Doll skeleton made of TPE?

E-Liz94 · Post by **E-Liz94** » Sat Oct 21, 2023 9:50 am

Been doing a lot of research, already have 2 topics on here, one about my DIY doll and the other about my machine to melt and cast.

I've been researching shore grades related to my project, the hardness of materials. There are 3 types of shore materials, Shore 00 which is ultra soft, probably ideal for internals of breasts. Shore A which is what TPE dolls are mostly made of, grade 30A I believe. But there is also Shore D which is for harder plastic, rulers and computer cases, etc.

TPE can have a hardness up to 85D, Human bones allegedly have a hardness of 90D on the shore scale. So this brings me to the question, does anyone think would it work as a skeleton material for a TPE doll? I apologize for being a bit of a mad scientist and slightly overzealous topic postings.

Nackers · Post by **Nackers** » Sat Oct 21, 2023 9:28 pm

I think the problem would be joining them. It's easier to weld or bolt metal and you can make metal "bones" hollow to reduce weight without reducing strength too much. I'd be worried a bit about how you'd join plastic/tpe bones at joints. Maybe you could cap them with a metal cap. But at that point it seems easier to just stick with all metal. Not sure about flexability at that hardness either. Would the TPE become a brittle plastic or would it still flex?

Mr Franz · Post by **Mr Franz** » Sat Oct 21, 2023 9:52 pm

If you made the skeleton out of harder TPE, wouldn't it just melt when you poured the surrounding TPE?

Wheezer · Post by **Wheezer** » Sat Oct 21, 2023 11:50 pm

Mr Franz wrote: ↑Sat Oct 21, 2023 9:52 pm If you made the skeleton out of harder TPE, wouldn't it just melt when you poured the surrounding TPE?

BINGO !!
A TPE skeleton in a hot cast TPE doll would just result in a gelatinous blob of different density TPE.
OK perhaps if the goal was a "Jabba the Hut" doll or one to simulate the blob from sci-fi movies.
Not really too good for a flexible and standing human sized sex doll.

That is one of the reasons they metal for the skeletons.
Also strength, ease of fabrication and common parts for joints and such.

Good catch.
Cheers!
... W ...

timetraveler1 · Post by **timetraveler1** » Sun Oct 22, 2023 11:00 am

i have wondered about other things used for a skeleton framework in a doll instead of metal ( not tpe material) , i wondered about carbon fiber molded but don't know how it would standup to the hot mold of the tpe body molding process.

Nackers · Post by **Nackers** » Mon Oct 23, 2023 12:04 am

Carbon Fibre (depending on the type) has a melting point around 1500c so it should be good. However, it may not be as simple as that since it may not be possible to *just* use carbon fibre, it'd likely be a composite. Which obviously could have a different melting point, or may have a "skin" that melts at a lower temp.

Wheezer · Post by **Wheezer** » Mon Oct 23, 2023 12:37 am

Carbon fiber has been mentioned many times over the years as an alternative to a metal skeleton, since it is "better".
However with todays dolls the weight is primarily due to the mass of flesh material (TPE or silicone), the actual skeleton does not really weigh that much.
So a slight weight reduction due to a lighter skeleton would not be a real game changer.

Light weight is a positive for CF, but its cost compared to steel is still high. While lighter than steel, CF has some issues with strength and occasional brittleness. This can be overcome with sheets having the fibers in alternate orientations, but might be a challenge for tube structures for a skeleton. One big issue is that there tends to be some weakness issues at the point where it bonds to other materials, say where a pivot for a knee would be attached to a tube for a leg.

CF has a lot of good points and is a good material, but maybe not for a doll skeleton.
Sort of like it might be fine for an airplane part, but we did see recently that is does not work too well for submersibles.

Cheers!
... W ...

