Ithorian: Miscellaneous improvements

This would have been a great reference shot if it were bigger. Still, it gives a good sense of proportion and another view of the hands & feet

This would have been a great reference shot if it were bigger. Still, it gives a good sense of proportion and another view of the hands & feet

During my head movement tests, I found that the side to side axis (the azimuth movement) was binding. I stopped by the hardware store to find a bearing, but nothing was appropriate. So, time to build my own.

I found this patio door roller with bearings that's the perfect size. Add in a couple of flat end caps that fit the PVC bones of the neck, and I'm ready to put together a smoother joint.

Drill and countersink the outer ring which will screw into the larger end cap

End cap gets pilot holes and a large clearance hole for the inner ring. Rough the surface for epoxy

The final set of parts for the joint. A clearance hole for the bolt has been drilled into the smaller end cap

I decided to epoxy the outer ring to the large end cap for additional support

Apply epoxy just to the edges, not the bearing

Screws and epoxy should hold these two securely 

The smaller end cap will be bolted to the inner bearing ring

The fender washer adds support to the assembled joint with very little friction

A short section of PVC connects the new azimuth joint (left /right rotation) to the elevation joint made by the PVC x joint (up/down rotation).

I'd been having some problems with the springs and the S connectors slipping off when moving to the limits of motion. I decided to add some washers to the bolts holding the springs, and crimp down the openings on the S connectors.

Washer added to the bolt and the loop on the spring crushed down smaller

The S connector openings were crushed smaller or completely closed onto their components

I also decided to glue together several of the PVC pieces that make up the neck to keep them from slipping and provide some additional support. Bring out the PVC adhesive!

A short section of PVC was glued to the large end cap of the new joint. Next, the pieces of the neck are laid out to be glues

The PVC glued is applied to each end of the tube and then then pressed into the joint. Keeping the joints flat on the table insured they were aligned properly.

The neck and new joint are installed back onto the base structure along with all of the other improvements. You can see that the steering bar on the new joint is now higher, making the push rods and the horizontal support tube farther apart.

I put the costume back on to see how all of these little improvements affected the movement. It was much smoother and more "solid". By that I mean the springs didn't rattle around, but maintained a level of tension that kept the pieces firmly attached to the joints. However, the new joint raised the steering bar higher up from the base support, and that had the effect of reducing the range of motion, as well as making the horizontal part of the neck thicker. I'm pretty sure some lever arms added added between the steering bar and the cross piece at the end of the base structure would solve both problems, but I'll wait to tackle that improvement until the next time I work on this costume. I'll also try to illustrate the geometry of the mechanism a bit better so that it's clear how I can reduce the neck thickness and get a bigger range of motion mechanically.

A profile shot to get a sense of the proportions. The hump covering my head is perfect relative to the eyes and the rest of the neck. However, the thickness of the horizontal part of the neck needs to be reduced. Plus, I now have to go outside to ge…

A profile shot to get a sense of the proportions. The hump covering my head is perfect relative to the eyes and the rest of the neck. However, the thickness of the horizontal part of the neck needs to be reduced. Plus, I now have to go outside to get a full body picture!

Today I received the silicone rubber I'll be using for eyelids and the overall skin coat. But, there's a lot more foam work to do, as well as the eye movement and blink actuators. I'll be taking a break on this cosplay until after San Diego Comic-Con in order to get things ready for that show.

Because, you know, it's COMIC-CON!

 

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Written by Alan Irwin On In , Tagged

Ithorian: Head movement

Another reference image, this one is a min-bust from Gentle Giant

Another reference image, this one is a min-bust from Gentle Giant

Several RL events conspired to throw off my scheduled on the Ithorian costume. A work trip to Australia took 10 days, and then the worst cold I've ever had took another week. Reviewing my schedule, I've finally decide that I'm not going to be able to finish the Ithorian costume before SDCC 2014. I'm sad about it, but it does reduce the pressure and lets me redesign the costume as I run into problems and look for alternatives. Instead, I'll unveil it for the 2015 con season.

However, I'm not stopping work on this. The additional time just lets me make the costume even more awesome! For instance, I've been following the Giant Creature build by Legacy Effects, Stan Winston School, and a variety of partners. This week, they were showing off the mechanical controls the puppeteers will be using inside the creature. That inspired a new mechanical control mechanism for the Ithorian's head. Also, I've gone a bit overboard on images for this part of the build.

Ball joint and mounting hardware

The key components in the mechanism are these ball joints that I bought at a radio-control hobby store. They are used for attaching control surfaces in model airplanes to servo motors. They're solidly built, have smooth movement, and are relatively cheap. I built them into "thrust rods" using threaded rod inside aluminum tubes with a ball joint at each end.

