HardWired II

[Mouldy]

Do your self a favour dont bother trying to mod a scorpion there awesome out of the box... and more importantly there built to be reliable... also stop talking maths... its going to be sweet... start cutting metal and upload some pics!

[Flag Captured]

Haha, I wouldn't touch it with a barge pole, I'm nervous enough about taking the back off one of HardWired 2's 900s to fix that, don't think I'd even attempt to change an even more expensive scorpion!

It might be worth looking at the inrunner options then too, truth be told I do need an inrunner (and an outrunner) for another project at some point so maybe making a mount that would suit both could work... More expensive but I'd be needing one of each anyway - see how both behave!
Personally I'm liking the outrunner option for size, but the inrunner might end up being more preferable voltage wise, and I'd worry about finding an inrunner that could cope with spinning the bar up to speeds I'd want it at at a lower voltage...

Got no money at the minute with which to buy stuff for it, but come September I'll be getting plenty done! I hope it's pretty menacing... I'll probably end up with the two sides of the coin by the time I'm done, Archangel being all offence and HardWired being all defense haha

I do like the maths though, I see the big numbers and in my mind I'm hearing this

Won't be too long though I'd imagine, I'd like to get it done before the year's out, by the end of January at the very latest... HardWired 2 wasn't finished till the week before the champs and it definitely showed in my driving ability! Need plenty of practice this year, certainly...

[overkill]

Custom winding a Scorpion using one of their kits would give you more power with your choice of KV but its not for the faint-hearted and plenty of research is needed! Its probably a 'plan C' rather than a first choice.

Part of Catastrophe's driving problems are simply the no-grip wheels; they are a a very hard compound and the Banebots wheels will undoubtedly do better. Ideally, the wheels should be right up at the front, but then inverted driving is not an option.

I will see if I can work all that maths into a spreadsheet and maybe do a table or a graph to visualise how various design changes affect the performance.

[GlenR]

Sup yall, That design looks good! Wheel placement and all looks nice

The 4*** series scorpions are wildly powerful! Demon has a 3L V-belt and it slips non stop at anything above 2000w~ the 4035 puts out much more than that so i would say going to the 5*** size is abit much if you're trying to keep the weight down, however the bigger diameter motor will draw less current so if you're having battery problems it might be worth trying (that's the reason i have upsized).

With the rewinds, Demons blade pulley is integral to the bearing block on the disk so it's size is fixed. It used to run the old 3026-880kv which is the lowest powered variant they had by 300w or so. I wanted the power of the higher KV versions but the stock speed so i pulled it apart and rewound it given i had two partially burnt ones. Definitely don't recommend it The stators are epoxy dipped so you have to heat gun it as you slowly unwrap the individual winds, half the time the stator insulation comes off with it and that needs to get redone. So so tedious... That was all due to having to make do with the original design constraints, Just design around an existing scorpion motor and you'll be fine. Although they have an aggrevating habit of changing specs constantly. Good luck trying to buy the same motor 2 years from now

Catastrophe runs some cruddy 5*** size $30 motor from hobbyking and it draws next to no current nor builds much heat at all. It's a really nice setup, but heavy. IMHO use one of those to begin with then get a scorpion if you need the additional power. I doubt you will though, they have so much torque Specially the SK3 turnigys which are rebranded hacker outrunners.

The support bars - They're an afterthought too :P Catastrophes weapon arms are way too small as you can see from the mega amount of pocketing, plus the way it was designed means they couldnt be welded on fully (cant get the tig torch in where the front plate slopes in). Demon has a big cut out in the base the blade runs through so the vertical arms weren't rigid enough at all thus the support arms. Surprisingly they work really well, but if the robot is designed proper to begin with you wont need them. Makes working on the robot a pain in the butt too lol.

Shouldn't need a sharp blade for plastic bots. With enough energy it'll just displace the material without slowing the blade down :P I had to fight this plastic square that was about 200mm thick at our last nationals. The disk would just plow straight in as far as it could go lol. Unfortunately doing that for 3 minutes melted my lipoly :P Got outsmarted on that one haha. Looks like most of the plastic armour robots are quite thin in the Uk however. So you should be okay there

Get building

[overkill]

I thought you bought that custom wound 3026 - kudos on getting it done yourself! I think the idea for a custom wound motor was to start with one of the motor kits rather than pull apart a perfectly good Scorpion - still a difficult job though.

