Team Deathly - first trainer bot

OK took the advice and opened a thread to post info on my first bot

This bot is not intended to be kept or battled though it may evolve in that direction. I want to build a rolling powered chassis first. Cutting the project into chunks makes it more manageable and will give me a sense of achievement - that's the idea anyway.

So my 'bible' for this initial build is the Haynes Manual for Robot Wars - should keep me on the right track and avoid asking too many dumb questions on the forum.

Parts:
If you read my blog I bought a very cheap FlySky i6 Transmitter and matched receiver for £32 from Amazon Warehouse returned stock. I also bought a 20 pack of ultra T-Plug connectors M-F for £5.29 from there too.
I ordered the critical part a Sabertooth 2x12A R/C dual ESC from Robotshop but its in transit unfortunately
For drives I purchased 2x the Argos Simply 14.4V cordless drills at £26
I think I have a small sheet of aluminium lying around that may do for a floor or I may use wood for this test
Also I have a part roll of mains cable I can strip for red and black wire if needed.

Need to buy a soldering iron. Thinking of a Maplin own 100W seems good value

Once the ESC arrives I will get going and see how easy it comes together

Glad to see you are underway. ;)

What sort of battery are you planning to put in this? You may find that if you go for LiPos or similar, the power output from them might cook the speed controller under moderate/heavy load if you are going for the Featherweight class. Beetleweight might be more suited for that type of speed controller.

I was about to ask if you had a link for your blog, but then noticed it's on here. Of all the years I've been on this forum, I didn't realise it had a blog function!
And I've just made the connection between your team name and surname, but only after seeing the symbol next to your blog posts. And I call myself a Harry Potter fan :roll:

I really had no choice when it came to the team name. JKR has a lot to answer for. Also if she used my surname without my permission I can use the symbol.
Oh and thanks I never realised the Avatar and the Team graphic were different - updated it now.


Regarding the batteries, according to the Haynes guide I can re-purpose the drill batteries or one of them. Meaning I have a spare on charge at any moment. They don't give brands in the parts list but it was easy to determine what was used from the photos.

Early morning bargain! I was in Lidl intending to buy some bacon, eggs and OJ for breakfast and walked out with a Digital Soldering Iron. Its not powerful 48W, but has temperature control, a stand, multiple tips, sponge and a couple of tiny spools of solder for £17. They also had a drill stand with vice that looked a bargain too, cheaper than buying a bench drill if anyone is interested. Different pliers too, needle nose etc. Wife said it must be "robot wars week"

Question - When people say spinners are not allowed in many competitions, I am interested to know what exactly is classified as a spinner? Is it any rotating weapon or is the weapon mass a part of the assessment to determine if it is a spinner?
As I was wondering about a chainsaw or circular saw weapons but if they can#t be used at many events that's a bit pointless.

This is something that you'll need to ask on a case by case basis with the event organisers. The first ever event I went to with The Honey Badger 1.0, the horizontal spinning bar/flail weapon (which I really should have clarified with them beforehand) was queried. I did eventually get permission to run it at half power only, not that it made that much of a difference. :P

The reason for this is because Robots Live!'s arena has got a mesh type roof and wooden flooring which, if a spinner made a good hit, would simply not have contained. Extreme Robots also have restrictions but they do have a steel floor and polycarbonate roofing. Robochallenge have a similar setup to Extreme Robots but smaller I think.

The rules does have it's own section on spinners and what is excluded under section 11 but always, you need to ask the event organisers in advance before turning up to the event as to wherever your weaponry is allowed or not if in doubt or not.

Thanks the Arena info was helpful. Section 11 I had read and compliance to two of the three would be OK as both ideas would pass the 20% rule. Not kinetic mass type spinner, (essentially it's about big impacts) but a cutting shredding weapon. Which I realise brings many challenges but, I just like the idea. I think it could work in lower classes where more plastic and aluminium.

With luck my esc arrives today. Bit worried about size, after comments on here. But it's definitely the right model shown in the Haynes Manual. If I blow it then I am going to be in trouble, with Christmas coming up going to hard to afford replacement parts.

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Which I realise brings many challenges but, I just like the idea. I think it could work in lower classes where more plastic and aluminium.

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Note to self, add more armour :P

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Bit worried about size, after comments on here. But it's definitely the right model shown in the Haynes Manual.

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If the drill batteries being used are NiCDs or NiMH (are you aware of what type they are?), then they'll be OK for the 12A ESC (my original attempt with The Honey Badger 1.0 basically took a pair of dismantled drills, mounted them on a garden planer with sellotape and wire it all together... worked well until I drove it into a glass picture frame :S).

