How will they perform. Im asking because i see that the 12V and 24V are the same price on technobots.
So will they work ok, what would the difference be compared to if they were 12V ones ?
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How will they perform. Im asking because i see that the 12V and 24V are the same price on technobots.
So will they work ok, what would the difference be compared to if they were 12V ones ?
The 24v version has a better bearing setup than the 12v version. At 12v the Gold should run as low as 1/4 of the power it would at 24v (half the voltage and 1/4 of the current), maybe 40w total power output, keep in mind it would aslso rev at half the speed.
The essential difference is the way the brushes are wound on the armature. Practically the 12v version at 12v would perform the same as the 24v version at 24v (exept with more current draw) were it not for the bearing set-up which consumes more power.
so really, i would be much better off just running 12V motors at 12V, Im a complete novice and i just wondered if it would be better because they would be very understressed and theres no chance of damaging/overheating them. 12V batteries are more in price range anyway.
You can look forward to lots of silly questions from me in the very near future as i try to build my first proper robot :)
Actually while im here.....
I want to build a featherweight based on two 12V 150W gold motors. Im fairly up to speed on how servos/speed controllers/H bridges etc etc work. But what i know nothing about is what is compatible with what and exactly how you connect them all together, also radio control i dont know much about.
So at the moment im thinking of a 4 wheeled robot with rear wheel drive (as i can only afford 2 motors) Would it be feasable to use tank style steering, would it still turn ok, or am i going to have to rig up the front wheels to turn.
At the moment im aiming for a robot i can just drive about, but making it so i can add weapons without much hassle in the future, and eventually 4 wheel drive.
So please help me out guys, i was looking at a 50V 20A H Bridge Speedo would that be good for me or can i get a cheaper alternative, i really need your experience here. Just to go over it again so you an be clear in what i want to build.
1.
4 wheeled robot - currently rear wheel drive but to be 4 wheel drive eventually
2.
just be able to drive about at the moment but be able to easily expand its outputs to incorparate weapons
So i need help on the best batteries to power it, what sort of steering i should use, what sort of motor speed control i should use and last but not least what remote control system to use.
I REALLY REALY APPRECIATE HELP ON THIS AS I UNDERSTAND HOW MUCH IM ASKING HERE
Ok, Ive got to start somewhere, so first Ill cover point 1. You want four wheel drive eventually, but if you put your mind to it, you can easily accomplish four wheel drive with only the two 12v Golds.
You can use gears (which are usually rated in MOD sizes) of about Mod 0.8-1 to get your initial reduction off the gold motors. You can then use timing belts and pulleys (rubbery belts with teeth on them), or chains, to link the rear wheels to the front wheels, or the other way round. A link worth bookmarking is the team hurtz drive calculator: http://www.johnhmreid.dsl.pipex.com/killerhurtz/howto/calculator.htmhttp://www.johnhmreid.dsl.pipex.com/...calculator.htm
It is worth mentioning at this point that you should use tank steering as it is the most manuverable type of drive. Also, most speed controllers designed for featherweight robots, work on the basis that the robot is tank steered with built in features such as failsafing and mixing (the process required for tank steering).
I advise you buy a Skysport 4, 40mhz RC set, complete with Rx which will cost you around 110.00. Once youve brought it, you should find it quite easy to plug into any speed controllers you may buy, and youll have two channels free for when you want to add weapons.
For batteries Id advise you just get some cheap 12v SLA (sealed lead acid batteries) of around 4-7Ah, and then you just need to get a cheap 4Ah or so SLA battery charger.
We run the 24v GOld Motors in Kitty at 14.4v. Kitty is quite nippy, and as its running a 24v motor at 14.4v, the current pulled is next to nothing. We havent blown any 20amp fuses yet. Means batteries last longer, etc, less power speedos needed, and also not as much gearing needed! saves alot of time, hassel, weight and effort, also as its been said, the 24v motors are better built - well the wrong bearing face is.
A 12v gold running at 12v, that will pull a bit of current. I think TKM2 (MIni M2) used 12v motors at 14.4v - and was pulling tons of current and all sorts, needed lots of gearing to gear it down and all sorts, and changed motors right away due to them pulling too much current. We had the same problem with kitty when we got the 12v motors, and quickly switched to 24v ones.
Kitty was the first robot to use the gold motors, and the longest running gold motor running robot. LOL!
So might be an idea to get the 24v version as you can use it at a lower voltage with less gearing and battery power- and can later upgrade grade your batteries/gearing to 24v or whatever to get more speed/power.
