Tombstone's weapon bar failures
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- Опубликовано: 5 ноя 2023
- We have had a few of the S7 weapon bars break on Tombstone, so this talks about the failures a bit. Hopefully we can keep these types of failures to a minimum going forward!
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This is cool, but I don't want to imagine the price to run tombstone
Or run a heavyweight in general. 😂
Beetles rage anywhere’s from 500 to over 1000 USD.
But if you look at jackpot from seasons 5, 6,7, and soon to be 8, the original build of that robot was 4K. Then their weapon black heart cost a believe 80$ to Waterjet and machine.
So it depends what you can get in n terms of quality without spending a ton of money.
I'm curious about the weapon failure against tantrum in the golden bolt tournament.
Tantrum used a concept pioneered by gruff called the "chocolate bars" where chunks of material protrude from the wedge that intensionally create a controlled catch point for horizontals.
I don't know their exact purpose but the goal speculatively was to create a catch point big enough for a horizontals to get a good bite on but slim enough that only a small portion of the blade braces the impact. It creates the opportunity for the blade it break buy focusing all of the kinetic energy into the short length of the chocolate bars. The seams reasonable robotics team was well aware that a brick like tantrum could break the bar on armor impact alone since the original tantrum vs tombstone fight.
Just from a non Builder perspective it seemed to work PERFECTLY with tombstones blade shearing off at the tip causing it to shake its self to death.
Is there any concern of other teams using this strategy in the future or is it an extremely niche setup that only a few bots could pull off.
In Tantrum's fight, we hit in the channel for the movable spinner, which did make us transfer all of the energy into one hit. And they took the hit better than we delivered it, so they certainly deserved the victory. But I pretty much always want to deliver all my energy so I don't think this is some super secret way to win honestly. There is always going to be monster hits between weapons and armor - sometimes I come out on top of that, but not always.
Tombstone, maybe more than any other bot ever really, has changed the landscape of armor and design in this sport. And if I can make all of these super smart and talented people worry about fighting me, well that's just kind of cool!
@@ray9368 yeah, I agree, I’m sure bots like endgame and sawblaze, still fear you. Win or lose, you always have an entertaining fight, and I hope you come back for season 8
Thanks, Ray - for taking us into your shop and helping us understand why things happen the way they do.
In addition, to the type of metal and the hardness, could the shape of the bar be adjusted to deliver a less self-damaging impact while delivering a more devastating blow to the opponent?
Yes he could but regardless he's still taking the damage cos physics says 50% of every hit comes back to you as weapon recoil like a gun pushing back into the body of the user when they pull the trigger. No amount of changes to the weapon tooth profile or material composition will help you escape that.
@@TheInvertedFollicle507 Hellachopper's spinning hammer configuration would disagree, but it's busy not competing, and being on fire :)
@@stonefish98
It's also the reason they first enforced the 250mph tip speed limit.
Certainly geometry always plays a part in this. The newer AR bars that I've run, with the widening at the ends to have higher MOI are a good example of that. I may try machining an S7 version like those and see how it holds up.
@@ray9368 I was wondering if a spike of some sort near the end that would poke holes would work
there are a lot of tricks that bladesmiths use for hardening where they leave certain parts softer than the cutting edge to give it more strength while still keeping the hardness of the cutting surface so you could look into that.
I really appreciate you going into detail about your robots. Thank you mate
as someone that is an amateur bladesmith, I have to wonder if a differential hardening process or a san-mai construction technique might improve the overall performance of the weapon bar. S7 at the core for the cutting edge hardened to around 53-54 rockwell, but a milder tool steel wrap to provide the impact flexibility to resist the inclination to shatter. Just a thought, and doing a san-mai on that size scale may be cost prohibitive, but I bet the results would be stellar.
I really love these videos where ray talks about how and why he makes certain design choices And what type of metal and geometry of said metal is good fir what , its only a matter of when not if ray finds the sweet spot and makes tombstone more more reliable then the giant nut will he his , after all he beat saw blaze who aka the most current winner of the giant nut
I would put a nice radius on any edges that do not need to be sharp.
It should distribute the load and resist propagation of fractures.