The concern was that if it was using Lithium batteries, the amperage coming out of them would likely cook the speed controller. I spent a age trying to find a LiFePO4 battery that would go with my Sabretooth 5A dual ESC for my Beetleweight/Antweight because the C rating of the battery x the amphours quoted often meant I was over the top of the peak that the ESC could handle.

The battery on the drill is a Lithium Ion rated 14.4v 1.3Ah 18.72Wh and weighing 284g
They're the ones from the Argos 14.4V simple Drill

My ESC will arrive today. Getting these wheels from Screwfix tomorrow. Hopefully have a powered rolling chassis no later than mid week if nothing goes wrong. <fingers crossed>

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Originally Posted by Team Deathly

The battery on the drill is a Lithium Ion rated 14.4v 1.3Ah 18.72Wh and weighing 284g
They're the ones from the Argos 14.4V simple Drill

My ESC will arrive today. Getting these wheels from Screwfix tomorrow. Hopefully have a powered rolling chassis no later than mid week if nothing goes wrong. <fingers crossed>

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I will be very interested in seeing how this combination of motor and wheels get on. Lots of picture!! It might be the way I will go with my first bot..

Life! Embryonic life but life none the less.

The ESC arrived and though either the soldering iron I bought is awful or my soldering skills are, I managed to get battery connected to ESC connected and talking to RX talking to TX. I know for many this is a simple task, and the working half an hour but for me it's an accomplishment.
Attachment 7388

Attachment 7389

Link confirmed lights on - happy days.

Pickup wheels tomorrow. Need a castor and a board as a test base. But have those in garage.

Today I got the motors wired up. The wheels look quite good, really solid things. Only issue is the bore is 13mm too big for any nuts I had lying around so I had to improvise and use some expanding cavity bolts. They don't stop them wobbling but allow me to see the spin. Wired it up all up my garage (it's freezing! can see my breath)

Attachment 7390
Attachment 7391

Test run was OK. The Sabertooth mixer is doing the job in that its combining the channels for variable turns, opposite rotation for on spot circling, brake works well too. But the motor speeds seem to differ quite a bit. Thought it may be the gearing setting but they were both set on screwdriver and speed 1. When warmer and I have more light i will try a few more settings. But would appreciate any advice. Is this normal? Is it something I can fix on the TX? One thought I had was that one is running in reverse (compared to normal) and one is running forward. Could this be a factor?

https://youtu.be/4-jMRON4yR4

I also use a Sabretooth 2x12 and I've not had this issue so far. Have you tried trimming the Tx? That can usually iron out some issues.

No not done anything yet. So it's not unusual then?
Need to get my transmitter manual out and watch some youtube videos.
I guess the transmitter could have different values or ramps on each axis too. Will have to check all these things.
Any tips on calibration? How do you ensure one rotation on one drive is matched by another. By eye may work OK at low speed but at 700rpm its going to swerving about like a cat being chased by a dog.

Most robots, or at least my two(both running sabretooth ESCs), needed adjusting. The ESC usually does most of it for you, but are you sure switch 5 is up? Because that controls the auto calibrate and my robots have it turned on. If that doesn’t work, try nudging the nubs around the control sticks to trim it. It’s just a case of trial and error.

Dip 5 is down and off. This was as per the instructions in the Haynes Manual.

The recommendations were as follows:
1 - Mixed - ON
2 - Exponential - ON
3 - Lithium - ON (recognises 4 cells)
4 - Ramping - OFF
5 - Auto Calibrate - OFF
6 - Timeout - OFF

That's how I set them - but will definitly try your advice

If that doesn’t work, adjusting the trim seems like the only option left but that will probably sort it. Hope it goes well anyhow!

Thanks Theo that seemed to work. However I have trouble getting axles in my wheels. The internal diameter of the bore is 13mm the max bit size in my drill motors is 10mm which I only discovered this after buying some nice M12 bolts and packing with PTFE tape to fit them nice and snug. So I am still unable to do a full test.

This picture is of the M12 bolts

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So as I said the aim of the project was to get a rolling chassis, so I am not quite there but so, so very close. I cut a base plate from some hardboard used some jubilee clips to fix the motors, picked up a castor wheel from B&Q for a couple of quid. It moves! It's a bit rough and ready But as already mentioned due to to having to fudge the axles not very well. If I apply any power quickly they just spin. Need to fix this. Perhaps I can find a reducer,I had no luck in B&Q or Screwfix.

Attachment 7395

This is the same problem I have at the moment; the wheel bore being that ever so bit big. Tape has worked ok for me in testing, but won’t stand a chance in combat, plus the motors also just spin if I suddenly apply power. I’d suggest Banebots wheels but they only do awkward American measurements to my knowledge. Smaller wheels might work better if you can sacrifice the ground clearance, around 100mm would work better and reduce the motor spinning freely. If it’s just for testing, though, this setup should do for now but I’d advise you to fully modify them (locking down the clutch mechanism) for combat but that’s for another day.

