Featherweight Discs

lol, Im glad Im not over there right now :P
My spinner is exceeding all three :proud:
a 4kg rotor(33% of the robots weight)
Spins at around 2000rpm
around 70cm in diameter

Just about to replace a lot of aluminium armour with policarb now to fit the new weapon motor in.

My input to those rules- at least for featherweights- dont agree with them. 20% of 12kg is 2.4kg. There are a LOT of feather spinners whose discs weigh more that 2.4kg! 500rpm- very very slow by featherweight standards.
24- OK not so much an issue with feathers, but it strikes me that one size limit applied to all the weight classes contradicts the claim that this rule is made with all weight classes in mind.

This needs further discussion on this thread for featherweight builders- most decent feather spinners will exceed 2 of those limits. It is too much hassle and red tape to have most good feather spinners subject to review, whatever that may entail.

Just some thoughts.

all spinners whether big, small, fast or slow will be reviewed by the tech check people at an event anyway, i dont see what this rule accomplishes. If someone turned up with a 23.9 diameter, 2.39Kg disc that runs at 20,000rpm does this new rule mean it would automatically be safe? surely the same rules will apply to it now as always did, if it is safe to run it will run, if it isnt it wont. Or is this a seperate review where it has to do a spin test and drive into the side of the arena to see if it is strong enough or something, i dont mean to be pedantic i just want to know where i stand as my new featherweight spinner will be subject for review (if it ever gets built).

Joe Townsend
Team Cut Corners

I really do think that this makes sense for feathers in most repects.

Lets be honest if your robot is to hold down a disc weighing over 20% of its weight and spinning at over 500rpm, you are either spending serious money on lightweight bits, a fantastic engineer or you just dont care about safety!! Most of us dont have bottomless pockets and sadly arent superengineer himself, therefore some form of peer review of our often hare-brained weopon systems is a highly wise precaution.

My first thought was that this was a simple and fair but effective means of evaluating feather spinners, nothing anyone else has said since has convinced me that it is anything else. It may even not be restrictive enough.

Regards

Tim Jones
Team Bernard

I dont think thats the case at all. Mag motor aside, the weapon system on vortex is really quite simple- anyone with some skill on a lathe and mill wouldnt have too much of a problem building a similar thing! Granted if one is building something like this is a basic workshop (woodworking tools, jigsaw, that kind of thing) then it may be an issue, but the second you gain access to a lathe and mill, as many people have, its a whole different ball game! It should be down to the EO as to what they feel is safe to run in their arena- there are just too many variables in spinner construction to have the entire weapon calss governed by 3 statements.

Its simply not the case that you are either spending serious money on lightweight bits, a fantastic engineer or you just dont care about safety!!

I have built the spinning mechanism for my feather for about £80. A dewalt 24V (£30), timing pulleys courtessy of RS, and the disc is machined form a motorbike breaking disc- very strong and tough stuff as my HSS lathe bit will attest! It has a 20mm silver steel axle, supported on both sides by 20mm needle roller bearings, mounted in 15mm thick 6082 bulkheads. Disc weighs about 3kg and spins at about 3000rpm. The disc spins indredibly smoothly- no vibration. It is very very solid indeed. It was made in my school workshop in my free time. It does not use expensive lightweight parts, I am definatelly not a fantastic engineer, and I can assure you Ive built it as solidly as i possibly can! I will not say its safe because no spinning weapons are. I have a very high regard for safety, which is why i treat the thing as if it could explode at any secong, even tho I know is build like a brick Sh!t-house. Its entirely possible to build a safe spinner whilst still exceeding the limits given above.

I know its a different ball game in heavies- scaling that up to heavyweight, wed have a 30kg spinner spinning at 3000rpm- which would be terrifying and enormously dangerous, but it isnt in featherweights. And if we go even smaller, Pete Wallers antweight spinners can weigh up to about 40g of 150g limit, and spin at about 20,000rpm! As you get smaller, the RPMs increase. This is why I dont think those rules can be applies to all weight classes. They work fine for heavies, but not for feathers or anything smaller.

