idea to make dolls slightly lighter

chaosninja7 · Post by **chaosninja7** » Thu Sep 20, 2018 11:27 am

I did my research and have to the conclusion that dolls should be made with Magnesium Alloy skeletons and not Stainless Steel.

1. Magnesium Alloy 75% lighter then Steel.
2. Magnesium Alloy is more durable then Titanium.

rubherkitty · Post by **rubherkitty** » Thu Sep 20, 2018 1:08 pm

but now the price just increased $3000.00 +

You can't weld magnesium that I'm aware of so all the joints will have to be cast and or machined then joined to the bones w/ threads, screws, rivets, etc.

Now if you're building a 1.7 million dollar robot, magnesium sounds great!

ILuvFemsNlingerie · Post by **ILuvFemsNlingerie** » Thu Sep 20, 2018 4:06 pm

Good luck finding Magnesium alloy tubing

Plus most of the weight of the doll is the TPE not the skeleton even if you did use a MA skeleton if might reduce 5-6 pounds but reducing the TPE somehow would reduce the weight much more IMO

Maecer · Post by **Maecer** » Thu Sep 20, 2018 5:56 pm

I think, finding a way to create a hollow shell, that you pour TPE over in your mold, would significantly reduce the weight. The shell would need to be very flexible and strong plastic.

alc123 · Post by **alc123** » Thu Sep 20, 2018 9:21 pm

“Magnesium Alloy 75% lighter then Steel.”

But the strength to weight ratio isn't much different from that of steel, so magnesium alloy is only good at reducing weight in situations where a design using magnesium alloy doesn't need to replicate the strength of steel.

A simple example of where this applies is a solid metal rod that has to resist bending. If you try to bend a metal rod, one side of the bar will have to resist being compressed and the other side will have to resist being stretched. If you increase the diameter of the rod, these compression and stretching forces will be reduced. Therefore, if you replace a steel rod with a magnesium alloy rod that is equally resistant to bending, you will reduce weight. The magnesium alloy rod will have to be larger in diameter than the steel rod. Increasing the diameter of the rod increases the resistance to bending in two ways:

1) It increases the amount of metal, which increases the strength.
2) It decreases the compression and stretching force that the rod needs to resist.

The key point here is that, while the magnesium alloy rod has a larger volume of metal than the steel rod, it doesn't have to contain enough metal to actually match the strength of the steel.

Doll skeletons contain steel tubes instead of steel rods, and a steel tube can be made as large a diameter as you want until you get to the point that the walls are so thin that they are vulnerable to denting. If denting is an issue, then switching from steel to magnesium alloy will let you use larger tubes and thus reduce weight. Otherwise, switching from steel to magnesium won't give you larger tubes, and therefore the tube walls will have to be equally strong regardless of the material.

Perhaps there are other components in a doll skeleton where switching to magnesium help. For example, if a ball joint contains a solid steel ball, and you could replace the steel ball with a ball the same size made of magnesium alloy, that would definitely reduce weight.

rubherkitty wrote:but now the price just increased $3000.00 +
You can't weld magnesium that I'm aware of so all the joints will have to be cast and or machined then joined to the bones w/ threads, screws, rivets, etc.

According to Wikipedia, “many standard magnesium alloys are easily welded by gas or resistance-welding equipment.”

grimreefer24601 · Post by **grimreefer24601** » Thu Sep 20, 2018 9:29 pm

ILuvFemsNlingerie wrote:Good luck finding Magnesium alloy tubing

Plus most of the weight of the doll is the TPE not the skeleton even if you did use a MA skeleton if might reduce 5-6 pounds but reducing the TPE somehow would reduce the weight much more IMO

This is correct. The TPE is the weight of the doll, not the skeleton. Several WM models use the exact same skeleton, but weigh 50-75 pounds more because of large breasts and butts. I order TPE in 40 lbs boxes. They're about 1 foot by 1 foot by 1.5 foot. It's really surprising when you see the box, and try to pick it up.

Tybalt · Post by **Tybalt** » Thu Sep 20, 2018 11:46 pm

Can we focus our efforts in reducing weight in the head and chest and torso area?

The biggest waste of tpe space in the torso. We dont need solid tpe in the lungs and abdomen. The head could be lighter.

Maecer · Post by **Maecer** » Thu Sep 20, 2018 11:57 pm

That's what I mean about making a hollow shell! You cut out the excess TPE in the torso and hips. The shell should feature bone contours; the torso shell will feature rib and spine contours, while the hips feature... well... hip hip contours. You stl get to have jiggly boobs and butt. Depending on how thick you make the TPE around these contours, determines how pronounced the bone contours are. Plus, having hips to grab instead of lots of TPE will help with maneuvering.

