Copperhead Custom Wheel Molding

[@douglasbutler4360]

For stubborn molds for my underwater robots I have put threaded holes for zirc fittings on the mold so you can use a grease gun to push the part out of the mold.

[@RobertCowanDIY]

That's a pretty good idea. Really once the suction or seal is broken, they come apart quit easily. So that would certainly help.

[@ShreddingZoo]

I couldnt wait to see this. Thanks Rob for all your hard work and sharing with the community

[@RobertCowanDIY]

Thanks for watching!

[@DefinitelyNotEmma]

Another thing regarding the bubbles, ever thought to use a vacuum chamber? Or is that unnecessary just for the wheels?

[@JulianHaardt]

All the bubbles went to the top and at this size of wheels its just surface pitting. Sure it's not going to win a beauty price, but at the same time its a battle bot. Structurally the wheels are fine. To find a vacuum chamber this size to fit the mold, probably cost some money and the wheels are expensive enough.

[@RobertCowanDIY]

Let it settle, get the bubbles out before you pour. Pour slowly and patiently. Should be fine beyond that.

[@wickedprotos1937]

You could build the vacuum ports into the mold itself. Just pull the vacuum while its not hardened to remove the bubbles., then open up the ports.

[@JonathanRansom]

Now I want to see an entire bot with this thick rubber as armor.

[@zomie1]

I was thinking an overmold like you see in some tool applications.

[@ThatBum42]

If your opponent's weapon can get lodged in the rubber then it might count as an entrapment device and be against the rules. Although, if we're talking ablative armor in general, I've heard of a few using wood.

[@DeAtHaToMiC88]

@@ThatBum42 I'm not sure that it would class as entrapment unless the armour was specifically designed to capture weapons though.

[@RobertCowanDIY]

Yeah, only when intentional.

[@ThatBum42]

@@DeAtHaToMiC88 Yeah you're right. With the hardness of the rubber and the forces involved at heavyweight it's unlikely. Though, I have heard that many venues dislike ablative armor in general and wood in particular because it makes a hell of a mess in the arena.

[@michahalczuk9071]

Did you think about possibly adding this rubber to some crucial elements of body for extra protection and hit dumping?

[@RobertCowanDIY]

It's tough because adhering it to those surfaces is the harder part.

[@andrewbot]

Awesome video! I'd love to make some custom wheels down the line. When pouring around the hub how do you make sure that the liquid rubber fills in the "undercut" that is facing the ground, rather than creating a cavity or air bubble? Can't wait to see how they perform on the upcoming season.

[@RobertCowanDIY]

We didn't really do anything to make sure that cavity was filled. I guess ideally it would be drilled through, but we didn't do that! But an air bubble wouldn't really do a while lot other than save weight.

[@greggv8]

@@RobertCowanDIY I'd definitely drill some vent holes through. I'd also use the mold release specified by the manufacturer of the rubber, and the surface prep or bonding agent they have for the hub. With the bonding agent a damaged wheel could be turned down on a metal lathe, prepped and a new layer cast over it. Takes the right lathe bit geometry and *really sharp* to turn rubbers, and there's a limit on how soft a rubber can be turned. Grinding rubber to shape can be done but it's horribly messy and the particles get static charged to the point they have to be scrubbed off with soap and water and can still leave some stuck.

[@rhtufts]

This video was great thanks. Have you guys thought of cutting a simple tread pattern into them for more traction?

[@DoRu42]

How did you get the polyurethane to fill the undercut which would be facing down in the mold? I did not see any air channels through the undercut surface to the other side so a huge bubble would form and prevent most of the polyurethane from entering the downward facing undercut.

[@DefinitelyNotEmma]

The moment when a design "weakness" becomes a strength xD

[@tostuk2528]

What if you put the wheel in a vacuum? Would that solve the bubble problem?

[@Fattoxthegreat]

2 wheels total or 1 set per robot? Incredibly bold to only bring the 2 if so. This was an awesome video, thanks for showing us this. Always keen on Copperhead info.

[@RobertCowanDIY]

2 total. We used the same two wheels the entire competition. We had spares, but never used them because swapping them is a bit of a pain, the whole drive side needs to come apart basically.