I think people are becomming Spinnerist.

If the robot passes its tech check isnt it enough to say its safe?

arent flipping arms or axes just as dangerous???

Limiting what a Spinner is allowed is like making your own rules! All the speeds and weight.size limits are not right for ALL weight classes! This includes Antweights as well :S

I think its appropriate for heavyweights and middleweights (who cant currently use spinner weapons at most live events). But Lightweights, Featherweights and Antweights are different. There is no reason to change the rules! If something works well dont change it.

If these rules do come into place then I hope that other weapon types get rule changes as well!

Jas

If you would all like me to bring it up at the next FRA meeting taking place this weekend, then i will. If anybody would like to email me with their concerns, or questions that they want answering, then i can take it up and try and find you some answers for you.
Email me at stu@featherweights.org

Mr Stu
FRA Featherweight Rep

Its all here Stu on this page.

Eddy well done you have built your spinner for small money, but dont forget to factor in the cost of the tools you have free access to. For many of us that is a serious money issue! Without the money tools or access to free bits, a set of limits within which you are not subject to a major review is to be welcomed.

I applaud those who push the limits, but in reality your situation will have changed very little, you always were going to be subject to review. Why object to a sub-class of spinner for those of us who are less fortunate and just cant afford to push the limits with the risk that our weopon will be declared unfit to run?


Regards

Tim Jones

its kinda true that it need holding back, as to be honest, both me and Ed Hoppitt have held back with our previous spinners.

Ed never (to my knowledge) run his mag at full voltage, or at full throttle on full voltage anyway, and Tantrum never approached his 24v design as 12v was too much.

as it stands, with my current workshp and knowledge and within 3 months with £400, I could have a 4kg 500mm disc at 10,000rpm reachable inside 5 seconds, but whats the point? Nobody will fight it, Id be filling my pants the whole time its plugged in, and it probably wont be allowed to run.

So, instead of setting strict rules we should advise common sense, as if your spinner hits hard enough to damage good robots, expect to be looked at closely. If it can wreak good robots, expect problems, and if nothing can take a hit from it, dont expect to run. If you want to be 100% sure of running your disc, make it a nibbler, not a muncher.

James I guess Im kind of unique then. We need spinners! Shovebots and flippers make very boring opponents. What is the point of turning an invertible robot over? If I wanted that sort of excitement Id be playing tiddlywinks.

As Aber demonstrated without decent spinners you just have to play with the heavies for real excitement and challenge ;)

Regards

Tim

so true, but what I mean is, if you show up with something rediculous (as Ive done) dont be surprised if its not run.

There are feathers that can take huge hits, and some are more heavily armoured than the arena... I would not want to see tantrum at full power being sent into the screens..... well, actaully I would, but only if I was 20 feet away and I did not own the said screen.

yes, we need spinners, we need powerful spinners, but we dont need stupid spinners. If the heavies cant have them at all, we should have limits, and the limit should not be a quantifiable value, but a common sense judgement on the day, with the actaul figures there to let you know if you can expect to go home early.

my 2 pence

on my new bot i am planning on having two different speeds of disc. firstly i can drive the disc 1:1 of the motor so it will spin at about 4000 rpm, this should be plenty for almost any event, it should nibble at robots pretty well but i doubt if it will cause significant damage (the disc only weighs 1.7kg) or i can change the gear on the motor and drive it at 1:2 against the motor hopefully giving it about 7000 rpm. this will only be used if taking on robots with similarly powerful weapons. It is always a good idea to have a backup plan if you think there may be a problem with your disc as something as simple as changing a gear and a tensioner may allow you to run. Similarly you could have a competition disc and a fun disc, i think razor do something similar with their hydrolic setup. Any robot should be able to tone down their weapon so i say build a robot to the limit of what you think will be safe but be prepared to change it if the powers that be disagree

Joe Townsend

I agree with above. There is nothing stoping anyone being rediculous and building a 36V mag power 4-5kg spinner- its entirely acheivable within the weight limit- but very few areans would hold it, and few roboteers would be willing to fight against it. As james said, common sense should be applied, or at least a clause to the effect of If you have the time and money, by all means, its your call, but be prepared to not be allowed to fight it. Tis a difficult issue. Spinners like tornados, which are effective but not rediculous as the complement the rest of the robot, as opposed to BEING the robot, are good direction to head, but then its always fun to have all-out spinners. Our March 6th event will be a good opportunity to see whats going on, and perhaps debate the next move etc. Thoughts?