Cutting threaded rod to size

Cleaning up the ends (really, I just wanted to get a shot of grinding steel with sparks flying)

Interrim construction of thrust rods showing ball joints attached to a threaded rod inside an aluminum tube

The steering arm is an aluminum rod passing through a 45 degree PVC joint. The arm has a threaded hole in the middle so that a bolt can hold it in place. Also, the ends are threaded so that the ball joints on the thrust rods are bolted into each end. Here's a more thorough sequence of pictures showing the construction.

My chop saw cuts the aluminum rod to length

Smoothing the edges

Drilling holes in the ends that will be threaded

Clearance hole drilled in the 45 degree PVC connector joint and another clearance hole for the lock down bolt

The ball joint at one end of each thrust rod is screwed into the ends of the steering arm

Sanding down the ends to clean up the rough cut

Drilling the lock down hole that will be threaded

Threading one of the holes with a tap

Lock down bolt screws into the threaded rod locking it on the PVC joint

The steering mechanism is installed so that the left/right axis is mounted into the forward/back axis (shown with the counterbalancing springs)

The drive levers are mounted on each side of my head. They are made from aluminum stock and cut to size for my head. A pivot hole is drilled at one end and used to mount the lever onto the outside of the frame. There's also a threaded hole used to mount the other end of the thrust rods. These are the basic head movement controls.

The lever arms cut to size, a clearance hole at one end and a threaded hole for the thrust rod attachment

The pivot point on the lever arm is loosely bolted to the frame, and the thrust rod is mounted to the lever

Since the lever arms are going to be "attached" to my head, all ends are rounded and deburred

Mechanical assembly is complete, and the lever arms control the neck assembly (left/right and up/down)

A headband loosely attaches to the lever arms so my head motion can drive them. I sewed the basic headband from strips I cut out of an old t-shirt along with some Velcro fasteners, and then I attached EVA form for padding. Some canvas strips are sewed down to wrap around the lever arms. All of this was sewn with our old Necchi sewing machine (sorry, no pictures). That thing is a work horse. At the end, it had to sew through 2 layers of canvas, the EVA foam and two layers of t-shirt material. Tricky, but it got the job done.

Finished headband showing the Velcro fasteners and the padded straps that wrap around the lever arms

The canvas straps on the padding wrap around the lever arms. The arms can move up & down inside the straps and have some room to twist.

The parallelogram structure of the overall mechanism translates my head motion to the head movements of the costume. It's pretty slick. Here are some pictures of me testing the rig. I was checking fit, range of motion, and looking for high friction joints.

The mechanical structure is mounted in the FX corset. The headband is firmly wrapped around my head for controlling the neck/head mechanism.

Checking some range of motion, my head is straight up in this shot. I can tilt my head back and forward as well as turning left and right.

As I bend my head forward and turn, the eyes turn and bend down as well. All the movement is in the neck joints. The eyes themselves are not turning.

I tried to limit my motion to just tilting my head down. The costume head followed pretty well. This isn't the full range. I just couldn't coordinate the shot well.

The rig is comfortable and the range of motion is pretty good. The problem I found was in the azimuth rotation around the neck (left-right). I need to find a lower friction bearing. But overall, I'm very pleased with the movement.

Okay, one last photo. So far I haven't shown the outer structure. I've been making some major changes, so a lot of the foam structures I've previously shown don't fit anymore. Here's what's left of my original foam outer layer on top of the current mechanism. It gives me a feel for the proportions with my head covered. There's lot's of room under that "hump", so my head and all the controls fit comfortably. I'm pretty happy with the overall proportions.

My head will be completely covered, and the rest of the structure has a good profile for an Ithorian.


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Written by Alan Irwin On In , Tagged

Ithorian: New approach to the eyes

Another reference photo of Ithorians, in this case Senators in the Republic

Another reference photo of Ithorians, in this case Senators in the Republic

Okay, I took a break from working on the Ithorian costume so that I could rethink some approaches. In the meantime, a new tutorial came out from Stan Winston studios, the third part of a series on making a T-Rex character. It's a vehicle for demonstrating a lot of foam construction techniques, but part 3 covered making the eye. That was the inspiration I was looking for. So here's where I've gotten so far.

For this version of the eyes, I need to get a couple of clear plastic half domes. I liked the size of the 4" Styrofoam balls I used in the first attempt, even though I didn't like the material. So I cut one in half, turned a 4" disk as a base support and glued them together. Then I covered the shape in Spackle, filling all the gaps and sanded it smooth. I used that structure as a buck (the mold) in the vacuum form machine (sorry, no picture of this stage). I then pulled a form using a sheet of 0.060" styrene.

