Go Back  R/C Tech Forums > General Forums > 3D Printing Forum
Making Tires with 3D Printed Molds >

Making Tires with 3D Printed Molds

Like Tree245Likes

Making Tires with 3D Printed Molds

Old 01-20-2024, 09:03 AM
  #166  
Tech Master
Thread Starter
iTrader: (9)
 
RC10Nick's Avatar
 
Join Date: Oct 2010
Posts: 1,930
Trader Rating: 9 (100%+)
Default

Originally Posted by JEdward91
Also, The Smooth-On store gave me cured samples of the different densities of FlexFoam so I could compare the to inserts at the hobby shop.
Oh that's cool. Do you have to go to an in person store for that or did you get the samples online/over the phone? And how much did they charge?
RC10Nick is offline  
Old 01-20-2024, 12:01 PM
  #167  
Tech Rookie
iTrader: (1)
 
Join Date: Dec 2022
Location: Michigan
Posts: 13
Trader Rating: 1 (100%+)
Default

Originally Posted by RC10Nick
Oh that's cool. Do you have to go to an in person store for that or did you get the samples online/over the phone? And how much did they charge?
I went in person to Reynolds Advanced Materials. They have a wall of bins with samples of the different products. No charge for the samples- and the staff was very helpful.
RC10Nick and Rallyfever like this.
JEdward91 is offline  
Old 01-20-2024, 02:53 PM
  #168  
Tech Master
Thread Starter
iTrader: (9)
 
RC10Nick's Avatar
 
Join Date: Oct 2010
Posts: 1,930
Trader Rating: 9 (100%+)
Default



Well, that mold didn't last long. I started a tire last night and tried de-molding it today around 4pm. The darn thing was stuck in there good and it was pretty obvious right away the whole thing was a loss.

I think the tread pockets are grabbing the tire too aggressively. I'm going to make the treads shorter and give them a few more degrees of taper. Hopefully that makes it easier to get the tire out of the mold without ripping the tire or destroying the mold. I'm probably also going to print at a lower quality just to speed things up.
RC10Nick is offline  
Old 01-20-2024, 07:41 PM
  #169  
Tech Rookie
iTrader: (1)
 
Join Date: Dec 2022
Location: Michigan
Posts: 13
Trader Rating: 1 (100%+)
Default

Any recommendations for mold release? I've been using the stuff by Stoner in the purple can, but it's difficult to clean it from the tires and inserts. Maybe I'm using too much?
JEdward91 is offline  
Old 01-21-2024, 05:49 AM
  #170  
Tech Master
Thread Starter
iTrader: (9)
 
RC10Nick's Avatar
 
Join Date: Oct 2010
Posts: 1,930
Trader Rating: 9 (100%+)
Default

I've been using the stoner urethane mold release exclusively and I use too much on purpose. I've been down the rabbit hole of what happens when I don't use enough - stuck tires and destroyed molds. I once bought the wrong can of stoner mold release and that was a disaster. I also tried a mix of mineral spirits and petroleum jelly and that, too, was a disaster. I'm at the point where I just accept that I have to slather the molds with urethane mold release if I want to get my tires out.
JEdward91 likes this.
RC10Nick is offline  
Old 01-21-2024, 12:00 PM
  #171  
Tech Rookie
iTrader: (1)
 
Join Date: Dec 2022
Location: Michigan
Posts: 13
Trader Rating: 1 (100%+)
Default

Originally Posted by RC10Nick
I've been using the stoner urethane mold release exclusively and I use too much on purpose. I've been down the rabbit hole of what happens when I don't use enough - stuck tires and destroyed molds. I once bought the wrong can of stoner mold release and that was a disaster. I also tried a mix of mineral spirits and petroleum jelly and that, too, was a disaster. I'm at the point where I just accept that I have to slather the molds with urethane mold release if I want to get my tires out.

Thanks for the help! I will use the same mold release then.

