Team MedBots

I am only using gimsons so I think I will go for rear hinged but I might make it so I can change it to either way and test both.
Also, if I wanted to make a dirt cheap heavyweight (I mean really really cheap and ineffective) could I use wiper motors for drive? I think on 150mm wheels they can shift 100kg wouldn't they? I could go for 4 wheel drive and that should help. Looking through old build diarys it looks like loads of people give up on their first heavy weight or 'put it off for a while' but I thought if I made it cheap and simple then I stand a better chance of finishing it? I was just thinking I wanted something to put in to the arena and didn't want to spend much money. What do you think?

I think wiper motors will probably be underpowered. I ran two in my Rex's Challenge machine on 178mm wheels and when I stood on it it struggled to move with my then 16-year-old weight (which would've been less than 100kg). One of the issues is the small size and fixing method on the shaft. It doesn't particularly lend itself to having large diameter or heavy loads bearing on it.

If you ran some form of gearing to your wheels, even if it's just 1:1 to remove a lot of stress from the wiper motor's shaft, it could help things but I'd still be dubious about their ability to shift 100kg of robot. If they do, on 150mm wheels it'll be pretty slow. Getting hold of a cheap pair of wheelchair motors seems to be the preferred option for building a heavyweight on a budget.

20 Argos drills, anyone? :lol:

I've often thought about using Fan motors in a heavy.

4 of them, chain drive, small wheels, should be fine.

i think a robot called wild willy used them for its drive in the robot wars series it was quite quick

Quote:

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Originally Posted by plargen

i think a robot called wild willy used them for its drive in the robot wars series it was quite quick

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Wiper motors or fan motors?
I've also thought of using fan motors for a heavy but wiper motors seem easier.

After a google search I've found it was 4 20A fan motors and it had an axe powered by a starter motor. Sounds very 'bitza'

u should find a vid i think it was quite quick, and sorry should have said fan motor

for a dirt cheap hw go for wheel chair motors as they often come with wheels and thereofre shafts along with fixing points. they will also move the weight and you can over volt them

then go for a servo board controller on / off / on

First video I find of wild willy saw it fight with 'flip flop fly' which was powered by 4 wiper motors! Lol
But the an motors were much faster and more powerful than the wiper driven one.

that was then and this is now.

wheelchair motors should see you fine, and be dirt cheap if you look hard enough.

you could spend say £150 on a wheel chair, and atach servos to the joystick, add some 10ah or so sla's and you are almost there

what do the rules mean when they say a walking mechanism must have 2 axis of motion?

I think in this case the interpretation would be

axis1 = UP & DOWN,

axis2 = FORWARDS & BACKWARDS,

In practice the walking gait (the path of the foot) should not track a circle,
The idea is to stop people putting feet on a wheel calling it a walker and claiming the extra weight!

So the mechanism should lift the foot, extend it forward, place the foot on the ground, support the weight of the robot, and then power backwards propelling the robot forward, the foot is then at the start position to do it all over again.

In combat few mechanisms have been able to do that well with this form of propulsion but I hope to do something in the next few years if funds permit!

With electronize controllers should the relays click if I plug it into the receiver with a receiver battery and move the stick on the tx without the main battery being plugged in?

yes im pretty sure thats supposed to happen

To be clear that is not happening with my controller, I am charging the receiver battery and will try it again

I've been at the metal workers today working on a new aluminium chassis for my rebuild of my fw lp flipper.
Here are some photos of the chassis with some of the main components placed in:
http://i1261.photobucket.com/albums/...t/cebfa0cd.jpg
http://i1261.photobucket.com/albums/...t/c7e97834.jpg

The next job is to get the ram sorted, the body is being made and I am Going to my pneumatic supllier friend soon to make the piston.

What's the thickness of the sides? It's looking good, will the wheels be exposed.?After looking Dave's new offering and NST, I'm thinking of moving to steel :)

Sides are 3mm aluminium, base is 5mm sides are stronger because they have been bent at the base to make a angle for bolting it to the base and the sides are bent around the base if you see what I mean. The wheels will be exposed but I won enter it in spinner events.

what are the buffer tanks?

The buffers are just powder fire extinguishers

What fittings are you using in the buffer tanks?

I've got some custom brass adapters which turn it from a funny thread to I think m12 then there will be a 12mm push fit connector going into the adapter.

Did you get them made up locally or is there a supplier? Would be great to get hold of something like that!

I'm afraid I had them made up locally.

Hi,
I'm mulling over making a new non-competitive tracked robot, I think it will way 30-50kg and would like it to be able to move a person around and move at a fast speed without someone on it (15-20mph).
I have been thinking about powering it with a singe chainsaw engine- would that be powerful enough for what I want?

