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Jolt & friends - Team Overkill - NSW
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Valen
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Joined: 07 Jul 2004
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Location: Sydney


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see if you can specify a filler rod, the long weld I think the issue is not a big enough weld bead, for what is essentially a T junction, unless you tell them to melt the upright (into the screen) portion a whole bunch more to get it down flusher with the sheeting.
Though on the rightmost side of that image I would expect to see better penetration there.
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Post Wed Oct 14, 2015 10:14 pm 
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Nick
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More video, Mr Mangle VS roadkill, the bot that just won't die: http://www.nswrfc.org/Nick/Mangle_Roadkill.mp4

At 0:33 there is a pause while I mash the weapon speed button - it was 39% after the match.
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Post Wed Oct 14, 2015 11:50 pm 
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Cpnwolfe



Joined: 29 May 2012
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Definitely need more penetration into the parent metal
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Post Thu Oct 15, 2015 5:56 am 
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Eventorizon-GB



Joined: 15 Nov 2013
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Location: Ripon, United Kingdom


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quote:
Originally posted by Nick:
Unless I can find a better welder, I have to go back to the company that did Shiny - but what should I say? Not knowing exactly why all those welds busted makes it hard to direct the welder on what to do differently. I could say 'just fix it' but if the guy made mistakes in the first place, he might not be able to do a better repair job.


We had a similar issue with both Binky and my BW robot Anvil when they were welded up. We told them the welds were not fit for purpose and they, rather grudgingly, redid Binky for free while cutting some of the cost of Anvil (Though for Anvil, it was already to late)

While combat robots isn't a regular purpose, it took such a relatively small hit compared to what Mr Mangle has taken that you have a comparison to prove the welds were not done to the same standard.

Best you can do I think is grind back the welds and have it redone.Not ideal as it will weaken the Ti on the corners but you may get another event out of Shiny a the least.

Post Thu Oct 15, 2015 6:06 am 
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Don
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Is there a weld prep on and of the parts?

Post Thu Oct 15, 2015 6:18 am 
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Nick
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@ Don: All the pieces were sanded with a fresh belt to avoid contamination with other metals, then cleaned with isopropyl alcohol. I also asked the welder to give the parts a final de-grease, which probably wasn't done.

@ Alex: I will see what's on offer from the welder but even if they agree to re-weld the broken parts, the remaining welds are probably just as weak. There are also some broken internal welds that I can't reach with a grinder. It could be that the fractured internal welds won't allow the side panel to close up, leaving a gap to bridge.

Its not hard to cut out the outside welds, so I will start with that and see how things go from there.
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Post Thu Oct 15, 2015 8:11 am 
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Nick
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Welding repairs:

Shiny's frame is stripped down and I can get a better look at the damage. I can now see that the entire weld along the bottom of the side panel is cracked from the back to the front. It also looks bad for the gusset in the back corner:



I have NFI how I can grind that out and no TIG torch will fit in there anyway. I can now see the back of some of the welds and it is even clearer that the welds have zero penetration. I am sending off some photos to the welder, let's hope they stand behind their work - all $730 of it.
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Post Thu Oct 15, 2015 12:57 pm 
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Glen
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That's a tricky one, the rear weld is definitely not fused to the rear panel properly. The inside ones are difficult to assess cause they've broken through the middle which is indicative of lots of things. Could well be solidification cracking as its a tiny part welded to two massive panels, the heat affected area looks large too.

Might be worth asking what filler was used, maybe using grade 2 instead of grade 5 (I'm assuming that's what it was done with) filler next time would work better so it's more ductile and less susceptible to cracking. That's common in high hardness steel for the same reason.

Hard to say though really, lots of factors can affect things with titanium. Contamination and so on. Time to learn to TIG weld maybe? Razz
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Post Thu Oct 15, 2015 2:34 pm 
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maddox



Joined: 21 Dec 2006
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For au$730... Damn, I need build that glovebox asap.

Post Thu Oct 15, 2015 2:57 pm 
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Nick
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Learning to TIG would be handy - I could buy a fairly good welder for the cost of welding three frames.

From what I've read, Grade 5 Ti should always be welded with grade 2 filler - grade 5 is too brittle, which might explain why so much of the welding cracked. If the original welder wants full price for the repairs, I found a new company to do the work. They advertise titanium and magnesium welding so they likely have an argon chamber - or they like putting out magnesium fires Smile
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Post Thu Oct 15, 2015 4:36 pm 
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Valen
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firefighting procedure for a magnesium fire, is a good pair of running shoes
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Post Fri Oct 16, 2015 7:32 am 
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Nick
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So if they are wearing steel caps rather than Nikes, that means they are good welders? Laughing
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Post Fri Oct 16, 2015 9:17 am 
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Nick
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Decimator:

I am uber excitied to be adding Decimator to the Team Overkill fleet! Without taking anything away from Glen's precision work and great design, I am already thinking of some tweaks to make it even better:

Weapon motor: Looking at using the stator from an HK Rotomax motor on a larger version of the mount that Glen made. If I can squeeze it in, it should have more torque than Decimator's current motor and will maybe run cooler. If possible, I want to make the motor pulley smaller to increase the belt reduction and slow the bar down a little; the damage to Badger shows the weapon is crazy powerful so a few RPM less will still be scary but less self-damaging.

Weapon bar: As well as the steel bars. I want to try out a composite titanium / steel bar like Scissorhands has. If I can reduce the total weight while moving weight out to the tips I get more KE per Kg, always a good thing. Also, having a symmetrical tip on the bar means it can be reversed for optimal damage to shell spinners Razz.

Drivetrain: The drive train is just about perfect but with some customising to the gearboxes, I can save weight and make maintenance a little easier. Adding an outside support bearing might also be possible.

Anyways, I won't be changing things just for the sake of it or rushing in to modifications without plenty of testing.
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Post Fri Oct 16, 2015 10:33 pm 
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Jaemus
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That thing will Decimate all at Race Wars
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Post Sat Oct 17, 2015 10:00 am 
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maddox



Joined: 21 Dec 2006
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Hardox to the rescue for the European Roboteers.
We're organising a group buy of 3.2mm Hardox 450. Currently, we're contemplating buying 30m².

To prove a point, Valkiri3 got a few good hits from Conker3 during MMM20, and the hardox just took those without even blinking, unfortunatly, transfering the force to the weakest point in the chain.

Post Sat Oct 17, 2015 10:18 am 
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