Some advice on spinners, please...

ive started planning a heavy weight robot, a spinner can anyone recomend a good motor to use to power the spinning propellor? oh and what grade os stell and what thickness would you surgest for the blade?

The advice.
The motor you want to use is the biggest and most powerfull you can pay for. Bosch 750, with the whole works to get them rugged enough is the bottom line these days.

For the blade, I imagine you want to use a spinner like Fluffy.
So, the best grade of steel you can find, as thick and wide as possible in the weight you have for that.

I myself would use a series wound motor from an hydraulic pump or winch- or a rebuilded car startermotor.Overrun on 24 or 36V-what comes first and is affordable on weight.Just relay switched Albright SW80B 24V ,and on seperate batteries, Hawker SBS 8 sounds just fine.
Timing belt drive, 3/1 ratio, with spring loaded tensioner.
The blade itself, mounted on 2 6310 bearings in mount .2 plates Hardox 12 mm- or simular steel-, 700mm long, 100 wide.Bolted together with a spacer between, so the weight goes up and the stiffness is garantied.

Budget spinner a la carte.

But if need to ask this simple info.. consider it again please.

Hard to say what size motor you need without knowing how bigger disk your planning. A tiny little one about a 100mm diameter or a massive 600mm diameter one.

I myself have built a spinner (check out my profile for a pic) and the biggest problem you will find is that there are very few events where you can run them because the arenas arent up to it OR people dont want to fight spinners. (To bloody right I dont want to fight spinners myself unless their is some substantial reason to do so). This is going to be even more of a problem if robot wars the TV series has as it appears demised.

If your still intreseted in building spinner despite the risk of hardly ever being able to use it Im only to happy to advise you. But hard to say more without knowing the sort of size of disk your thinking of. If you can tell us this Im sure there are plenty of people about who will be happy to advise you.

Richard Wenman
Team Mayhem

my advice, never, ever, underestimate the energy involved in a heavyweight spinner.

i can vouch for that one james!

But yes, it would help daniel if you gave us a few more indications of the size of the disc or blade that you intend to build.

Dont be put off by the whole you cant run them at live events arguement (no offense intended Richard) as they provide a heck of alot of fun and you can always enter the robot without the disc running.

Yeps, Pulverizer, our Dutch Elvis powered spinner is at the most Dutch and Belgian Live events. And will run without disk, against everybody? Only the high power flippers like Gravity are asked to keep the weapon off.So it can still be a real fight, and not a tossing party.

Twisted metal, another good Dutch spinner, did go further ,and fitted a linak scoop/fork in place of the disk.Still a fearsome opponent.-I missed that one in Series 7.

Are you thinking of Twister?

No offense taken Gary. And it is true that you can go to events and not run your disk as I myself have done. The other option is to design interchangable weapons like a scoop or maybe some pincers etc

I just wanted Daniel to know the facts before he goes to a lot of effort designing a disk weapon which he can seldom use.

I still think spinners are great and am half way through a complete rebuild (including new body) despite what Ive said about them.

Richard Wenman
Team Mayhem

Nope Christian, Im talking about Twisted Metal.Not Twister-that one was in series 7.
And I must admit, I was forgetting about Meshugah an ICE driven vertical spinner, using a turbineblade from a F16.Also a nasty machine.

Theres actually more events now allowing spinners to run than there ever has been in the past.

This year alone we have or have had:

Enginuity Robot Crusade
Debenham
RAF Cosford Robot Crusade
FRA World Championship

And thats without the ones we dont yet know about.

Its becoming a far more regular occurrence than it used to be.. and there are plenty of roboteers who actually enjoy the challenge of taking spinners on.

Dont be put of from building Daniel, theyre a great entertaining and fight winning option.. do be aware though that there are problems from the safety point of view, dont ever underestimate one!
As to building a truly effective spinner.. well I can count those so far on 1 hand!

Sam

Just out of interest Sam, who do you rate? (Im not fishing - you understand ;-)

Si

oh and what grade os stell and what thickness would you surgest for the blade

perhaps look into getting something like hardox (our hardox cutters only need a slight sharpening after series 7) and put as much weight as far from the centre as possible. A simple experiment with a set of compasss can show you why.

1) Spin the compass with the legs shut
2) Spin it with the legs fully open

You should definately feel a difference between the 2 and so this gives a simple demonstration as to why to get as much weight to the outside as possible.

Simon

Hmmm, I think Ill have to skip that one.. could be a real can of worms :)

I think our friend Gary here could certainly claim to be one of the few at this point though!

Sam

For a future project I am getting a disc custom CNC milled. But I am wondering would it be better to have the teeth cncd onto the disc (as in non removable) or should I use bolt on teeth?
What are the advantages and disadvantages of each?

Regards
Ian

we currently have welded on teeth on typhoon 2 and typhoon. The guys that did it for us did a very nice job and the cutters havent let us down.

At extreme 1, we had bolts coming out the side of typhoon and all of these were either sheered off or bent. This is the main problem with removable teeth is that the weakest point on them is always going to be the join and it could result in an unbalanced disc, however it does mean that you can change the cutters. Eg -have one set which are designed to cut and another designed to smack.