My thought are spinners are what the crowds love.....but we need some good axe-wielding featherweights.

So true Rob!

I€™m considering building a featherweight using an EV warrior on a disc...the disc will probably weigh about 2kg, this wont be around for some while, However, so some rules may come up between now and the 3months in the future when I start work. But what thickness would people suggest I make the bulkheads of the robot supporting the disc from...I was thinking 8mm Ali...As 10mm is OTT? Any thoughts?

Regards
Dave moulds
Team Turbine/PLF

No Dave, 10mm aluminium is NOT OTT for supporting bulkheads. All of the bulkheads in Storm Vortex were 10mm 2014T aluminium

Ed
http://www.teamstorm.comhttp://www.teamstorm.com

Tim - sorry, couldnt let that pass. Youve persuaded me, Im going to *have* to build a robot just so that I can teach you to play winks in the pits between fights. (People have been hospitalised, you know.)

--
Andrew Garrard
Publicity officer to the English Tiddlywinks Association
Winking World editor
Webmaster of http://www.cutwc.orgwww.cutwc.org

I agree with Ed- tho you can pocket it loosing very very little strength, but reducing the weight alot. Just be careful about how much/where u pocket.

I agree with Rob that we need some more none-effective weapons, that the crowd will still love. I was toying around with an axe-bot but gave the idea up as It wouldnt stand a chance with any of the new bots.
As there are so many featherweights about I think we should set different leagues for different robots (e.g The under 15s could go in one group and the rest in the other) This would give a chance for the new bot builders out there to fight someone their own size... My personal excuse for building not so good bots so far is one word... MONEY

Seeing as Im still only 12 I aint got much of it :sad: (at least now Ive got two sponsors I can promise the next bot to be better:))

Anyway you big guys should still make OTT spinners, fight each other and start to hear the ohhhs, and ahhhs from the crowd...
Cheers, Ewan
http://www.micro-maul.co.ukhttp://www.micro-maul.co.uk

Well Im glad to see people are looking at having a sensible spinner rather then OTT spinners. Even though our tri rotor going back onto Annihilation is 4kg, it is built fairly damn sturdy. we have uses 20mm box section for the hammer supports and we have 5mm solidbox between the hammers to stop them from bending the arms. We have the whole weapon mounted on a 22mm ride on mower bearing. There is a picture of the rotor on Annihilation back before it got the paint job and the weapon change on the http://www.featherweights.orgwww.featherweights.org database for those who wish to have a looksy

hey, forget what I said earler.......
new spinner is 10kg at estimated 1500rpm 450mm diameter......

mwahhhaahhaaaa
(not as impressive as it sounds actually, youll see when it next appears.)

Mr. Baker- If youre trying to make what I think youre trying to make- its extremely difficult to get something so light to translate properly with only a 2kg ****** (just so its not too spoilt :-) a 3kg is much better. Having said all that, theyre still exceptionally difficult to make! The one Im working on (kinda a 2 year project due to really slow rate of income) is going to have translation speed control, via means of a cunning little variable eccentricity cam my friend came up with. We have the design sitting on Pro Engineer, a few parts, little money to do it, and trying to find a friendly firm for the large number of CNC parts it requires! Incidentally, the G Forces on the rim of ours (similar speed) are about 850G- so a kilo of batts suddenly weighs 850kg as far as the chassis is concerned! Its really quite a scary prospect!! Also, our little MDF mockup which we built to test translation, and only ran about 180rpm, FLEW when we caught the edge of a workbench. Just imagine what it would be like at 1500rpm. I am genuinely worried about this particular type of robot- they really are quite astoundingly dangerous, and Ive heard it on the grape-vine that other slightly better funded builders (no prizes for guessing who) have similar plans for a heavyweight version. If thats not what youre building, my appologies! Its just the figures youve quoted there would suggest it might be (unless its a walker, of course, in which case Ive just made myself sound very silly :o)

Regards
Ed
*Insert Something impressive sounding written in red*

Yep, as soon as someone makes an effective featherweight walker (no offence to mammoth:)) theyll be able to stick a 12kg disc on it...
If only I had a few more sponsors...

