# Compact Head Turning mech



## dave the dead

I am currently working on a small version of a witch stirring a cauldron. The more I thought about it, the more I wanted to add some head movement to the Witchlette. I have made head turning mechs before, but always on a larger scale where the overall size wasn't an issue. This project has several design demands that I have not encountered before. The projected size of this prop will be approximately 2 feet tall leaving very little space inside the body. (for reference, the head is slightly smaller than a softball)

* The mech must be small enough to fit inside the body.
* The mech must be reliable. In the past, I have made props for myself, and troubleshooting always seems to be par for the course. This mech must work flawlessly and provide trouble free operation.

The mech shown utilizes the built in mounting holes on a 5 rpm vent motor. 

















This is my first successful configuration that will meet the necessary requirements. After the pictures were taken, I have tweaked a few dimensions to make the mechanism even more compact than pictured. The design will allow me to easily adjust the overall height and neck-to-torso dimensions, but for now proof of concept has been achieved.

Video can be seen here.


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## RoxyBlue

Pretty cool, Dave. Would you be able to use the same motor to drive arm movement or just stick with having a motor down in the cauldron?


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## dave the dead

I will be placing a motor in the cauldron to drive the arm movement. I'm not saying it would be impossible to make the arms move from the same motor turning the head, but it just seems like it would be too complicated. I will also be sending different voltages to the two different motors so they turn at different speeds, making the movements seem more natural.


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## IMU

Been following your blog and saw it there ... looks wonderful.


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## Jaybo

I also saw this popup this morning in my blog reader. Very nice. Every time I turn around you are finding another use for those little vent motors. Who knew they would be so handy?

Looking forward to seeing this one completed.


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## Lunatic

Great design Dave! Nice usage of the motor mounts and rods. I've got some of those motors and was looking for another reason to use them. It's like a mini leering prop mechanism. It runs forever. Maybe I'll give it a go one day. Thanks for showing us.


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## dave the dead

I have switched to a 5vdc source for the head turning....slow deliberate movement seems much more menacing. I will start setting up the jointed arms and cauldron motor next, running that one on 12vdc. 

My next major challenge with this project will be designing a body that allows easy , yet hidden access to the motor and mech just in case something goes wrong later.


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## Lunatic

dave the dead said:


> My next major challenge with this project will be designing a body that allows easy , yet hidden access to the motor and mech just in case something goes wrong later.


I'm thinking a pvc or wire frame with a black, light-weight fabric dress to throw over the frame. Maybe add a burlap shawl over the shoulders.


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## dave the dead

Lunatic said:


> I'm thinking a pvc or wire frame with a black, light-weight fabric dress to throw over the frame. Maybe add a burlap shawl over the shoulders.


While working on the arms, I found an attachment point at the top of the stationary head support rod to mount the shoulders. This will also give a place to incorporate some sort of shield to keep any fabric from getting caught in the head turn mech. I am envisioning a mache encasement with a flap built in for motor access.

I have two choices for the power supply that I will experiment with. One is a desktop power supply with 5vdc and 12vdc. If I use this, I would run the 12vdc to the stirring motor and the 5vdc to the head turn motor. My other option is to run them off the same 12vdc source.


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## jaege

Very nice. Gotta steal that idea...for something...one day.


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## beelce

Cool Dave......


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## Daphne

Yeah, what Beelce said!


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## hpropman

Nice design for those that do not want to mess with a servo and a microcontroller.


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## Daphne

Please don't forget to take tons of pictures, especially since it sounds like you've tweaked stuff from the original pics. 

I have a new project in mind and this design may be just the ticket for some of the movement! I don't know how I'd build anything if wasn't for all the terrific ideas y'all come up with for me to steal (oops, I mean borrow).


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## halstead

Very inspiring! I got several of those motors and am just starting to use them. Where did you find a plug for the wires? I've been cutting the motor casing open and soldering the wire connection. Can't wait to see the finished project!


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## dave the dead

halstead said:


> Very inspiring! I got several of those motors and am just starting to use them. Where did you find a plug for the wires? I've been cutting the motor casing open and soldering the wire connection. Can't wait to see the finished project!


I have been hacking an ATX plug from a computer power supply ( the larger of the two pictured below. Sliced apart in pairs, this will make 12 plugs.However, in this project since I didn't want to deal with loose wires, I just opened the casing and soldered directly to the motor


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## dave the dead

I added a bracket to the top of the main head support rod to mount a shoulder. Also notice that the linkage is now closer to the crank arm center and the head turn linkage is shorter than in the first pix. 









Dowel rods and eye hooks were used for the loose jointed arms. 









