Big wheels on a heavyweight

wait til u c my new toy stu :lol:

its the new beast aint it jonno :)

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

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

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

Stiffness isnt anything special according to me.

Thanks Mario:)

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. :)

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.

Thanks for bringing that up Leo, I agree but I don€™t know the rules on this forum for this sort of thing! But if it is ok It gets my vote.:)

Im thinking of running the Bosch 750 motors @36 volts, through the Sidewinder Speed controller, has any one done this in the past?:uhoh:

Yes, Tough as Nails runs its Bosches on 36V trough a Sidewinder. Works like a charm.

Hades and if im not mistaken, Perlito too.

Great news what settings do they run the current limiter on them?

Full pelt, 80A. The Bosch 750s can draw a lot more, but it doesnt add a lot to the effective power.

But, you have to watch the gearing. Dont want to be too fast. It diminishes controlability, and draws unneeded amps.

Have the speed controler ever blown as a result of excessive load

if i were you craig i would stick with 24v. bosch motors burn out on 36v. i have learnt lessons over the years and 36v would be fine for a competition or if you were to go on tv but if you are doing live events as part of your main hobby then realibility is the key. most speedos blow when there is something wrong with the robot i.e. jammed gear or short on the wiring. 24v bosch will be fine with your big wheels and will prove to be a lot more realible. just my opinion that is. :)

We had a Sidewinder failure in the start, a mistake in the current limiting setup, only 1 side was limited. The other side blew when the motor jammed. This was in 2006.

RobotPower corrected that issue, and all sidewinders now are ok in that respect.

Mario
Thanks for that I was worried it was going to cost me a lot in Sidewinders I will to keep the current limiter on.


Shane
Thanks for the warning perhaps I could arrange it so for whiteboard fights I would use 24volts with ballast for the third battery, and use all three when it becomes a competition fight.
:)

Ive run ripper on 24v and 36v with the sidewinder, ive now put a roboteQ into it as the drive locked and I blew it up.

It ran fine on 36v and 24v, just make sure you drive system never locks up as they dont appear to be as bullet proof as other controllers.

We were talking a while ago about a reduction in speed, now that i have put the roboteQ in, it appears to be as fast on 24v with the roboteQ as it was on 36v on the sidewinder.

And my burkets fire without a problem, where as before on 24v with the sidewinder they wouldnt fire while i was driving.


John

sidewinders r rubbish!

beast hasnt done well since we had the roboteq in

go for roboteq

if u blow ur sidewinder aswel it will take yrs to come back - u wont see it! been over 3 months for us now - but i wont go into that here! roboteqs r back fast

you can talk direct with sidewinder and get it sorted that way tho - no point sending to somewhere so they can send to where you could have sent in the 1st place is there?

u can get the email easy - i dont want you to be messed about like many of us have bin

namin no names!!

Exactly why I asked if the application for the forum of Chris Baron could be allowed, he may have an easy or less easy answer to this.

So Robotec speed controllers are better!
How much are they for my project? (24-36 volt, 2* Bosch750 from 18Ah SLA batteries.) Would a watty be better? Were do I get these from?
:uhoh:

Roboteq controlers are a lot more expensive, larger, heavier and to fancy compared to the bare bones, but small, light and easy to use Sidewinder.

The Wotty is in between on pricetag, but suffers from the voltage limit of 30 volt and the lack of housing.

And it seems Team RCC doesnt suffer from a lot of Sidewinder blow ups. The first one we had was a combination of 2 things. The single channel current limiting and a Litton/T axle drive unit that was worn out and failed- jamming the windings between the magnets.

The other one a human mistake, dont try to charge your sidewinder. Now rectified by using a fool proof charge plug/seperate removable link set-up.

The single channel limiting is solved by Robotpower.

if you deal with roboteq and not the shops then i think you may get them cheaper - i think you can get like repaired ones cheaper but when repaired my dad doesnt think there anywhere near as good as brand new

my dad started dealing with roboteq after having so many blow up for various reasons - he sorted all that and then tib went straight through a motor lol

but as jonno said the roboteq seems to make the robot alot faster then with the same setup on the sidewinder - i noticed this at uk champs as in the fight vs big nipper i just couldnt get over to them fast enough and this made me lose the fight :sad:

there is a weight difference but when building a heavy it doesnt matter you can easily build around it and its not that much heavier

To me, TAN doesnt look any slower after the conversion to a Sidewinder.
Neither did it show in Hannibal or Obsidian after their conversion.

But that can because the Sidewinder likes to calibrated to the receiver its being commanded from.

my dad doesnt read manuals so thats prob the problem his support is jonnos mobile and i doubt he reads manuals either ! lol

stu is my manual when it comes to side winders, so we need to ask him if he read it ?

Stu ????

Is in America, bet he didnt read it though, he played sims instead!

Well for me there are too many people claiming that their robot is significantly slower after building in a Sidewinder to dismiss it as a user error.

I am very happy with my Sidewinders, and use them as default in all my heavies. But if there are so many people that dont agree, there must be something more to it. Id like to hear from James or Chris about this.

well it was at the uk champs that i noticed it was slow

last few events it has seemed up to speed just flipper hasnt been working but hopefully can sort that soon

we have been using the very old sidewinder out of big cheese since november - waiting for a new one

i thought stu was in paris at the moment, and going to folrida in may?

Hi All,

Now that Im approved for this forum I thought I would weigh in on this discussion and answer a few of the points:

1) 36V and Bosch 750s.This is a maximal combination for the Sidewinder.The motors will draw a lot of current if stalled or jammed and when stalled the Sidewinder current limiter works least well.I would recommend gearing low enough so that the wheels will not stall but will spin in all cases or better yet stay with 24V.

2) Sidewinder vs Roboteq vs Watty.Obviously we think the Sidewinder is a decent controller.VAlue for the money is something you decide.

3) Sidewinder slower than xxx controller.Hmmm.I dont think a properly calibrated Sidewinder will spin a motor noticeably slower than any other ESC.It does reduce the absolute output voltage slightly 5% over the input voltage.This is because the Sidewinder does not go to 100% on, it always pulses.This is because of the current limiting scheme.So at full throttle youll get more than 95% of full voltage.If the unit is not properly calibrated to the radio it is possible that it wont reach full power at full stick.This could make it seem to be running slower.Same speed at 36V as 24V with yyy no this is not possible with a properly working unit.

4) Service speed.Yes service is slow.Too damn slow.We have lost our service guy and havent been successful at getting a UK service outfit yet.No excuses. We get them turned around as quickly as we can.

Unfortunately I cant follow this forum day to day so if there is an item of interest or a question on our stuff please someone send me an e-mail ping and Ill address it.chris@robotpower.com

Chris Baron
Robot Power

Hi chris,

Glad your finally on the forum.

Im going to try and calibrate my new one properly when i get it, if thats where im going wrong.

John

yes ditto John but i see it takes 3 days for you and i am still waiting 4 months now

dibolical is all i can say

The Big wheels project at the moment, is on My profile. it is going well hope to have something ready for the champs!!

NOW THEY R BIG

What are the largest wheels fitted to a HW robot? Now that€™s an interesting question, the wheels on mine are 525mm diameter. Is this a record?:)

How big were Stingers wheels?

I can measure them, as i have stinger, but they are not as big as craigs.

The biggest i can think of, is the drum spinner one, barberous is it?

John

Thunderrings wheels were biggest. Seen that machine only once, at the Chatham event in 2004.

Following its first real outing at the Robot Crusade, Thundering€™s 1m diameter steel wheels proved a little vulnerable and might as well have been made out of chocolate.