[GlenR]

I have both Back when you could order the motors directly from them they'd do specific winds for you. My own are just single larger winds that are apparently better for getting more copper on the stator and the scoprion ones were parralleled fine winds that im lead to believe are easier to wind. They both performed about the same really. The DIY cores are about the same price anyway, easier to just use the existing options unless there's a specific need for a certain KV

[Flag Captured]

Cheers Glen!
I see with the 50-size ones, I am tempted to go for a 50-20/25 because I've seen some cheap ones, though if the belt slips like mad even with smaller motors, it's nice to know I could probably downsize a little! I guess I'm stat chasing a little, but the torque and just general power of those 50-sized motors is something I'd like...

That said, I did find this motor after having a quick look at those SK3s you mentioned http://www.hobbyking.co.uk/hobbyking...ize_heli_.html which is a high power and surprisingly low voltage motor, which could help me out with the whole battery issue, and saves more precious weight that can go onto the bulkheads! Not sure how suitable it is but may be along the right lines! Certainly won't be rewinding one myself though, sounds like it's an incredibly difficult task and it's not really something I reckon I'd be able to do with my tools/skillset haha!

Afterthought the may be, but they seem to do their job nicely! The reason I wondered about using some on Archangel was more to offer protection in case they were to get hit by a horizontal spinner or something... I'll have to mill down the bulkheads a fair bit and I'm worried about their strength as a result. Perhaps I could bolt them to the front/back plates more securely and use those as the support bars?

I think I saw that fight too, Plastic Fantastic or something? That looked a brick of a thing if ever there was one, I feel sorry for the person who had to clean the mess up afterwards! Most over here I believe use around 15-20mm (Ricochet uses the thickest I think at 30mm) so that's plenty below the 200mm mark haha! Won't be too long till the build now I reckon, few creases to work out in the design and then I'm on it!


Side note too, been cracking on a little with HardWired 2's planned upgrades - given that it's designed around Speed 900s which are literally more expensive than solid gold these days, I'm running into plenty of problems now that one of the motors I have is broken... I've had a few ideas, some of which involve cutting the robot in half and replacing the back/middle sections with pieces of longer hardox (same 6.4-7mm thick) and then putting some banebots gearboxes and accompanying brushless motors (high power) in there or something. Effectively, the machine will probably be about 10-ish cm wider. Other option is a silly compact two-stage gearbox (or in-wheel setup) and using those outrunners I posted earlier at about a 16/24:1 ratio or something to carry on with the silly speeds, but enough torque to deal with as many magnets as I'd like in there. I'm still not fully sure though...

One thing I do know is it definitely won't be making it to the northern tour either, or indeed any upcoming events for that reason! Only got one working motor now, so it's pretty pointless bringing it until I upgrade the drive system with new motors...

[overkill]

That SK3 motor is very similar to the Hacker out-runner I have in Mr Mangle; a higher KV winding and the same dimensions. I am really happy with the motor's performance but your weapon would have 4 or 5 times the energy of my beater and the SK3 motor is going to struggle to spin it up. That 4,150 watts is the maximum power, probably only for 5 to 15 seconds and the continuous power is going to be closer to half that.

[Flag Captured]

Hmm, that's unfortunate
It is looking more like the better option will be to go for a higher speed motor (inrunner, I'd assume) and gear down a lot. The Scorpion does seem a good option but if I can get the same sort of effect with a cheaper motor, it's probably better...

What sort of power would I be looking at for this sort of bar? I am starting to realise that 7000rpm is a pretty hefty target too, may be pushing it a little!

[overkill]

Rotational Moment of Inertia. Solidworks give it to you in in the Mass Evaluation tool in each place and axis, and around the objects centre off mass and the origin.
On its own its not much use but its great for comparing designs. I think as I have weird settings the numbers are in Kg/mm.

Can you check the units that Solidworks is using for that RMI figure? I scaled the number to Kg/m, plugged it into the calculation for kinetic energy and got 12 million joules of energy! When I used a RMI calculator for a straight bar 400mm long and weighing 3.45Kg, the RMI was 0.156 Kg/m - less than what your design would have, but not too far off.