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Another project for my fairly humble Ender - some recently acquired TPU filament and a need for traction tires that may or may not be readily available. Highly experimental right now, long term durability TBD through lots of running but the fitment is no problem whatsoever as dimensionality can be adjusted until satisfaction. This is my High Iron K4 I just got last night and it showed up without traction tires. I originally got the TPU filament to make experimental tires for my Q1 and may try it before the weekend is over. Grip seems ok and the TPU is described as having 95A durometer. I do not know the durometer of current traction tire material but the TPU may not be as grippy. The killer app for this approach may be tires that are just not obtainable from an OEM or for temporary use. The 8-10 minute print per tire uses maybe 1 gram of material so it’s very cheap to make many copies for fit-up or replacement.

Here’s some quick imagery and a no slip startup of a 16 car train.

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Last edited by Norm Charbonneau
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It's just as easy as PLA and I used the same nozzle and bed temps. Also same print speed. I could probably print these without brim supports for less trimming. I have quite a bit of 3rd Rails now and finding tires to fit can be a challenge. Even if these aren't as good as factory ones they're so cheap and easy to make it's an OK trade-off. Long term durability should be interesting. Not sure how they will stand up to oil and grease exposure. Only one way to find out!

This is a very interesting thread. I made measurements for a traction tire and printed a PLA version to see if looked feasible.

The measurements were Outside diameter = 31mm,  width = 2.5mm,  and the thickness = 0.5mm. The picture shows the result.

So far I have never used any filament but PLA, but after reading this thread I have placed an order for some TPU filament.

After I receive the TPU I will post my results on this thread.



Tire

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I'd love it if more people tried! I got a bit frustrated snapping tires right at the end of long upgrade/mod projects. As said above, many of them are getting hard to find now and it's not unusual breaking precious ones in your stash trying to fit them to something they weren't made for. More experimenters would get more durability data too. I am not aware of any softer durometers available in TPU but it would be neat to try them if they are out there. Printing them in clear, gray or silver would be neat to see.

It’s a trade off the softer material will grip better but will wear quicker. My guess is 70-80 shore A is what you want to be, depending.

Other factors would include stretch or modulus of elasticity and uniformity in thickness and width. I think some older traction tires were rubber,I’m guessing they were around 60 duro shore A. Interestingly some older traction tires I’ve seen had a cross pattern.

As a wear test think tubular track with gaps.

I have  been looking at traction tires as sort of a hobby project.

I think you’d want urethane due to wear properties and elasticity. You could get all fancy and cast and mandrel cut.

One thing to consider as the tires stretch the material will get thinner. Somewhere one of the manufactures will have tolerances on existing traction tires. Be interesting to check it out.

Of course I don’t know about 3D printing PU.

You could have different duro’s in different colors or dual duros stacked, if you had the thickness to work with. I sold micro pitch urethane timing belts eons ago. The casting and cut mandrels would be pricy but at ten dollars a set who knows it may be doable.

JM2C

Steven

Great result, Norm!

Just so folks know, TPU is short for thermoplastic urethane. TPU's are a family of block copolymers  which can be tailored for different applications by changing hard segment and soft segment composition and content. Generally, greater hardness results in better wear but less traction and vice-versa. TPU's have good resistance to oil and grease. Because Norm's selection is readily printed by additive fabrication via melt printing in the same range as PLA (polylactic acid) , I assume it is a polyester-based TPU.

Super!

Bob

Thanks Norm... timely thread.  I replaced a tire on one of the Challengers today and saw that the tire had sort of adhered to the driver and that the tire had ripped itself apart.  It was still a whole tire... just all limp/stretchy and such.   It did take a little force (not much but force nonetheless) to remove the the remnants of the tire from the driver.  I'll be keeping an eye on this thread as well.

Norm,

  Before I jump fully into making traction tires, I have a few questions.  As a test, I found a tire for a toy car on thingverse and was able to scale it down to the diameter that was needed and printed it with PLA.

1.  how elastic is the filament when you go to put it on over the wheel?

2.  Any thoughts on durability?

3.  I was able to get the outside diameter and width pretty close but how did you adjust the thickness of the tire?

4.  Is it a plastic you can use for models of structures such as accessories and scenery around the railroad?

thanks,

Marty

There’s only three dimensions needed for a tire, OD, ID and width. Tweaking the ID can give a proper fit, OD can be adjusted for grab. Width has to close otherwise the tire won’t seat well. These tweaks are trivial for a printer. So far, the material mechanical properties of TPU seem very close to regular traction tires. Please keep in mind I am not running a full suite of static deflection and dynamic characterization on the these parts, only trying to see what I can get away with at this point. If these tires are only half as good as regular ones, the cost to make them is somewhere around 35 cents apiece.

I am using Novamaker from Amazon: https://www.amazon.com/gp/prod...00?ie=UTF8&psc=1

I should have bought gray for the traction tires. Not sure what else I'll make with the stuff. I'm a bit surprised I haven't seen anyone else try this yet.

Norm,  I'll give it a go.  What other Shore rating would you like to see tested (90A, 98A)?   Any other specification variables (other than color)?

I ordered a sample

This is available for My FormLabs 3

Materials in this family

  • Flexible 80A

    Hard Flexible Prototypes

  • Elastic 50A

    Soft Flexible Prototypes

Flexible 80A

Hard Flexible Prototypes

Flexible 80A Resin is the most stiff soft-touch material in our library of Flexible and Elastic Resins, with an 80A Shore durometer to simulate the flexibility of rubber or TPU. Balancing softness with strength, Flexible 80A Resin can withstand bending, flexing, and compression, even through repeated cycles.

Handles, grips, and overmolds
Cushioning, damping, and shock absorption
Seals, gaskets, and masks
Cartilage, tendon, and ligament anatomy

Durometer

Soft
80
Hard

Springback

Slow
35
Fast

Ultimate Tensile Strength

Low
75
High
Flexible sample parts

Bryce pointed out that he liked the NinjaFlex. Maybe try the 85A in Silver? I wish I was a little more imaginative when I picked my color!

LOL!  Those are 'designer' tires Norm.     Ordered - NinjaFlex 85A TPU in Steel (Gray)

Alan!!!!  Crank out some clear tires!

It probably wouldn't be a bad idea to send each other a few sets for individual testing.  Maybe I'll send a set to Gunrunner after I adulterate them on my Atlas track

Anyone else notice this?  A quick inspection of a dozen or so Locos showed a few dried out and cracked tires... but, the number of soft, spongy, swollen tires really surprised me.  The newer, say post 2016 were the spongy & swollen and pre 2016 were the dried & cracked.  Looks like someone changed suppliers?

rubber has a short lifespan, especially when it is repeatedly stretched and compressed.

Recall all the "blackened" damaged rubber hold-downs on the Post-war flat cars.

Maybe resin "rubber" has a longer life as is stated in FormLabs description as

"Flexible 80A Resin can withstand bending, flexing, and compression, even through repeated cycles."

I have no idea how accurate that is as applied to engine drive wheel tires!

I make a few TPU resin tires today.  Took some tweaking of the printer for the TPU to work but got some pretty good results.   If you plan to print it you do not need any supports. I used Lionel`s dimensions and got pretty close to what was needed.  I will probably have to make additional adjustments to get a better fit, but it works.  I found the printed tires incredibly strong.  They were hard to cut with a razor knife.  They were able to stretch quite a bit to get them into the groove.  They were harder than the original tires. The TPU had a rating of 95.  Have not had an opportunity to run them on an engine.  But at least I know that there is an alternative if tires need to be replaced.

Marty

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