I think 180 and 360 should do a dance video... for other fat lazy robots to work out too :)
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I think 180 and 360 should do a dance video... for other fat lazy robots to work out too :)
would be a hat-trick if you could get hypno-disc to lol
Got a bit of 100mm x 50mm aluminium box section and have now mocked up a bit of a chasis for the kilobot (it weighs about 500g so far so this one might just get in the weight. I have a few lipos which i got a while back which are 11.1v/800mAH/20C.
I have one of these kicking around and looking at it it'll fit and it still leaves quite a bit in terms of weight for a drum on the front. http://www.hobbyking.com/hobbyking/stor ... oduct=4909
Firstly I reckon it's a bit overpowered for both the battery and the robot but would like some idea on peoples views. Never used brushless before so just getting an idea for it.
Also I will be using a car type fuse as a removable link and would like to get this sized properly for the lipo. I was thinking about 20A would be sensible but again some advice would be good.
to compare the motor for the disc in 180 weigh's 45g so yours is a beast of a motor lol
So a bit big then?? might just use one of the brushed ones I have then and use the weight on the drumQuote:
Originally Posted by teamkenny
Well your battery at 20C can kick out 16A, and that motor draws about 50A, so yes far too big for your robot. The Speed controller for it would be pretty heavy too i expect.
I would look more towards either a much smaller brushless or a brushed motor with somethijng like a battle switch to turn it on and off.
Yep got the message!!! So would a 20A fuse on the battery provide enough protection or would I be better off going for a 10A or 15A................or is it just a case of try a 10A fuse and see if it blows under normal use?Quote:
Originally Posted by grant_ploughbot
I'd say use a 10a automotive fuse and see how you go. Auto fuses don't blow at there stated rating. I'd suggest a smaller motor or a bigger lipo though.
I'm interested...............exactly what is the purpose of the fuse. I am talking from the point of view of the technical reason. I am well aware of what fuses do but just want to know the purpose of it and what type of current it is overload or short circuit or both.Quote:
Originally Posted by mr_turbulence
The reason I'm asking is because if it's to protect against overload then the fuse size is significant, if it's to protect against short circuit then it's not as significant as the short circuit current would be massive in comparison to the normal currents used from the battery.
(got the message on the motor size :rofl: )
Andy
The fuse is to protect your robot from pulling more current then the maximum discharge rate of the lipo. Over discharging a lipo will cause the cells to become damaged, which in turn can cause ignition of the pack.
Right, so just making sure I understand this properly (not necessarily for this, just that it's good to get an idea on how to size the fuse for future reference):Quote:
Originally Posted by mr_turbulence
- If everything is sized correctly and runs at a lower current than the battery can deliver then there is not too much of an issue with the fuse. Meaning that the fuse doesn't need to be selected for overload on the equipment.
- In the event of a short circuit or motor stall where the current can become considerabley higher than the battery output for long durations then the battery needs to be disconnected quickly to avoid damage etc.
- The fuse needs to be sized pretty much to the maximum output of the battery (in this case 16A output=15A fuse) BUT considering that the fuses do not blow quickly at their rated current it's necessary to de-rate them so they will blow relatively quickly and disconnect the battery ASAP.
Had a look at the data sheet for the fuses and it is relatively clear what you say about automotive fuses:
http://octopart.com/atc-10-cooper-12063#datasheets (Click on link to AT10 data sheet)
Seems that a 10A fuse would take about 1 second to disconnect at about 18A, with a 5A fuse taking 0.1second at 15A.
May start off with a 5A fuse as the drive motors draw nothing and in reality once the motor is up to speed for the spinner then the current draw on that should be minimal. Quite shocking actually as a 15A fuse doesn't seem like it would blow at anything less than 20A and even then it'd take almost ten seconds.
Sounds like a plan.
You should be sizing your pack in order to make sure that your electrical system WON'T overload it, so the only cases where the fuse will become important is if there's a short in which case the fault current will blow it close to instantly.
Quote:
Originally Posted by Metal Demons
Yup, but you also need to consider that the fuse should blow as quickly as possible in the event of a short circuit.Quote:
Originally Posted by widow_twanky
The short circuit current is limited by the ability of the battery to deliver current so if the fuse is too large it either wont blow or will be slow to blow.
Personally I'd rather clear short circuit currents in the shortest possible time (having had a 300mah lipo start swelling on me before and realising that when you say to people 'get out' whilst you deal with it the natural tendancy is for everyone to come into the room and have a look :rofl:). As I recall, tas soon as you remove the current the swelling of the cell stops meaning that if it hasn't exploded by then, it wont. Apart from that short circuit currents aren't good for stuff like speed controllers, receivers and stuff.
If the lipo hasn't exploded by the time it's been un plugged it doesnt nessasarily mean that it's safe. It can sometimes take upto 5 or so minute's for a lipo to catch fire after a short even when disconnected.
The fuse it to reduce the biggest risk of lipo fire's which is shorting them out for prolonged periods.
Well that's not good is it, suppose that's the reason for the rule saying you need a bag of salt to cover it in if it gets affected by stuff like that. Makes sense really.Quote:
Originally Posted by grant_ploughbot
Any news on when we might have an arena to fight these marvelous beasts?
