The segment at 00:53 concerning motor modifications is a gold mine. In less than 1:10, we have bearing supports, drive shaft mods for torque transfer, sensor fixation for shock, stator protection, and even magnet expoxying for rotor longevity. Great tips for motor longevity beyond combat bots!
Hey Robert , love the vid. Have you considered adding thin shear surfaces between the nylon? You mentioned the torsion and impacts these units take and adding connections between the standoffs would significantly increase your shear stiffness around the motor for negligible weight. This would still allow you to maintain the nylon bumper method you mentioned.
All the thinking that went into every upgrade to Copperhead... I wish more teams documented it like this (or if they do, they'll release the videos after the season). I wouldn't be surprised if Copperhead actually doesn't have any self-fails this year, though. You seem to have addressed every issue from the last tournament. That said, if something fails, we can come back here in a few months and timestamp the moment that part is shown. Here's hoping we don't get to do that!
Do you have any concerns with the motors overheating? The TPU piece might be stopping the motor from heatsinking to the aluminum piece and you could save some degrees if you let it do that
Nah, in the previous tests, we were burning up the wheels for several minutes, driving it with extra weight outside in 100F heat, etc. In all cases, the motors were slightly warm, but not too hot to touch or anything. They don't really need much heat removal. When they get damaged it COULD be a problem, but they should be OK. I think the battle hardening is worse on them, but that's critically important.
@@RobertCowanDIY Is there a material (other than TPU) that conducts heat better, but still has similar cushioning qualities? It might not be needed in this robot, but maybe a different robot could make use of something like it.
Looks awesome! My concern is the wiring looks like it could make contact with the drum potentially, I’d take some more loom around the wiring to hopefully save you from a short. My 2 cents from building random junk in my garage lol
@@lokedog916 Oh, it very much is close. BUT, it doesn't really want to bend INTO the motor, it needs to be taped or secured in place to get TOO close. It wants to bend away. This is pretty common and not really a concern.
@@RobertCowanDIY ah okay good, I really want you guys to do well this season! I’m so stoked for it, ever since I found your channel I’ve been rooting for copperhead!
Not really. If it's completely unsupported, it can move a LOT. I'm just trying to lower the acceleration/deceleration during hits. But during normal operation, it's good to support the rear can.
BattleBots usually need high torque at relatively low final drive RPMs. Outrunners generally produce more torque at lower RPM than inrunners, so less gear reduction is needed to achieve a useful final drive. This makes construction easier, more compact, and lighter.
Yep, what others have said. The biggest reason for us choosing an outrunner is form factor. We don't have the length (depth?) that inrunners require. We only have room for a larger diameter motor, which means we have to use an outrunner. Also, we don't have the room to gear down an inrunner, which usually has much higher RPM.
I was getting worried until I saw the TPU bushings, it seems like Copperhead's only weaknesses in the previous season were firmware gremlins and shock loads transferring through the armour and into the vital components. If Copperhead now has all the vitals shock-mounted then I don't think anything will seriously harm it.
Hey Robert I gotta ask cos it's been bugging me for a while thinking about this, is the aluminium 7075 or 6061? I presume it's one of those two cos 6061 is more likely to bend under load and the other alloy is more likey to crack but they seem the most commonly used Al alloys for structural components.
Which, the ones that attach to the motors? Not really since there won't be significant lateral force to shear them. It can't pull them out (nowhere to go) and very limited lateral movement.
@@RobertCowanDIY This is probably where my inexperience with electric motors shows, but I'd have thought that with all the bending the assembly is made to accommodate, those screws being metal to metal seems like a stressful relationship. But then again, the motor itself might flex too, which would minimize the forces that I'm imagining.
@@ekner Oh you're not wrong. If I had to do it over, I would do some sort of dowel pin or something. They really only need to keep the motor from spinning, not really hold it in place. But I do think it will be fine. I always look at failure modes. If all 4 get completely sheared off, it can still MOSTLY function.
@@RobertCowanDIY That's a good point, they only need to fill the role of dowels. With any luck, the heads will pop off and the threads will survive. I had that exact thing happen on a sprocket recently, where it all held together and I only noticed something wrong after I was finished running the machine.