That first pull was terrible. There was a lot of webbing (folded plastic) and the texture of the Styrofoam was revealed, making the surface all bumpy. So I left the plastic on the buck, cut the webbing away, and did some sanding to try & smooth the surface. I also researched methods that other folks use to reduce webbing on vacuum forms. Using a wooden block to raise the height of the buck and a cardboard ring to force the melted styrene down around the buck, the second pull had no webbing, and the surface texture came out better. Still, I left it on the buck, sanded the surface, and pulled another form.

The final buck after 4 layers of plastic and followed by sanding

It took 4 pulls, each sanded smooth and left on the buck, before I was pleased with the surface and the shape. At that point I moved onto the the clear plastic form.

Clear plastic vacuum formed around the buck using techniques that forced any webbing off of the desired shape

Here's how the clear plastic looks after the pull. The buck is elevated on the wooden platform and the cardboard ring was used to push the plastic down around the buck before applying the vacuum. These are the important steps needed to eliminate webbing on the desired part of the form..

Plastic cooled down and removed from the vacuum former

There's a lot of plastic that needs to be cut away from the plastic dome. You can see the wooden stand is still captured in the plastic, and you can see some webbing down on the base of the plastic, well off the critical dome shape.

Using a surface gauge to score the plastic

Next, most of the flat plastic waste is cut away using a razor cutter and scissors. What's left is the wooden stand and buck covered in the clear plastic. Then I created an ad hoc surface gauge using a craft razor and my anvil/vise in order to make an even score line on the plastic. All i needed to do was turn the buck against the razor and I got a level score on the clear plastic. Once scored, I could peel away the waste and then pop the dome off of the buck.

Final clear plastic dome for one eye.

I'm pretty pleased with the dome shape, and so I made 2 more (one of which has a flaw and I used it for testing).

Original eye image

Final cornea image after Photoshop

Off to Google! I needed to find a nice image of a cornea for the eye. I settled on a nice brown eye with a large pupil (but not too large). Then I used Photoshop to remove light reflections and to make a complete round image with a dark border. That was sized so that I could print it onto glossy photo paper to make a well proportioned eye.

Printed cornea positioned inside the clear dome

Eye veins painted on the inside of the dome

Polyester resin filling up the cornea

The sclera painted on the inside of the clear dome

I marked the position of the cornea onto the clear plastic and then painted some veins on the interior of the dome using the position line to limit the area. The veins will give eye a bloodshot look. Next came the tricky task of mixing up some clear polyester casting resin in order to fill the plastic dome up to the line, and then place the printed cornea onto the resin. After that dried, i painted the rest of the interior of the clear plastic dome with two colors of spray paint; a textured and speckled light brown and a solid off white. This defined the sclera of the eye. 

Sizing the outer support ring

While all of that was happening, i started to build the mechanical support for the eye. This time I decided to limit the eye movement to a side to side motion. That will make the eye movement much easier and more secure. Once again, I decided to use aluminium as the material for the structure because it's light, strong, and easy to work with. A solid ring around the eye will give a support to the movement axis and the blink pivots.

Unfortunately, I didn't get any close ups or interim shots of the bracket attached to the aluminum rings. As you can see in the above photo, I used aluminum U channel. On each end of the channel, I cut out about a half an inch of the middle, so that each side of the channel could be folded out. I drilled and tapped those "wings", and then drilled matching clearance holes on the ring. An additional strip of aluminum was cut to size with clearance holes. In the image above, you can see that screws slide through the aluminum ring, through the additional strip, and then screw into the U channel wings. All together in made a solid mount for the aluminum rings.

One end of eye pivot and the back half ring support

Back side of eye showing mechanical attachments

I placed an additional half ring on the back of the eye support rings to provide additional mounts and to strengthen the eye socket. The eye pivot shaft was cut from 8-32 threaded rod. Plastic washers provide spacing as well as a frictionless surface for the rotation. An aluminum tube was cut to size in order to provide internal support to the plastic eye. Also, a metal bracket was cut and folded to provide a lever arm (for the side to side pivot) to the back of the eyeball. Some elastic was mounted from the back of the eye socket to the sides of the eyeball support bracket. The elastic provides a return resistance to the left & right eye movement. Finally, a ball joint was added to the eyeball bracket so that a brass rod can connect both eyes, coordinating the side movement.

Basic pair of eyes, mounted

And here is a final shot of the pair of eyes mounted on the U channel and aluminum tube supports.

 

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Written by Alan Irwin On In , Tagged