Study topic: Making a large ball joint type love doll.

[MannequinFan]

Beatiful project!
I Love the hip joints, they allow verry hot positions.

Thanks very much Dagobert!
I'm happy with how this is working so far. This is all just rough right now to see if/how everything will work.
The Makehuman torso needs some refinements as the body details really aren't very well developed in certain areas.

Here are the details of the knee joint. I'm really happy with how this came out...

knee joint detail2.jpg (609.7 KiB) Viewed 6328 times

knee joint detail.jpg (588.61 KiB) Viewed 6328 times

[DollAfficionado]

I haven't posted in this thread yet, but I am interested in your ongoing work. Please continue.

[rubherkitty]

Nice design.
Will the joint be tension adjustable externally?

You might think about bumping the 1/4" bolt up to 5/16"?
I'm just thinking a 4" x 1/4" bolt could bend pretty easy.
Maybe go w/a grade 5 if available.

I would also be concerned about the washer coming unglued from the pressure post and getting stuck to the magnet. Maybe screw the washer to the post via 2-3 small countersunk screws or have the washer countersunk into the post so you can also glue it around the edges. They make washers in different thicknesses. A thick washer w/ the edges coarsely filed and glued in would hold pretty good.

[MannequinFan]

I haven't posted in this thread yet, but I am interested in your ongoing work. Please continue.

Thanks for your interest DA,
I'll probably be posting occasionally whenever I come up with something new to show.
I'm planning on printing a reduced size version of these legs for my little Abby doll project so we'll see how the knee joint works.

Nice design.
Will the joint be tension adjustable externally?

You might think about bumping the 1/4" bolt up to 5/16"?
I'm just thinking a 4" x 1/4" bolt could bend pretty easy.
Maybe go w/a grade 5 if available.

I would also be concerned about the washer coming unglued from the pressure post and getting stuck to the magnet. Maybe screw the washer to the post via 2-3 small countersunk screws or have the washer countersunk into the post so you can also glue it around the edges. They make washers in different thicknesses. A thick washer w/ the edges coarsely filed and glued in would hold pretty good.

Thanks RK.
Those are all valid points of concern that you raised. The joint tensioning would work just like the shoulder and elbow joints I did for Abby.
You'd need to remove the lower leg to access the screw through the hole in the washers.

Could certainly go to a 5/16" bolt. However I think with the force required to bend the steel bolt you'd probably be breaking the plastic first.
McMaster-Carr says that these types of bolts are stronger than grade 8 - I'm not an expert on steel grades and such. Here's the page from MMC...
http://www.mcmaster.com/#90044a131/=zr3suj

Good point on the washer. I think your suggestion of adding a couple of countersunk screws is a good one. Plenty of room to do that with 1-1/2" washers.
Thanks for bouncing the ideas RK. Your insight and experience is always very helpful.

[Fiberglass guy]

Could yoy scale up that knee joint to fit Evas knees....I'd be highly interested in that! Also elbow joints, I would have no problem adapting these to MQ's at all! I'm also liking this whole idea as I have wanted a "project" for quite sometime that would keep me busy! and as far as torso details those could be added to a blank torso allowing different breast sizes etc most could add what they like or have some printed! And I have thought about a printer but I have ZERO computer skills, I can hardly post here without issues...

[MannequinFan]

Could yoy scale up that knee joint to fit Evas knees....I'd be highly interested in that! Also elbow joints, I would have no problem adapting these to MQ's at all! I'm also liking this whole idea as I have wanted a "project" for quite sometime that would keep me busy! and as far as torso details those could be added to a blank torso allowing different breast sizes etc most could add what they like or have some printed! And I have thought about a printer but I have ZERO computer skills, I can hardly post here without issues...

Hey FG, yeah they could be scaled up no problem. Unfortunately I don't have Eva's legs scanned so I'm not sure how much they'd need to be enlarged.
Going by height, I'd say maybe 120%? Lots of printing though. Might get a little expensive.

Regarding the printer, they use these Afinias in elementary schools. You don't have to be a computer whiz to use them. Pretty much plug and play.
You can get a small one like mine for around a grand ($999 on sale now).

[rubherkitty]

Thanks RK.
Those are all valid points of concern that you raised. The joint tensioning would work just like the shoulder and elbow joints I did for Abby.
You'd need to remove the lower leg to access the screw through the hole in the washers.