The bladed edge had a specific purpose. The weapon bar just moves a significant amount of air around, and with the weapon edged that way it could simply spin faster since it was fighting the air resistance less. This is one of those things that worked great for many years, but less so now and we'll need to adjust going forward.
@@ray9368 Would it make sense to have the bar with something of an aerofoil design? Also, maybe case-hardening would make the weapon bar more durable while still being hard enough on the outside, although the hardened layer may be too thin.
Thank you Ray. This was useful information for me (gunsmith) as well as very entertaining. Seeing your hand on one of the blades puts the size of the machines into perspective.
Love this type of info, thanks!
Thanks Ray.
We learn a lot from loss honestly, this is epic to see and learn about.
I acquired a bot named flight risk which turned 20 years old this year, and it has an S7 bar that Brian Nave machined, this bar went through so many fights that Jamie (the original builder) probably couldn’t even count, it’s bent a little and a little chipped but it survived so much abuse, seeing these amazes me of how well this bar was treated
@Ray Billings, You might need to add more carbon to the steel allowing it to flex more instead of snapping.
have you considered using a differential heat treat?
That's almost certainly worth looking into.
Two thoughts; I don’t see a need to put an edge on the entire bar. Could you put an edge on the outside 4” and keep the center portion square? As I write this, you made a comment to that effect. The second thought I had was to differential heat treat. If the could make the tip hard and the area away from the tip soft it would reduce the chance of a shear failure.
He does mention that as a possibility, though it is worth considering that sharp corners (like the one between a blade and a square section) are stress concentration points - you wouldn't have to worry about chips as much, but you would be concerned about a big enough hit just directly causing a catastrophic failure, no stress cracking or chipping needed (this depends on the material properties of the steel and geometry of the blade) - not to mention you would almost guarantee stress cracking at that corner, making the risk of failure even higher, and I wouldn't be surprised if the average lifespan of the bars went down as a result.
Of course, Ray is a far more experienced engineer than I am, and I have no robot combat experience, so he knows better than I would. But it would definitely be a trade-off to some extent.
-- I think I see. All of these bars, or, at lest most of them were smelted from bigger and pointedly thicker stock, then lathed to specification. And it's top or bottom from the stock, thus, the differences in color and melt topography, to keep it in limens, of specifically those last two bars.
So you're buying a blade from someone who cut it, they bought it from a dealer, who just rates it all the same. And the manufacturer, well, Lord knows their specifications save max profit in many cases. And it looks like (I make swords at ren fares with pete moss) they quench with different oils and temperatures. So 'tool steel' as you say, is a gamble pending on where it comes from.
So, AR500 from China, not going to add up to Japanese or American AR500 despite the rating. And that means, just like everything else, production cost (pointedly how to skimp) using the same rating is the issue ... just like everything else on the face of this earth.
Boy if you want something done right, do it yourself, never mattered more than now.
Thanks Ray. Fascinating. But expected.
What's the bare minimum we can do to slap a label on this product people 'think' they understand and will go ahead and buy. Reminds me a bit of the Titanic. Citing rivet slag there.
Most get cut out off sheets of metal
There certainly are differences in material, even the same alloy from the same vendor. It does happen, and when you are trying to get the absolute limit out of a part, bad things can happen. I'm certainly not going to have every piece of plate brought into the shop material tested to verify alloy content, or xray every weld, like you would with say the space shuttle. Our sport just isn't there yet :)
One interesting point is AR material in general. AR stands for abrasion resistant, and the number after is hardness on the brinell scale. So steel that is AR400 for example, as long as it is the basic abrasion resistant steel and that hardness, then it's legit to advertise it that way. But there really aren't specifics on how it is alloyed! AR400 from 3 different vendors could have the same, or fairly different, chemical makeup and you as the buyer wouldn't know.
-- Thanks for taking the time out to explain, Ray. Always learn from you. Why I'm here :) @@ray9368
Why do you harden the entire bar? You only need the striking edge hardened so the rest of the bar can absorb the shock and be able to flex.
3:22 I wonder how hot these weight-reducing holes got during the milling process?
If he doesn't the bar just snaps instantly, cause un-heat treated tool steel can't take those forces lol
@@dareapermanstormearth1891 Do you really think the same hardness on the surface is throughout the entire bar to its core???