Total newb question here: with drumspinners like copperhead (my fav type of bot) i wonder if anyone thought about putting the weapons motor and battery for it ''inside'' the drum rather than powering it via chain belt from the outside i.e. making the motor and drum rotate in unison. i could see a more bulky drum like for example yeti's to have enough space inside and it would naturally add to the weight of the drum (and make the bot even more front heavy which i think is an advantage for one like copperhead).
You can certainly do a 'hub motor' which is kinda what you're describing. The problem is that you have now coupled all the shock and impact directly to the motor. We use a belt since that de-couples these loads from the motor. A weapon motor INSIDE would see all the forces that the weapon sees and would most likely explode. Other teams have tried this as it's common at lower weight classes. But at the 250 pound class, the motors would rarely survive these big hits.
@@RobertCowanDIY thanks for the quick and thorough reply. i guess it has pros and cons and from the overwhelming usage of chainbelts and external motors probably more cons 😀. Maybe someone will someday find a way to leverage the pros and bring one super heavy to the arena. cheers
Then it becomes heavier, slightly magnetic (and potentially conductive), and makes an absolute mess when it rubs away. What's the problem you're trying to solve with iron filings?
Nope. The epoxy only adds a few grams per motor, and the whole thing is going on a chain drive with a 15 pound wheel. Balancing the motor isn't really worth it considering what it's getting attached to.
Seeing the inside of those maytechs is pretty disappointing. I had thought that they were a direct clone of the Leopard 8072, re-branded as an 8085 (which was already irritating to me, that they are lying about the size of the motor in the name). But upon seeing the inside, I realized that Maytech has taken the stator length down a bit to accommodate the sensors. The 8072 I have will take 300 amps happily before saturating and causing Vesc freak outs, Do you know what these will handle?
Maytech states in the product description a stator size of 68 (diameter )* 30 (height) * 25 (inner diameter) with a note: "This motor actual length is not 85mm, according to customers needs, we have modified the motor length once, but model number is not changed, the motor actual length is 74mm."
@@mattgolman combat robots are already approaching that cost. I have no idea how something complex like chomps 500lb walker cost but even a more standard 250lb robot like hypershock cost $67k
Then you'd have maybe 2-3 teams with the financial capabilities to compete. 250 lbs is already pushing it, there are a a million more teams in lower weight classes.
The segment at 00:53 concerning motor modifications is a gold mine. In less than 1:10, we have bearing supports, drive shaft mods for torque transfer, sensor fixation for shock, stator protection, and even magnet expoxying for rotor longevity. Great tips for motor longevity beyond combat bots!
Thanks!
Looking forward to seeing this new drive module in motion. Looks great!
Same! We want to see how it works out this year.
Hey Robert , love the vid. Have you considered adding thin shear surfaces between the nylon? You mentioned the torsion and impacts these units take and adding connections between the standoffs would significantly increase your shear stiffness around the motor for negligible weight. This would still allow you to maintain the nylon bumper method you mentioned.
I'm not sure I understand what you're asking?
All the thinking that went into every upgrade to Copperhead... I wish more teams documented it like this (or if they do, they'll release the videos after the season).
I wouldn't be surprised if Copperhead actually doesn't have any self-fails this year, though. You seem to have addressed every issue from the last tournament. That said, if something fails, we can come back here in a few months and timestamp the moment that part is shown. Here's hoping we don't get to do that!
Something will still fail! We're making stronger links in the chain, but there's always a weak link! We'll just have to see what breaks next.
they look great!
Do you have any concerns with the motors overheating? The TPU piece might be stopping the motor from heatsinking to the aluminum piece and you could save some degrees if you let it do that
Nah, in the previous tests, we were burning up the wheels for several minutes, driving it with extra weight outside in 100F heat, etc. In all cases, the motors were slightly warm, but not too hot to touch or anything. They don't really need much heat removal. When they get damaged it COULD be a problem, but they should be OK. I think the battle hardening is worse on them, but that's critically important.
