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Making Tires with 3D Printed Molds

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Making Tires with 3D Printed Molds

Old 01-28-2024, 01:10 PM
  #181  
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Dang I should have mentioned that before. I used to work for a tire retreading shop and they remade tires with moulds. I didnt get into all the info about the rubber used but they did mention carbon black is an essential element in the rubber compound. The company could make rubber compounds in any durometer (hardness) rating you wanted, and a lot of it had to do with carbon black.
I had been toying with the idea of getting some rubber dust from them and blending it with silicone to make tires. This dust is super fine like talcum powder.
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Old 01-28-2024, 04:59 PM
  #182  
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Originally Posted by andreas78
What about Silica? This is also used for tires to increase wear and grip.
Andreas
That was another one I saw come up a lot and it's also equally easy to find cheap (at least, silica fume is. there's a bunch of different silica additives that seem much more specialized and hard to find). I might get that next, but carbon black seemed like the more common/fundamental additive so I wanted to go with that first.

Originally Posted by kamlooper
Dang I should have mentioned that before. I used to work for a tire retreading shop and they remade tires with moulds. I didnt get into all the info about the rubber used but they did mention carbon black is an essential element in the rubber compound. The company could make rubber compounds in any durometer (hardness) rating you wanted, and a lot of it had to do with carbon black.
I had been toying with the idea of getting some rubber dust from them and blending it with silicone to make tires. This dust is super fine like talcum powder.
Dang, you were withholding this critical information from me this whole time?! What else are you hiding from me? lol.
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Old 02-01-2024, 10:41 AM
  #183  
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The carbon black pigment showed up in the mail earlier this week and I've managed to get two tests done so far.

First test was mixing the carbon black into some platinum cure silicone I had sitting around. That was a complete fail - the silicone did not cure one bit with the CB in it. Not surprising, plat silicone is super finicky.

Second test was mixing the CB into a batch of the PMC-780. The first sample is without CB and the second sample I added CB in at 20% of the resin weight (i.e. 100g resin + 20g CB). My first observation is the CB noticeably thickens the resin. It also does not appear to disperse as well as I'd like as the resin seems a bit lumpy after mixing it in. After an overnight cure at ambient temps in my basement (55F) and a 4 hour heated post cure (104F), the CB sample is noticeably harder and stiffer compared to the no CB sample. When I hold them in my hands I can feel a difference between the two samples. I would liken that difference to how a shiny, smooth glossy surface feels vs a matte surface. The no CB sample feels like it has a more glossy surface while the CB sample feels more matte. I know this isn't terribly descriptive or even useful information for determining either rubber's suitability as a tire, but it's just interesting to note that there is a difference in how the rubber feels to the touch. And if it feels different to the touch, then I think it's likely it will feel different to drive on.

I did some quick testing by trying to push a sample across my work bench and measuring the force with my scale, but I don't think the test method is rigorous or repeatable enough to be useful. At first I though the CB sample was providing more grip, but a second round of testing with a slightly different setup has completely different results. Not sure what to make of that other than I need to rethink my test setup.

The next thing I want to do is try mixing this stuff into VytaFlex 40 and see how that turns out. After that, I'm not sure if I want to jump straight into making tires, or if I want to take things a bit slower and design some test procedures for measuring grip and abrasion resistance.
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Last edited by RC10Nick; 02-01-2024 at 01:45 PM.
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Old 02-03-2024, 12:14 PM
  #184  
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I decided I want to be able to characterize the rubber with some testing before I start making more tires. I came up with this Project Farm inspired abrasion tester:




I had 4 samples of rubber - VF40 with and without CB, and PMC-780 with and without CB. I ran each sample on the tester for 10 minutes and recorded each samples' weight before and after testing.

I'm a bit surprised by the results - the rubber samples with carbon black in them lost MORE rubber during testing than the samples without carbon black. Not what I expected at all.

I've got some ideas for why that might be.
  1. Polyurethane rubber is already a pretty abrasion resistant material and perhaps any fillers added to it may only make it less resistant.
  2. The carbon black I bought may just be a paint pigment meant to mimic carbon black and not actually contain any real carbon black
  3. The carbon black may be making the rubber grippier and cause more abrasion as a result
I'm not sure where to go from here - do I try to do more testing with more samples? Do I try to test other fillers like milled glass fiber? Or maybe I just don't worry about it and jump straight to making some tires to test out.
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Old 02-03-2024, 08:12 PM
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Old 02-04-2024, 07:56 AM
  #186  
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Don't be a "Karen".
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Old 02-04-2024, 10:47 PM
  #187  
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Try harder. Try again.
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Old 02-05-2024, 06:42 PM
  #188  
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What?! Thats seems legit. LOL...just dont place your hand their. grab hold. lol
-d
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Old 02-05-2024, 07:30 PM
  #189  
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ughh... broke another mold today. this is quickly becoming not very fun anymore.

I tried making another set of tires for my mini-b. I mixed up a batch of VF40 and only added 10% CB this time. My first attempt was a complete fail - the CB thickens the resin and I think it's clumping up as well. I couldn't actually inject the resin into the mold. The next day I cleaned out the mold, drilled the resin inlet ports out to 1.5mm and tried again. It worked better that time, but as the resin started getting near the top of the mold it felt like it got clocked up again. I rigged up my resin syringe into a caulk gun I had sitting around and was able to use that to force more resin into the mold to finish the tire, but that tire ended up breaking the mold when I demolded it. I did get the tire out intact, but it doesn't seem feel gripper or any better than if I had made the tire without the CB.

I did make a test sample of the VF40+10%CB that first night when I couldn't inject the mold with much resin. On my abrasion tester it lost the most weight, and it also got the sanding drum the hottest. Heat comes from friction so maybe that's another indicator the CB does make the tire grippier. But if I can't actually make tires with it then what does it matter?

I think I'm going to take a break from this project for a bit to cool off and calm down. Like I said, it's gone from fun to stressful so that's my sign I need to take a step back until I can have fun with it again.
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Old 02-05-2024, 10:35 PM
  #190  
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Be sure to keep notes on what youve done so you know where to go when you give it a whirl again.
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Old 02-07-2024, 06:13 PM
  #191  
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Originally Posted by gwhiz
for you

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