HardWired II

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I would assume it's because they're 'custom' (at least in the case of Alienpower) but I can't understand it either to be honest! Rather wish Hobbyking would do a range of sensored NTMs but I don't know if that'd work out cost effective for them...

Shame though, guess I'll just have to keep waiting for the Aliens to come back in stock!

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Actually, I've just seen this on there... http://alienpowersystem.com/shop/ser...nsors-service/
Not sure if this replaces the existing stock of sensored outrunners!

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Question for anyone who's relatively spinner-savvy, are inrunners or outrunners better for a small, high RPM disc?

Plan I have at the minute is to go for a 150mm OD single tooth disc, probably made of 10mm hardox 500 (or whatever gets it to about 1/1.5kg) on 20mm HDPE bulkheads (fixed shaft if possible) and I'd like to aim for around 10-15,000 rpm which might be pushing it a bit but means it'd get some very nice engagements. There are a few outrunners that would do it on the 6S I'm planning to use at maybe 1:1/2:1 sort of ratio, but is it a smarter idea to just go for an inrunner and gear down some more?

[overkill]

The problem with using a small diameter disk is that there is less space to use a high reduction unless you want to risk the pulley on the disk getting hit. In this scenario, I would go for a high KV inrunner and a lower gear reduction. Will the disk be single toothed? 10K rpm and above is a bit high for a multi-toothed disk.

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Definitely single tooth, more awkward to design I guess but definitely worth the effort!

As for motors, I'd spotted this - http://www.hobbyking.com/hobbyking/s...or_2350KV.html which for, let's say a 15k-ish rpm on 5S would need a 3:1 reduction... Not sure if that'll be good enough though. I don't know how brushless motors react to overvolting either, but it could be an option to run it on 6s, perhaps?

In an ideal world I'd like to put a really small pulley on the disc and essentially hide that within the bulkheads, but it's if the reduction suits it really. 2-stage isn't that much of an option given it's going to be sitting on top of a machine that's no bigger than a postage stamp either!

[Revsmin]

I'd say that 150mm is too small for a disc, especially considering there are beetle weapons bigger (Newton/Red Wedding). I'd say go for 200mm OD and make it closer to 2kg, that should give some nice impacts.

[Eventorizon]

He is restricted by weight and size due to the geometry and current weight of the machine. Ideally you should go for the biggest Diameter you can but looking at Rango its not totally necessary if you have out right speed. I cant remember the graph shape but you can gain back your RMI in speed but doing it in the mass of the weapon is ^2 in terms of efficiency... I may have that wrong.

A 1.5-1.8Kg Rango style Drisk doing 12'5000 would pack a massive punch either way!

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If the size permitted, I'd definitely go for something huge to get a really powerful spinner, but I'm having to make it super compact given it's an addition to a machine which didn't have a great deal of internal space anyway, but also because I'm building the uberspinner (Archangel) at some point in the future, this is more just a small spinner to help add to the existing pushing power.

Also, if we're using the 'there are beetleweight weapons bigger than that' argument... Lynx says hello (in fact, I'm fairly sure Lynx's bar is bigger than HardWired 2 itself...)
I'd go bigger with it all, but it presents so many problems by doing that really... I do have about 4/4.5kg to play with but I'm adding some more armour and a few bits of things to improve general reliability and I'm not sure how much that'll add!

The inspiration is somewhere between Rango and Enigma I guess, it's not designed to be the most damaging thing in the world, but consistent hits and that high speed are pretty vital to the whole thing. I don't mind changing it to be a more drum/disc hybrid thing but I'd rather keep it as a plain disc for now if I can get away with it!

[daveimi]

~Sorry if I sound daft but is this the same robot the money's run out for or is that another one? I couldn't work out if you had a few feathers on the go.

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I have more feathers on the go than there are machines that compete in the champs haha

Seriously though, this is just a bunch of upgrades to HW2 to make it more competitive (and weaponised), Archangel (the one that the money ran out for) is going on the shelf for a bit until I get the cash to do it properly. I've got a few other plans in the pipeline for potential feather designs, but I doubt any of those will make it past the drawing board to be honest.

[overkill]

If you want to keep the pulleys as small as possible, that means using a timing belt. All belts have a minimum pulley radius and the thinner the belt, the smaller the radius. Just keep in mind that the smaller the motor pulley is, the more likely it is to slip and strip the teeth off the belt.

In theory, brushless motors should over-volt better than brushed motors; they are more efficient and generate less heat, plus they don't have brushes to burn up. The main problem is still overheating; most brushless motors don't like to get over 60 or 70 deg. C. If you used a motor that is power full enough for the job and has some built-in cooling, then over-volting shouldn't be an issue.

Keep in mind that the motor you linked to has a maximum power rating of 2,400W and the continuous rating will be half that or less.

[mrsam]

Lynx's weapon WAS bigger than Hardwired, i've seen sense and had the new one designed at 250mm...that's sensible...right?

I don't really see the problem only having the disc/drum at 150mm, if it's for HW2 i'm guessing you'll be using it as more of a kinetic flipper alongside the robots speed. Besides how big is the disc on Satan's Mutt? if i remember correctly it had enough power to flip robots up in the air and it was only about the size of an ants bumhole.

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Yeah, that's my worry with going smaller, Nick - I've learned that in a roundabout way with wheels too!

I'm more than happy to amend the motor too depending on what I can find/afford (got to get a working drive system/battery and this done for £250-ish at the most) but I think that may be a nice starting point - after all, I'll be pulling the most current on startup I'd imagine and 2.4kw sounds like enough. Of course, I've not a single clue as to whether this is actually enough but the potential for overvolting may make it more viable. Could be worth a few experiments at least if it comes to that!

That bar was insane too Sam, I did measure the dimensions you gave me for the machine against HardWired, and you've either built a feather-size beetle, or I've built a beetle-size feather haha
The idea for the disc was basically along the same lines as Rango/540 used their spinners, drive being the focal point and then the spinner being there to add just a dash of chaos into the mix haha. After seeing the hits that Rango and 720 got this year though by driving into things at relative speed, I think the engagements it could make at high RPM might potentially be utterly insane... but time will tell!

[overkill]

Have you thought about axle size and bearings for the disk? Its a real PITA trying to get a small pulley and a large bearing fitted into the hub of a disk.

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Ideally I'd like to go for a 20mm axle, may be OTT but makes it reliable at least. I was tempted to go for a fixed shaft and bushings on it rather than bearings, but I'll see how the cardboard mockups go and work from there, might be better going for conventional bearings in the end