[@CSparzo]

Have you tried using a release agent for the mold? PVA release agent works really well and its water soluble so you can just rinse it off after demolding. I usually apply it with a nice bristle brush. Another thing you can do to help reduce the amount of bubbles is make a vacuum chamber to put the entire mold in after you pour it. A simpler, but slightly less effective alternative is to vacuum the bubbles out of the urethane while it is still in the bucket (i.e. using an off-the-shelf vacuum chamber/bucket). Also, if you apply heat to the part while it is curing it can exponentially decrease the cure time (it looks like you could fit that in a regular oven). Usually this also increases performance of the final product (follow manufacturer recommendations there, though).

[@aserta]

I wonder what would it take in terms of price (to be read, vs the current setup) to make the wheels out of actual vulcanized rubber in a home setup. One of my RC airplane mentors as a kid would make his own rubber wheels for this big airplanes. I still have one, perfectly pliable to this day, so i know it can be done, but would it be cost effective...hm.

[@RobertCowanDIY]

There is a company in Brazil that can make vulcanized rubber wheels. I kinda looked into it, but couldn't find too much information on a DIY process.

[@aserta]

@@RobertCowanDIY I should think the biggest hurdle, has to be getting the raw rubber blocks, the rest, is public knowledge, has been for years. I mean, sure, we don't have modern blends, but we've been doing vulcanizing for years. I know there's a company in Germany that did custom bicycle tires, but i don't know if they are still in operation. A friend's firm got custom tires for their employee's bicycles a few years ago as a Christmas gift. My mentor had access to raw rubber blocks directly from a tire factory in Ukraine, but that was ages ago, i think they even shut down recently.

[@greggv8]

@@RobertCowanDIY A source for rubber like that is spin casting suppliers like Conquest Industries. They make heat vulcanized rubber and silicone. To heat vulcanize a wheel of that size would require it to be wrapped with insulation around the sides while it's in the press, and the mold would need more features (preferably through bolts horizontally) to hold it together. Also the hub would have to be made of something more heat resistant than Nylon since these rubbers cure at over 300F. Takes 1 hour per inch of thickness with the heat and it has to be held under clamping pressure both to keep the mold together and so the material will cure. Can't just toss a chunk of it onto a hot plate and cure it. I use the silicone to make spin casting molds for Zamak alloy. I've also been doing silicone mold and urethane casting for 20 years, plus ceramics, fiberglass, and a whole lot of other things starting with handing my father tools and parts when he worked on cars, starting when I was around 5-ish about 45 years ago. There's just no fighting robot scene in a small Idaho town of around 5,000 people. ;)

[@lowlifeangler]

@@greggv8 Yeah I use around 172-182 C degrees on the mold surface making Air Flow Tubes for Honda and Toyota. The raw rubber in spun a company called in Akron, Ohio

[@lowlifeangler]

@@RobertCowanDIY the nylon material I use is Dupont Zytel PA 66 33% glass filled nylon, Honda has been using alot of that for their engine parts instead of metal

[@yashpatel3123]

Great information. Thanks.

[@schalotten]

Hey, you have on the nylon core these two "grooves" wouldn't air be trapped on the bottom groove during the pouring-process? Just wondering...

[@Fresco272]

Yeah, there must ve some air pocket but probably not so big to be any isue in application like this. But for example just 3 small holes drilled around the ring would solve that for sure.

[@nickloeschke8209]

I was thinking the same thing....

[@Outland9000]

Good content Robert!

[@TheStuartstardust]

Do you re-use the hubs? 🤔 I think the hub under cuts at 2:00 give you trapped air if mold is not tipped during pouring - drilling axial from void to void should help.🤓 Also - drilling some small 3 mm holes on top will bleed the air bubbles, like regular tires I guess, to be cut off later - but agree no functional impact 🙂 Cool vid - thanks 💪

[@RobertCowanDIY]

The hubs aren't reusable. There's no way you're getting the rubber off once molded. And you're right, the undercut could trap air, and cross-drilling would help, we were just lazy ;-) The top does have two vents, but it would need MANY to get rid of the bubbles, best to start with as bubble-free rubber as possible.

[@Kallekringla3]

What about making forms and covers for the internal electronics in this material for shock damping?

[@RobertCowanDIY]

you COULD, but that would just suffocate them, they need some air flow or else they can overheat.

[@jfirebaugh]

Fit your mold with some grease gun fittings. When de-molding, a couple of pumps with a grease gun will break that suction grip in the mold.

[@RobertCowanDIY]

But wouldn't there be a hole that would get filled with rubber?

[@jfirebaugh]

@@RobertCowanDIY Fill the hole with a little dab of grease before casting. There will just be a little dimple in the finished part.

[@davebullard]

I know that the bubbles aren't a big deal, but did you consider pulling a vacuum on the mixed rubber before pouring?

