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Team RCC's Heavyweight Bullfrog.
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miles&Jules
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Joined: 19 May 2010
Posts: 3973
Location: ipswich QLD


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Sounds cool....Any video of it flipping stuff?
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Post Mon Sep 17, 2012 9:04 am 
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maddox



Joined: 21 Dec 2006
Posts: 786
Location: Belgium


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Not yet unfortunatly.

Will be at Maidstone I fear

Post Mon Sep 17, 2012 9:13 am 
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miles&Jules
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Joined: 19 May 2010
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Location: ipswich QLD


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is there a way of working out how big your buffer tank has to be? I'm building a beetle weight and i'm just guessing/experimenting how big it needs to be at the moment.
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www.mulesfilm.com.au
www.wombokforest.com.au

-Pickasso- Vivid Sportsman champion 2015

Post Mon Sep 17, 2012 9:18 am 
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maddox



Joined: 21 Dec 2006
Posts: 786
Location: Belgium


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In the industry a guideline of 5 times used volume is standard. So if the users use 10L air , the buffertank will be 50 liter.


I use 3 times uservolume as guideline in the robots.

Post Mon Sep 17, 2012 10:09 am 
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maddox



Joined: 21 Dec 2006
Posts: 786
Location: Belgium


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Here one of the fights of Bullfrog at Maidstone.

http://www.youtube.com/watch?v=xCHZzxy_Rjc&feature=bf_next&list=UUz0xv5rbwl_ry7jPQdN15lg

Post Wed Oct 10, 2012 6:40 am 
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miles&Jules
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Joined: 19 May 2010
Posts: 3973
Location: ipswich QLD


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Ha thats was cool ......great to see actual heavy weights fighting these days....so what was happening with your flipper, it was having trouble closing? Self right looks good.
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Miles Blow - Julie Pitts
www.mulesfilm.com.au
www.wombokforest.com.au

-Pickasso- Vivid Sportsman champion 2015

Post Wed Oct 10, 2012 8:32 am 
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maddox



Joined: 21 Dec 2006
Posts: 786
Location: Belgium


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It was the second fight in anger for Bullfrog.

A small piece of "welding dandruff" came lose and kept the main valve leaking. the exhaust valve couldn't dump all the CO2, so the ram kept open with a leakage. That froze everything over. At the end of the fight, the main valve was frozen shut, and the flipper could return.

Oh well, it's a known problem in custom build pneumatics. Next time the chances for that will be a lot less.

In any case, we have 5 kg to play with.
Part of that will be used to reinforce the flipperarm. After the 3 fights it was a tad "crooked" sideways.
A more effective way of stopping liquid before it enters the buffertank is deviced and will be implemented.
And an exhaust tube will vent the used CO2 to the outside. Now it just cools everything down.

Post Wed Oct 10, 2012 9:35 am 
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maddox



Joined: 21 Dec 2006
Posts: 786
Location: Belgium


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Maidstone event report.

The event started a day early (again), saturday 6 october. Around 10 am , Kos arrived. Tough As Nails would make the trip with Leo's van, Kos and Jeroen were traveling with Gravity 5.2, taking the chunnel around 5 pm.

A bit later ,Marien and Leo joined us, and we started the first round of "Van loading for advanced roboteers". After this, Bullfrog got the last bits of electronics , a touch up on the 2 CO2 bottles, and a short test. And to the van with the Green Mean Machine.

Having time to spare, we started reparing and upgrading Ltn Lee, Mariens Raptor. It got quite a beating at MMM14, cracking the 10mm polycarbonate baseplate and a series of dents and rips in the steel 20*20*2 box section. The box section got some welding and grinding , the cracked PC plate replaced by HDPE, and for giggles, added some hardox here and there.

Still time to spare, rummaging trough the stockpile here, the idea's started to percolate. It ended up with a drive to a nearby DIY, buying a very very very cheap anglegrinder (and a spare).

A txt message from Jeroen set us to the heavier work, and some cutting later, more stuff was loaded in the van. It seems Bullfrog is contagious.

Saturday, keeping in mind that we would start traveling around 3 am, was closed of with a spicy stew and some gentle talk.

A very early morning drive, and around 9 am local time we were setting up shop at the Maidstone leisure center.

Team RCC had 4 fights. 3 with Bullfrog, and 1 with Hannibalito 3.

The first fight with Bullfrog did show a disadvantage of a very low robot. It can slide between the steel cables of the RR arena flipper-annoying infrastructure.
After this fight, refill the bottles, remove the LifePo4 batteries and charge those,mount everything, ready.