Nackers · Post by **Nackers** » Mon Oct 23, 2023 12:55 am

Yeah I first thought about it a few years ago, mostly because my golf clubs are graphite shaft (which is essentially carbon fibre) and they're noticeably lighter than the steel clubs, while at the same time being quite flexible and strong. Ditto my last fishing rod (graphite versus fibreglass). Whether they'd be able to achieve a weight saving once scaled up to skeleton size I don't know. I do know that I'd love to see any research/testing that anyone had done in that area.

In terms of strength though, I would think that shouldn't be an issue, at least if they were made right. At least based on articles like this: http://melbournehipsurgeon.com.au/carbo ... hopaedics/

And you're right, a carbon fibre may be achievable but wind up costing as much as the whole doll. At which point you have to ask whether it's worth it. You can source it (even as a hobbyist) fairly cheaply in a variety of shapes and sizes. eg: https://www.supercheaphobbies.com.au/st ... 72_77.html but it's still probably more expensive than the comparable steel tubing. And that's not counting assembly.

Maybe one day I'll bite the bullet and have a crack at making one myself.

Wheezer · Post by **Wheezer** » Mon Oct 23, 2023 3:36 am

From a perspective of a doll hobbyist or basement mad scientist creator, I'm sure that something could be made for a doll.
Most of the innovations have been started by folks who are intrigued by finding the solution and cost does not really factor in.

So if cost is not an option , then anything is possible! We even put a man on the moon once.

Skeleton improvements seem to occur slowly for the doll. Probably since they are the last visible item of the doll.
We did get to almost universal standing foot plates, then better joints, then EVO, gear stuff, hinged wrists, and now articulated fingers.

So improvements are slowly chugging along.

Right now the issue is probably cost. Both for the material and that their trained (?!) group of fabrication folks are metalworkers.
Tooling and training would not be insurmountable, but it would be a cost and cause some changes.
Until the manufacturers see an upside, either $$$ or bragging rights, then we will keep dealing with steel.

Just my two cents.
Cheers!
... W ....

Nackers · Post by **Nackers** » Mon Oct 23, 2023 8:04 am

Absolutely, the retooling/training costs could be the biggest issue preventing uptake on something like this. I suspect the first prototype will be from an obsessive amateur. Once the proof of concept is out and shown to be working I could see some of the companies taking a punt on it.

E-Liz94 · Post by **E-Liz94** » Mon Oct 23, 2023 10:02 am

What about heat welding protective layer of TPE over the skeleton of the same shore grade as the flesh? From my understanding, cold TPE doesn't magically fuse together that well unless you purposely heat it to its melting point with something.

Wheezer · Post by **Wheezer** » Mon Oct 23, 2023 2:46 pm

E-Liz94 wrote: ↑Mon Oct 23, 2023 10:02 am What about heat welding protective layer of TPE over the skeleton of the same shore grade as the flesh? From my understanding, cold TPE doesn't magically fuse together that well unless you purposely heat it to its melting point with something.

I'm not sure about the point of this.
How do you think this would help?
... W ...

chippyminton · Post by **chippyminton** » Mon Oct 23, 2023 6:08 pm

318-grade stainless steel. LIght, durable, and won't rust and destroy your doll when the vaginal TPE plug falls out.

Wheezer · Post by **Wheezer** » Thu Nov 02, 2023 2:18 am

chippyminton wrote: ↑Mon Oct 23, 2023 6:08 pm 318-grade stainless steel. LIght, durable, and won't rust and destroy your doll when the vaginal TPE plug falls out.

Good point with the stainless.

But maybe ...perhaps ... just seal the damn plug in correctly in the first place.
GRRRRR
(rant over)

Cheers!
... W ...

RevJack · Post by **RevJack** » Tue Feb 27, 2024 10:44 am

chippyminton wrote: ↑Mon Oct 23, 2023 6:08 pm 318-grade stainless steel. LIght, durable, and won't rust and destroy your doll when the vaginal TPE plug falls out.

It's the joints that are mild steel and rust. The skeleton is already stainless and rust resistant.