Thread: My 3 axis skull...in progress

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I just finished making the additional 3 Plexi-Glass inserts that you mount the servos to.

I actually made them out of 1/4 inch Lexan.

Here are two of the finished products (I have 4 all together now):



Making these was easy because I was able to use the right tools!

My neighbor with the machine shop has a drill press with a CNC X-Y table under it, so the square holes were cut with a router bit in the drill press, and I adjusted the table which was holding the lexan from side to side and up and forward and back the cuts.

This picture is one I found on the net of a similar machine. I didn't take a pic of my freinds press.



Anyway, I used the drill press to cut the square holes and to make all the holes for the screws that I later tapped with a 440 thread tap bit.

I cut out the main outer shape with a bandsaw and then filed the edges with a buffing wheel.

The large center hole was cut with a bit similar to a doorknob hole cutter, just smaller.

I have an actual size template that you can download and print out. I used this template to cut all the pieces of Lexan.

First, I sprayed some 3M spray adhesive on the back of the paper template, then stuck it to the protective paper coating on the lexan. Once it dried, I cut a rectangle out of the lexan around the glued paper template making sure that the outside edges were parallel with the square hole cuts I needed to make for the servos.

So I had a rectangle shaped piece of lexan that had a piece of paper glued to it with my template design printed on it.

Here is the template:

TEMPLATE

Right Click on the above link and select "Save Target As" from the right Click Menu. Print the file using the windows Picture and Fax Viewer full page to get the correct size.
There are ruler marks on the left edge of the image. If they are one inch apart, then you have printed it to scale.


Here is what I mean by the edges being parallel to the square holes:



Then I was able to put the lexan into the CNC table and cut the square holes easily with the drill press. If they weren't parallel, I would have to make constant adjustments and would not have been able to make straight edges.

Here is what the plate looks like with a servo through one of the holes:



And finally here is how the plate fits into the skull:



The back end of the plate is mounted right at the top edge of the skull with two screws which go through the skull and into the edge of the lexan. The front is screwed down to the inside base of the skull between the eyes using the single hole at the very bottom of the template. It rests in the skull at an angle on purpose. When the lexan plate is parallel to the ground surface, the skull is lifted up slightly and seems to be looking straight ahead instead of looking down. This provides a "Center" spot with range of motion in both up and down directions.

This template is made specifically to fit the "Pirate Skull" by lindberg. It is a lightweight skull kit that can be found in many places such as this one:

http://www.monstersinmotion.com/cata...ducts_id/10457



I will post more pics and instructions when I finish making the custom rods I will be using that fit through the rod ends.

More to follow....

I want one of those drill presses for christmas. I was so ready to get started yesterday and must have called 20 machine shops and they were too busy, so I have to wait till Mon to get started. I must have looked at your pic, drawing and videos a million times, but believe I can do this. I really appreicate the time you are spending on the how to's. Thank you

I hope all my instruction is clear enough.

Perhaps I should have put this in the Tutorial and How To Section.

Maybe I will make a condensed version when I'm all done and put it there.

Once I get the new rods made (Hopefully next week) I will take detailed pictures of each step as I assemble one of these buggers.

Halloweenbob, How do I print the template out full size? I can only get a small version. I have already ordered two of the lindberg skulls and am waiting or them to arrive. Can't wait to see more of your tutorials. One other question; what size and brand of servos are you using. I want all of the mounting holes to match up. Thanks for sharing.

Right Click on the link to "TEMPLATE", and choose "Save Target As" from the right click menu. Save the image on your hard drive. I have added a bunch of lines on the left hand border of the picture that are exactly one inch apart. After you print the image, check it with a ruler to be sure that it is actual size.

Once it is saved on your hard drive, double click on the image and let the windows "Picture And Fax Viewer" open up. Click on the printer icon at the bottom and follow the prompts printing the item full page.

It should come out the correct size that way.

The servos I am using are Hitec HS-425BB servos.

http://www.servocity.com/html/hs-425..._sport_bb.html

Most servos are the same standard casing size, however.

WoW Bob, I have been following your project. You sure have put alot of hard work into this. And I know that the Haunters here Apperiate your hard work.
Do you think you will have all the spooks up a running in time for this Halloween? I Hope you do. Love ya Blinks

At the beginning of this thread I mentioned that I had bent the threaded end of the Rod End to achieve the correct angle.

Turns out that was a bad idea. I must have bent the casing slightly when I did that, and the rod end became VERY stiff, exerting extra pressure on the servos making it difficult for them to move the skull smoothly.

I have rethought this and decided to make a minor modification to the skull which will allow me to mount the rod end at the correct angle without any alterations to the rod end.

Here is the skull before I started the mod. Note the shape of the neck hole:


That's a view from the top, now here's the same skull from the bottom:



Now I start the modification. I needed a heat gun (Which I had) and a pair of plyers with wide grip ends. You will see it in the pictures.

Setting the skull upside down on a piece of metal to absorb the heat, I started heating the area around the neck hole:



Once the plastic became soft and pliable, I got my plyers and grabbed the plastic area that I was going to attach the rod end into:



Very slowly, I moved the plyers upwards to change the angle of the mounting area for the rod end:



When I was done, it looked like this:



Then, I had to drill the hole for the rod end. I discovered that by changing the angle of that area, I no longer had a clear shot in there with a drill, so I used the edge of the drill bit to carve a small slot in the plastic which allowed me to hit the right area with the bit.


...to be continued

Here's what it looked like:


Cutting through here...here's what the slot looked like:



Then it was time to make the hole:



So now, this is what the skull looked like...Top view:



And bottom view:



All that was left was to mount the rod end, which went something like this:



And here's the bottom view:



Thought I would share that bit of info.

And Blinky, I will have them all done and operational for this year! Thanks!

Hi Bob

Nice work, Where did you get the Rod End?

I get most of my hardware from http://McMasterCarr.com. Go to that website and enter Part # 59915K271 in the search window.

They are about $9.00 each.