Returning to build my first HW

[Bodge Job]

I’ve been thinking about finally build a heavyweight since they announced they were restarting robot wars, and I might take the plunge. Its been a few years since ive done anything robot related (4 maybe? ) and only have experience with featherweights (none did very well, but ill blame that on cheap ebay parts 😝 ). But as I now have access to a workshop and a little more money available think a heavyweight may now be in reach.

Before I start investing in parts I thought id clear up a few things. My current plan for drive is one 24v 800-1000w ebay scooter motor (the MY1020 ones) per side, with a ragebridge 2 controller running of a 7-8 cell lipo and a single stage 4.5-5:1 reduction with 20cm wheels. The power to push others would be desirable so this set up might be a bit lower end, but finding the funds is an issue so I be leaving enough room for future upgrades to higher power motors.

I had a few questions about this set up:
Motors:
I’ve head lots of people mentioning they are trying these scooter motors out, and was wondering on the verdict. Are they up to scratch? how does the actual power compare to other better known motors? And has anyone opened them up and seen if there’s anything internally that can be done to toughen them up?

Ragebridge 2 speed controllers:
when people refer to them being used are they normally referring to them being used in single channel mode, or would a single controller cope in with both drive motors in dual mode. (they will be fitted with a large heat sink and fan, and then shock mounted). And i've only found them on the robot marketplace, has anyone found a uk supplier, or is the RMP the only option (if so what kind of delivery cost am I expecting)

Chain size:
I had been planning on using half inch chain, but the scooter motors mostly seem to come already with 8mm sprockets, would 8mm chain be a viable option instead, or is it a bit lightweight for this application?

Alternatively, I had been considering the E30-400 AMPflow motors, but only just found this source, how would they compare running in the same conditions? (although would probably need an extra stage of reduction due to the higher rpm)
https://www.amazon.com/AmpFlow-E30-4...ywords=ampflow

Sorry for the long post, and I know some of my questions have probably been previously answered but after quite a bit of forum surfing I still wasn’t clear on these bits + thought a post might get the ball rolling
Thanks Alex

[RogueTwoRobots]

Motors:
I’ve head lots of people mentioning they are trying these scooter motors out, and was wondering on the verdict. Are they up to scratch? how does the actual power compare to other better known motors? And has anyone opened them up and seen if there’s anything internally that can be done to toughen them up?

Aftershock used the 24V 800W versions in Robot Wars and said they were great. I've recently bought them to replace the 750s in Coyote and so far, so good. I haven't given them a proper test drive, just a cautious run on the workshop floor (which isn't huge) but they seem to have plenty of grunt. I've opened mine up to add epoxy to the magnets to help hold them in place and to replace the stock wire with larger gauge stuff. Getting the endcap back on afterwards is tricky though but the general build quality is good.

Ragebridge 2 speed controllers:
when people refer to them being used are they normally referring to them being used in single channel mode, or would a single controller cope in with both drive motors in dual mode. (they will be fitted with a large heat sink and fan, and then shock mounted). And i've only found them on the robot marketplace, has anyone found a uk supplier, or is the RMP the only option (if so what kind of delivery cost am I expecting)

I'd recommend using one for each side, I personally haven't used them but understand they might not be beefy enough to cope with two 800-1000W motors in dual mode. The Ragebridge is just made by Charles Guan from the Overhaul Battlebots team as opposed to a large company with European distributors, so as far as I know, RMP is the only option at the moment. Hard to say on delivery cost; throw them in your basket and go through checkout (but not completing the payment) to see how much it tacks on.

Chain size:
I had been planning on using half inch chain, but the scooter motors mostly seem to come already with 8mm sprockets, would 8mm chain be a viable option instead, or is it a bit lightweight for this application?

I personally feel 8mm chain is a bit on the small side for HW drive applications, but I do know of some people who are planning on sticking with it. I have 1/2" drive chains on Coyote but in contrast, they feel a little overkill. Might be worth switching to 3/8" chain for a good middle ground; I think this is what most heavyweights that aren't designed for pushing power use for their transmissions.

[Bodge Job]

awesome thanks its good to know those motors seem to be usable, will make things a bit easier.
Its a shame a single ragebridges wont cope in dual mode, that will add to the costs quite a bit, not surprised though, they seem more like feather sized controllers.
Ill have a look into using 3/8'' chain then, as seems like a good size. Whats the best way to tension chain correctly? would accurate motor placement be enough or would an adjustable idler of some sort work better?

And what's the shaft like on the scooter motors, is its a keyway with a threaded end? there's always a sprocket in the way so can't see whats theres to work with

[typhoon_driver]

I ran a ragebridge 2 in PP3D in series 2. Great controllers. I used it in twin channel mode on two T64s with 10 inch wheels. I used the 3D printed case in nylon with a fan fitted. The fan lasted all of one fight but that didn't matter at all as it ran fine the rest of the comp without. The only modification I'll make if I use it again will be to solder the servo leads directly to the board rather than use servo plugs on the pins.

I'd order them direct from charles website equal zero designs. When he sent mine he declared their value as being like $30 so I paid next to nothing on import tax.

