Big wheels on a heavyweight

**maddox** · 23rd April 2008, 06:54

Craig. 30 amps max for a pack.... I think I can show you what such a pack does in a high power 4WD 4 Graupner speed 900 driven FEATHER.

http://www.bugs.nl/media/album/view.php?&path=L3J3L2JydXNzZWwyMDA3L2JlLWJhYnMvV2V 0ZW5zY2hhcHNFeHBvXzA0MS5KUEc=http://www.bugs.nl/media/album/view....L2JlLWJhYnMvV2 V0ZW5zY2hhcHNFeHBvXzA0MS5KUEc=

http://www.bugs.nl/media/album/view.php?&path=L3J3L2JydXNzZWwyMDA3L2JlLWJhYnMvV2V 0ZW5zY2hhcHNFeHBvXzA0Mi5KUEc=http://www.bugs.nl/media/album/view....L2JlLWJhYnMvV2 V0ZW5zY2hhcHNFeHBvXzA0Mi5KUEc=

In other words, youll need at least 4 parallel in a heavy with a decent reduction gearing. And even then , even a good current limited speedo (like the current Sidewinder) will get those packs very very hothot.

**craig_colliass** · 5th May 2008, 10:17

Hi

Just thought I would give an update on the Big Wheeled robot,
Now named St Hammer.

The Hammer has had two outings now the first one was dogged with transmission failure this was due to me under estimating the forces on the final drive. Most of these failures have now been sorted, and the robot on its second trip out had no more problems. But I intend to strengthen these areas a little more to make the thing even more reliable.
The 3mm ARM steel has so far coped well with the collisions with only one dent!
The stub axle mounting bent when the Hammer was flipped out of the arena this took some straightening! I then re-enforced the areas with 3mm ARM steel in channel section, the stub axels are now secured through 9mm of ARM steel!
Now for the wheels themselves, I used 20â‚¬Â bike tyres these have proved quite good, they are ripped to bits now, but the grip was amazing and I can get new ones for a tenner a pair. The wheels are made from 15mm UHMWPE this has proved a success, I may try some 12mm HDPE next, the reason is because I think a little more flex in the wheel may help save the stub axle problem from returning, and some robots with crushing weapons tends to put holes in the wheels and HDPE is weld able. So when the inevitable happens I can fix this.
The hubcaps work well to self-right the Hammer if it gets stuck,
The only disappointment is how hard I have found it to drive and deploy the weapon at the same time; this is not the fault of the robot but the driver!!!

Still the audience seem to like St Hammer, and so do team Bad Bolts.

**swanaldo** · 5th May 2008, 12:04

and so do team bud

**craig_colliass** · 11th May 2008, 19:27

I have just been testing out the robot and I found a fault with the control when the robot has been used for a little while the robot looses power on full left turn the robot stops moving if I go to 9/10 left on the stick the robot works it just has a dead patch there.
But only after a while first thing its ok and if I leave the robot then go back after a short while it is ok again I donâ‚¬â„¢t think it is a radio fault I think it is the speed controller not interpreting the signals correctly when it gets warm.
I have adjusted the travel on the aileron control the one in question, between 100% to 150% this has made no difference. The radio is spectrum DX6 and the controller is Sidewinder,

what do people think?

**woody** · 11th May 2008, 19:51

I think youll find that there is a + AND - travel adjustment ...check that you have 100% on EACH .
http://www.spektrumrc.com/ProdInfo/Files/DX6_Maunal.pdf http://www.spektrumrc.com/ProdInfo/Files/DX6_Maunal.pdf
Page 11

Tried recalibrating the Sidewinder to the Spektrum stick range ..... http://www.robotpower.com/downloads/RobotPower_Sidewinder_quickstart.pdfhttp://www.robotpower.com/downloads/...quickstart.pdf
Page 2 Radio Calibration?

**woody** · 11th May 2008, 21:31

Id also check your batteries ...preferably under load....seeing as how your symptoms indicate that you might possibly have a combination of problems.

**craig_colliass** · 11th May 2008, 23:19

Thanks Woody I will check the items mentioned I dont think it is the batteries with an intermittent fault, as the problem when it starts to happen is repeatable. only on the left only on full travel. also I dont know what voltage the batteries are delivering under load but it is more than sufficient to spin the wheels on my drive, so I think the batteries are delivering the current required.
I was wondering with the Sidewinder they have a habit of running out of alignment when hot (one or both wheels will start to spin when the Tx is switched off) I was told by the guys at Sidewinder this is normal and part of the current limiting circuit.
But before I get technical! I will recalibrate the sidewinder just to make sure the fault is not that.
Thanks for your help

**craig_colliass** · 24th May 2008, 10:53

I have decided to make a sword for the saint 200mm long handle and 1000mm long blade!

Also Iâ‚¬â„¢ve decided to fit â‚¬Å“the haloâ‚¬Â on the old saint, so it can run in the Rebel Robots bash in August. Are there going to be any other spinners for that one?