Damn! I though I was the only one crazy enough to design Translational Spinners! Ill have to get cracking then!

@Ewan
Age In my opinion should not be the restriction. There are some people that at 12 will have the cash and the facalities to make very good robots. It could be much fairer to go by money than age.

Regards
Ian

I agree, but age is mostly a way of judging income.
It would be very hard to judge someone by how much money they have.
Cheers, Ewan

Not by how much they have but by how much money they have spent on the robot. By that i mean they may have spent 5pounds and got loads of sponsership but anything that was sponsered has to be taken as they paid for it.

Regards
Ian Mc Donald

Again I feel that would be rather hard to judge, a roboteer could quite easily say they got something from a scrapyard when it cost 200.00, youd need to make a huge table with details of how much a certain item costs which is now gettig rather ridiculous...
(and no, I dont get THAT much sponsorship :))

well have to wait and see about mine, but the well off team you mention abandoned its plans if we are talking about the same thing.

Well have to wait til it happens then panic

Scuse my stupidity, but whats a translational spinner? I could interpret that as either something like Y-Pout, or something like Tip-Top, but Ive never heard the term before.

--
Fluppet

It is similar to Tip-Top in that it uses the power, and rotation of the disc to create a linear (forwar/backward/side to side) movement of the robot. It is quite a complex idea involving many parts...

Nope, its simlar to Y-Pout and why-not. The PDFs of the real robots articles can be downloaded from their website, and so quite a good job of explaining the principle. If you have Pro Desktop, I can email you a CAD file demonstrating how the mechanism works (in that you can move all the parts around and watch the wheels turn in and out).

Stupid me (*slaps himself*)... :)
A Y-Pout style spinner would have the problem in that you cant just decide you want to go forward, and go forward. You wouldnt be able to move in any forcefulway (trying to push someone) from a standing start as, if the motors are high rpm, thus less torque (Ed put awy the lem :))then it would take a good 3-4 seconds to get to any good speed.
Then again they may have more advantages than disadvatages. But seeing as I may be getting some sponsorship from a Bristol-Based CNC company... Id like to go the walking route to a MAJOR featherweight spinner.

Or you could try making a simple robot that works?

all wrong, it is not a tip-top and not a y-pout

its something, different :)

still can be described as an transitional spinner, but not like either of those 2.

See the 2004 FWS, thatll be a simple bot... :)

:-) If everyone was assuming a different thing, I now feel a little less stupid!

Eddy: thanks for the link (once Id worked out that their meant teamwhyachi.com, not realrobots.com) - better explanation than last time I looked at it. No luck with the CAD Im afraid, but I get how they work (although before I read the RR articles Id assumed the cam was spun by a motor running in anti-sync with the frame rather than being on a central mini-bot - *weird* way to do it). Since Ive never seen them run, I look forward to your implementation - from a safe distance.

Ewan: as with all noncircular horizontal spinners, the stuff them in the corner of the arena and keep them pinned there approach is pretty effective, so the motion is a problem, yes - especially when you rely on spinning to locomote. Although less so if youre running with 3 LEMs or 3 magmotors, as the Team Whyachi robots do (they could probably bounce themselves out).

Tip-Top is a very simple idea, in contrast - two lifters at the rear wheels and the weapon motor. Very pleased to see it at the Rumble last year, having remembered it from an early Robot Wars. Interesting engineering design. Never going to have much traction, of course, but they have my approval for doing something different.

