Hand mod, proof of concept, am I wasting my time?
- Tyr
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Hand mod, proof of concept, am I wasting my time?
For quite a few months, when I have the enthusiasm, I have been working on an idea to get Ami's hands back, so here are a few photos of the concept so far: To start with I scanned Ami's right hand, (She was quite impressed with that ) Then mapped out the joint positions using my own hand as a template and adjusting for proportion. I think it's quite close here. I then got busy with Fusion360 and started designing the hand, Here is the first printed assembly, the fingers seem fine but the thumb doesn't work. Here is version 2, the thumb is better but not perfect. you can also see how the hand splays out. All of the joints have stops so the degrees of freedom are the same as a real human hand, or at least mine. The models have been printed with PLA, I don't have the facilities to print ABS and haven't tried PETG. The parts are so small tho' I'm worried about strength and durability. I'm going to try and bake them and see what happens, it's supposed to strengthen PLA with a small cost to dimensional stability. I guess I'll find out. I have some white PLA on order for the proper ones and a couple of modelling universal joints to try out for the thumbs. They're coming from China some time. The fasteners are 3mm stainless (they will be trimmed flush) with nylock nuts. So far, none of the joints have loosened off although I might add some locktite as well.
But:
I am concerned about the existing palm plate in Ami's hands, size, type and so on. I suppose I could replace her hand structure entirely and design a screw-in fitting at the wrist, as Ami has rotating wrists, although I don't know the exact mechanism. I'm guessing there is a thread of some sort in there. I'm baulking at opening her up and crossing the point of no return. I'm also a bit concerned that I'll be able to get the structure to actually fit inside the TPE without ruining her. The knuckles are still quite big (8.5mmø) although they're as small as I can go and get working parts off of my printer. I can re-design and print the palm plates to suit what I find too, I suppose. I'm worried because the TPE of her hands is in such a terrible state.
I'm going to push on right up to the point where I will have to cut flesh and have a review then. It may be a little while before we get there.
If anyone has any comments, or advice, please chime in. I've had it with fucking wire tho'. Am I wasting my time?
Tyr
The Late, Great, Ian Fraser Kilminster.
My 'e' key is getting sticky, so now and thn words may look a bit odd.
Re: Hand mod, proof of concept, am I wasting my time?
I really think every Doll should have Phicen type interchangeable hands & feet ......... IMHO !!!!!
(but who am I 2 say,right?)
Awesome concept looks soooo "Terminator" too!!............. just watch out if it starts to grab at you or your girls eyes glow red ..............
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Re: Hand mod, proof of concept, am I wasting my time?
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Re: Hand mod, proof of concept, am I wasting my time?
Body: YL165, Head: WM#15
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Re: Hand mod, proof of concept, am I wasting my time?
2 Titties!
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Re: Hand mod, proof of concept, am I wasting my time?
That's very nice work on the design and printing BTW.
I'm thinking it might be a bit tough to retrofit into the existing hands though TBH.
If it helps, here is a photo that my friend Grimreefer sent me of a factory hand fitting used for the wire fingers.
It's only about an inch wide and just shy of 3" long.
I'm assuming the 4 finger wires come out the end and the thumb wire comes out the side on top in the photo. Also, here is a video that our dear departed Crazy Cajun made showing the surgical process involved in the palm plate replacement.
Notice that his new palm plate is fairly small and shaped to fit in the existing void in the hand.
https://youtu.be/QHqftsp9k8k
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- Tyr
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Re: Hand mod, proof of concept, am I wasting my time?
Tybalt, I have no plans to sell this mod. It may be that the cure is worse than the disease. I only work on this when I feel like it, so It may be a while yet. I don't think I could sell a mod that would require a skill set that may be beyond reasonable expectations. I don't even know if I'll go through to the bitter end even with Ami. Thanks for asking though.
Mf, Thanks for posting the photo and video, There's no way that my design would be so unobtrusive, It will probably necessitate removal of material from the hand. I was planning to open up the hand entirely as I have Indigo20's comfort kit, with which I have some experience, then close her up again after. But I have been visualizing the problems that I'll be running into. I was even going to print a jig to hold her fingers in place. Watching CC's video just adds to the list of problems to be solved. Do you know what type of wire that is, NM? it doesn't look like domestic wire?
Yeah, It might be a bit of a dead end. Hmmm.
Tyr
The Late, Great, Ian Fraser Kilminster.
My 'e' key is getting sticky, so now and thn words may look a bit odd.
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Re: Hand mod, proof of concept, am I wasting my time?
First, I would suggest maybe something a little simpler for the fingers.
I realize a fully articulated hand is the ultimate goal, but something in between might be a little more realistic to retrofit.
