# 2-axis eyes for Lindberg skulls



## Frosty Don (Nov 25, 2005)

Hello All:
Several people have expressed interest in the 
2-axis eyes on my skull project so, now that things have 
settled down from the Halloween season, I thought I 
would write something up.

The skull is built using the standard  "Halloween Bob" 
design on the Lindberg skull. Let me start by saying that 
it is very nearly impossible to add normal eye linkage to these 
skulls as there is virtually NO room available without 
serious modification of the cavity. I tried several 
different configurations only to reach a dead end when I 
tried to hook them up. This method does allow eye 
movement to be added to the standard setup, but it is 
very awkward to work in the small area available, so 
those of you who aren't in the top 1% of stubborn fools, 
need not read further.

If you are now considering 
building a 3-axis skull from scratch, and insist on 
moving eyes it would be infinitely more practical to 
follow the procedure outlined by Dr. Morbius in the 
following thread:


Dr Morbius Skull

If you are still here, lets move on:

It was my hope to build the system using only tools and materials
that everyone would either have or be readily available everywhere, so 
it may appear crude at times. I work in a machine shop so my usual solution
to any problem involves me manufacturing the most complicated thing possible to do a simple job. 

While I did my best to make it as simple as possible, it unfortunately
is still relatively complicated. Hopefully others will be able
to work with it and perhaps come up with something better.

It is based around hollow half eyes that are available in a number of
places; mine were mail ordered from EBay. 

Sorry about the quality of some of the pictures.

First step is to glue a section of 4-40 threaded rod into a standard 
rod end. I used "JB Weld", an automotive epoxy used for steel repair. It is
available at most hardware/automotive supply stores and is very strong.
You can use other stuff, but this joint is the basis of the entire system
and is under stress so it has to be very strong. An alternative is to 
use nuts to secure the rod, but it severely limits the range of motion
of the eyes and there is no room for the cone washers normally used.


View attachment 3395


he next step is to lay two pieces of line, crosswise inside the eye cups.
It helps to use a dab of hot glue to hold them in place. I use dacron
braided fishing line for most things. It is very flexible, durable, and 
holds knots better than monofilament.


View attachment 3396



T
Now cut a rod end to length so that the ball is centered in the eye cup and
carefully hot glue it in place. If you have a high wattage glue gun set it to 
low or you'll melt the eye cups in the next step.

View attachment 3397


Fill the cups with hot glue to hold the lines and the rod ends in place. Be 
careful not to get any glue around the ball or it won't move properly anymore. 


The next step is the guide for the control lines. It is made from a four hole button. Drill out the center to fit onto the rod and attach it using nuts. Try to keep the nuts as close as possible to the eye while still allowing full range of motion.

View attachment 3398


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## Frosty Don (Nov 25, 2005)

We now turn to the skull. We need to make some space for the linkages and mounting plates. I routed out an area with a dremel tool. The more room you have, the better. Just be sure you don't cut into anything that will show through from the front. I actually mounted the bracket for the eye rods and then determined what needed to be removed. I made the bellcrank assemble for the up and down movement and then routed enough to mount it.

The eye rod bracket is a simple strip of aluminum. Since each skull is a bit different, you will need to insert the eye assemblies into the skull eye sockets and determine the dimensions of the bracket. Mark the holes so that the eyes are centered in the sockets and drill the bracket to suit. 

Attached to each rod ,at the eye rod bracket, are two little angle brackets that will be used to mount the servo horns for the control linkage.

View attachment 3399


View attachment 3400


View attachment 3401


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## Frosty Don (Nov 25, 2005)

The bellcrank bracket is made from a piece of aluminum bent into shape. The crank itself is made of hobby store brass tubing and the control lever is a piece of copper wire soldered on. I have no dimensions for these parts as you need to make them fit your individual skulls. 

It is not clear from the picture but the ends of the brass rod are passed through the aluminum bracket and then split into a fork shape on each end with the upper lines on the top fork tines, and the lower lines on the bottom.

The bellcrank is driven directly by a servo and controls the up/down movement. When you have the assembly in place you drill a couple of small holes to tie the control lines to. Any knots in the line will need a drop of glue or nail polish to keep them from coming untied. Do NOT cut any lines at this point as adjustment will be necessary when fully assembled.

View attachment 3402



As you can see, the left/right movement is controlled by lines attached to individual servo horns, which are linked by a piece of wire. They will be driven by another wire from the servo itself.


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## Frosty Don (Nov 25, 2005)

The control servos are mounted on the standard plexiglass plate, just beside the jaw servo. The fit nicely side by side.

The jaw servo is not mounted in this picture, but it is installed in the usual way.

View attachment 3403



When the plate is attached, the servo with the slotted horn is set over the control wire on the bellcrank and drives it directly. The linkage from the other servo is necessary to redirect the movement of the servo to control the left/right linkage via a control wire between the round wheel and the line control linkage. Impossible to get decent pictures of the completed assembly, and I didn't take many when I was working on it since I didn't think this method would work either.


 


Clear as mud right!

I know this *SUCKS*, but it's how I did it and it does work. I can't recommend it to anyone due to the amount of tinkering required to make it work properly but you asked for it. 

Hopefully someone will soon come up with a better idea soon.


Don


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## danandmeg (Jun 8, 2008)

Hey Don - 
Looks good to me! The one thing I found this year doing a 2-axis eye was how amazingly jammed everything gets in the skull which was why we decided on 1 eye instead of 2. I found that the epoxy/hot glue didn't bond well to the plastic of the doll's eye we used. The workaround was using the deodorant ball method. I cut the top part off a roll-on deodorant stick and then popped the ball out, cut it in half, then drilled and attached the horizontal axis to it prior to epoxy-ing (word?) closed. The vertical axis was actually placed on the horizontal axis so the two never had to fight each other and fluid motion was somewhat achieved. It was EXTREMELY sloppy, but it was our first attempt and mistakes lead to innovation, right?

I will be disassembling soon to make it more efficient knowing what I know now, so I will make sure to take pictures as well. Thanks again for posting, I'm still trying how to get these two darn eyes to work flawlessly!


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