Big wheels on a heavyweight

**john** · 16th January 2008, 00:39

wait til u c my new toy stu

its the new beast aint it jonno

**craig_colliass** · 18th January 2008, 09:24

I had an email from Chris from robot power this helps I think.
My note to Robot power.

Hi I have a Sidewinder in my heavy weight robot
it runs two 750w Bosch motors with 2 hawker SLA batteries.
At the input to the controller I read 24.1v and at the output to a
motor I read 23.1v with the motors freewheeling at full speed is this
normal? I have been discussing this on the FRA forum in the UK.
http://www.fightingrobots.co.uk/forum.htmhttp://www.fightingrobots.co.uk/forum.htm the thread is Big wheels on
a heavyweight I have re-set the unit and adjusted the trim on the
radio can you advice?

The reply
Hi Craig,
This is normal. The Sidewinder does not go to 100% PWM because of its
current limiting scheme. The voltage drop is not burned up per se but
is simply not supplied to the motors. Your drop seems a little larger
than nominal but not too far off.
Try calibrating the radio with the trims cantered and then move the trim
slightly while measuring the voltage. You may be able to get a little
more voltage out of the controller by expanding the range of the signal
(ATV setting) after calibration - not much but some.

Regards,

Chris Baron
Robot Power

P.S. If I could ever get approved for forum membership I could monitor
and reply to these questions directly but Ive applied a couple of times
and never heard back so I dont follow the forum

**craig_colliass** · 24th January 2008, 08:54

Hi Ive made the first wheel out of 15mm UHMDPE 500mm Dia I hope to take it to the Swindon show, I would like anyoneâ‚¬â„¢s opinion on the material, and I think it may still be a little stiff. Has anyone used 15mm for wheels before?

**maddox** · 24th January 2008, 13:08

I did, the wheels from the Dutch Enderbot. And the series of wheels for Touch As Nails.

Stiffness isnt anything special according to me.

**craig_colliass** · 24th January 2008, 14:52

Thanks Mario

**swanaldo** · 24th January 2008, 15:15

i am interested in your wheels craig as i am about to embark on building another robot with big wheels. this of course means that i might keep the gear boxs and use them myself but i will still bring them for you too look at. might be able to get you some more.

**leorcc** · 24th January 2008, 15:40

quote:

P.S. If I could ever get approved for forum membership I could monitor
and reply to these questions directly but Ive applied a couple of times
and never heard back so I dont follow the forum

Since the Sidewinder and Scorpions are in use with UK robots I think it is a good idea to have Chris Barons application approved so he can answer any issues directly on the forum.