Mr Stu
If youre wanting 4 wheels, but only driving 2 of them, just drive the opposite corners rather than the 2 back wheels....... will make for a robot that behaves like a 4WD one, and youll find it runs far better !
Welcome to the forum BTW !
Ed
http://www.teamstorm.comhttp://www.teamstorm.com
well i will definately be getting 12V batteries as they are in my price range, i havnt seen any 14.4 ones. So i dont think the 24V motors will be good for me.
The motors i am looking at are at http://www.technobots.co.uk/en-gb/dept_201.htmlhttp://www.technobots.co.uk/en-gb/dept_201.html are the specs for the 24V version the same for the 12V then ?
I cant work out what kind of speed controller i need. if i am correct in thinking the elctronize range can only handle one motor per controller then is an H bridge going to be a cheaper solution as they handle 2 motors. Looking again on technobots i am unsure which one i would need http://www.technobots.co.uk/en-gb/dept_518.htmlhttp://www.technobots.co.uk/en-gb/dept_518.html I think i could use the first one if i get a heatsink for it, but i am not sure. I dont know what current my motors will run at or what actually controls the current for that matter ?
Also how many batteries would i need ? Coz i see they are listed as producing a certain current for 5 minutes. So i need my current question answer to work this out.
those controllers should be fine with a heatsink. You would need 2 of the electronize, but they do have failsafes were as the H Bridge ones dont (that an extra £20 at least). But i would probably go for the H-Bridge.
SLA batteries are mainly only available in 12v, to get 24v you wire 2 in series, when stu said 14.4v this is achieved by using Nicad or NiMh batteries (better but more expensive). Your battery size will depend on gearing ect, but i would suggest for a pusher then one 12v 4Ah SLA battery is probably enough.
Golds are great little motors, ive used them for years in Alpha and have served me well, but make sure you get your gearing right, ive seen alot of robots with golds that have never seemed to get all of the power out of them, and considering they weigh 800g its alot of weight, to only be using a small amount of their potential.
So where would i find a suitable heatsink and how would i go about attatching it. Is it set up so i can easily screw one into place ?
What would you suggest as a gear ratio to get all the power out of them ?
Also, so what happens if i got two batteries and wired them up in parallel, they would just last longer right ?
actually after playing with that calculator link u sent me Ewan :) how does 7 to 1 sound ? That gives me 10.8mph and 13kgp, 123N, 28lbs of tractive force with 125mm wheels.
Those are solid rubber wheels, good ?
Ah and ive just realised the current the motor draws is due to how hard it is working right ? So what is the maximum the motor will draw, can i limit it to something sensible or what ?
Andrew,
Have you considered the Zeobot motors that they have at technobots. You can get these with gearboxes already fitted. They work well with the electronizes. I have just finished a 4 wheel drive bot that uses two electronizes (one each side powering two motors each)
Have a look at http://www.technobots.co.uk/en-gb/dept_528.html on the Technobots site or give Paul at Technobots a ring/email.
Ian
yeah i had a look at them, but there nothing like as powerful as the Gold motors are they ?
they arent as powerfull, but they are an easier option and you can always run multiples of them. The max current a 24v gold will pull is 25amps, a 12v one in theory will pull 50amps. You can buy controllers with current limiting but it starts to get expensive then, the easiest way of stopping them stalling is to have it so your wheels spin just before they stall.
are you sure a 12V would pull 50, i though it would be 12.5 coz otherwise a 12v has a heap more resistance than a 24v one and i dont see why that would be.
if it can pull 50Amps doesnt that mean that neither of the h bridges on http://www.technobots.co.uk/en-gb/dept_518.htmlhttp://www.technobots.co.uk/en-gb/dept_518.html would be able to cope with it ?
No, power (W) is equal to the voltage (V) multipled by current (A). If you halve the voltage, you have to double the current to get the same output power. The 12V version of the motor will have a lower resistance to allow more current to flow through it.
In most cases its best to go for the highest voltage you can as its easier to deal with higher voltages than higher currents - up to a point. Over 36V is dangerous and would not comply with the FRA rules.
ah ok i understand now.
so will the h bridges cope with that or will it fry them, i thought they were only rated to around 30 Amps
Just a point on lower power motors. I am more interested in manouverability than pushing power. If you have an effective weapon like Vortexs spinner or a good flipper, the pushing ability is less important.
Do you plan to have a weapon?