Bolt ons also mean that it is easier to change teeth if they become mishapen

It does of course depend on materials etc but as long as bolt on cutters are supported well enough there should be no problems with them.

But its up to you!

well the blade from top to bottom will be about 1m so ill need a very fast motor to put alot of energy into it, before you say it i am going to build my robot so that it can take the shock when it hits an opponent, ive looked into shock mounting and im confident that the robot will do more damage to its opponents that it does to its self. oh an by the way its not a disk its a proppelor spinning at about 45 degrees kind of like the one the six million dollor mouse uses.

our friend Gary here could certainly claim to be
Id agree with you there!

Daniel,
so that it can take the shock when it
hits an opponent
One other thing you need to consider besides the shock, is the reaction torque when you try to steer - you will notice this most on fast/heavy (high angular momentum) disks - and most particularly when they are not horizontal.

I would say most spinners have welded on teeth - and I know one or two have moved from bolted to welded. We of course, having steel teeth on a plastic drum do not have that luxury! If the placement and type of bolts are appropriate - bolting will not be an issue. It gives a number of advantages like being able to make rubber teeth for friendly fights and being able to taylor the tooth profile to different opponents.

Si

Supernova still use bolted teeth.

Supernova still use bolted teeth

and break them/lose them in almost every fight!

Id personally go for integrated teeth if I were you Daniel, bolted teeth need to be incredibly well mounted (to the point of almost impossible) in order to stay put when the energy transfer occurs.
The only problem with integrated teeth is that youll need to make sure theyre the right material, as the last thing you want is to have to replace the whole disk every time a tooth chips!

Sam

Daniel if your looking at a 1m diameter your looking at a serious amount of energy (dependant on the speed its doing). The key thing with a spinner is to get it upto speed quickly so you dont leave yourself open to attack.

What speed are you planning to spin this thing at since the energy is related to the square of the RPM.

E=0.5Iw^2
E=energy in disk/propeller in Joules (I aim for around 14000J)
I=Polar moment of masses kg m^2
w=angular velocity in radians per second (=2pie x rpm/60)

Assuming you are spinning this at any sort of speed youll probably be looking at Magmotors, Briggs & Stratton, Lynch motors or a petrol engine.

Richard Wenman
Team Mayhem

Ian, since you are getting the disc CNC milled, you should be able to machine slots in the disc for the teeth to slide into. If the disc and teeth are appropriately keyed, the bolts should not take any significant load from an impact.

Sorry that should be I= Polar moment of inertia of masses. For a rectangular plate
I=M(a^2+b^2)/12
M=mass
a=width
b=length.

To increase the I value you want to make the propeller broder at the tips.

Also you want to make it of pretty thick material to stop it bending. Mines 12mm thick steel and Matilda still cut through it and bent it slightly up where she hit it.

Richard Wenman
Team Mayhem

richard, what grade of steel do you use for your disk?

I just used standard mild steel since I figured that this would be strong enough in 12mm thick.

Oh boy was I wrong.

What sort of speed are you looking at for this propellor Daniel?

Richard Wenman
Team Mayhem

We use Mild steel aswell. Matilda managed to bend our disc slightly aswell, its 33mm thick at the rim!

Not to mention the contact with Mechaniac that had some effect on the teeth.

Gary

Consider an IC motor like ours for Executioner.

The advantage of our IC is that it weighs 3kg and yet still spins the disk to over 8000 in 2 seconds from dead stop. Another advantage is we dont have to carry any extra weight for batterys to power an electirc spun disk! This leaves us more weight for ARMOUR.. A good quality chainsaw motor will never cut out and will start everytime first time. It will also quite happily run in any orientation even upside down too.

The downside is price :sad: I paid 300 I think for the Stihl! So not cheap I know.

We have learnt our lessons from series 7 and now sport a new very tuff scoop at the front and also an aluminum hub for the disk itself with bolt on blades. This has enabled us to increase the reach slightly of the disk and also lessen the weight overall. Along with the new speed controler from here (Anyone want a secondhand vantec?)

http://www.roboteq.com/index.shtmlhttp://www.roboteq.com/index.shtml

We HOPE to at least once manage to get past the first bloody round :sad:

If you know what youre doing, you can get some chainsaws to peak at over 20 horsepower! There are already some teams who have done that with a chainsaw from the Swedish Husqvarna.

I see Whyatchi superheavy i think uses 2 15hp ic engines.

im planning on using a small chainsaw in my featherweights spinning weapon.

did you have to modify the clutch to take a pulley/sprocket and if so how did you do it?

anymore info you can divulge on petrol engines?

thanks, glen

Hi Glen

Yes we had a clutch and sprocket made up because we had to lose the chain one that came with the saw. We also seriously chopped the motor down and lost all its brackets and handles etc etc

Mark

Any use?
http://tziscooterworld.evodesign.com.au/motorized/tzi1/http://tziscooterworld.evodesign.com.au/motorized/tzi1/