Here are my inserts, insert mold and rally tire:





Last edited by JEdward91; 01-21-2024 at 12:36 PM.
JEdward91 is offline  
Old 01-21-2024, 12:11 PM
  #172  
Tech Rookie
iTrader: (1)
 
Join Date: Dec 2022
Location: Michigan
Posts: 13
Trader Rating: 1 (100%+)
Default

example of my molds- another pattern for rally tires- still need to remove supports.
JEdward91 is offline  
Old 01-21-2024, 12:58 PM
  #173  
Tech Master
Thread Starter
iTrader: (9)
 
RC10Nick's Avatar
 
Join Date: Oct 2010
Posts: 1,930
Trader Rating: 9 (100%+)
Default

Originally Posted by JEdward91
Thanks for the help! I will use the same mold release then.

Here are my inserts, insert mold and rally tire:
Originally Posted by JEdward91
example of my molds- another pattern for rally tires- still need to remove supports.
WOW!!!!

Fantastic work! I'm seriously impressed. Your tire and insert look really good. You should do a write up or a video on your design. More people need to see this!
RC10Nick is offline  
Old 01-23-2024, 10:04 AM
  #174  
Tech Master
Thread Starter
iTrader: (9)
 
RC10Nick's Avatar
 
Join Date: Oct 2010
Posts: 1,930
Trader Rating: 9 (100%+)
Default

Heartbreak! I broke ANOTHER mold! It's not a total loss this time. I was able to fully extract the tire without damaging it, and not all of the mold was destroyed either. But its still a bummer, obviously.

I have two key observations that I think will help guide me towards a way around this problem.

1) I cast two tires last night, a rear tire using the tread design, and a front tire using my old tread design from last year. Even the front tire felt significantly more difficult to de-mold this time. I think the higher shore rating is contributing a fair amount to this problem, and in hindsight it makes sense that it would.

2) This is really two observations, but they're related to the same root problem. I noticed my printer was under-extruding lately and the molds definitely looked under-extruded when I printed them. I also noticed the resin overflow reservoir on the top of the mold was significantly lower after curing overnight in the pressure pot. I think the under-extruded mold pieces let too much resin seep in between the layer lines so the tire bonded itself into the mold. Basically I think it's the mold seasoning problem I discovered way back at the start of all this. Also, now that I think about it, under-extrusion might make the mold weaker.

So thinking about it, I've got two ways I think I can go about fixing this problem. 1) devise a test method to understand the problem of resin seeping between the layer lines and how its affected by extrusion rate, and 2) figure out if I can find/predict an ideal time in the curing process where the rubber isn't cured to the point where de-molding the tire becomes difficult, but cured enough that the tire won't tear. I really want to understand these two different factors before I try messing around too much with mold design or anything else.

Last edited by RC10Nick; 01-23-2024 at 10:15 AM.
RC10Nick is offline  
Old 01-24-2024, 12:54 PM
  #175  
Tech Rookie
iTrader: (1)
 
Join Date: Dec 2022
Location: Michigan
Posts: 13
Trader Rating: 1 (100%+)
Default

Originally Posted by RC10Nick
WOW!!!!

Fantastic work! I'm seriously impressed. Your tire and insert look really good. You should do a write up or a video on your design. More people need to see this!

Thanks! Your videos and information posted here helped me a lot with it. Maybe I'll do something next time I make inserts. I'll be starting that soon, so I have tires for rally racing in the spring.

I forgot to mention- Your printed syringe design works very well. Thanks for posting that, too!!
RC10Nick likes this.
JEdward91 is offline  
Old 01-25-2024, 05:15 PM
  #176  
Tech Master
Thread Starter
iTrader: (9)
 
RC10Nick's Avatar
 
Join Date: Oct 2010
Posts: 1,930
Trader Rating: 9 (100%+)
Default

Originally Posted by JEdward91
Thanks! Your videos and information posted here helped me a lot with it. Maybe I'll do something next time I make inserts. I'll be starting that soon, so I have tires for rally racing in the spring.

I forgot to mention- Your printed syringe design works very well. Thanks for posting that, too!!
Glad to hear I'm not just shouting into the void, and that you find the syringe useful!
JEdward91 likes this.
RC10Nick is offline  
Old 01-27-2024, 05:58 AM
  #177  
Tech Master
Thread Starter
iTrader: (9)
 
RC10Nick's Avatar
 
Join Date: Oct 2010
Posts: 1,930
Trader Rating: 9 (100%+)
Default

I've got another race update with my tires!