Ian
Ian,
I know a couple of girls who would take issue with you about the importance of pushing power! :)
But seriously Andrew, Ian makes a very valid point regarding the required balance between drive power and manoeuvrability. Also Jim is right when he says its easier to deal with higher voltages than higher currents My personal preference would be to use the 24v gold motor @24v with a reduction of 6:1 and a 100mm dia. wheel.
This would give you a speed of around 12mph with a reasonable amount of torque. As for speed controllers, with this set up you could get away with a pair of Electonize 30A units and a mixer you can get details of these from http://www.technobots.co.uk/http://www.technobots.co.uk/
It may be helpful to you to try to get to one of the many live events held around the country. Make yourself known to the roboteers and Im sure they would be more than happy to show you their machines, you will see most types of drive systems, everything from the Zeobot motors through gold motors right up to 750w Astroflight cobalt magnet drive units. You would probably also be offered more advice that you would know what to do with.
Check out the live events section of this forum and also http://www.roamingrobots.co.ukhttp://www.roamingrobots.co.uk
I hope this is of some help.
Good luck with your robot.
Geoff.
Hey Andrew, why not use standard drill motors for the moment? they are very cheap and easy to use and you get batteries that you can test it on with the drill. Also for the price you would save on buying gold motors and seperate batteries, you could afford four motors!
If you need ANY help with building or designing then Rc Wars/Robo-Challenge will be able to give you help and advise. We build many robots (6kg to 12kg) and have a fleet of just over 15 at the moment and so we would be able to build any components for you if you do not have the facilities. Where abouts do you live? we have facilities for testing your robot aswell if needs be, and supply electronics if you are uncertain of where to get things.
Grant
Andrew, we have got 2 of those 5Amp (without heatsinks) H-Bridge controllers and have fitted them to 2 of our featherweights. They dont have failsafes, but I dont see why as its only a simple change to the software, I did concider re-programming them but found an easier way, but as it stands you would need failsafes, a PCM type Tx & Rx would do but they are more expensive than the standard ones.
As for the Heatsink, my brother came up with the Idea of using a standard PCs CPU heatsink and cutting it in half and bolting them threw the MOSFETS, these heatsinks are very cheep and on one of them he added a small fan too.
We altered them to work with a 0V-2.5V-5V signal to control the motor speed as they were slightly jumpy with the RC servo signal and the steering reverses going backwards, but so far we are happy with them and will test them out in combat at Sheffield.
One is running on 33.6V with 30V drill motors and the other is running on 19.2V with 12V drill motors, both have a 30Amp fuse on the batteries and has not blown them as of yet.
Current rating is a little difficult to figure out, If you have a 200W motor and your Gear ratio and traction can only deliver 100W before the wheels start spinning then it wont use any more then the rest is wastefull. But if it needs 300W of power to start the wheels spinning then your motor will try and deliver 300W and start to overheat, in time it would burn out if overstressed for too long. So its better to have an overrated motor and not use the power to be on the safe side but at the expense of wasted weight.
The lower the voltage you use the higher current needed for the same power output, also high voltage motors are more effeicnt and as they use less current they also generate less heat.
Well ive already got too much advice than i know what to do with !!!
One reason i havnt considered using drill motors yet is i dont know where to get cheap drills and i dont know how easy they are to get out of the drill.
I live in the north east of scotland (no robot clubs or any live events that i know of round here)
Geoff, would it not actually be cheaper to use a H-Bridge than a pair of electronizes and a mixer ? Feel free to prove me completely wrong though :) Does a H-bridge also do the work of the mixer ?
At the moment im swinging towards using 24V Gold Motors since ive got all this advice. I can only realisticly afford 2 of them though, ive been told i could sort out with pulleys etc for each motor to drive 2 wheels, how practical is this, how expensive would that be and how complicated
Where exactly in Scotland Andrew ?
Put simply Andrew 4 drills would be less cheeper, easier and less current hungry (possibly wrong there!). Getting the drills out is not too hard at all.
And they can be easily moded using doms mod kits!
Regards
Ian
homebase are doing their own make 14.8v drills for £15. :)
I live near Aberdeen in scotland.
How powerful are the drill motors, whats the Wattage for those 14.8V drills ?
Hey andrew i live in Montrose :) not so far away... im a bit sad that there is few robot events for us Scots ;)
fantastic, is that 4 feathers that we now have in scotland?
