|The Shoulder Frame
To support the head and neck, a shoulder frame is bent out of 1/2" copper tubing. I want the neck to be able to turn left and right, so a pivot point was built at the bottom of the frame.
A tube framework was made to hold the small 5-pound CO2 extinguisher, this was then soldered to the bottom of the "V" shaped frame. Two tubes, just under three feet in length, were soldered from the shoulder supports and the top edges of the extinguisher frame. An additional supporting brace was added near the bottom to maintain the spacing between these extensions. The tail assembly will be attached to these two tubes.
A curved section of tubing was then soldered to the front of the shoulder braces. This curved section serves two purposes. A control console will be mounted to the frame with switches to control the various motors and electronics. The curved section also maintains the distance between shoulder supports.
To allow the head and neck to swing easily, two ball bearings were placed in a 1" copper "T" joint. The base of the "T" was soldered to the shoulder frame. Originally, I created a pin using 3/8" copper tubing with a fiberglass core. This seemed to be strong enough, but as I added additional weight to the head, I elected to replace this with a steel pin. A section of 1/2" steel rod was cut to about 8" in length, and the sharp edges ground off. A flat spot was ground for the set screw of a steel bearing collar attached to the bottom of the shaft.
A steel pin replaced the copper tubing to support the neck and head. Steel shaft collars keep the shaft in place through the bearings.
To center the neck tubing on the steel shaft, a section of 1/2" copper tubing was inserted in a piece of PVC pipe, inside the end of a length of 3/4" copper tubing. Two screws hold the assembly in place on the end of the steel shaft. These can be taken out to allow the neck and head to be disconnected from the frame for transport
To prevent the neck from pivoting too far either direction, a short length of 1/2" copper tubing is soldered across the neck tube. The end of this section hit against the shoulder frame as the neck turns.
Another "T" adapter is soldered to the end of the neck tubing, and an assembly of 1/2" and 1/4" tubing forms an extension with a curved loop that is positioned over my head. As I tilt my head left and right, the neck will pivot back and forth.
Another "T" joint and some tubing creates the control arm between the costume neck and my head motion.
Follow-up Notes: This was one of the first things to be removed as the costume was being built. For one thing, even with foam padding on the frame, the weight of the costume compresses the foam until my head was well above the neck-body junction. About 18 inches of the neck was removed to lower the head before I took the costume to Conglomeration.
As I was starting the foam covering for the body, I started thinking about how I was going to maneuver the head through 7 foot doors. This would involve bending forward to have the head clear the door frame, but it would put a lot of stress on the neck tube, and with the center of gravity being behind me, would tend to swing the head around. To help compensate, I added two stiff springs, attached to the end of the stop tubing, and fastened to the back frame with cable ties. The springs will help center the head, and slow down any sudden twisting of the head and neck.
The shoulder frame with bearing assembly made from a copper "T".
A side view of the evolving framework. A curved section at the front will hold switches for the various electronics and motors. A frame basket for the CO2 extinguisher is located low on the back. Two tubes extend down and back to attach the tail mechanism.
The steel shaft is held in place by two collars. These also keep the bearings from falling out of the copper "T" mounting tube.
Two screws hold the neck tube to the shaft. A section of 1/2" tubing acts a stop to prevent the neck from turning too far either direction.
|Follow-up Notes: When I got to the final assembly stages, I finally noticed
that all of this special effort was wasted. The tubing for the neck and head runs up the
back of the neck, just like a spine would. The problem is to swivel the head, the pivot
point for the neck and head needs to be in the center of the neck, not at the back. If the
head actually pivots on the frame as designed, the front of the neck section would be free
to swing as much as 4-6 inches back and forth. The actual movement is restricted by the
springs, so no real modification was required.
Like I said - a waste of time and effort.
|Springs running from the ends of the neck stop and the back frame will minimize twisting of the head and neck.|
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