I drilled a hole thru the stirring stick and inserted a wire loop to act as a pivot for the wrists. This is critical to give the arm linkage a very smooth and natural stirring motion.


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## psyko99

Very nice Dave. I can't wait to see her finished.


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## Lunatic

Loving the process...can't wait for the end result! It should run smooooth.


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## dave the dead

Here I have added a plastic bottle over the entire mech, leaving ventilation above and below the motor. This acts as a guard to keep the costume from getting caught in the mechanism. Over the bottle I applied a layer of burlap that has been soaked in Sculpt or Coat. This gives me a fabric base to begin the final costuming. The cauldron form has been finalized and the stirring motor secured to the base. 
At this point I gave the old gal a 24 hour test run. There was absolutely no heat buildup in either of the motors or any of the wiring and power supply. The mechanism performed flawlessly.

note to mods< this might be better in how-to's since it has progressed beyond just the head-turning mech into a fully documented build>


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## dave the dead

I've done some work on the eyes and skin tone. The eyes are handpainted with several thick layers of nail polish to give them a nice wet look and shine. It also adds depth to the paint.










For the skin tone I knew I wanted to stay away from the classic 'green witch' look. I sort of fumbled my way thru several different colorings and washes, settling on what you see here. It is an odd color of light-ish green/grey, but has much more depth and character than is shown in these shots. It will work well with my plans to finish her out.


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## RoxyBlue

So you paint the eyes and then coat with clear nail polish?

I love her face - so full of character.


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## dave the dead

RoxyBlue said:


> So you paint the eyes and then coat with clear nail polish?
> 
> I love her face - so full of character.


Yes, that makes it more clear...I painted the eyes and THEN coated with clear nail polish ( not painted them with clear nail polish:googly Thanks for the clarity Roxy!


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## DarkLore

I love the face on the witch. Especially the way you painted it. Very expressive. I'd love to see images of the final prop.

Is there a reason for the second offset (bolt)? I have a head pivot prop using a gear motor that turns a pvc neck.


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## DarkLore

Dave - you've got some great props on that blog site. I missed the link the first time I read this thread. For those who didn't see it...check some of the other great props Dave's got on his blog.

Shadow Farm


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## dave the dead

Darklore, I have also used a pivot as you have shown in some of my larger props. It is a fine way to set up a turning motion when space is not as much of an issue. In this case I needed the entire assembly to be self contained within the body of the prop. Since her overall size is quite small, this was a good solution to the problem. The small amount of offset is imperceptible after I added the head and body covering.


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## dave the dead

DarkLore said:


> Is there a reason for the second offset (bolt)?


May have misunderstood you question or not explained clearly...I'll try again.

The offset bolt is what the head is attached to. This keeps the entire mech self contained, eliminating the need for additional structure to support a pivot. Having the head mounted slightly away from the fulcrum point also creates a sweeping turn of the head that seems very natural.


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## ctarpey

perfect ive been looking for this method of mounting my motor. question: what did you use as a power supply for your motor there seems to be a clear piece that goes into 2 pins on yours can anyone direct me where to get one.
Thanks.


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## dave the dead

Witchlette is finished.

Click here to check out the video.


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## corey872

Magnificent!! That thing creeps me the heck out and I am setting here in the living room with the lights on! Can only imagine what it would look like with a little fog and mood light.

I meant to ask earlier, I noticed you used a linkage with 3 arms instead of a more direct connection. This seems to give the head more of a 'look left, pause, look right, pause' motion as opposed to a more cyclic 'left-right-left' motion. Did you use any specific measurements for this set-up of cranks?


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## dave the dead

corey872 said:


> Magnificent!! That thing creeps me the heck out and I am setting here in the living room with the lights on! Can only imagine what it would look like with a little fog and mood light.
> 
> I meant to ask earlier, I noticed you used a linkage with 3 arms instead of a more direct connection. This seems to give the head more of a 'look left, pause, look right, pause' motion as opposed to a more cyclic 'left-right-left' motion. Did you use any specific measurements for this set-up of cranks?


Corey, I am sorry but i do not have the specific measurements that i used on this. 
I'm sure there is way to calculate the measurements, but I find that setting it up and running a few trials is the easiest way to get the desired motion. The way I figure the length is to install the crank and the push bar, leaving the center linkage out. Position the crank arm pointing directly away from the pivot. Then position the push bar to point directly at the center of the crank. Measure this length, then add a bit Install the linkage bar and test the motion by hand, making sure there is no binding If the bar is too short the linkage angles can hyperextend and cause a major bind ( and possibly ruin the motor or linkage)


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## PirateLady

Absolutely love this little lady.... great job...


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## IMU

Great job!


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