No you dont the forces wouldnt be equally divided
@@AndyFromBeavertonyes when done properly it is
I wonder if you would get better results if you were to forego a bar shapes weapon for a large saw blade.
Yes, you would sacrifice the visual appeal of "Big Hits" but you might deliver more consistent damage, especially against faster opponents that attempt to take a glancing hit then quickly readjust and move in while your bar is spinning up again.
No matter what you decide, I'm looking forward to seeing you compete next season.
There are two factors to consider when thinking about a spinner - energy and 'bite.' Energy is a function of mass, rotational speed, and mass distribution - the 'farther out' the mass is from the center, the higher energy, this is called moment of inertia (MoI). Ray has a great video explaining why he uses toothed bars where he talks about this more. A solid disc, like a sawblade, would have lower MoI than a bar (especially a toothed bar), and so therefore lower energy. A hollow disc (think like the ones Valkyrie or RotatoR use) has the highest possible MoI, but is in turn more fragile and harder to manufacture.
'Bite' is how effectively you transfer that energy, and is not nearly as mathematically defined as energy. Think of a perfectly smooth cylinder spinning (like a saw disc with infinite tiny teeth) - it could have tons of energy, but it would be terrible at transferring that energy due to low 'bite,' it would just kind of rub against the enemy. Now imagine if that disc had one giant tooth sticking out, anything that tooth hit would take the full force of the blow. An example of 'bite' in action is Cobalt - Cobalt's weapon actually isn't that big or energetic compared to the "big weapons" (Uppercut, Ripperoni, etc.) However, their design, with one *huge* tooth, gives them massive 'bite' - this is how they vaporized Ghost Raptor. High kinetic energy is useless without solid bite. Pretty much by definition, a bar is the weapon with the highest possible 'bite' and switching to any other design would reduce Tombstone's effectiveness.
The only thing that beats a symmetrical bar like Tombstone is an asymmetrical 'key-shaped' weapon like Bloodsport or Triton use, but that introduces weird physics things - look up the "tennis racket theorem" if you ever wonder why Bloodsport always lands on its side after a big hit.
Ray have you looked at Ar600/Hardox 600? It's getting popular in lower weight classes.
I don’t know if you watch NHRL much but yeah there’s a robot called Minimizer who uses a ar600 disc.
Hardox is similar to ar so he would still need the tool steel as an option to cut deep into an opponents armour and that basically puts him back at square one with the s7.
The weapon disk on Stink Eye was made from ArMax which is an AR material around 530 brinell. And it worked ok, but still shows some damage after the fight with Manta. It's really going to be hard to get away from using something that is harder than AR alloys honestly.
@@ray9368 Huh I thought S7 would be harder than Ar steel but I'm probably confusing the rockwell hardness rating which I'm sure is higher in comparison to wear plate.
@@TheInvertedFollicle507 ar 500 for example is 500 brinell same goes for ar 600 which is 600 brinell and so on, but ar 500 being 500 brinell, if you convert that over to the c scale on rockwell it is in the 52 to 55 range roughly. which in this case is about the same hardness as rays s7 that he wants at 54. but to make a bar like that exactly 54 through out is pretty much impossible. Generally good heat treat places can get it with in 2 rockwell. as you can see rays blades are right on with that spec. the fact that those blades are also really long and on the one side of the blade they held 2 rockwell is pretty impressive. the bigger it is the harder it is to keep everything the same naturally.
Those blades are pretty much as good as they will get heat treat wise. however the one note he made about the one blade being 50 degrees hotter, something like that could be fixed, but in general for the final product being within 2 rockwell is about as good as it gets. maybe there is someone out there that is precise enough to get it within 1 but that would take some extreme skill
Hey ray huge fan why don’t you use the wedge cutting blades for most of the robots with wedges. I’m pretty sure almost all the times you don’t you get knocked out like in the fight against rotator in 2018 or 2019 i don’t remember which it’s been a while but anyways have a good day hope you respond soon, bye
Would case hardening be an option?
Can you imagine getting hit in the shins with Tombstone?
Just a thought....
Considering any calculations would put the Kinetic Energy of Tombstone's blade above the Kinetic energy of a ram from an *Elephant*, you wouldn't have legs anymore.