Could you not flatten off a side of the shaft (or cut a keyway in) and then get a wheel hub that uses a grub screw to hold the hub onto the shaft (like this for example?)

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Originally Posted by Theo

This is the same problem I have at the moment; the wheel bore being that ever so bit big. Tape has worked ok for me in testing, but won’t stand a chance in combat, plus the motors also just spin if I suddenly apply power. I’d suggest Banebots wheels but they only do awkward American measurements to my knowledge. Smaller wheels might work better if you can sacrifice the ground clearance, around 100mm would work better and reduce the motor spinning freely. If it’s just for testing, though, this setup should do for now but I’d advise you to fully modify them (locking down the clutch mechanism) for combat but that’s for another day.

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Thanks for the advice. In my case the large washers and PTFE really held them solid. Turning up the torque on the blots would be very solid. I could further strengthen by drill 4 small holes through the washer and hub and bolting them in. Even some small screws, fixing the washer to the hub would work for this class I think. As you see they are chunky hubs. Plan for now is lighter wheels with smaller bore. But if I find a solution I may put them back on. This is only a 'test bed' but they looked so tough and chunky a real shame.

Attachment 7401

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Originally Posted by Ocracoke

Could you not flatten off a side of the shaft (or cut a keyway in) and then get a wheel hub that uses a grub screw to hold the hub onto the shaft (like this for example?)

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Ah I think I see. I can imagine fixing the wheels securely is a major task for many robots. Certainly using drill chucks is easier at this stage. I was looking at the drill motor mounts on the forum and if I did use those I would need to find another way. For now I hope this next set of wheels have 8mm or 10mm hubs (there seems to be some confusion on the website). Either way some 80-100mm bolts, suitable washers and nuts should give me what I need to let me get it ready to whip around the garden patio.

Why I chose fairly big wheels - I gave it some thought and I see some advantages:

- A larger wheel makes more contact with a surface than a smaller one
- The rolling circumference is larger, so a higher top speed is achieved for same RPM and more control at low speed
- Larger wheel can flex more shock/energy absorption
- Allows more flexibility in mounting position so in theory with correct design the ride height could be adjusted

In all my designs I intend to use the biggest wheels I can get away with for the above reasons.

The converse of using big wheels is that they present a bigger target if mounted outside of the bodywork so you'd need to consider how you'd protect them.

The Honey Badger 2.x uses some RC car wheels from a 1:6 (I think) monster truck which measure some 110mm diameter by 40mm wide wheels, which are secured to the wheel hub by some M5 bolts. They have been thoroughly abused, way more than its intended application but are still in round and in one piece.

As an aside, it stuck me when I first saw your robot, it looks vaguely like a old Battlebots competitor, Das Bot from Season 1.0 (http://battlebots.wikia.com/wiki/Das_Bot).

Not raining and I had an idea how to fix the wheels. So this still has temporary axles and is just a test bed. Hell it's quick! I think I got my calculations wrong for my speed estimate. I need to measure them again, I wonder if the diameter was just the hub? With so much weight at back it definitely needs wheelie bars. I need to retain the battery and build a cover or at least roll bars. Then I can play with this and improve my driving skills while I design the my first real robot. I would plan to have inside wheels if possible. Weight could be the issue though, I need to weigh what I have already and see what I have to play with for chassis, armour and weapon.

Note: the sticks have ramping on and I never got more than a few degrees of movement. When I tried I wheelied and flipped. May need to adjust the gearing to slow it down a tad.

https://youtu.be/6AJNEDZZX_4

I doubt at this stage you'll have an issue with weight- mine weighs at 9.6kg with a similar "rear heavy" setup where I even went and added about 600g of ballast to the rear to keep the rear wheels from breaking traction. The wheelie problem you may find simply goes away when the body and weaponry is added.

Looks good though, keep it up ;)

Very progressive speedy building-I made a similar baseboard a few years
back with the drill layout identical, I was going to make a fleet of four
for pay as you battle events but lost interest.
There's no reason you can't continue with this concept into a fully
working featherweight.
I found that when the drill was reversed the spindle tended to come
loose in the chuck so you could maybe weld it in and the jaws shut and
also the bearings in those drills are designed to take a downward force
not support a laterall weight so you would need to fit a bearing and extend
the spindle at the other side of the wheel.
Some kind of weapon will pevent the front end flying up when you drive.

Cheers - thanks for the feedback.
Yes when I ramped up the spin (couldn't help my self a little vistory spin) at about 80% power the wheel flew off. But by then the thing was a blur. That was hand tightened. Now I have used two grips and taken it as tight as it will go. When I convert this to a battle bot I will probably change the connection if I find a good alternative.