Flex Filament with lowest shore hardness

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oakdesign
Posts: 109
Joined: Thu Jun 15, 2017 10:21 am

Flex Filament with lowest shore hardness

Post by oakdesign » Fri Jul 07, 2017 1:45 pm

Hi all,
I'm currently testing with flexible filament. The Field of application is to print Carburator flanges for 2 stroke engines.
My first test was with TPU Medium rated at shore A98. The print result was pretty decent and at least the idea working and I can use those in production on a real engine.
On the other hand the original flanges or made out of rubber and from the feeling mitght be in the range of shore A60-A70.
So the filament with the lowest shore hardness I have seen so far is Ninjaflex with a shore of A85. Lots of Flex Filament don't have a shore hardness specified.

So my question which is the "softest" flexible Filament you have printed so far?

Regards Richard
Opa's bester Rat: Probieren geht über Studieren, Grandpas best advice: the proof of the pudding is in the eating

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PartTimeRonin
Posts: 85
Joined: Mon May 22, 2017 2:33 pm

Re: Flex Filament with lowest shore hardness

Post by PartTimeRonin » Fri Jul 07, 2017 2:53 pm

Didn't try it but might be what you need
https://flexionextruder.com/shop/x60-ul ... ent-black/

oakdesign
Posts: 109
Joined: Thu Jun 15, 2017 10:21 am

Re: Flex Filament with lowest shore hardness

Post by oakdesign » Fri Jul 07, 2017 6:29 pm

Ok thanks for that tip.
At least it's clear that this won't work in my Bowden Setup.
Mext I will try Ninjaflex as there I can get 50g probe first. Maybe that's already soft enough.
Even the 98A TPU that I already printed might do the job, it's just a bit harder to get it installed in the motorbike frame between the carborator and airbox. If the engine ist assembled outside and but in the frame with the printed part preinstalled I'm already 100% fine with the Material

regards Richard
Opa's bester Rat: Probieren geht über Studieren, Grandpas best advice: the proof of the pudding is in the eating

DonV
Posts: 2
Joined: Sun Jul 09, 2017 6:23 pm

Re: Flex Filament with lowest shore hardness

Post by DonV » Sun Jul 09, 2017 7:00 pm

May I suggest, as a solution, that you try what I do now to produce for very low Shore hardness parts made out of flexible materials. Rather than try directly print the part in a thermoplastic elastomer, instead I now just create a one or two part mold, then cast the part in any material that can flow into the mold, including off-the shelf RTV silicone. There are some good commercially available spray on mold release agents, but I have found that simple things like vaseline, WD40 and even spray on PAM work sufficiently well to release simple things like gaskets, grommets, and toy rubber tires. You can also buy a wide variety of two part elastomers that have any number of properties that match/optimize the specification of your end objective. For instance, your gasket application might not only need flexibility for effective sealing, but also high temperature and gasoline/solvent durability. My most recent use of this technique was to recreate functional flexible grommets that had worn out, when I tried to I repaired the front bumper on my old Honda Civic hatchback. Sourcing OEM grommets proved to be impossible. Creating a solid model of the grommet was very easy, as was creating a solid model of the mold for the grommet. In less than an hour I had a two part mold with runners, made out of Edge with 6 grommets. I went to the hardware store and bought some black RTV, squeezed some RTV into both halves of the mold, clamped the two halves together, then waited a couple of hours for it to cure. I cracked open the mold, and voila! - six functional black grommets that looked and performed exactly like the originals. I did have to cut off the flash with a pair of kitchen shears, but I now have a mold that I can reuse if I ever need similar grommets again.

oakdesign
Posts: 109
Joined: Thu Jun 15, 2017 10:21 am

Re: Flex Filament with lowest shore hardness

Post by oakdesign » Sun Jul 09, 2017 11:39 pm

Thanks for your suggestion,
I already do injection molding especially for high temperature treated part with silicon.
The TPE parts I'm going to print are not stock OEM replacement parts, most likely they are custom tuning parts for race engines.
To use directly printed ones is just amatter of fact to reduce the prototyping and production process. Once the right design is found they will be manufactured in an injection molding process.

Regards Richard
Opa's bester Rat: Probieren geht über Studieren, Grandpas best advice: the proof of the pudding is in the eating

DonV
Posts: 2
Joined: Sun Jul 09, 2017 6:23 pm

Re: Flex Filament with lowest shore hardness

Post by DonV » Mon Jul 10, 2017 12:55 am

I think you might have misunderstood my suggestion. I was not suggesting you make a steel mold for your part. Or that you injection mold with a TPE. Rather I am suggesting you first use your 3D printer to print out a mold of the part you wish to make in a somewhat flexible plastic like ABS or better yet Edge. Then use that cheap throw-away mold to cast your rubber parts. There are more low durometer material choices for cast elastomers than for TPEs. The secret to success using this casting method is to use a good mold release to be sure you can get the part out of the 3D printed plastic mold.

oakdesign
Posts: 109
Joined: Thu Jun 15, 2017 10:21 am

Re: Flex Filament with lowest shore hardness

Post by oakdesign » Mon Jul 10, 2017 2:02 am

I understodd your suggestion, I'm already printing injection molds with ASA. But still as I might have to test 10-20 different designs until the final one is found, it's easier to print them in TPE and once the design is found convert it into a mold for small series production

Regards Richard
Opa's bester Rat: Probieren geht über Studieren, Grandpas best advice: the proof of the pudding is in the eating

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