[blazerbotics]

We used them on the Celeb bots, and most failed but we're not sure why. We didn't have them in cases, so it could be just swarf etc getting on them. In testing they were fine on the T64's at 8s, I know the concussion guys ran on one at some point, but no idea is it was single or dual channel.

8mm would be pushing it on chain, you might get away with it, I've always ran 3/8 pitch on boschs, 1/2 is overkill for drive.

[typhoon_driver]

How were they mounted in the celeb bots?

[Ellis]

How were they mounted in the celeb bots?

They kinda weren't, lol.

I remember Bruiser, and the axe weapon you later built. Always liked the shape. Welcome back!

[teamshock]

We would definitely recommend the scooter motors. Used two of them in Aftershock with a single stage 3/8" chain reduction. The rear wheels were 160mm and had a 4:1 reduction.

Really nice motors but I would suggest going to a larger chain size and supporting the end of the motor shaft. We are going to swap the rest of our heavies to these once we run out of Bosches.

[Bodge Job]

Ahh brilliant, glad these motors are up to it and wasn't planning on supporting the ends of the motors so thanks for the suggestion, ill add in some more support. Using 3/8" chain should be no problem so glad checked before started anything! Ill try to get the ragebridges directly from him then, and use one per side. (but its nice to know their potentially capable of driving two, means I could shove one it dual mode if I burn out all my other controllers aha)

And yeah good old bruiser, I still have that kicking around somewhere, and sadly the axe never worked reliably enough to compete it (and the small issue that the whole thing weighed like 16kg with the axe attached) so it never made it to an event. Might have to drag it along (axeless to an event along with the new feather at some point

And I've ended up being involved in two heavies. I have been wanting to build my own so am most of the way though the designs of that, and hopping to start to get the parts when im home over Easter. But a few weeks ago I ended up joining with a group of people at my uni who are also in the process of building a heavy. Some electrical engineers had started the club and managed to get funding from the uni for it (took nearly a year but they have managed to get a decent amount now) and then invited some mech eng people along (me and a few others) to help with its construction, as we have access to the uni workshops and are supposedly meant to have a better idea of how to put it together :P. So been helping them out how I can, and hopefully steering the design in the right direction (Im obviously not that experienced my self, but tried to give them what knowledge ive picked up over the years and introduced them to a lot of the online resources like here, and riobotz tutorial etc). So even if I cant afford to build my own, ill still be involved in making a heavy
But was wondering (particularly for reference for the uni design) what kind of ballpark is the current energy in heavy spinners? Vaguely remember reading pp3d was something massive like 60kj (can’t find where ever I plucked that figure from though), but what energy are the more “average” spinners achieving? :P

[typhoon_driver]

PP3D - 65kJ theoretical from the disc alone. In real life it will be below that but there's the added weight of the shaft (4.5kg) so it balances out in the end.

Carbide is pushing 60kJ from memory

Realistically you need to be storing 20kJ plus to be anywhere near competitive with a heavyweight these days.

[Bodge Job]

ahh brilliant thanks, looks like the weapon I have in mind is plausible then. Lower end, but hopefully that means it won't wreck itself (I thought I replied to this ages ago, but apparently haven't).

I had wanted to purchase one of those MY1020 24v motors before I started anything else, but annoyingly they seem to be out of stock everywhere at the moment (something to do with rw coming up maybe?) . So was wondering if anyone could tell me what the shaft is like, and if it could be plausibly replaced with a longer one? Also, was hoping to mount them via the front plate, rather than the stand, would the motor be up to this without major modifications?
Secondly I’m trying to source 20mm aluminium plate, had found some cheap on ebay but the listing finished, so currently looking at http://www.aluminiumwarehouse.co.uk/...f67dl30ja91cu1 but was wondering if anyone knew of anywhere cheaper? Or is that the kind of prices I should be expecting?
Thanks

[maddox10]

https://www.aliexpress.com/wholesale...28&needQuery=y

[typhoon_driver]

Previously ordered ali from those guys. I thought it was reasonable. Just bear in mind the tolerance they give as the pieces will likely be plus 2mm as mine were.

[Bodge Job]

Ahh brilliant thanks, now ordered the main construction materials, and will be ringing up a few water jet companies about the hardox weapon in a few weeks time.

And thanks Maddox10 but that site doesn't seem to have the 24v 800w version either, every where i've looked still has the 36/48v 800w motors (and the odd 1000w) but all the 24v 800w motors all say out of stock, or have been removed. I had wanted to run the 24v motor on a 8s lipo (so mild over volting) using a ragebridge. But the 36v motor is at the limits of the controller voltage so could only be run on a 9s, so will be slightly undervolted.which is why I wanted to avoid using those if could.
or am i being a bit thick, I had presumed the were the same armature with slightly different windings inside. But are they actually the same instead, and just mislabeled? with the the 24v version being just an undervolted 800w 36v motor, so would actually be a lower power (500w motor)? or was I correct in thinking it was wound differently?

[maddox10]

The windings could be different in wirethickness and turns per loop, but using the same armature/rotor.

Now the simple math. A 36V 800W nominal motor will draw around 25A when operating at good efficiency. Providing the same motor with 24V , it will become a 400W motor for the same efficiency.

But this could be an option.
https://www.aliexpress.com/item/24V3...4-d73b1595e964