), I'm looking at what to add to the outside of the wood as an extra layer of armour.
In another build diary, I remember reading something about 10mm HDPE being pretty good against most axe/hammer bots. Would this be enough, or would we be better spending the extra cash and weight on metal armour? If so, which metals and how thick do you recommend?

[maddox10]

10mm HDPE will hold out most hammers and axes in the featherweight class. For heavies, 30mm ain't enough.

If you go metal armor in the featherclass. The least I can advice is 3.2mm hardox 450, and if you can afford it (weight or money), thicker. If money is a problem, you can try thicker in normal steel.
If weight is an issue, I can advice HDPE, or else , with enough funds, titanium.

[R9000]

So what thickness of HDPE is enough for heavies, if 30mm isn't?

[callumhoy]

Thanks for the info.
Chances are we'll go with HDPE this time for money reasons. Hopefully, if this design performs well, it'll be worth the investment into Hardox for the next version.