[@RobertCowanDIY]

We considered it, yes. BUT, for something like this, it really wasn't necessary. In a normal application, you would want to pull a vacuum or even pressurize the mixture before pouring it in.

[@CraigDanby]

finally!

[@RobertCowanDIY]

now go finish that beetle!

[@CraigDanby]

@@RobertCowanDIY Neva!!!!

[@CraigDanby]

Have you considered sandblasting the hubs to get that fuzzy surface for bonding too?

[@TheQuinto2010]

I like that it's smooth with no threads. I see so many bots with threaded tired and wonder why they have that for a smooth combat surface. It'd be different if the arenas were dirt or 'offroad'.

[@andrewburghgraef4556]

is there any draft on the mold (to help demolding) or is the wheel molded with a completely square profile?

[@RobertCowanDIY]

I think there's a tiny bit, the wheels are a tad rounded when they come out, we just drive them on asphalt to make them flat. but more draft would help getting it apart, but then the wheels wouldn't have a flat tread.

[@davidlewisii4303]

Do you think kevlar fiber reinforcement would be beneficial?

[@RobertCowanDIY]

Whenever I see suggestions like this, I want to ask: "what's the problem you're trying to solve?" Are you trying to make them stronger? Because we don't have issues with them failing. Are you trying to make them lighter? The kevlar wouldn't do that. Are you trying to make them cheaper, easier to make, etc? I always look at design with that question in mind. What problems exist, and what's the best and easiest solution to fix them.

[@davidlewisii4303]

@@RobertCowanDIY Its an attempt to make it stronger per mass. If the overall material strength is higher perhaps you could create hollow sections to make it lighter.

[@neilrhoades5951]

Hey Robert, curious if you would have advise on an idea for using Polyurethane Rubber as a weapon. Im thinking of coating a truncated cone shape full body spinner 1lb robot and using the catch and bounce of the material to push opponents around. Thoughts?

[@RobertCowanDIY]

I think no matter how you did it, it would be too delicate. People are using titanium, AR400/500 and other materials for weapons, I don't think it would hold up. The whole idea of a spinning weapon is to generate, store and transfer kinetic energy. Using a rubber can accomplish the first two, but will be unable to effectively transfer the energy into your opponent, making it act more as defense. That's not what you want for a weapon.

[@neilrhoades5951]

@@RobertCowanDIY Thanks Robert. I have also been working on an adjacent design in which there would be a rotating shell but it would just free spin as armor like you mentioned. Do you think 50 durometer rubber would work ok here? I was also thinking of attaching steel wire brush to dissipate vertical and horizontal spinners.

[@RobertCowanDIY]

@@neilrhoades5951 Sorry, but I don't think this design would be effective. read my previous comment. you're basically designing a weapon with a feature that invalidates the purpose of having a weapon. I'm not saying it won't work, I just don't believe it would. But I could be wrong.

[@neilrhoades5951]

@@RobertCowanDIY Thanks Robert!

[@glyphthegryph4536]

Could adding fiber or mesh to be cast within the wheels make them more durable? Something sort of like rebar in concrete, though I have no idea how well that would work for rubber.

[@RobertCowanDIY]

See my reply to David Lewis II. Same thing, what are you trying to solve? They are plenty durable, but chunks can get taken out easily enough. Carbon fiber would maybe prevent that, but that energy has to go somewhere. It might end up just cracking the wheel instead of taking out chunks of rubber. Concrete is very brittle and needs the rebar to stabilize it. Rubber has the opposite issue. Making it stiffer doesn't really add a significant benefit IMO.

[@aceshelander1281]

We (Gemini) use 3d printed wheel molds for our wheels (even used the same mold for 3years) The trick is sulfur free modeling clay, by applying a thin coat to all the seams we get ZERO FLASHING. you can even smear it on the whole surface to eliminate print texture but stopped as it didn't seem worth the effort (even tough it only takes 15 min) This could be used on aluminum too but 3D print is dirt cheap in comparison and I don't see much downside I should also mention we use a 2 (or now 4) part mold with diametral splits and a free top surface (no molded upper surface just pour till the mold is full)

[@Aagggyy]

Gemini, you ever coming back?

[@heartofdawnlight]

You Mention not wanting to risk dying other colors. What I recomend if you want cooler looking wheels, even if black. Using Mica Powders. Every time Ive used it in materials for coloration it cures without really changing color

[@aserta]

3D print + the salt oven method to make it a solid plastic piece. Then you can do the hub and trust it.