Could certainly go to a 5/16" bolt. However I think with the force required to bend the steel bolt you'd probably be breaking the plastic first.
McMaster-Carr says that these types of bolts are stronger than grade 8 - I'm not an expert on steel grades and such. Here's the page from MMC...
http://www.mcmaster.com/#90044a131/=zr3suj

Good point on the washer. I think your suggestion of adding a couple of countersunk screws is a good one. Plenty of room to do that with 1-1/2" washers.
Thanks for bouncing the ideas RK. Your insight and experience is always very helpful.

Good deal on the tensioner since you just have to slip the legs off. If find once a tension is set it seldom needs adjusted.

Yeah, those are good bolts. I was thinking of a std grade hex head bolt. Too bad you can't find a solid shank bolt w/ the allen drive head. The aircraft industry used solid shank bolts except for the actual threaded end that is needed. All thread style bolts tend to break or bend in the middle.

Glad you're not offended by my chiming in.

[MannequinFan]

Glad you're not offended by my chiming in.

Not at all my friend. Always glad to see your comments!

BTW, McMaster also has the partially threaded bolts - just a little pricier...
http://www.mcmaster.com/#91251a558/=zr81ri

I think you can custom order these from Home Depot as well and do a free ship-to-store. Not sure if they have the partial threads though.
I checked the store the other day and they don't carry them in stock.

[rubherkitty]

For the $2.00 xtra on 10 bolts i'd use the solid shank. How much shipping going to hit you?
Maybe you could just buy 2 from a big hardware store?

The cheapest way would be to buy a piece of 1/4" all thread from the h-ware store, cut to length and use a hacksaw to cut a screw driver slot on one end. Can do the same w/a solid shank hex head bolt, by cutting the head off and slotting the end. I do a lot of the bolt slotting and jamb nut type thing making adjustable fixtures.
Figure a couple of bucks for a home made slotted end bolt vs having to by a box of 10 that may run you 18.00 by the time you get them shipped.

Oops, I guess you need some type of head on the end for the pressure post. You can always use a hex head bolt and grind the shoulders off and slot it. I make a lot of slotted fillister head bolts out of hex heads in my business.
I usually grind the shoulders a little then turn the bolt heads round on a small lathe, but I don't think you have one of those in your junk drawer. You can use the old electric drill and file lathe method!

[rubherkitty]

The bad thing about the socket head cap screws is the head is not very big to be bearing against plastic. Maybe put a flat washer underneath it? Also remember the shank of a 1/4" all thread bolt may only be around .240 and the solid shank around .244. I could probably make you some 1/4" slotted fillister head bolts and ship them to you.

[MannequinFan]

The bad thing about the socket head cap screws is the head is not very big to be bearing against plastic. Maybe put a flat washer underneath it? Also remember the shank of a 1/4" all thread bolt may only be around .240 and the solid shank around .244. I could probably make you some 1/4" slotted fillister head bolts and ship them to you.

Thanks RK. I'll have to keep this in mind if/when I do the 4'-6" BJD.
Here is a better cross section detail of the pressure post. I did use washers at both ends...

knee joint pressure post.jpg (155.58 KiB) Viewed 6214 times

I kind of like the allen head because the wrench will fit through a small hole.
Looking at this again it may be better to use a 1-1/4" fender washer recessed into the post like your second suggestion above. The allen wrench will still fit through the hole in the smaller washer.

Looks like Home Depot has some 4" screws that can be ordered with free ship to store- 5 pack for 12 bucks isn't too bad and they're stainless steel...
http://www.homedepot.com/p/The-Hillman- ... /204794898
Even better, these flathead socket screws may also work without a washer...
http://www.homedepot.com/p/Crown-Bolt-1 ... /203575600

For Abby's legs, I'll just stick to using the pan head sheet metal screws that screw directly into the ball, which works fine for that size of doll. You can get them at Lowes up to 4" long in a #14 screw.

[rubherkitty]

The allen wrench is the better choice I agree. Just a little pricier.
The HD option looks decent. More per unit, but you only need 2.

Hope you are able to do the project!

[r363b]

I thought this fitting and a caster wheel assembly (remove wheel and replace wheel with pvc "bone" would give a shoulder or hip joint with 360 degree rotation and the "bone" would move up and down like human's leg or arm... just thinking out loud, more a skeleton joint than a full and finished part, but maybe you could 3D print a component for your project that uses the caster in some way.
http://www.formufit.com/1-1-4-in-pvc-ca ... ster-post/

Also, thanks and great find for design software and the your ideas on using http://www.makehuman.org/

[rubherkitty]

Thanks for adding to the ideas r363b.

I'm kicking around the idea of trying to make a foam w/ skeleton doll this winter and that type joint would be great for shoulders and hips.

[sture]

Have you seen this Obitsu 150 cm?

http://www.obitsu.co.jp/doll/150.html