We should get together somewhere and have a wee battle up north when we are finished building
lol cool cant wait to see little hornet slicing everything . My robot Byte may be delayed a while as i have some exams to do and some serious cramming to do but will get as much done before then .
hey cool, my grandparents live in montrose.
small world...
drills are very easy to modify to get into a robot, but if your not too keen on using them, then pulleys will work great. i use pulleys on ploughbot to get the drive from the gold motors at the back to the front. pulleys and belts could end up costing more than an extra drill or two though(mine do but i havnt researched the average prices for pulleys and belts)
Good look with your robot, and if all else fails, go with Eds ida of 2 diagonaly powered wheels(blue/LH2 ran like that amd performed suprisingly well)
ok ive been doin a little research and i think drill motors would be the best idea for me as they include gearboxes and ill get chargers/batteries for them. So can someone show me where i can get good priced drills ?
Also im having a little trouble working out exactly how robots are controlled, usually i would just buy all the bits and have a fiddle but im really want to know what im doing before i buy stuff as i dont have a huge budget and i dont want to break anything so could someone please give me a for dummies explanation of how my receiver interacts with my speed controller, how my speed controller then interacts with my motor and where along the line and how do i acheive tank style steering, oh and why do i get servos with my transmitter and receiver, what do i do with them.
Please forgive my ignorance - im sure you guys had to ask aswell sometime !
Yo Andrew - Try Maplin.co.uk or your local Homebase or B&Q for cheap drills.
As for how to control motors and so on using your transmitter, radio kit, speed controllers - have a look here - http://www.stupoo2000.pwp.blueyonder.co.uk/teamkat/technical.htmhttp://www.stupoo2000.pwp.blueyonder.../technical.htm
Mr Stu
wow fast reply ! Im checkin out that site right now
ok, drills either
12V http://www.maplin.co.uk/Module.aspx?ModuleNo=37950&TabID=1&source=15&World ID=&doy=8m3http://www.maplin.co.uk/Module.aspx?...15&WorldID=&do y=8m3
24V http://www.maplin.co.uk/Module.aspx?ModuleNo=44605&TabID=1&source=14&doy=8 m3http://www.maplin.co.uk/Module.aspx?...rce=14&doy=8m3
I guess, 24V is better, as its easier to work with the lower currents etc ?
But i just want some advice incase i manage to buy the only drill that its impossibe to remove the motor from or something
How can i find out the wattage of the motors without buying them and testing them?
If you really wanna get into the nitty gritty of how the receiver interacts with the speed controllers etc try here
http://homepages.which.net/~paul.hills/http://homepages.which.net/~paul.hills/
Andrew, Im not sure what the 24 volt drill is like, but I bought two of the 12 volt drills a wee while back - that gave me my two motors, four batteries and two chargers for just under £30 (plus I ordered a power LED to take it over £30 and get free postage) not to mention two (in a manner of speaking) speed controllers - the drill triggers. So far Ive only had them running in a test chassis and havent actually used them in battle yet, but they seem to be fairly reasonable for the cost, more than adequate for a robot.
Another bit of advice regarding how to dismantle them, just make sure that when you unscrew the drill chuck that you turn the screw clockwise (as opposed to the normal way of anti-clockwise) to remove it otherwise you may chew up the screw head and might have to hacksaw them off - I learnt that bit the hard way :sad:
All thats left after that really, is to remove the drill motor from its casing and decide what to do with the torque ring (the black collar) whether you want to leave it on as it comes (probably a good idea) or take it off and modify it to a fixed torque holder (an area Im not that skilled at doing - best for someone else to explain it probably)
Regards
Jamie
Unlike most people I have actually tried to modify 24V drills. http://www.maplin.co.uk/Module.aspx?...dID=9&doy=8m3>
Hi Andrew, If your not sure which drills to use keep in mind that most people who use drill motors and gearboxes use the 18V ones, the 12V or 18V from Maplin seem to be fine, but be careful of drills with Hammer Action as they are more complex and harder to adapt for robot use, same goes for 2 speed drills, as you will never use the low speed and its just wasted weight. The 550rpm ones need bigger wheels (6) for reasonable speed but some are 700rpm and smaller wheels can be used.
ok well i think ill get the 12V drills as i will be able to buy 4 of them http://www.maplin.co.uk/Module.aspx?ModuleNo=37950&TabID=1&source=15&World ID=&doy=8m3http://www.maplin.co.uk/Module.aspx?...15&WorldID=&do y=8m3
Ive just thought though, for speed controllers, will i need 4 electronize controllers for 4 motors ! Is there not a cheaper way ?
Also for batteries, should i connect all the batteries in parallel and they will just last much longer ?