Better joints challenge for XT Doll

[Jugo]

XT Doll I have two challenges for you.

Challenge number 1 - no more loose joints:
All doll owners sooner or later struggle with loos joints. To prevent this joint pressure must be consistent over the joint life. The only way that I can think of to fix this would be to make the joint spring loaded and prevent the washers from wearing down. Hence, lubrication and a spring must be introduced in the design. Below is a schematic picture of a geared knee joint. To add lubrication the red washers can be made from brass metal rater than steel as brass against steel is self lubricating. To add spring loading the pink washer can replaced with a nested wave spring washer which is a type of compact spring. Please XT Doll - try this design and tell us the result .

Screenshot from 2024-03-17 20-00-45.png (29.38 KiB) Viewed 776 times

Challenge number 2 - heel to butt:
It is not possible for dolls to reach their butt with their heels, the geared skeleton is not flexible enough. Also, the dolls do not have a kneecap so when you bend the knee far enough, the gear pokes out behind the silicone making the knee ugly. One solution to these two problems would be to make the knee joint quadruple geared and to add a plastic kneecap, see picture below. The quadruple gear would increase the distance between the thigh and the chin so the the joint could be bent further than with a regular geared joint. The kneecap is in green in the picture would hide the mechanism, adding realism to the knee. Again, please XT Doll step up to the challenge, test this design and tell us the result .

Screenshot from 2024-03-17 19-29-31.png (32.51 KiB) Viewed 776 times

[XTDoll]

XT Doll I have two challenges for you.

Challenge number 1 - no more loose joints:
All doll owners sooner or later struggle with loos joints. To prevent this joint pressure must be consistent over the joint life. The only way that I can think of to fix this would be to make the joint spring loaded and prevent the washers from wearing down. Hence, lubrication and a spring must be introduced in the design. Below is a schematic picture of a geared knee joint. To add lubrication the red washers can be made from brass metal rater than steel as brass against steel is self lubricating. To add spring loading the pink washer can replaced with a nested wave spring washer which is a type of compact spring. Please XT Doll - try this design and tell us the result .


Screenshot from 2024-03-17 20-00-45.png


Challenge number 2 - heel to butt:
It is not possible for dolls to reach their butt with their heels, the geared skeleton is not flexible enough. Also, the dolls do not have a kneecap so when you bend the knee far enough, the gear pokes out behind the silicone making the knee ugly. One solution to these two problems would be to make the knee joint quadruple geared and to add a plastic kneecap, see picture below. The quadruple gear would increase the distance between the thigh and the chin so the the joint could be bent further than with a regular geared joint. The kneecap is in green in the picture would hide the mechanism, adding realism to the knee. Again, please XT Doll step up to the challenge, test this design and tell us the result .


Screenshot from 2024-03-17 19-29-31.png

Wow, I can refer to this. Very good

[Synthian]

...
Challenge number 2 - heel to butt:
It is not possible for dolls to reach their butt with their heels, the geared skeleton is not flexible enough. Also, the dolls do not have a kneecap so when you bend the knee far enough, the gear pokes out behind the silicone making the knee ugly. One solution to these two problems would be to make the knee joint quadruple geared and to add a plastic kneecap, see picture below. The quadruple gear would increase the distance between the thigh and the chin so the the joint could be bent further than with a regular geared joint. The kneecap is in green in the picture would hide the mechanism, adding realism to the knee. Again, please XT Doll step up to the challenge, test this design and tell us the result .

Screenshot from 2024-03-17 19-29-31.png

Thank you Jugo! Her Knee Cap is what I miss every day when we sit on the couch together. Your design is well thought out. Bravo!

[Echo_Chamber]

XT Doll I have two challenges for you.

Challenge number 1 - no more loose joints:
All doll owners sooner or later struggle with loos joints. To prevent this joint pressure must be consistent over the joint life. The only way that I can think of to fix this would be to make the joint spring loaded and prevent the washers from wearing down. Hence, lubrication and a spring must be introduced in the design. Below is a schematic picture of a geared knee joint. To add lubrication the red washers can be made from brass metal rater than steel as brass against steel is self lubricating. To add spring loading the pink washer can replaced with a nested wave spring washer which is a type of compact spring. Please XT Doll - try this design and tell us the result .


Screenshot from 2024-03-17 20-00-45.png


Challenge number 2 - heel to butt:
It is not possible for dolls to reach their butt with their heels, the geared skeleton is not flexible enough. Also, the dolls do not have a kneecap so when you bend the knee far enough, the gear pokes out behind the silicone making the knee ugly. One solution to these two problems would be to make the knee joint quadruple geared and to add a plastic kneecap, see picture below. The quadruple gear would increase the distance between the thigh and the chin so the the joint could be bent further than with a regular geared joint. The kneecap is in green in the picture would hide the mechanism, adding realism to the knee. Again, please XT Doll step up to the challenge, test this design and tell us the result .


Screenshot from 2024-03-17 19-29-31.png

I like, I like.

[seagull]

red washers can be made from brass metal

Brass contains copper, not the best combo with TPE

[Space1invader]

Function kneeling on differend surfaces will be helpfull. Dolls dont have that positions in aviable poses

[Jugo]

red washers can be made from brass metal

Brass contains copper, not the best combo with TPE

Interesting, do you know why? There is one manufacturer who I think uses copper washers and they sell both TPE and silicone bodies. You can find pictures of their skeletons here.

[seagull]

Prior to articulated fingers, there a few attempts at finger repairs, using un-coated brass or copper, which turned green and made an awful mess of the surrounding TPE material

Copper washers with joints seems safe as these are always wrapped in a tough cloth, keeping the soft TPE away from unforgiving metal

[chris0113]

Copper and brass is a soft metal. Won't they wear eventually, leaving the joins loose?

[Jugo]

As I understand it, the problem with steel against steel joints is that small balls of metal forms as the surfaces rubs against each other. That's the black gunk often seen in doll repair photos. This either causes the joint to become loose or in some cases to seize up. Brass against steel on the other hand is self lubricating and the two surfaces polishes each other without wearing down. In fact it is used a lot in car engines on critical parts such as connecting rods and crankshaft. I'm not 100% certain it will work here, but it should at least in theory work better than steel against steel.