One idea I played around with was to use typical 14 AWG braided copper wire with brass tubes for the phalanges. This would allow the fingers to bend only at the joints. The braided wire should be more resistant to breaking than solid wire. Yes, you'll be able to bend the fingers the wrong way, but at least they will look natural when bent the proper way.
The 14 AWG wire with insulation fits perfectly inside the 5/32" brass tubing (I.D. about 1/8"), so the tubes could be easily epoxied to the wires.
Leaving about 1/4" to 5/16" gap between the tubes gives a nice natural bend.
I got the tubing at Hobby Lobby and wire at Home Depot. In order to facilitate the retrofit, I think the palm plate needs to be kept as small as possible.
This one is about the same size as the one CC did. I'm not showing all the finger tubes here, just the ones that would be epoxied into the palm plate. I think the easiest way to assemble this in place would be to have a two piece palm plate.
The finished finger wires with tubes would be fitted into the fingers then bent as required to fit into the palm plate. The the second half of the palm plate would then be screwed on with epoxy to cement it all together.
The thumb tube was moved so this is a little rough, but you should get the idea.
If you want the design file I'd be happy to share it.
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- da_putzler
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Re: Hand mod, proof of concept, am I wasting my time?
- Tyr
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Re: Hand mod, proof of concept, am I wasting my time?
Mf, if you would share your design I would appreciate it, I could get the basic sizes and develop my thoughts from there. It would save me from opening Ami up prematurely. It also occurred to me that allowing the joints to bend both ways isn't such a bad thing as it allows for small mishaps, I sleep with my doll and I was worrying about snapping a finger with my design, although the test prints do seem to be pretty strong. Fit and forget is what I'm looking for now.
Cheers,
Tyr
The Late, Great, Ian Fraser Kilminster.
My 'e' key is getting sticky, so now and thn words may look a bit odd.
Re: Hand mod, proof of concept, am I wasting my time?
The 3D printed palm plate looks a good idea too.
It would be great if somebody could use the 3D print files that MannequinFan has kindly created to manufacture some of them for use by TDF members.
I'm sure that members would be interested in buying them.
I think MannequinFan is already snowed under creating his other 3D printed parts like the fabulous eyes!
- MannequinFan
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Re: Hand mod, proof of concept, am I wasting my time?
I'll need to clean it up a bit before I post.
I can post a basic solid one that you can modify for a different finger attachment and the 2 piece one set up for the 5/32" tubing.
The wire I used in the test is this stuff (14 gauge copper stranded)...
https://www.cerrowire.com/product/circu ... hn-thwn-2/
They sell it by the foot at Home Depot.
The 5/32" brass tubing is made by K&S Engineering. I got them at my local Hobby Lobby but I'm sure you could find them elsewhere online.
https://www.hobbylobby.com/Crafts-Hobbi ... 32/p/24131
My Blog-> mfcreations3d.blogspot.com ... Easy Move Eyes™
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- Tyr
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Re: Hand mod, proof of concept, am I wasting my time?
Thanks for the links to the hardware. The tubing won't be a problem, as for the wire, I've downloaded the specs. I'll see what I can find here.
Appreciate your help.
Cheers.
The Late, Great, Ian Fraser Kilminster.
My 'e' key is getting sticky, so now and thn words may look a bit odd.
Re: Hand mod, proof of concept, am I wasting my time?
I have worked on a similar idea and will have to post screen captures of my Solidworks models, which I can also share with you in various formats.
I made mine so that one connection of the knuckle goes in between the next knuckle. I have 120 degrees of rotation on each knuckle.
The biggest part, for me at least, will be making a "cast" of the hand, putting the skeleton in the hand cast, and then pouring TPE or Silicone in the cast. Then you have to replace the entire hands. I am sure it will be noticeable at first, but maybe with enough bracelets or a watch, it won't be as noticeable.
By the way, the printer I have available is a Markforged and it prints with Onyx carbon fiber which is really strong and durable.
- MannequinFan
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Re: Hand mod, proof of concept, am I wasting my time?
I thought I may as well finish this idea while I was thinking about it.
It actually worked a little better than I thought it would. At first I thought the wire would be too stiff, but with the tubes added the fingers bend quite nice.
During the installation process, each finished finger bone can be super glued to the plate after they are inserted in the fingers and the thumb tube can be snapped in place. The cover is screwed on with a generous amount of epoxy to make it all solid.
For the fingertip I might want to strip the insulation so it bends a little easier and glue on a printed tip with a rounded end instead of a brass tube. https://youtu.be/zaOOU7zYO6M
Rhino 4.0 file... Print files... Download the files to your computer, change .pdf to .zip and extract.
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