@@RobertCowanDIY that's actually pretty impressive
@@RobertCowanDIY Is there a material (other than TPU) that conducts heat better, but still has similar cushioning qualities? It might not be needed in this robot, but maybe a different robot could make use of something like it.
Looks awesome! My concern is the wiring looks like it could make contact with the drum potentially, I’d take some more loom around the wiring to hopefully save you from a short. My 2 cents from building random junk in my garage lol
I'm not sure what you're seeing, but it won't make contact. You're not seeing it fully installed, there is a LOT of tape and zip ties ;-)
@@RobertCowanDIY fair enough, from the camera angle it looks awful close to the can on the motor when you bend it into its slot
@@lokedog916 Oh, it very much is close. BUT, it doesn't really want to bend INTO the motor, it needs to be taped or secured in place to get TOO close. It wants to bend away. This is pretty common and not really a concern.
@@RobertCowanDIY ah okay good, I really want you guys to do well this season! I’m so stoked for it, ever since I found your channel I’ve been rooting for copperhead!
Doesnt soft mounting that rear bearing defeat the entire point of that bearing?
Not really. If it's completely unsupported, it can move a LOT. I'm just trying to lower the acceleration/deceleration during hits. But during normal operation, it's good to support the rear can.
Can you explain the design choice/reasoning for going with an outrunner motor vs something that might be inherently more robust like an inrunner?
BattleBots usually need high torque at relatively low final drive RPMs. Outrunners generally produce more torque at lower RPM than inrunners, so less gear reduction is needed to achieve a useful final drive. This makes construction easier, more compact, and lighter.
Yep, what others have said. The biggest reason for us choosing an outrunner is form factor. We don't have the length (depth?) that inrunners require. We only have room for a larger diameter motor, which means we have to use an outrunner. Also, we don't have the room to gear down an inrunner, which usually has much higher RPM.
@@RobertCowanDIY makes sense! I appreciate the response!
I was getting worried until I saw the TPU bushings, it seems like Copperhead's only weaknesses in the previous season were firmware gremlins and shock loads transferring through the armour and into the vital components. If Copperhead now has all the vitals shock-mounted then I don't think anything will seriously harm it.
Eh, even going from steel to aluminum would help. The last setup was just steel on steel. But the TPU should help further.
Amazing work!
That’s cool and all, but why are you guys waiting so long to finalize the lever arm punter?
That was an April Fools joke. It's not real and it's not even remotely viable.
Ohhh I see, trying to underwhelm the competition until they see copperheads true power. Gotcha 😉
These must me the drive motors that sucked up all the debris during the WhitchDoctor fight and failed. - Karl copperhead super fan
Hey Robert I gotta ask cos it's been bugging me for a while thinking about this, is the aluminium 7075 or 6061? I presume it's one of those two cos 6061 is more likely to bend under load and the other alloy is more likey to crack but they seem the most commonly used Al alloys for structural components.
Any worries about those button head face screws breaking off? Seems to be the stiffest point of the assembly.
Which, the ones that attach to the motors? Not really since there won't be significant lateral force to shear them. It can't pull them out (nowhere to go) and very limited lateral movement.
@@RobertCowanDIY This is probably where my inexperience with electric motors shows, but I'd have thought that with all the bending the assembly is made to accommodate, those screws being metal to metal seems like a stressful relationship. But then again, the motor itself might flex too, which would minimize the forces that I'm imagining.
@@ekner Oh you're not wrong. If I had to do it over, I would do some sort of dowel pin or something. They really only need to keep the motor from spinning, not really hold it in place. But I do think it will be fine. I always look at failure modes. If all 4 get completely sheared off, it can still MOSTLY function.
@@RobertCowanDIY That's a good point, they only need to fill the role of dowels. With any luck, the heads will pop off and the threads will survive. I had that exact thing happen on a sprocket recently, where it all held together and I only noticed something wrong after I was finished running the machine.
Hello Robert! What are your thoughts on the new "platform" that will be in the arena in this new season? Will it advantage/disadvantage Copperhead?
We haven't experienced it yet. I think overall it will be neutral for Copperhead. We'll see how it plays out.
