Watch this space, hoping to come back bigger and better.. well only if we can get the maooosive cnc mill working :twisted:
Will be going back to the orignal design but with a more powerful punch.
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Watch this space, hoping to come back bigger and better.. well only if we can get the maooosive cnc mill working :twisted:
Will be going back to the orignal design but with a more powerful punch.
Right pretty much got the stats in my head. Could not get the mill working yesterday but when we do I might be able to take requests for parts but that's just an idea at the moment could be a year off.
Also can someone point me in the direction for the latest rules, and what are the current opinions on lipo? are they allowed and what are the limitations. I would like to use a decent brushless system but A123 won't suit my application.
Was going to link you to the rules page on the main FRA site but having read them, they haven't been updated since June 21st apparently (although they may currently be getting re-written to incorporate recent changes). The main thing missing is that HWs now need to be on 2.4GHz and FWs have to be on 2.4GHz from 1st January 2011.
Lipos are currently allowed in feathers with rules such as 2mm minimum thickness baseplate, charging box for them, bag of salt (I think?) handy incase of fire etc. I'm not too clued up on them though. Grant, Dave M or Kenny could probably enlighten you more on that.
Nice to see you coming back into it. Haven't met you before but pictures of your robots helped me quite a bit when I first started designing my drumbot. Good luck with the build
Have the lipo contained in a secure box inside the robot. You cant just cable tie them down or strap them down. Always charge them in a lipo sack. Have a container of salt with enough salt to cover the entire lipo incase of an accident.
Well I will be needing a new tx anyway so 2.4GHz it is, anyone recomend which to go for either a Spectrum or another brand with 2.4GHz module?
As for LiPo i've really been in touch american bot builders and seen their rules as they are more common over there than the UK. They seem to be ok with them, charging them in LiPo sacks and making sure they have the correct fire fighting equiptment and thats it.
Spektrum
My understanding is that for a fire you require either sand or a dry powder extinguisher to control the flames. But a damaged cell will require being submerged in salt water rather than just salt, as the water will flow where the salt on it's own cannot reach.Quote:
Have a container of salt with enough salt to cover the entire lipo incase of an accident.
Jamies pretty much got it right.
Salt water is better then just plain salt if they go up,
Charge them in a lipo sack
Id suggest always balance charging them- its not a rule but its not alot of effort to do
2mm base in the robot
battery box is best- foam lined
as with anything make sure its all insulated
dont charge/ discharge above or below manufacturers spec
put a fuse inline with the lipo thats rated below its max discharge rate- (if your lipo can give 125amp put a 100amp fuse inline)
Low voltage cut off - (abit of an undecided rule at the moment as aparently there hard to find-360 has them built into the esc's)
When your done with the lipo and you want to bin it fully discharge it and pierce it, then place it in salt water.
..theres probably somthing ive forgotten, im tierd.
I was told the low voltage cut off was more of a 'nice if you have one' than an actual requirement, I'm using one on the featherweight drive but can't seem to find any weapon switches that have them built in.
The plans are to have them in a vented hard case anyway to protect the other components more than anything incase of an incident. Does a 2mm thick cardboard base plate count?
The design is going to be similar to the first MDF version of Conundrum, two main side rails slightly different design but much lower. Joined by cross members which will support the components, i'm thinking of either using 10-12mm Nylon 66 or pocketed aluminium for these. Then alittle armour on the outside to protect the wheels.
I'm alittle undecided on what to make the drum out off, until I get some parts together I won't know what weight I will have to play with but i'm thinking about something custom made.
Battery may be LiPo just for the weight saving, as I believe A123 are only really good for a current burst of 138A which my system my exceed at some point. To make sure the brushless is as efficient as possible I need to get a pack which will be able to cope and not limit the performance.
Drive motors are a conundrum at the moment as I need something like a drill motor but capable of handling high voltages which are reliable, gear box's will be custom machined like Conundrum Mk2's. Drive system isn't really planned out just the frame and weapon.
hi
i not sure a cardboard base would be suitable in any robot-it's hard to sense sarcasm on a forum post so sorry if you meant it as a funny comment and i'm missing it
i think the 2mm base has to metal nothing else- definitely not cardboard
speed 900's with some good gearboxes on can cope fine with high voltages
:rofl: :rofl: :rofl:Quote:
Originally Posted by psycho_fling
Yeah I think Chris exhibited the classic signs of sarcasm in his post :)
Imagine a brushless drum fw, the amount of shocks going through the chassis and then picture a 2mm cardboard base on that. The words epic and fail would spring to mind in that case :P
To be fair, we didn't actually say what the material for the base was, so yeah its a 2mm minimum thickness metal baseplate :)
I would of thought it was painfully obvious but then again i suppose things should be made idiot proof.
cardboard + lipo fire = bad idea.
Well if I could not use cardboard I was going to think about asbestos board about 5mm thick.. but since you say it's got to be metal then it'll be around 4mm steel/ali/hardox or similar. :crazy:
Asbestos board + lipo fire = really bad idea! :twisted:
On Jamie's point the chassis is the main structural element, the way it's being designed the top and bottom plates won't provide any support or have anything mounted to them. Just there purely to stop people poking my expensive bits with an axe. Should be a long way away from epic fail.
As for drive motors I think the Speed 900 is out of the question because of shear weight alone although it should run 40v. I'm looking at a Thunder Power 8S pack so i'll be running around 29.6v unless I use a 24v motor and set the controller trims, think i've heard of people doing this before. How well does it work?
Setting travel limits on the transmitter works well. Did it on hornet recently. I was using an 8 cell pack of A123s but my drills were only of the 12v mark or thereabouts so I ran them at 50% and they handled it fine.