[@JulianHaardt]

And you going to have a rough surface the urethane never can slip off.

[@RobertCowanDIY]

someone watches CNC Kitchen ;-)

[@aserta]

@@RobertCowanDIY Guilty as charged, mon capitaine. :)

[@aserta]

I was ruminating on the de-molding process over night and figured this. Each mold section would get one threaded hole, through that hole, a threaded screw can be inserted and made flush with the inner surface. During the molding process and curing, it stays in place, but once that's complete, all you have to do is remove said screw, insert compressed air, and it should pop out the wheel.

[@RobertCowanDIY]

I drilled and tapped two holes in the top, so I can separate the top and bottom by just threading in a long bolt. Works well enough. The next mold design would have features like you suggest to be able to pull it apart easier.

[@MrMaxymoo22]

Do you follow Charles Guan, creator of "Overhaul" by chance? He had a fantastic blog post or two about casting your own wheels for this exact purpose.

[@RobertCowanDIY]

I do.

[@microflowmeter]

Great video~

[@wickedprotos1937]

What do you think the weight rating on these could be?

[@RobertCowanDIY]

That's a good question. They can easily handle probably 500 pounds (a bot on top of ours), but beyond that I'm not sure.

[@robertwood6297]

good stuff!

[@maroonmonkey7475]

LezzzzGooo FINALLY!!🥳

[@peteross9267]

What is Copperhead ?

[@RobertCowanDIY]

Ha. Copperhead is a robot on the TV show Battlebots. It's a 250 pound combat robot.

[@DeAtHaToMiC88]

Strange... i just got a notification for this video 2 days after it was posted and still had to type the channel name in to actually watch it because the video wasn't in my sub box.

[@RobertCowanDIY]

Huh, odd. It's a conspiracy!

[@BenRyherd]

Last I knew Extinguisher was going to make their wheel molds from 3D prints, I think their hubs are bigger compared to the tire diameter (so less liquid being poured in) but the overall wheel size is fairly similar and it's a heavyweight. I think the plan was "If they come off, great, if they don't we'll break them off [they're cheap 3d prints]."

[@RobertCowanDIY]

I hadn't heard anything about that. I might try molding my own with 3d printed molds and see how it goes. T

[@SBBurzmali]

I'm curious, why not embrace the bubbles? Assuming you could trap the majority of the bubbles in the body of the tire, you could probably shave a couple pounds off the weight without a major loss of strength.

[@ITman496]

I want to see someone make the whole robot out of the cast rubber for the wheels....... It seems to be able to take so many direct hits, maybe an indestructible robot?

[@RobertCowanDIY]

I think all the mechanical parts would have a hard time working... You need a rigid structure for drive and weapon power transmission.

[@ITman496]

@@RobertCowanDIY haha yeah I know, mostly a silly idea. Maybe you can cover crippling depression with a giant 220?lb layer of it. 🤣

[@alexheyer3034]

How much is a pound of pu more or less?

[@RobertCowanDIY]

It varies considerably with what you get and how much you buy. The stuff we use is around $150 for 16 pounds, so roughly $10 a pound. So yes, every wheel is around $150 in just rubber...

[@doofus_robot7287]

If you french fry when you pizza, you're gonna have a bad time.

[@saddlepiggy]

You guys should see how many wheels you need to stop a bullet. They seem like it would only take 1 lol.

[@RobertCowanDIY]

That's a pretty interesting idea, I'd be curious about that too.

[@lowlifeangler]

Need more clamping pressure (tons?) LoL

[@RobertCowanDIY]

Yeah, the next version of this should have something to hold it together. It's not that bad though, just cumbersome to put together.

[@lowlifeangler]

@@RobertCowanDIY sorry to be silly Robert , I deal with molding injection, Rubber injection, and blow molding. The mold you have is close to the blow molds that are made at Toledo Tool and Die. Love your vids

[@huckstirred7112]

fork lift tires

[@TilmanBaumann]

That's a lot of weight. I guess some voids or foaming agents would not hurt durability and give you some kg back.

[@DefinitelyNotEmma]

Hmm, I think it would really effect the structural integrity of the whole wheel. After all it's meant to absorb blows from the likes of Tombstone, Gigabyte, SOW etc.

[@RobertCowanDIY]

The wheels came in right at weight, which would suggest there aren't too many voids.

[@kenotmanowski6743]

Great video, but please don't say "polyurethane rubber." It's one or the other. :)