Total newb question here: with drumspinners like copperhead (my fav type of bot) i wonder if anyone thought about putting the weapons motor and battery for it ''inside'' the drum rather than powering it via chain belt from the outside i.e. making the motor and drum rotate in unison. i could see a more bulky drum like for example yeti's to have enough space inside and it would naturally add to the weight of the drum (and make the bot even more front heavy which i think is an advantage for one like copperhead).
You can certainly do a 'hub motor' which is kinda what you're describing. The problem is that you have now coupled all the shock and impact directly to the motor. We use a belt since that de-couples these loads from the motor. A weapon motor INSIDE would see all the forces that the weapon sees and would most likely explode. Other teams have tried this as it's common at lower weight classes. But at the 250 pound class, the motors would rarely survive these big hits.
@@RobertCowanDIY thanks for the quick and thorough reply. i guess it has pros and cons and from the overwhelming usage of chainbelts and external motors probably more cons 😀. Maybe someone will someday find a way to leverage the pros and bring one super heavy to the arena. cheers
@@RobertCowanDIY just found out that you got a few videos about hubmotors uploaded. watching now :-)
I would like to see copper head vs random objects with the drum at full speed I find it fascinating to see please.
I mean, we all want that, but no one wants to clean up afterwards and it's a huge safety risk. Debris can fly very fast and go really far.
What happens if you impregnate the expoxy in the motor with iron filings?
Then it becomes heavier, slightly magnetic (and potentially conductive), and makes an absolute mess when it rubs away. What's the problem you're trying to solve with iron filings?
Will the epoxy in the motor impact the cooling? Nice job!
Quite a bit lol, but it's a worthwhile tradeoff to keep all the fiddly bits where they need to be, and the motors can handle it.
In theory, it should. But I've never noticed a significant increase in temperatures after battle-hardening motors.
@@RobertCowanDIY Maybe because the duration of the battle is short enough. Thx!
how much # for 2 of those drive modules?
hey what happened to the flipper mechanism you were innovating on?
That was an April Fools joke. It's not real and it's not even remotely viable.
What radio do you rely on for controlling Copperhead?
We use a couple Taranis QX7s and an X9D.
@@RobertCowanDIY Thank you!
Do you bother to rebalance the motor after battle hardening?
Nope. The epoxy only adds a few grams per motor, and the whole thing is going on a chain drive with a 15 pound wheel. Balancing the motor isn't really worth it considering what it's getting attached to.
At this point outrunner motors are just inrunners with extra steps, change my mind.
Yeah for combat robots pretty much. The spinning outer body has to be protected so it doesn't touch anything.
Inrunners are much higher KV (RPM) on average, and much longer. We went with what would fit.
Seeing the inside of those maytechs is pretty disappointing. I had thought that they were a direct clone of the Leopard 8072, re-branded as an 8085 (which was already irritating to me, that they are lying about the size of the motor in the name). But upon seeing the inside, I realized that Maytech has taken the stator length down a bit to accommodate the sensors. The 8072 I have will take 300 amps happily before saturating and causing Vesc freak outs, Do you know what these will handle?
They handle what we need them to handle, and they fit inside the space they need to fit inside of.
Maytech states in the product description a stator size of 68 (diameter )* 30 (height) * 25 (inner diameter) with a note: "This motor actual length is not 85mm, according to customers needs, we have modified the motor length once, but model number is not changed, the motor actual length is 74mm."
How do i introduce a new weight class into this sport? Max limit will be exactly 1000 LBS. BTW do you think 1000 lb is possible?
Ha, figure out how to make an arena to handle those bots, then worry about the bot... 250 is the biggest because of the limitations of the arena.
In addition to the arena, cost of the robot would be insane. You'd be looking at $100k+ per machine, without spare parts.
@@mattgolman combat robots are already approaching that cost. I have no idea how something complex like chomps 500lb walker cost but even a more standard 250lb robot like hypershock cost $67k
Then you'd have maybe 2-3 teams with the financial capabilities to compete. 250 lbs is already pushing it, there are a a million more teams in lower weight classes.
First comment again,. Nice work sir