The arenas Built we just need the polycarb sides
Lol, kenny you've tempted me to make a fail antweight version 90 xD
'The arenas Built we just need the polycarb sides'
How much do you need and what thickness?
4off at 10mm thick , 2m long by 1m and a 2m by 2m lol
fail 90? a mini version of 180, the mini version of 360 which is a mini version of Hypnodisc?
Dunno what to call mine...Megadrive or Chuck Norris?
Chuck Megadrive?Quote:
Originally Posted by mr_turbulence
MegaNorris?
Chuck Norris FTW!
2 New Rules for this class,
A Ban of rambots (pushers) without a active weapon will be enforced in this class
Shufflebots will be Allowed 150% weightlimit
For the arena to be 100% finished we need
4 sheets of 10mm polycarb 1975mm x 800mm
2 sheets of 10mm polycarb 1000mm x 2000mm
6 Strips of 3-5mm polycarb 50mm x 1000mm
After we get the polycarb we have to cut a doorway into 2 of the 1975mm x 800mm sheets.
I have been thinking about it and maybe if we double up on 5mm polycarb it will be better. That way if the inner 5mm gets damaged its cheaper and easier to replace.
I know on this size arena 10mm polycarb all round is way ott and fw arenas dont even have to be 10mm all over but id rather it be way ott then I can run my feather in it.
Also it has removeable 50mm high inner arena walls so theres an out of the arena area . What would you guys prefer having arena walls like robot wars or just a box arena like battle bots?
a box style arena with no outs would be cooler
So the kilobots are really taking off? or is the arena just for various classes? and where are you situated? SO MANY Qs clearly having a nerdgasm
For the arena to be 100% finished we need
4 sheets of 10mm polycarb 1975mm x 800mm
2 sheets of 10mm polycarb 1000mm x 2000mm
6 Strips of 3-5mm polycarb 50mm x 1000mm
After we get the polycarb we have to cut a doorway into 2 of the 1975mm x 800mm sheets.
I'm having trouble visualising this. Are the 4 sheets of 10mm polycarb 1975mm x 800mm the sides? If so, why does it need two doorways?
Are the 2 sheets of 10mm polycarb 1000mm x 2000mm fpr the roof? Given the cost of 10 mm polycarb why not consider making the roof of weldmesh with a secondary screen over it to catch any small bits?
A plain box with no internal arena seems the best approach to me; I've seen fights in a bare 8 foot by 8 foot box with this class and they were spectacular.
all the odd sizes are so they fit into the bracing bars etc , i like the idea of the welding mesh
The arena is just a 2 meter by 2 meter box with an 800mm high roof. The arena is on legs so the arena floor is 1 meter from the floor just to make loading easy and stuff really.
On the arena thing i'm going to be awkward and say I think a robotica style arena could be interesting. With sides which come down after a while. It doesn't need to be suspended 10ft above the ground though.
'i like the idea of the welding mesh'
I am trying to get some 10mm polycarbonate for you so the arena can be finished and put into use. Could you live with a roof of welding mesh and plywood for one of the sides [say the loading door side]? That would cut the amount of polycarb required in half but still give good light and visibility. Contact me directly if you want to talk this over.
If i were you Tom - knock the roof down to 5mm. like you say 10mm is OTT even for the outer screens, but if your running feathers for testing then 10mm is safe. Any form of meshing/netting/fabric roofing has been proven to by insufficient for any form of arena protection sadly. You would be amased how effective just 3mm polycarbonate is in comparision to other materials such as high quality plywood.
Just FYI, 3mm polycarbonate is about equal to 18mm plywood in terms of stopping projectiles (if a large enough sheet is used then much better than 18mm ply).
Realistically, to be safe for the kilobot weight limit i would recomend about 4mm sides and 3mm roof as a realistic thickness in polycarb if you werent testing feathers.
Also, if your having a battlebot's style arena, it's still worth having a reasonable distance from your inner walls to your outer screens (even if by a raised platform to drive back in) as it will stop your oter screens getting hit all the time and therfore wont get scratched and damaged so easily.
I asked someone in the US who runs an arena for Beatleweights what wall thickness he used for his. He said that damage to the walls from weapons was a problem and so he used an insert with 20 cm high sides and allowed 15 cm clearance between it and the sides. He uses 6 mm polycarbonate for the sides and roof and doubles it up for the bottom 30 cm of the walls to allow for machines that get thrown OOTA but are still runing. His arena is a bit bigger than the one being discussed here but I think you could get a 180 x 180 cm insert into the one being discussed here and still leave 10 cm clearance around the insert edges. A picture of the US arena can be seen here: http://www.calbugs.com/CIB%20Arena.jpg
Hi. I just remembered I have a set of tracks, they're pretty buckled but in good condition otherwise. They're about 3cm wide and 18cm long (depends a bit on hub size).
http://www.mutr.co.uk/images/track.jpg
Would this be at all suitable for this size bot? They're quite durable, nice and thick.
Here is a fight between two 3 lb machines that took place in the US last weekend:
http://www.youtube.com/watch?v=nRz2INC4tmQ
Wow. The one with the spinning weapon was impressive but I must say I was more amazed by the other robots resilience. Fantastic fight.
Can't help thinking that if there were a pit the wedge would have one in seconds.