As long as we're making a Christmas list here, I'll add my requests.

1. I think this has been asked before, but can we have a start setting for servos and pistons? They always jump to their halfway point when an animation starts, and sometimes I don't want them to move until I move them.

2. Any chance of a non-static mesh? It sure would save time trying to make swiss-cheese style objects!

3. Also, what is this mysterious "magnet" joint I have seen some models using in the warehouse? Is this planned on being a part of the next SP? If it is, can you turn it on and off, reverse polarity, or set the strength like an electromag?

Even if none of these things happen, I'm still stoked with SP the way it is now! Great work!

I've been failing miserably at trying to make a hopper that will drop it's contents in a predictable way.

I've tried different size spheres, different size holes, and even put the entire hopper assembly on a motor to spin with no success. About half of the contents make it through and then the rest "bind" up and don't drop.

The only thing I can think of is adding some kind of "mixer" to the hopper to keep things moving inside.

My goal is to have one (or two) spheres at a time to fall out of the bottom until it's empty. Dimensions are not important right now, just a working model would be great. If anyone has any solutions, let me know!!!

hopper1.skp

Without a picture or the skp file, it's hard to see what's going on, but there are two possible reasons for what is happening.

First of all, check the bottom of the shape page of the tutorial. It explains that a "hole" in an object won't behave like a hole unless the object is set to static mesh. But if you want to make the object moveable, the only other way to make a hole is to make the object a "group of groups." (DEBUG your geometry and see what's going on.) Take a look at the pic below, and you'll see the arch is actually seen as a half-circle when debugged.

The other reason is that if the "pin" is not a true 3-D shape, it probably won't interact with the model. If it's just a line, it won't work, instead make it a small cylinder.

Hope that helps, and DEBUG DEBUG DEBUG.

Check out the model below. The "D" objects have their collision geometry turned on so you can see what's happening.

d_rings.skp

Just changed the address of the tut:

http://sketchyphysicstutorial.googlepages.com/home

I also added two new pages covering the basics of using the UI, setting multiple joints to move at the same time, and some other stuff I've learned.

Hey guys, I had some time to kill on a plane recently, and thought I'd share this creation. (Thanks again to C. Phillips, you made an international flight go by in what seemed like just minutes because of my SP addiction!!!) Well....that and a half-dozen Bloody-Mary's ....anyway...

This started as a ragdoll, and then I became ambitious with the idea of making a walker... and well, it ended up some where in-between. He doesn't really "walk", he more or less "hops" around stupidly, but I still find it quite entertaining.

If you do play with it, I suggest right clicking the body and select "Camera Follow" after you press the run button. From there just move the single joint slider back and forth at different speeds to see how much of an idiot you can make him be.

I've learned alot from this one, and I might get the time this week to update the tut with some tips on using the UI and making multiple joints move in sync.

(If anyone can tweak this one and actually make him "walk", I'd love to see it!)

(And yes, it is not a TRUE walker because I cheated and hid two gyro's in the calves.)

dancebot.skp

WOW! Those renderings are phenomenal! Great work guys.

JGB: Try the joint tut again, I just did it step by step from a blank SU file, and it worked fine.

I think you may be overthinking the whole joint-grouping thing, and it's probably my fault for posting the tut before Chris' insight.

I am confused as to why you would joint-connect a part and a joint, and then group them together. The grouping will negate the joint-connecting you just did. Usually it is one or the other (joint-connect or group.) I find it helpful to group the joint and object right away, so I can think of them as one piece. Then I just have to find another object to joint-connect them to to make it work.

I don't want to confuse you if you have a method that works, as there are multiple ways to do it, but I think you'll have more success with:
(1 joint/1 object grouped)---joint connected to----(parent object)

(Thanks Chris for the simplicity of helping me understand that.)

I also haven't set the shape of the resulting groups, but haven't had a problem yet.

I agree if you edit a shape and it changes it's geometry, the joint may make it work differently, but as long as the original axis is maintained, you should't have a problem. And yes, there is no shame in deleting a joint and putting a new one in if you're thoroughly confused.

As far as a hinge, servo, and motor, I've found they all attach the same way, but this "way" may change from model to model. If you can make a hinge work right in a certain model, then a motor or a servo should be able to be substituted the exact same way in that model.

I think a lot of the problem stems from breaking joint-connections when new groups are made. As soon as you re-group an object with something else, any joint connections made to it previously will be lost.

As far as burying joints where you can't see them, don't be afraid to place a joint off of the part itself, as long as the axis will work for you. I haven't looked at your model yet, but I made a simple 3 arm, 2 servo, 1 hinge model (inspired by your original model) that can show how easy it is to start a "chain" of joint-connected groups.

This first shot shows that there are 2 servos and 1 hinge, each on moving parts:

The second shot shows an exploded view with the joint-part grouping, and even though none of the parts touch, the axis' are all still the same, and it moves exactly like the unexploded model:

Take a look at the model, delete the joints if you want and try to put them back in using the 1,2,3 method:

1. Add a joint for a moveable part.
2. Group the joint and the part.
3. Joint connect the joint to a "parent" to "ride on."

The pics don't show the connecting, but if you start at the ball arm and work your way back to the block, each joint-connected parent is the piece behind it. (Which is another group including a joint.)

The only thing to watch out for is the breaking of joints when you make new groups. I first added all my joints and did the grouping, then I started the joint-connecting process so I knew there wouldn't be any broken connections.

(Also disregard the gyros, they just keep the ball-arms from going crazy when you move them.) And don't apply any of this discussion to the gyros, they seem to be a whole different beast!

Anyway, I'll be traveling out of country for a few days and I don't know what my internet acces will be, but if I get a chance to look at your model, I will, It was already looking great before.

joint grouping2.skp

Thanks for the tip, I've wondered the same thing.

You're right about using it to set up a scene. I would hate to try and make that bowl full of fruit in Sketchup WITHOUT SP! That would be a LOT of move copying, and the placement probably would never look right.

After seeing Remus' model, it sparked my imagination:

How else could you model a jar full of gumballs without SP?

I've attached the model. It's a whole lotta fun to press PLAY and watch it fill up! (Sorry if you don't like white gumballs, I didn't feel like coloring tonight!)

Gumball Machine1.skp

Excellent model!

I have updated the tutorial based on "the better way" of jointing and grouping.

The basic process boils down to:

1. Add a joint for the part you want to make move.
2. Make the moveable part and the joint a group.
3. Joint-connect the joint to a “parent” object in the model.

Thanks for the suggestions guys, hopefully people will a better understanding with the new tut, I know I do!

New jointing page here: http://curbs77.googlepages.com/sketchyphysicsjoints22