Cause yeah, Elephant rams are a bit over 125 Kilojoules, Tombstone's blades usually come over 200 Kilojoules at top speed.
@@dareapermanstormearth1891 Hmm, Ray has said his most powerful weapons are probably the aluminum bars with the bolt on steel inserts are hovering around the 106KJ mark I'm not sure where you got the 200KJ result from.
google it up. tombstone hits with about 50 times the force of an AK-47! can you belive that?
@@TheInvertedFollicle507 calcing the weight and speed of Tombstone's blade lol
@@FreeNeato4Me apparently Tombstone's most high energy blade also hits with the force of approximately 10 times the force of a 50 cal sniper rifle. The rifle bullet stores around 10-15 KJ of kinetic energy.
the 2 times i recall the bar breaking were bite force and witch doctor
Would it be worth sacrificing some of the hardness for a bit more ductility? You could call the blade "blunt force trauma" 😊. Or keep the same S7 hardness and redesign the impact edge completely.
I believe that's the exact purpose for the AR400 bars that Tombstone also runs
Do you think the lightning holes helped heat treating deeper into the 20 fight bar than the 2 fight bar.
I wonder if the holes where drilled into the bar before heat treating and that helped spread the heat into the inner of the bar.
Can you make a video about why you use chain and not belt for the weapon?
Have you considered a harder type of AR? Like AR600/Hardox 600? or higher? Do you think they would be viable options for a bar like Tombstones? Or would they as well be too brittle/expensive?
I love these behind the scenes videos, keep up the work!
I wonder if an AR500 main bar with S7 "rails" along the edge would be a viable option? It might give a nice balance of absorption vs cutting power. Or alternatively, use a weapon similar to what Hypershock used against Gigabyte, and use S7 sandwiched between AR500?
Bolting one type of steel to another wouldn't be ideal. If I was to do that, I would use aluminum for the bar then steel teeth since that maximizes MOI for a bigger hit. Downside is if the tooth comes out :)
Welding dissimilar steels together creates its own challenges. There's now way to really handle heat treating before welding, since the welding act would change it. And heat treating afterwards would be awkward since different steels have different recipes for treatment. S7 is an air quench for example, while many others are oil quench. It's not that this can't be done, but I've never seen it done in a way I thought would work in my usage.
Sandwiched weapons do work, and I have even done that myself on some bots. The problem comes with weapon length. Any short spin circle sandwich can work just fine really, but the longer the distance from the mount to the tip, the more the differential flex between materials starts to be an issue. You can reach a point where the flexier material will oddly pull on the fasteners and can actually make it easier for the harder material to snap then.
There are no single answers really, just continued refinement of your ideas, with the hope of finding that sweet spot. Of course everyone else is doing that too, so even when you do find something that works, it may simply not work next season! Always a challenge :)
@@ray9368 Wonderfully said, sir. I'm looking forward to seeing whatever you come up with next!
did you mention the bar that snapped way back in 2004 against Alcheholic Stepfather?
Did you get rid of these or do you still have them somewhere? And what do you plan to do with them? Study them for future bars or sell them for double of what you paid to make them for fans?
Do you ever megalux them after fights ?
You should make the weapon bar out of whatever they make forklift blades out of. Them things being like an inch thick maybe an inch and a half and able to lift 8000 pounds without breaking or bending super hard would probably work nicely.
hardness and strength are 2 different things
@kraftzero2957 One type of alloy commonly used in the construction of forklift blades is 4140 or 4340 chromoly (chromium & molybdenum alloy) steel.
This is softer than some other types of steel like ar500 or especially tool steel and while some spinners do use 4140 like riptide, black dragon and minotaur as its more easily sourced and cheaper but more easily damaged as its not as hard as the more specialised alloys.
Hey Ray, is there a reason you aren't using a forged steel weapon with tool steel "tips"? aside from most likely a full redesign of the geometry of the spinner.
might be significantly more durable and repairable. not sure. have you looked into it, and if so do you have any thoughts?
you said that the bar that broke against bite force only had 2 fights, including that one. what was the other fight that it was used for?
Are you through hardening or case Carburizing?
What bar would you use against HUGE?