2004 FWS?

Mike: You can, in theory, make a much mechanically simpler version of Y-{pout|not} just by varying the power to the motors mid spin - that is, dont change the pitch of the wheels, change their speed. I believe people have tried it for Stinger-like devices (allowing the robot to spin while moving). Im sure its a faff electronically, but Im surprised nobodys taken it further - it cant be *that* hard to do. (Do gyros work when you spin them fast, or would it need to be kept still-ish?) Er, said with my Ive not yet built a robot hat on, of course. Stopping the batteries from dying on impact is another matter, too - someone needs to market impact-proof batteries (internal bracings?), and theyll corner the market.

It also strikes me that the mechanics needed to fit all the motors (including the drive) to the shell of something like the Typhoon family, thus increasing the weight of the spinner component, arent all that complex. Might be heavy enough that you may as well leave the motors in the middle, though.

James: Ill look forward to seeing it when youve created it! (Im keeping my designs to myself until theyre built too - I dont mind someone copying my robot, I just dont want them to do it until Ive built it!)

--
Fluppet

Andrew-

Appologies for being unclear about the link :o)

I am in complete agreement that its a *wierd* way to do it, and am actively looking at other options. However, electronics is really very very difficult to impliment. Yes, the electronics are fast enough, but the motors simply cannot increase and decrease their revs 30 times a second- that kind of speed is approaching a usable PWM frequency for larger motors, so clearly the overall affect will just be that the motors see the average voltage given to them.

Batteries are a problem, but in our tests, wrapping the batts in low density foam, and placing that package into a higher density foam (like the stuff smaller flight cases use for cameras/Txs/telescope parts etc). However, we have not run our rig above 500rpm, as its only MDF and angle ali put together in a bit of a rush. Also I feared for my life when running it at that speed.

Another interesting factor to note is tyres- use tyres towards the springier end of the spectrum, because theyll give some suspension, which makes the whole thing spin more smoothly- when we tried with harder wheels, and hit a lump in the floor, the thing started dancing around due to the gyroscopic forces, and any hope of steering it went out the window- the only way to recover was to spin down then spin back up agin.

The most importent part of the design is undoubtedly getting the cam mechanism as smooth as possible. We orgionally had a piece of ali mating onto the cam. Whilst it was a nice, smooth sliding fit, and whilst translation was acceptable, putting a bearing in to slide over the cam made a world of difference- it massivle reduced the counter torque being transmitted to the NavBot (due to much lower friction).

As mentioned, Im toying with ideas for doing it differently, as I dont really want to copy whats already been done- afterall, theres really no fun in that. Making a translating spinner the way Wyachi have is really nothing more than a money spending exercise, which is dull and boring and not what the sport should be about imho.#

All the best,
Eddy

No problem re. the link - at least I got to see what RR had covered recently. Looks like I missed some interesting articles (I read a few that come in to newsagents, but my fiancee would kill me if I subscribed.)

Guess youre right about the 30Hz problem - originally discussed wrt Stinger-esque robots, which only rotate at 2-3 times/sec; the problem is exacerbated for feathers, of course. Still, methinks there ought to be a way. Ill have to ponder on it.

If youre sticking with the cam and are using a navbot, I should clarify what I was saying about motor driving the cam and why I thought the navbot was weird:

Id suggest the cam - and anything else you want stationary - could be connected to the outer shell so that it can be rotated by a low power motor. That is, hold the shell still, spin the motor, and the cam twirls round. Then put a gyro on the same stationary bit as the cam, and make it feed the small motor. There might be some issues in coping with the amount of gain (although the relative voltage change is small), but the principle is there - spin the shell one way, spin the cam the other at the same speed. Receiver drives this small motor, obviously.

Nothing needs to be in contact with the ground, and since you can attach the spinning motor to the outer frame (although not mounting it centrally might be fiddly) you get more weight spinning. Strikes me as easier than a completely separate sub-robot, which is why I thought it was weird. Maybe theres a good reason for not doing it this way.

But maybe you didnt mean a navbot in this sense anyway. (Apparently this might be a good thread for not assuming we all know what we mean. :-)

--
Fluppet