Saturday, August 16, 2014

Motion Control Rig Part 2

As we continue, the next thing I tackled was the camera cage. This was made from two 6" steel L brackets attached to two half-inch thick expanded PVC halves. Using a Dremel, I routed out channels in each of the PVC halves for accessory rails to slide through. I attached a quick release camera mount and bolted all the pieces together.

Using a small stepper motor from one of the printers, I was able to make a focus/zoom controller. I designed parts in Adobe Illustrator based on the size of the motor and the distance between the accessory rails. I was then able to use the CNC router at work to cut the parts out of acrylic.

I wrestled with a couple of ideas on how to get the tilt function working. After figuring out that my first option was going to be more complicated than it needed to be I ended up going with option two, which you can see below. I attached a Nema 17 stepper motor on to the upper L bracket and screwed a gear into the lower L bracket. I then ran a bolt through both brackets and the gear for a turning point. When the motor turns, the whole lower bracket tilts. The holding power of the motor keeps the position of the bracket when stopped.

For my Z axis, I was given a linear slide powered by a Nema 23 motor (thanks, Ivan!). I used the CNC router again to cut a mount out of half-inch thick acrylic.

I attached the mount to a pan mechanism that I had already built. The pan system was built around a bracket I had pulled from an expired vacuum fan out of a large flatbed printer. A small "Lazy Susan" connects the bracket to a round MDF piece with a hole cut out of the center.

Using silicone, I glued a timing belt around the outside of the MDF circle. I then mounted a Nema 17 motor to the bracket so that the motor's gear grips the timing belt and turns the MDF piece when powered.

That's it for now.  Still more to come...

Sunday, July 27, 2014

Motion Control Rig Part 1

Well, it's been 4 months and I still haven't finished the painting on the plant so we'll just move on for now. Today we'll take a look at the motion-control camera rig that I've been building slowly since February.

This system can be controlled with Dragonframe, the software that I will be using to capture my frames. It's the same software that was used to shoot the stopmotion features ParaNorman, Frankenweenie, and the forthcoming The Box Trolls. I will be able to program my camera movements so that each time I shoot a frame the camera will move to its next position automatically. This helps me spend more time focusing on animating my characters and not worrying about whether or not I remembered to move the camera during dynamic shots.

To start things off, here's a shot of my manual, one-axis wooden rig to get an idea of what I started with. Each turn of the knob would move the 2x4 wood block down the threaded rod. It works for what it is and I may still use it for various shots.

What really got this thing moving, so to speak, was the good fortune of being given two large format printers that were getting decommissioned. These were great for parts. They each had a set of 5 foot long steel rails, bushings, belts, gears, motors, and other random parts. 

My first inclination was to use one of the stands from a printer as a base that I could roll into position as needed. It would have both an X and Y axis, pan, and possibly a tilt function.

I soon realized that the lack of space in my garage wasn't going to be fun to contend with. So I got even more ambitious and decided to look up. I was going to build an overhead rigging system.

 I had already installed some hanging storage racks above so I figured I could use that to my advantage. They had some sway to them so the first step was to secure them to the wall to make them a more solid base. Next, I fastened some supports from some extra printer parts onto the rail system and set the whole thing on top of the rack.

More to come...

Sunday, March 30, 2014

Drum Plant Part 1: Concept to Casting

The concept for the percussion part of things is pretty much an alien plant that plays itself. It has five pods as the "drums" that its stems will beat. I plan on rigging up LEDs to make each pod glow whenever they are struck. We'll see how that works out. Here's my initial drawing:

Using Super Sculpey Firm clay, I sculpted a single pod and stem that will be duplicated in the casting process:

After smoothing out some of the features, it was time to make molds of both the pod and the stem. I poured an RTV urethane rubber over the clay sculpts in two parts to create the molds.

After the molds had cured it took me a couple of months to get to casting the pieces. I'm a slacker. Sue me. I used an RTV tin-cure silicone that I had on hand to cast the first pod, but realized it wasn't going to work because it ended up being too stiff and opaque. I needed the pods to be softer so I could animate a "squash" when they were hit. Also, I wanted them to have some transparency so that I could light them from the inside to get the glow effect that I mentioned earlier. A bit of research later, I ended up getting some Dragon Skin platinum-cure silicone from Smooth-On. It had the softness and transparency I was after and I found it much easier to work with. Really cool stuff and cures in a quarter of the time. Blue pigment was added to get the base color that I wanted.

To cast the stems, I used the opaque tin-cure silicone since there will be aluminum armature wires down the middle of them that I don't want to be visible. Part B of the silicone mix is already blue so I didn't give it any pigment.

Here's all five of the pods and three stems. I was planning on having five stems, but it's getting a little crowded in the space and animating is gonna be tricky enough as it is. I may add a fourth or fifth since I'm into the challenge, but I'm definitely no Harryhausen.

That's it for now. Part 2 will be all about painting these bad boys.

Saturday, January 18, 2014

Bass Guitar Prop

The bass guitar that the hairy giant will play was a lot of fun to make and I wanted it to be as realistic as possible. I started off finding a vector image of the basic shape I wanted and added lines where the neck and body connect. I have the privilege to work in a shop that has a cnc router and I programmed the cuts in the routing software.

I routed the design out of half-inch MDF. I cut two of them in case I didn't like how the first one came out.

After sanding the edges down to get a smoother and more realistic look, I started working on all the add-on pieces. For the fretboard, I found a piece of thin wood laminate that I cut to the basic width of the neck then sanded it down to an exact fit. I measured out the frets and used a Dremel to route the channels where the frets would lay. The frets were cut from a thin steel rod.

Next I cut a back plate from 04 aluminum and drilled holes to attach the neck to the body. The pickups were made from black acrylic. I used two small nails for each pickup which gave me a way to attach them and the nail heads added a realistic look. I then cut a piece of 02 styrene into the shape of the pick guard and cut holes for the pickups and marked screw holes.

The fretboard was then stained and then glued to the neck and the steel frets were glued in the channels. I found some knobs, small screws, and random hardware to stick on. Next I painted and gloss-coated the body of the bass then reassembled everything. Lower guitar strings were strung which worked as scaled down bass strings. Lastly, a strap was made from the leather of an old belt and a mini chord made which can be plugged in or out as needed.