With A123's having a limited current burst i'm looking at LiPo's which can provide +200A, but what is the verdict on them and are they worth buying because I know some US competitions have started to pull them out of there larger weight classes like the 30lb's. Mainly due to venue issues like fire and large plumes of smoke which would set of a venues alarms meaning an evacuation of the building and canceling a show.
Quick idea of the rough spec so far..
- - 4kg Drum (we'll see)
- Around 5hp brushless weapon motor
- Bosch 35w's for the drive motors, rate limited
- 3800mAh 8S 29.6V LiPo (see post above)
- 200A Brushless ESC
- Milled Ali & Nylon chassis
..think that's about it.
What brushless esc you going for? and what gear ratio from what motor?
The motor is only a low 170Kv so with 8S it's only going to be running 5000rpm so i'll leave it at that I think. But going back to the battery issue I might go for a smaller controller as alot of these brushless motors never really reach there peak power unless you spend £££'s on a big brand like Plettenberg or Neu. The one i'm waiting for is rated 5500w but it will realistically reach 4000w if i'm lucky.
what esc and voltage?
Id suggest running the motor below its rated voltage..
I ran my old scropion 6s motors on 6s and 2 of the 3 phase wires melted themselfs :)
Id suggest getting an esc rated a fair bit over what you'd expect to pull.
The motors max voltage is 48v, a 8S battery provides 29.6V so it will be running just over half the max rated voltage. R/C aircraft forums report a peak of 125A.
Flight Power EONX 30 8 Cell Pack
- Voltage: 29.6V
Cont Discharge: 30C (114A)
Burst Discharge: 60C (228A)
As parts arrive i'll have more details as at the moment untill key conponents show up I don't know if i'm going to fit them all in the weight.
The new range of Flight Power Batteries dont sound all that great from recent reports (reports of using cheaper cells). The newer Hyperion G3 cells would probably be your best bet, or the new Thunder Power 45C cells, although abit pricey.
Always get a higher capacity than you would generally use, just to make sure your dont over discharge them and and up ruining the cells. Its not dangerous, just not good for longevity at all.
Go as high a voltage as you can on the motor, I would probably look at 10cell and gear it down a fraction. Brushless dont like un nessasary loads especially on start-up, so a better gear ratio would help your motor alot i think.
Would agree with grant Ive owned flight-power, thunder-power and Hyperion from experience id say thunder power are the best, Hyperion a close second and flight power..were pretty pants.
the new thunder-power 45c range look awesome, there pretty light as well.
8s sounds like a good plan... i don't think 10s is needed, i've been ok running on 4s until now!
If you haven't already checked out ESC's take a look at castle creations new ice line. Ive just had two ICE 160HV's arrive, i know of people using the ICE100's and from what Ive seen they seem to be the dogs, the inbuilt data logging will be very helpful as well helping to maximize your machine... but they come at a cost. but the service castle offer is second to none.
I've been looking at all sorts of different cells Thunder-Power 45c's would be nice but I cannot easily source a single 8S pack in the UK.
TP-3800-8SP45
- Voltage: 29.6V
Max Continuous Current: 171A
Max Burst Current: 342A
I had look at the Castle Creations Ice range and read some poor reports with bigger brushless motors, the 160 Hv is only rated at 160A burst not it's constant current. Also they a note that the burst current is with a 5mph air flow. So for the price your getting more tech but less spec, I cannot justify the amount of money to another decent brand of controller with the full spec.
Ok a drum motor has arrived but I think I under estimated the size of this thing, its a Turnigy 80-85-B and I think I may have gone alittle overboard. Looks like this motor is going onto my pile of rusting bot parts and i'll go find a sensible Scorpion motor. :oops:
Heh :P That happens sometimes, you could always sell it to one of the other spinner guys and get some of your money back...or build something else, when I started with ants I accidentally did the opposite and ordered a motor that was too small, so I just scaled the robot I was building down to fleaweight size :)
Right i'm back on top of this, i'm going to shelf Conundrum Mk2's design with the drum and wedge and skip straight to my next idea which is a completely different concept but still using a spinning drum.
I'm still looking for a suitable battery and still welcome to suggestions it's going to be a squeeze. But if I can build around an EV Warrior and 24v BotPacks with mild success i'll be able to use this monster brushless. Not sure about gear ratio yet.
ESC i'm looking at the moment is the Jeti Spin 200, overkill maybe but i'd rather spend money on a decent one than worry about burning out a medium cost controller in battle. I can always scale down and sell on parts if needs be.
I have also sourced a nice aluminum tube for the drum. I started thinking about Hardox but I don't see any simple way of forming it into a balanced tube. The Ali tube has a 1 thick wall so I can see what weight I have left then I can mill it to suit and fit some heavy duty teeth. Again i'm welcome to suggestions to what material to use for the teeth.
Jeti Spin 200 is going to be dropped, other than Castle Creations Ice range what other contollers should I look at?
Finally decided on a weapon controller, mainly because it was a bargain. It is a Castle Creations Phoenix ICE 200. The controller was on sale on a US website I stumbled across and I got it for under £185 inc shipping from the US. Sadly it was the last one as they was having a clear out sale otherwise I would have got some spares.
Also received the Bosch 35w's, is there a brass gear mod or something for these motors to make the gearbox's more reliable?? I recall something like that. Also waiting for the Sabertooth to arrive so I can start mapping out the internals.
Most of the parts are coming together now. Only problem is i've contacted all the Thunder Power suppliers in the UK and none of them can get me the 8s pack I would like so i'm wondering if I can order it from overseas.
All the parts so far, just need some batteries and material to start work...