As for the head? I haven't cut open a doll head to see what's all inside; I know it's not brains or air. Ha! The same thing could probably be done; have a contoured shell, so you can have definition in cheek, jaw and nose.

I think it could be possible to 3D print the shell, and for sure make a hollow mold using casting methods.

grimreefer24601 · Post by **grimreefer24601** » Fri Sep 21, 2018 12:42 am

Tybalt wrote:Can we focus our efforts in reducing weight in the head and chest and torso area?

The biggest waste of tpe space in the torso. We dont need solid tpe in the lungs and abdomen. The head could be lighter.

That would be great, but you would have to drastically rework the skeleton to provide a flexible, strong area, to support that hollow space. TPE dolls don't have a rib cage. To do what you ask would require a major skeletal redesign. The current skeleton can't do it.

You've got a basic trade off. Weight vs Construction. Actually there are at least 5 trade offs in this case. Each one the manufacturer decided the trade off was the best design.

Honestly, I can understand why. Guys are into boobs and butts. They tend to think first with their little head. They buy the biggest bestest doll they can afford. Then she's too heavy. You can't send her back for that. So buy another doll. This one a little smaller.... And she's too heavy.

You've got to accept at some point that these dolls have weight. And they don't help you move them (unless you figure out some tricks).

Based on the current skeleton, TPE dolls weight is entirely dependent on the amount of TPE used in the mold.

Maecer · Post by **Maecer** » Fri Sep 21, 2018 1:05 am

I fully agree. It would take a lot of time and effort to build a new skeleton. Shia, if I could design a better skeleton, maybe see if manufacturers are interested? I'd still use the spine as connecting points.

What I'm proposing would be a do it yourself kind of thing. For support, let's look at silicone dolls. I mean, some silicone dolls have a soft foam core, so expandable foam could be shot into the hollow core for additional support.

What would be possibly feasible, but tricky to execute? Make multiple voids in the doll while the TPE is still attached to the skeleton. Then inject foam into the voids after the TPE is cooled. Kind of like a build a bear. Sealing everything inside would be tough. Or even a TPE skin if you will. The skin could have solid TPE everywhere except the torso

rubherkitty · Post by **rubherkitty** » Fri Sep 21, 2018 1:32 am

Sorry to be a Debbie Downer but, no matter what great idea you come up with, chances are a Chinese doll maker will not take the time to do it. They sell plenty of dolls as is and go for cheap + volume. More complex will mean a higher price and more chances for the new design to fail. They can hardly get current dolls right.

Of course it doesn't hurt to toss out ideas. Maybe someone will come up w/ something very simple that will work.

Maecer · Post by **Maecer** » Fri Sep 21, 2018 1:33 am

I'm not downed by you Debbie

I know money talks the most for manufacturers. I'm just spit ballin' ideas

rubherkitty · Post by **rubherkitty** » Fri Sep 21, 2018 2:33 am

Reminds me of the Vendor Wars some yrs back when TPE first came on the scene. Hit the "All recent Post" button and 35% of the post were vendors undercutting each other by $5.00 on a doll. Or contact us via PM for special offer!

Anyway, all idea chat is good. Maybe things can't be implemented now or used on TPE, but may be valid later.

One issue w/ air chambers and TPE is the heat. Maybe some type of partially air filled asbestos bag that would fully inflate when surrounded by the hot TPE, but not burst? I'm not a thermal air pressure specialist. Might also depend on how much moisture is in the air that is used.

flying42 · Post by **flying42** » Fri Sep 21, 2018 7:14 am

rubherkitty wrote:...no matter what great idea you come up with, chances are a Chinese doll maker will not take the time to do it. They sell plenty of dolls as is and go for cheap + volume. More complex will mean a higher price and more chances for the new design to fail. They can hardly get current dolls right.

Of course it doesn't hurt to toss out ideas. Maybe someone will come up w/ something very simple that will work.

All chinese skull shells are fiberglass, so material choice and method has been solved, and they are mostly hollow already. The torso is the biggest area for weight reduction, and the compartment would need to consider how the TPE is stressed when posed for eliminating stretch stress, bulges and wrinkles, already a problem in the shoulders, hips, and knees without a padded skeleton. Add the extra step of securing the fiberglass sub-molded part to metal skeleton accurately, and possibly 10-25 lbs could be reduced, which would put most of the curvier dolls within range of 60-75 lbs.

Pentiki · Post by **Pentiki** » Thu Jan 10, 2019 11:32 pm

So, how about aluminum instead of steel. Total skeleton cost should only go up a couple hundred bucks, the aluminum would need to be somewhat larger than steel to reach the same strength, still at a lower weight. This would contribute positively to skeleton feel, lower weight slightly, and aluminum is weldable.

For the thoracic weight, a hollow fiberglass "barrel" could perhaps fill in for a hollow chest cavity, at a lower weight than solid tpe.