Due to the issues I had with molds breaking, I wasn't able to have any rear tires ready for race nite, but I did at least have another set of my fronts made. This time I didn't soften the PMC-780 at all to see how the tire life would be. Unfortunately it still wasn't great. The pins held up better this time, but there was still a pretty big fall off in performance through the night.

Like last time, I ran my car in two classes - stock and mod 2wd buggy. With practice I probably had around 10 runs on the track through the night. In practice I was able to hit 16.9s and 17.0s laps. In the first round of qualifying I had a 17.2s fast lap, and in the second round of qualifying it dropped off to a 17.4s. In the mains it dropped even more to a 17.5s. The drop off was likely even worse than what the numbers say - as the night went on and I got more familiar with the track I was running better and cleaner lines. Rather disappointing, honestly.

Improving tire life is going to be my primary focus moving forward (after resolving the mold issue, obviously). I think my new tread and carcass design will help, but I also want to research any additives to see if any can be used to increase abrasion resistance.

Last edited by RC10Nick; 01-27-2024 at 09:27 AM.
RC10Nick is offline  
Old 01-27-2024, 10:12 AM
  #178  
Tech Elite
iTrader: (7)
 
kamlooper's Avatar
 
Join Date: Jan 2005
Location: kamloops
Posts: 2,046
Trader Rating: 7 (100%+)
Default

I must say, you are driven on making your own tires! Nice to see people keeping this rc car thing a hobby, building is what its all about.
RC10Nick likes this.
kamlooper is offline  
Old 01-28-2024, 04:18 AM
  #179  
Tech Master
Thread Starter
iTrader: (9)
 
RC10Nick's Avatar
 
Join Date: Oct 2010
Posts: 1,930
Trader Rating: 9 (100%+)
Default

Originally Posted by kamlooper
I must say, you are driven on making your own tires! Nice to see people keeping this rc car thing a hobby, building is what its all about.
It's just the way I'm wired - once I get an idea in my head I just can't stop myself until I'm satisfied that I've got it all figured out. Plus, it's just fun racing on tires I made and learning new skills in the process. I never knew anything about mold making before and now I feel like I'm practically an expert.

Anyway, I spent a ton of time yesterday googling rubber additives, specifically those for tires. One of the first hits I found was a research paper testing various different additives to polyurethane systems and their affects on various physical properties, namely abrasion resistance. At first I was excited because it was exactly what I was looking for, and scanning through the paper I found the most effective additive with a very drastic drop in material lost during their abrasion testing was silicone oil - aka shock fluid! But, reading the paper more, and confirming what I had suspected, the reduction in material loss through abrasion was achieved by reducing the rubber's coefficient of friction - aka less traction. Probably not the right compromise to make for tires, but I'll keep it in my back pocket as something to test later on since it would be a pretty easy test.

I kept looking after finding that paper and I think I hit pay dirt - carbon black. It's THE main rubber additive used in real tires. Apparently it can comprise up to 30% of some tires. It's the reason tires are black. It "drastically" improves abrasion resistance (according to marketing copy), along with giving tires their black look and also making them UV resistant. So far so good. I've also seen some marketing copy state it can improve grip as well. That would be a lovely side benefit. The effects come from a unique property of the carbon atoms that make up carbon black - namely that the particles have incredibly large amounts of surface area in relation to their particle size. That does some magic things apparently. It seems like it's used as a "filler" so I think just its presence in the rubber is what makes it work, not any specific chemical interaction with the rubber itself. Basically I think that means it should work with polyurethane rubber as well as the natural rubber of which tires are made. It's also easy to find - outside of tire manufacturing one of its main uses is as a pigment making it a common item for art supply stores to carry. I was able to buy an ounce of the stuff for $10 shipped to experiment with from a random pigment vendor online. I can't wait for it to show up so I can start playing around with it!
Mac The Knife and JEdward91 like this.
RC10Nick is offline  
Old 01-28-2024, 11:41 AM
  #180  
Tech Adept
 
Join Date: Jun 2010
Location: Munich, Germany
Posts: 187
Default

What about Silica? This is also used for tires to increase wear and grip.
Andreas
andreas78 is offline  

Thread Tools
Search this Thread
Rate This Thread
Rate This Thread:
You have already rated this thread Rating: Thread Rating: 4 votes, 4.75 average.

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.