Some questions about doll's hip joints.

The holes give more mobility to the leg and in how you can move it as the elastic can have more room to move. I prefer the more mobile dolls.

In my opinion, Iplehouse dolls are very pretty, but they move like crap. They gave up mobility for a great looking body.

 

To add to what @RabbidBunnies said, the longer slots allow the leg to bend at a 90-degree angle from the hip -- which means that the doll will sit up properly and stably, rather than leaning back or tending to flop backwards without support. In the early years of BJDs, it was common for owners to cut longer slots in order to improve sitting stability, especially on the original Volks SD bodies.

You will find a lot of discussion about sculpting and jointing in the Making a BJD area of DoA!

 

Agreeing with others, lack of the slot makes sitting or any poses with the knees raised high nearly impossible. It is prettier without the visible holes, but personally, mobility is more important to me.

I wonder if you could do some sort of cap or sheath to cover the holes? I'm not sure if/how it might work in a hip joint, but I've seen it work very well in knee joints. For example, Blue Blood dolls have a little "cap" sort of thing in the knees and elbows between the main parts to keep the the hole covered, but the functionality of it is still there and poses beautifully. I think of it sort of like an armadillo's back. lol

 

For dolls with the slits in the legs, they have a string going from the neck down to each leg, and the hole is needed to let the leg bend 90 degrees. Otherwise it will only bend until the elastic hits the edge of the channel. Dolls like the Iplehouse dolls instead have the elastic going sideways into the legs. Either the legs are strung together with one separate string, or there is a hole somewhere in the hip/groin that the strings go through sideways.

My Souldoll had hips like that, this is what it looked like:


They were absolutely terrible to pose and I modded them to be like the first style instead. The strings are much more stable when they can go straight down. The sideways/hidden hips don't like to more independently (bending one leg tends to bend both) and the legs don't really like to pull apart. They're basically always straight or both straight forward at a 90 degree angle.

Twigling has an excellent resource about the mechanics of different kinds of joints for dolls if you are interested.
How We Make Dolls | twigling

 

Iplehouse hips work by having an additional piece at the top of each thigh that sort of "hooks" into grooves inside the hip. Kind of hard to explain. I'm not part of the "Iplehouse sucks" camp that seems to be so popular around here, but you do have to learn how to pose their joints (so that the hooks catch), whereas with the legs with visible slits, you just move the leg and it stays there (provided it was carved and strung correctly, of course). I've got an SID man, SID woman, two KIDs, and a bunch of BIDs. The only one with any posing problems is the SID woman. Her hip hook pieces have problems catching, and I'm not sure if it's a stringing problem on my specific doll, or something else. She did come to me very loose overall, though. The rest of my Iples pose beautifully.

So, if you want to sculpt a doll without visible slits at the hip, don't let the naysayers discourage you You'll figure out a way to do it. And please do post pictures in the sculpting section!

 

I've heard quite a lot of criticism about any Iplehouse dolls in comparison to other manufacturers, so it's nice to know you've had so much positive experiences with posing your Iple dolls. I have a EID and SID female dolls myself. EID is still factory strung, and pretty tight, so she doesn't have that much trouble with posing. My SID, however, is another story. I've re-strung her around 10 times now with varying elastic thickness and tightness, but her legs are dangling from the hip joints. It seems to me that the triangular hip fixer pieces inside the hip are too small to snap to the grooves in the back of the hip when posing. So far this doesn't seem to be a problem for my EID, so I wonder if the piece is to small for the SID line dolls.

Without that slit at the top of the thigh sitting poses can be more difficult. Some dolls' torso arches back when they can't go all the way to that 90 degree angle, so you might need to use some support to prevent them from falling backwards.

 

That's entirely possible. I may mod them to be a bit bigger and see if it helps.