I then plan on connecting the engine to a hydraulic pump and having a hydraulic motor thingy to power each side. What I can't figure out is how I could change the speed of each side independently using the hydraulics. Ideally I would like it to gain more power when it goes slowly an less when it goes fast, is that possible? I know I could have a gearbox or different cogs to change speed but is rather just use the hydraulic system to keep it simple and compact.
I know it's not really combat robotics but there may be someone on here who can help!

I would look at the Badger, Mini-Rip and the Ripsaw. The Badger is entirely hydraulic for drive and steering. The mini-rip and ripsaw use a new type of track technology.

I personally think that if you are going for hydraulic drive you will never have to worry about power (The badger can drive clean through a solid brick wall) To get more speed, gear up the input to the hydraulic pump rather than the output to the tracks themselves. The hydraulics will produce so much torque they might break any gearing you put in. Just a thought

Another key point is how they make use of the breaking to assist steering. The mini-rip is fitted with a small differential so that when one side is stopped the other is sped up, not wasting power. This does make for an interesting driving style but it means that you put less stress on the motor and can turn quickly and efficiently.

I have looked into making my own Ripsaw style tank and they are all points I had to think about and I am going to try and use some of it in a tracked combat robot if I ever get round to it.

Quote:

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Originally Posted by Max

Hi,
I'm mulling over making a new non-competitive tracked robot, I think it will way 30-50kg and would like it to be able to move a person around and move at a fast speed without someone on it (15-20mph).
I have been thinking about powering it with a singe chainsaw engine- would that be powerful enough for what I want?

I then plan on connecting the engine to a hydraulic pump and having a hydraulic motor thingy to power each side. What I can't figure out is how I could change the speed of each side independently using the hydraulics. Ideally I would like it to gain more power when it goes slowly an less when it goes fast, is that possible? I know I could have a gearbox or different cogs to change speed but is rather just use the hydraulic system to keep it simple and compact.
I know it's not really combat robotics but there may be someone on here who can help!

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Flex has such a setup , it's just waiting for the right time and person to get it working.

Spent yesterday in with my pneumatics supplier friend working on my ram. I got most of it done I just need some new o-rings and seals for the bottom, anyway here are some pics:
http://i1261.photobucket.com/albums/...F547327A96.jpg

Here is the piston and rod and the end plate:
http://i1261.photobucket.com/albums/...F55FA0D324.jpg

And here it is in the robot, I will shorten the rod when I decide how long it should be:
http://i1261.photobucket.com/albums/...F56F6F7D84.jpg

http://i1261.photobucket.com/albums/...F579505166.jpg

Finally tested the ram this afternoon and it seems to work! I need to wait to get the rest of the pneumatic parts before I can test it firing it fast.
http://i1261.photobucket.com/albums/...61132FD1DC.mp4

Edit: that link doesn't seem to be working, heres a link to the video:
http://i1261.photobucket.com/albums/ii5 ... 2FD1DC.mp4

Today I tested the ram with the QEV and large piping, the system was only at around 5bar as it was leaking like mad but eventually it will run at 10 bar. I thought it was very impressive but my mum who was filming was no so happy with the massive bang and has now quit her role as camera woman :sad:
Anyway here is the video:
http://i1261.photobucket.com/albums/ii5 ... 473696.mp4

Eh...I quit using thread tape, its a pain to obtain a leak free joint with it :angry:
I find thread locking compound much better - btw the camera person did get the fright of her life! I did too when I fist fired mine :roll:

looks great, and with a ram that big it should be incredibly powerful. i look forward to seeing it and hopefully fighting it at maidstone!

Imagine a 1 bsp valve @50 bar opening.... That is what I endured 3 weeks ago.... Ringing ears...

Hi,
For the locking mechanism for my flipper arm can I just prop the flipper arm up above the rams maximum extension so if the ram fires it will not hit the flipper arm?

The problem there being that the ram is still moving and therefore still a hazard to a miss placed arm, finger, hand etc. By locking the flipper down over the ram and securing it properly nothing can move.

Hi,
When using woodies QEV system won't the ram fire when you the dump valve?

I have tested the system and it does fire when you use the dump valve! Doe this matter? I'd rather not be firing the ram into the flipper arm when the flipper arm is in the locked position as it will start to damage the robot. I'd rather prop the arm up so the ram fires but doesn't hit the arm. Does that sound acceptable?

Hi,
I am thinking of building a heavyweight and am thinking about motors. I know I could use wheelchair motors but would like more power and would like to build the gearbox. I have a few questions, could you use a shunt wound motor, and would you need a lower rated speed controller to control it? Also I think someone said they used forklift motors, am I right? What kind can you use (eg. From the pump or drive of the forklift)?
Apart from wheelchair motors and Bosch 400s or 750s, what other motors could I use?

there are these if he still sells them

http://users.breathe.com/planteng/motors.htm

and ther are the iskra 800w motors ..... i think there used in tail lift units generally

just found these which should be powerful enough

http://www.ebay.co.uk/itm/36-VOLT-800-W ... 982&_uhb=1