My guess is the red thin s7 one with the 45° bevel down the sides. Long and has a cutting edge for attacking the wheels of huge. Or the short black ar500 bar for taking the uppercuts from the spinner.
They might be reading this, so I'd say one made out of marshmallows, or maybe styrofoam :)
Seriously, we'd have to give a lot of thought at the time.
Could you weld harden the edge? Or harden the blade like a sword and only harden the cutting edge leaving the rest soft and durable?
Not with this alloy, but possibly with others. I do plan on playing around with options there in the future, probably with Mortician at the next Robogames.
What fight did the red bar get damaged during?
That damage came against Black Ice, so not really even a hard hitting match.
What is the blue bar made of?
S7, and it has held up well. Dark art vs science I guess :)
Have you ever looked into nickle alloyed steel?
I have tried more than a few different alloys over the years, but I don't think any of them have any significant nickel content. Always on the lookout for other options though
Just typing my thoughts, correct me if i'm wrong, but can't you make the tip hard and the body soft?
I know little about the material science involved, but i think i know enough of the process, heat it up and quench it to make it hard, then slowly heat it up to release stress and soften it right?
Can't you idk, differentially heat the middle of the bar to release more stress there to make it softer, tougher and less brittle, while keeping the tips hard to dig into armour?
i Know they did something like this with katanas? with mud or something like this to keep the blade hard and the body soft
Your basic ideas on heat treating are correct. Steel is heated to its austenitic temperature (~1420f) which changes the crystalline structure inside the material. It is then cooled quickly by various means to set this hardness. Heating the material after cooling, to less temp, will stress relieve and lower hardness. This tempering step varies in temp and time, depending on material itself and hardness desired.
Heat treating of something this large is done in an oven, to very specific temperatures. So although edge hardening, case hardening, and differential hardening are possible, it just gets harder to make happen as the size goes up, and the hardening recipe gets more specific.
There are other options certainly, and the time may be to start moving away from S7 as my material of choice. We'll see :)
Would it be possible to have a bar that is AR500 with teeth made of S7 tool steel
Probably not, remember, any welds are a weak point, it screws with the heat treating of the weapon, and if you heat treat too much, using Ray's red blade as the example, it gets brittle; it gets too hard.
I wouldn't think that would make too much sense, because if you're already using a toothed bar, you're assuming/hoping you never take any hits to the 'body' of the bar anyway. Why use the weight on steel? Instead, make the body out of something lighter and softer, like aluminum or titanium - this is what Ray already does with his toothed bars. This also allows you to make the teeth bigger, giving you more MoI.
Ray, have you ever considered taking a page from History, and maybe borrow the blade shape from a Flanged Mace, or a Bar Mace, or maybe even an Ablative Awl Spike. Probably being stupid, from lack of sleep.
Hi Ray, can't you somehow get them melted down and reused sense they're all S7?
Steel in general is almost completely recyclable, so in a broad sense yes it can be melted down and reused. In a more specific sense though, as in melt down just the broken S7 pieces, and then reforge them into new S7 plate - it just doesn't work out monetarily. The reason steel is sort of inexpensive is because of how much they make at a time - literally tons and tons daily. It makes much more sense to just buy new plate and make new weapons out of it.
And for me, I can sell the broken weapon pieces and recoup a lot of the costs involved too :)
@@ray9368 thanks that makes sense, I've been watching the battlebots regularly, I'm hoping to see tombstone once again 😎
Has tombstone ever used a giant disc, or anything experimental at all or is the bar just the go-to?
It's always been various shaped bars, and most likely will continue that way too. Every once in a while I draw up something else but never seriously enough to actually get it made :)
@@ray9368 Haha fair enough, I suppose there’s only so many shapes that would be effective.
It's all about the stiffness. 😉
Looks like a very expensive sport, financially and emotionally.
What about a steel like H-13?
I have not used that alloy before, but I have been considering it. A great thought!
@ray9368 I'm a knifemaker, buy trade, I don't know what you know about steel. S5 and s7 are good tool steels. A blacksmith or a heatreater would know the the property's your looking for any how, good luck.
S7 is very elite but very self go boom😂
I'm curious. Does Rick own both Jack and Jill or do you each own one?
Rick is the one who did the work on those bots, so he has them both.