Quote:
Originally Posted by mattsdragons
Printable View
Quote:
Originally Posted by mattsdragons
what?
I'm as confused as you harry :lol:
Ok, just to clarify
By private fight I meant battle between robots not as part of a competions but private. I quoted matt to say it was not an actual event but a private fight afterwoods
Happy?
Good, now can we get back to answering my questions?
Just to get back on topic, could I make my own controller for the drum with a servo and micro switches?
use a battle switch and one of these
http://cgi.ebay.co.uk/Automotive-Relay- ... 1e6344df4e
or one of these
http://www.jaycarelectronics.co.uk/prod ... BCATID=754
The second relay is more expensive however it is far more reliable as it is a solid state relay (no moving parts). The lack of moving parts means that there is no chance of the relay fusing when it switches over (the spark that comes when you connect wires). I would not recommend a servo because it isn't an iron clad failsafe when radio contact is lost.
Boner, when it used speed 900s, used the solid state relay and a battle switch (battle switch to interface with radio gear and switch on the larger relay which directly controlled the motor)
i am conserned that those second hand batteries will be knackered so want to buy a new set. i came across these:
http://www.batterymasters.co.uk/Product ... _1916.aspx
would they be able to do both the drill motors for the drive and the speed 900s for the drum? I was not sure if they would be able to deliver the amount of current needed.
Thanks
Max
i'd say shove in a lipo
If a speed 900 is too expensive then lipos will be well out.
Those batteries will not be suitable. They are designed for standby applications where the current draw is minimal so they won't be able to supply the current. The second hand ones that Ed is selling are a good deal. Knowing Ed he will have only used the best chargers to charge and maintain them.
i will buy the 2nd hand nicds and i will buy speed 900s for the drum,
where can i get a v-belt pulley for the speed 900 and what type do i need?i will buy the battle swithch from robochalenge and the other relay as well.
Hi
could i use this as my second relay (in conjuntion with a robochalenge battleswitch) to control a speed 900 motor to power the spinning drum:
http://www.halfords.com/webapp/wcs/stor ... e=shopping
the 100A relay of jaycar looked way to expensive for a relay
and again, what gear ratio do i need between the speed 900 and the drum?
thanks
Hi, where do people get the pulleys and belts from?
Technobots
I use rs components for mine. Less than 2 quid for a replacement belt
O and you can pick up dirt cheap relays on ebay. Do a search for 24v relay and look for one in the 30 to 40 amp range. Seen them for less than 2quid each
You can also get relays for a quid each from a scrapyard :)
Getting ones that can handle 24v from a scrappy might be tricky
Hi,
I've got most the parts for the robot apart from wire, connectors and relay which are on order from Jaycar electronics but have not arrived yet(even though I've been waiting for 20 days!)
I have bought the 12v sanyo nicad batteries but don't know what I need to charge them? I've got an overlander power rc 6s charger but It looks much smaller than the ones shown on this forum.
Also, I have calculated that I've got around 1.5kg for the drum and have figured out that if I use steel it will only be 1.5mm thick, will this be strong enough or should I make it out of aluminium?
Thanks,
Lol they're coming from australia so it's not surprising on the time!
You need a charger that can charge nicads/nimh. As long as it can charge a 12V pack it should be fine as long as it can supply around 2A to the battery pack. Could you pop up a pic of your charger?
What diameter drum is that for? What style of teeth are you planning on using? (ring or bar)
The drum will be 75mm in diameter but 85mm including teeth, I plan to weld on a number of hooked teeth like the ones on a circular saw but much thicker and with only two teeth in a circle, it is quite hard to explain.
Take a look at either boner or drumroll. Are the teeth a similar design? (Jamie has a few in his build thread)
I would recommend a drum material thickness of around 3mm. This is the same as both boner and drumroll and the drums have survived hits with some of the worst spinners in the arena.
My drum design is pretty similar to drumroll's but I defiantly can't afford to use 3mm steel for the drum, it's either 1.5mm or a push 2mm thick steel or 3 or 4mm aluminium ( not 100% sure on the thickness for aluminium as I havn't done the math. Which material do you think would be best?
Then make it 2mm thick. Not only will you have a hard time welding to 1.5mm without blowing through it, but a vertical hit to it will make a decent dent if not go through. I'd also advise stainless steel if possible. You can pick some stainless tubing up pretty cheap on ebay (it's used for those stupid boy racer exhausts).
I wouldn't use aluminium. You can't weld steel teeth to it.
Could I use hardened steel?
Hi, sorry to re-post this but I want to get the drum made soon, can/should I make the drum out of hardened steel?
Also do people use some kind of glue as well as screws to fix hdpe together?
what do you mean by hardened steel? Mild steel that's been tempered or some other material?
Glue's don't work well with HDPE. The best way to join it is to heat it up and melt the edges of the panels together.
I mean heating then cooling the steel drum once it's made to strengthen/harden it
Yeah sure, should be fine. Just make sure you temper it to the correct hardness. You don't want it to be brittle.
Hi again,
The drum is being made and i don't want to start putting together the rest of the robot until it comes in case it is not done to my exact specification meaning I will have to change to design slightly to fit it in.
One quick question, i have (and only have the weight to have) two 12v batteries. Before I thought I would use on for the drive and one for the weapon, now however I want the weapon to run off 24v but still want the drive to only be 12v because otherwise I fear the batteries will run low in the battle and I get no gain as it is not a pusher from the extra drive power.
Is there any way of getting these two voltagesfrom my two batteries?
Thanks
How much ground clearance do you think I'll need because at the moment I will only have a few millimetres and am worried that the bot may get beached on the ground!
What capacity are the batteries?
A few mm will be fine in the robochallenge arena as it is flat. I can't vouch for other arenas though.
They are 2400CR each if that's the capacity?
Because it's a drum spinner it can only compete in robochalenge area anyway so I hope ground clearance will be ok.
I know there are only two robochallenge events a year but when are they?
2400mAh. Those cells should be fine to run both the weapon and drive from at 24v for a 3 minute fight. If you attempt to use one of the packs to power the drive and both for the weapon then you will be discharging one pack more than the other. A potentially dangerous situation.
Would my sabertooth 2x25 be able to handle two drill motors at 24v without blowing up?
24v is a bit of an overkill for the sabertooth, you'll need somethink like a victor 883 or a sidewinder
On dimension engineering's website it says it can take 6-24v nominal 30v absolute maximum, but I have heard that when put to it's limits it may explode, what do people think?
I've never tried it personally on a sabertooth, but going by the specs 2 drills on 24v would be fine on a 2x25a ESC.
Fully charged 24v packs could be getting close to 30v though so might be tight in that sense.
Could I protect it with some kind of fuse?
.....Or a voltage regulator or a Zener diode? Has anyone used any of these devices/components before?
The sabertooth is a nice controller but I have blown two in the past (they were replaced as I hadn't exceeded the specs but was at the limit).
I was running 2 18v drills on 24v worth of nicad cells. The interesting thing being, if I remember right is that the manual states that only 18 nimh/nicad cells should be used, well below 24v. I ran it with 20 cells. Initially the controller was fine but after a minute it blew (nothing beyond moving the robot around).
Stick religiously below the limits and it should be fine
Could I use a voltage regulator so that I only have 12v out of the 24v going to the drive system from the batteries but still have 24v going to the speed 900 motor to power the drum?