Thread: My 3 axis skull...in progress

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I'm, sorry HB, you had already stated that the beveled spacer was custom machined. DUH!!! If I could learn to pay attention maybe I could finish this but I get way too excited when you do updates.

Keep watching. I will have another update on my alignment issues soon. Going to try to get it worked out today.

This one will be awesome if it works as expected.

A full post with pictures (Of Course) will be included once I get it done.

Dr Morbius,

Sorry, I missed your question earlier.

Yes, I don't see why you couldn't use 2 beveled spacers with a nut on either side to hold them into place. Should have the same effect.

Problem is, you still have to machine those beveled spacers. I haven't found anything like them for sale.

The other reason I wanted the thicker main rod was for better support and more rigidity. With a long 3/16 rod, you might get some shaking and swaying when the skull moves.

OK, I have made a fix.

First, let me recap.

Very early on in the thread on the first page, I mentioned that I needed to bend the shaft of the rod end that attaches to the skull in order to get the correct alignment within the skull with respect to all the servos.

Then I realized that this had damaged the rod end, so I decided to modify the skull with a heatgun and mount the rod end on the modified skull......MORE problems. Each skull I modified came out at slightly different angles. Making this mod also ended up lowering the position of the rod end within the skull. All of this combined caused real problems when I hooked everything back up. The skull would not run off the same program as before because all the servo arms were out of alignment becuase of the rod end.

So I thought and thought and then thought some more about how to mount the rod end so it would be aligned exactly the same in every skull. Just where I needed it so that the servo linkages all line up right.

Everything needs to be 90 degrees from everything else in order for them to work, otherwise each servo will start affecting the other servos and they will fight each other.

Then it came to me. I didn't need to mount the rod end in the skull at all! I could attach it to the lexan plate! The plate is screwed to the skull so it will move with the plate and the result will be the same.

This solved a multitude of problems! It makes it easier to hook up the tiny screws to the center rod that hold the linkages on, It keeps the rod end exactly where it's needed and can be precisely reproduced in every skull no matter how the angles may vary, and it makes mounting and removing the mechanism MUCH easier. In fact, it is now all one piece ready to drop into any skull.

Here are pictures of what I did. I started with some raw steel. Actually, this was a part for a garage door, but it would have been just as easy to cut and bend a piece of a steel sheet. Here is what I started with. I have already drawn the outline of what I was going to cut out on it.



Then I put it in the vise and started cutting and drilling.



When I was done, I ended up with this:



The bottom is measured out to fit around a servo, and slips under the servo bracket for the "Nod" servo in the lexan plate. I removed the screws from that servo, slid the bracket under the servo mounts, and screwed the screws back in (actually, I used longer screws) to hold down both the new bracket, and the servo.



Here are some other angles:







You can see where I bolted the rod end into this bracket. The mounting hole for the rod end is 1 11/16" up from the feet of the bracket and is roughly centered. Be sure to adjust your mounting hole so that the center rod extends through the neck hole of the skull in the center and has enough clearence on all sides so that movement is not restricted.

I had to re-adjust all the servo arms, and actually used different arms. These are two piece arms that you can slide in or out to change the alignment of the linkage. These also sit higher up on the servo giving me clearence to mount some of the linkages under the arm instead of over it.

The servo arms came in the package with the servo. The servo box looks like this:


And the small package of servo arms that comes inside looks like this:


This package contains the adjustable servo arms that I am using.

The tilt servo linkage should come in at 90 degrees from the nod servo linkage when the center rod is straight up and down. They should be mounted so that they are at the least possible angle, making them as parallel to the lexan plate as possible. Keep adjusting the servo arms so that all linkages are either parallel to each other or at 90 degrees to each other.

I hooked up the mechanism again and tested it with the program I originally made and it is working again now that my alignment has been corrected.

That's really cool, in that it is now a self contained mech...no advantage to it, really, just very elegant. Nice solution...you genius you.

isn't that a cool and weird feeling when you figure something out all of a sudden?! for me when that happens on a tough project it's like i don't believe myself at first. kind of like, "no, it can't be that simple".

very nice solution indeed! i love the drop and screw method of it. (wait that didn't sound right =P )

Bravo halloweenBob! Looks like you came up with an excellent solution there! Thanks for the update! Keep em coming!

HalloweenBob, thanks for the inspiration and tutorial. I just got my bucky up and running. It feels like Christmas morning. I need some input on why my servos are not responding when I run Brookshire VSA. They work fine when I run with the Parallax program but not the VSA. The controller is receiving the signal but no movement. Anybody had this problem. I've got a msg into tech support but I remember a thread about them being very slow in responding. Thanks

Make sure your controller board is running at the right baud rate. I forget the actual setting, but it should be set for the fastest one. My SSC-32 board came with the baud rate set at 9600. It did nothing. After a call to tech help, they explained it to me. I changed the jumper on the board and everything came to life.

I'd love to see some pics of your creation.

yea I had the same problems with the baud rate on my board as well, just one click and the dang servos started working lol! Show us some picts!