hand skeleton - aluminium castings of finger bones

[mark123]

Currently, the skeleton of the hand is implemented as a metal plate for the palm, then the fingers are implemented as wires, which can easily break, and hard to pose.

I understand why the carpal and metacarpal bones are simplified into one metal plate, as they form the palm of the hand, which does not change shape. However, for the phalanges, to enable finger movements and durability, why can't we have aluminium casting for each of the phalanges bone, and implement the phalangeal joints as hinges?

And is such hands skeleton available commercially at the moment?

[seagull]

Comparing wire diameter to cast aluminium bones suggests that it is impractical to make castings that fine to be hidden by the doll material

[mark123]

Have a look at the dsdoll skeleton:

https://www.dsdoll.us/products/introduction

https://www.dsdoll.us/pics/upgradePics/ ... ail_03.jpg

However, if screws are used for finger joints, then they may come loose. Why can't they use something like rivet instead but fit the rivet in a way that the fingers can move freely?

Also, why do they use plastic or 3D-printed parts for the wrist? So that it can break, and the user will be forced to buy a new body???

[moodflow]

Have a look at the dsdoll skeleton:

https://www.dsdoll.us/products/introduction

https://www.dsdoll.us/pics/upgradePics/ ... ail_03.jpg

However, if screws are used for finger joints, then they may come loose. Why can't they use something like rivet instead but fit the rivet in a way that the fingers can move freely?

Also, why do they use plastic or 3D-printed parts for the wrist? So that it can break, and the user will be forced to buy a new body???

We can't be sure those are 3D-printed parts, and to me those joints actually look like they may be made of PTFE (fluoroplast) which is an extremely durable material routinely used in sleeve bearings due to its low-friction and slow-wear properties against metal.
If you ever had a solid piece of this material and tried destroying it by throwing it at a concrete wall or using a hammer, - best of luck to you!
A commonly known type of PTFE is Teflon by DuPont, but that one is applied in a thin layer which makes it susceptible to scratches when heated. But if you place a block of PTFE flat against a flat steel surface, it slides like the hockey puck on ice.
So, the tightening bolts you see on those joints allow for a very accurate control of joint tightness.
I can't guarantee that's the material they're made of, but being an engineer that's exactly what I would've used for that application.

[seagull]

moodflow
Some of us tend to use the word Teflon as a substitute for PTFE and for sure it is tough stuff
The tightening bolts on those joints allow for a very accurate control of joint tightness, if and only if the process is automated or there is a highly skilled worker applying tension (hopefully with a torque wrench)

[mark123]

Ah I see.... apart from DSDoll, which of the other manufacturer also have finger skeletons?

And is it likely that finger skeleton will become widely adopted?

[seagull]

If an articulation system can be developed that compares favorably with wire, then it may be adopted by more manufacturers but to loosely quote one supplier, A set of articulated hands would cost almost as much as a budget model

[justintime]

I guess many of you own articulated hands and fingers in this thread.

Placing a skeleton in a mold is quite tedious work. It must be placed just right, other wise the skeleton will be to close to the surface.
This is not as important in the over all body as it is in the hands. There is no room for a mistake, (mass production as in TPE ) will not work for this.
TPE will tear almost by looking at it, so a articulated hand may ,with the lightest of pressure cut the TPE.
Companies like Sino/IL, and others still use wire, this may be the reason.

Great care needs to be taken, when using your doll with articulated fingers,
( the rough stuff/sex will lead to breaking the fingers. Due to the lack of mass in that area.)


Finger pokes will happen for sure in the best of dolls.
I wish they would find a way to make the silicone in the hands harder. This would make the hands hold up better over time.
Much easier done in silicone than TPE due to the hot VS cold pour.
Edited like hell:..........
I never think suggestions and advice is taken into advisement by doll makers.
But it's fun to think it is.

[moodflow]

Ah I see.... apart from DSDoll, which of the other manufacturer also have finger skeletons?

And is it likely that finger skeleton will become widely adopted?

I believe Gynoid and XYColo are the other two.

[justintime]

XYColo is not fully articulated. The little finger is wire, and the range of motion is small compared to Gynoid.
Not sure about DS in regards to what they can do.

XYColo can not do this.

[seagull]

One requirement is the range of finger movement meeting international expectations

Range_Finger_movement.JPG (21.87 KiB) Viewed 974 times

These dancers can bend their fingers back over the wrist and touch it
Essentially 180 degrees of movement, bolted joints will do this for full sized fingers but the limits of material strength when scaling down to 3/8" fingers becomes problematic and at present wire is the only cost effective solution

[Arthur1960]

One thing that would help make the fingers more durable on a tpe doll would be to simply make the fingers thicker. I'm not saying give them all gorilla hands but just thicken up those thin fingers. Most of my tpe gals have hands and fingers which are rather petite with one obvious exception which is my WM158G. Her fingers are twice the thickness of most of my others and so even just as they are I can see they would be more durable but if they were fitted with articulated metal finger bones I would bet they would cope with the movement range of such fingers. The metal would still need to be wrapped in string or cloth due to the extreme heat involved in the pouring of the molten tpe but surely it would be possible while, of course, adding to the cost a tad. It baffles me slightly why I don't see more hands like the 158G, maybe it's an aesthetic thing where smaller hands are perceived to be more attractive? Whatever the reason if we are to get articulated metal finger bones in tpe dolls then the hands will have to be bigger to deal with the frequent bending etc, certainly whoever comes up with the goods is likely to get my money!

[mark123]

One thing that would help make the fingers more durable on a tpe doll would be to simply make the fingers thicker. I'm not saying give them all gorilla hands but just thicken up those thin fingers. Most of my tpe gals have hands and fingers which are rather petite with one obvious exception which is my WM158G. Her fingers are twice the thickness of most of my others and so even just as they are I can see they would be more durable but if they were fitted with articulated metal finger bones I would bet they would cope with the movement range of such fingers. The metal would still need to be wrapped in string or cloth due to the extreme heat involved in the pouring of the molten tpe but surely it would be possible while, of course, adding to the cost a tad. It baffles me slightly why I don't see more hands like the 158G, maybe it's an aesthetic thing where smaller hands are perceived to be more attractive? Whatever the reason if we are to get articulated metal finger bones in tpe dolls then the hands will have to be bigger to deal with the frequent bending etc, certainly whoever comes up with the goods is likely to get my money!

That's true! So is it a good tradeoff to over-dimension the hand say by 20-30%, or same length, but just 20-30% thicker? I guess the proportion will not be too distorted?

Or how about 20% longer, but 50% thicker?

[seagull]

Suspect there would be a resounding Hell no! from the Asian customers

[Arthur1960]

Hand of my WM158G, much thicker fingers, she never looses her rings like all my other gals!...