Author Topic: Wobbly forearm  (Read 341 times)

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YKW

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Wobbly forearm
« on: December 27, 2017, 08:46:13 AM »
I've got a JY doll from October of this year with a slightly wobbly forearm. The wobble is coming from the non-hinged joint pictured below. I'd love to find a non-surgical way to repair this issue, but I'm prepared to break out the scalpel and heat gun if necessary.


Z-Dr

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Re: Wobbly forearm
« Reply #1 on: December 27, 2017, 11:01:40 AM »
The question is, what are the actual mechanics of this specific type of joint?  Is it rotational only, or does it have swivel capabilities?

If the joint swivels, it looks like it might be a hime type joint which would mean crimping the collar to tighten it.  But if it only rotates, then it is likely threaded on the inside which would require closer inspection.

The only way to know for sure is for someone who has actual experience with this specific type joint to offer their input.

How would you describe the "wobbliness"?  Is it side to side floppy or distendable (proximal to distal slack)?


Best of luck to you! :cheers:

YKW

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Re: Wobbly forearm
« Reply #2 on: February 14, 2018, 08:54:05 PM »
Apologies, I'm just noticing your kind reply now. The wiggle was distendable. The doll was sold with the buyer's knowledge of the issue. Thanks again.

LuLu

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Re: Wobbly forearm
« Reply #3 on: June 28, 2018, 09:09:48 PM »
Old news I know. But just for info sake. My doll is made like this. They have the flex wires for fingers. I've replaced both hands. These tubes screw into forearm.
For dolls left hand it's not a reverse thread, so it could have come loose. They both screw in the same.

EDIT: These types of wrist and finger flex have a nut welded onto them, and are bolted to forearm.
It is possible a weld could have broke, causing wobble.
When I did the first hand on my lady, I did break weld. Welds are very small tack welds. So I re-welded it. The second hand I beefed up by adding more welds.




JY dolls as of late are still using this system, but apparently are upgrading to a hinged wrist.

Here is my invention:
A ball bearing rotating wrist. Side to side, up and down and wrist rotation.
Fingers are plastic with ball joints. Built like a brick outhouse. And there is give to them as well. All 3 knuckles on each fingers. They are sized from my doll's hands.

My cost? much time, but about $1.75 in material, if that :)


My idea was balked at on TDF.  This is for post production sake. For owners who want an idea that is rugged. I do not spend my time for manufacturers LOL

Still not complete, but it is all there mostly. 
Metal constructed fingers seem like a bad idea to me. Safety is a concern.




Z-Dr

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Re: Wobbly forearm
« Reply #4 on: June 30, 2018, 02:19:54 PM »
Metal is necessary with TPE, at least during original pouring due to the temperatures.

Plastic is plausible for a retrofit.  Let us know how this turns out. :cheers:

miss_Vix

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Re: Wobbly forearm
« Reply #5 on: July 01, 2018, 02:28:28 AM »
That hand looks great. Did you 3d Print it?

I bet you could get away 3d printing it carbon fiber or something maybe to handle the high heat. dunno
but I hope the idustry can make better hands instead of.. ya know.

LuLu

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Re: Wobbly forearm
« Reply #6 on: July 01, 2018, 08:41:19 AM »
That hand looks great. Did you 3d Print it?

I bet you could get away 3d printing it carbon fiber or something maybe to handle the high heat. dunno
but I hope the idustry can make better hands instead of.. ya know.

It's Polymorph Plastic Pellets. Little beads, put them in boiling water and shape as desired. Have about 3-5 minutes before it starts to harden. If not happy with what you've made? Re-heat and shape again.
I use a hot air gun lightly to re heat. Once hard it is tough stuff.
Getting the fingers thin is a task. Too thin, they flex too much. I'm just playing with this.
Yes, this is for replacement sake. Wont work if you are going to mold your own doll. :)

But in the case of WM or similar, this stuff may work amazing for a little palm plate inside the palm plate to hold wires in place. Rather than using epoxy or adhesives.