The second fight did show some other weak points, but it was a good fight, as can be seen here .
As can be seen, liquid CO2 was being vented, but it wasn't a big concern at that moment. Not a big disaster in itself....
Refill bottles, charge batteries

3th fight. Razerdave at the wheel. Unfortunatly, the flipperarm started rising slowely when I opened the first bottle gently. Closing that bottle, and into the fight.
Was a good fight, pity about the weapon as some great flips were in the offering.

Hannibalito 3. Just entered it for 1 melee. Last week it came out of the arena at MMM14, gassed up and recharged batteries at that even. At home we did grind off some sharp edges, and at Maidstone we trew it in the arena, and it went for it. No complaints, no nags, no sags. Just plain flipping anything on the flipperarm

Post Sat Oct 20, 2012 1:20 pm 
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maddox



Joined: 21 Dec 2006
Posts: 786
Location: Belgium


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Long overdue report on this machine.

With one or 2 events a year, this machine isn't utilised a lot, but it got a steady series of improvements after each event.


Main changes are in drive, position of the pivots and some new ideas in pneumatics.

The drives got turned around, so the motors are in front of the wheels.
This diminishes the wheelie effect a lot.
Changing batteries from 10S 2P Zippy 4200mah LiFePo4's to 10S Zippy 8000mah LiPo gave another boost in speed and runtime.
The old airtyres replaced with a set of runflats given to us by the Sewersnake team, way back in 2004. Great change in grip.

The pivot of the arm was placed shorter to the ram, so the leverage ended up around 7-1. Disadvantage, the forces on the pivot are so great I had to mill a new mounting block and construct a brace in the monocoque frame/armor to spread out the power.

Now we run on 1 2Kg bottle.
The space gained is used by a liquid heatsink to keep the setup "unfrozen".


This year was heavy tough. First trying to get into Series 8

Here the promo film.

https://www.youtube.com/watch?v=PN7eB-amryY

When we got news we weren't selected, it went with Kan-Opener to the Russian event in Moscow.
8 shows in 3 days with machines like Beast and Ripper are tough on any machine, but except some CO2 and flipperarm issues.
Bullfrog came out in flying colors. Not only surviving, but also pinpointing some small issues on ease of maintance.

And soon after adressing the Obvious issues, we went to Portsmouth.
This was equaly heavy on the machine, and now age and wear started to show.

The wheelarmor isn't hardox, but 4mm 15Mo3 boilersteel, and that's buckling and cracking now. Needs to be replaced.
Also, the liquid heatsink doesn't have enough capacity to keep the setup from freezing, so it needs some enlargement.

But that will be for november, at earliest.

Post Thu Aug 18, 2016 1:56 am 
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miles&Jules
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Joined: 19 May 2010
Posts: 3973
Location: ipswich QLD


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Cool machine- what drives you got on it?
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Miles Blow - Julie Pitts
www.mulesfilm.com.au
www.wombokforest.com.au

-Pickasso- Vivid Sportsman champion 2015

Post Thu Aug 18, 2016 7:14 am 
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Nick
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Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW


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How does the liquid heatsink work?
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Post Thu Aug 18, 2016 8:44 am 
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maddox



Joined: 21 Dec 2006
Posts: 786
Location: Belgium


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The drivetrain is "non standard".

Iskra AMG 24V 1.2Kw motors, with a 20-1 gearratio to 260mm runflats. But the motor is directly in front of the wheel.

ESC, a ruggedized Sidewinder, seriously shockmounted.



The liquid heatsink works fine, if it is large enough.

Post Thu Aug 18, 2016 4:12 pm 
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Eventorizon-GB



Joined: 15 Nov 2013
Posts: 111
Location: Ripon, United Kingdom


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Liquid heat sink? I'd be interested to see that!

Post Thu Aug 18, 2016 7:11 pm 
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maddox



Joined: 21 Dec 2006
Posts: 786
Location: Belgium


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It was in use at Portsmouth.

So, you propably have seen it in use.

The 2 liter version worked great. the smaller 1 liter version not so. Next attempt will be a 1.5 liter one.

Post Thu Aug 18, 2016 7:28 pm 
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Spockie-Tech
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Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia


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Waters heat capacity is huge, which is why we use it for cooling/heat *transport situations to move heat around from car radiators to nuclear reactors, so *theoretically it should make a great heatsink.

The trick is is *containing it only where you want it to be, without it getting everywhere that you dont.. it needs pipes, tanks etc, which tend to be heavier compared to just a chunk of finned metal that easily stays where you put it for a given heat capacity.

Be interesting to see what he has up his sleeve Smile
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Post Thu Aug 18, 2016 7:33 pm 
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