[indianaholmes]

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.

 

[HalloweenBob]

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-425bb_super_sport_bb.html

Most servos are the same standard casing size, however.

 

[Guest]

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

 

[HalloweenBob]

IMPORTANT Rod End Modification

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

 

[HalloweenBob]

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!

 

[propmastertucson]

Rod end

Hi Bob

Nice work, Where did you get the Rod End?

 

[HalloweenBob]

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.

 

[bandacoot]

Are you using the standard 90 degree rotation on your servos? and standard clockwise?

Thanks!

 

[HalloweenBob]

Yes. Although the range I need to use is much less than that, everything I purchased or set up was standard.

 

[bandacoot]

Are you using the same servos for the Jaw and eyelids? They look smaller or something..

Also what servo arms are you using?

Thanks for you help!

 

[HalloweenBob]

All servos are the same except for the one controlling the eyelid action. That is a much smaller Hitec HS 65HB servo.

Remember, that my eyes are not going to move back and forth, instead they will appear to blink.

The servo arms, I go at Servo City. They are very small (http://www.servocity.com/html/2-56x3_16__mini.html)
I use bits of 2-56 threaded rod to hold the two ends together.

 

[HalloweenBob]

I have completed some more of my skeleton Quartet, and wanted to share some more "In Progress" pictures for anyone who might be following this project.

I'll start with all the linkages, since that's where I left off before.

This is what the linkage pieces look like. In the next picture, I have two linkage ends and one long 2-56 threded rod from McMasterCarr.com
(The linkages are from ServoCity.com...see link above)

I start by cutting a piece of the threaded rod. You might need to file the sharp edges off:

Then screw one linkage end on each end of the threaded rod piece as shown in the next diagram:

With my arrangement, most of the linkages end up touching each other with no rod showing inbetween. It just worked out to be the right distance. If you need one to be longer, just don't screw them together all the way. You shouldn't need any to be shorter, but if you did, you could snip a little off each of the linkages with wire cutters. They are made of plastic.

Anyway, next, we want to attach the linkages to the servos. I opened up the bag of servo armatures that came in the package from HiTec. I started with the armature shown in this picture:

I cut off one side of the arm, since it wasn't needed, and might hit the edge of the skull if left there.

Then I needed to tap one of the holes for a 2-56 screw. For the nod and tilt servo, I tapped the hole farthest to the outside. For the rotate servo, I tapped the center hole:

Then I mounted the armature onto the servo:

And finally screwed the linkage onto the armature using a 5/8ths inch long #2-56 screw into the hole that I just tapped:

Always be sure that when the servo arm is in the "Rest" position, which is how it is shown in the last photo, that it is set so that the servo is roughly "centered". As soon as you apply power and control wires to the servo, it will attempt to find it's "center" position. If you just screw the arm on without checking to see if the servo is centered, it will move to the center position which could possibly be beyond the possible range of your skull once it is all hooked up. This could result in breaking something, stripping some threaded screw holes, or hurting the servo itself. So when you screw the arm on, swing it all the way in one direction, then the other and make sure that the center is just about as pictured above.

 

[HalloweenBob]

Then, I worked on making the small steel armatures that attach to the center rod that goes through the rod end which is attached to the skull.

I posted a drawing of this on the first page. I will have all 4 of my rods in the next few days, and will take pictures of those as soon as I get them. For now, here is the drawing again:

The thin piece of metal between the two nuts where it says, "Rotate Armature Attached Here" is the piece I made next. In the drawing, you are seeing a side view, so it doesn't look like much. Using the one my friend fabricated for my first complete rod as a model, I made three more. Mine didn't come out as pretty, but they will be just as functional.

I started with a small random piece of steel.

Then I drew the shapes I needed to cut out with a sharpie and put it in a vise:

Next, with a hacksaw....a VERY DULL hacksaw, I did my best to cut out the pieces, and file the edges down. I put the three pieces back in the vise and drilled out the large holes where the rod goes through, then turned them over to drill and tap the holes that I will connect the linkages to that will rotate the skull left and right:

Finally, I tapped the holes:

And now I have all 4 of the rotate armatures needed for the central rods:

As I said, Mine were not pretty, but the holes are in the right places. My friend made the second one in. That's the one I copied. It does not have to be exact....thank goodness.

As I mentioned, I'll have a lot more detail on the central rod in the next few days.

 

[buckaneerbabe]

Thanks Hb, your timing is perfect. I got my rod back from the machine shop and cut my plexi, next on my list to do was the armatures. Yea!!! No guess work.

 

[HalloweenBob]

Finally, today, I drilled and tapped the holes that will hold the lexan plates I made the other day in place in the skulls.

I found that the easiest way to get it lined up right was to drill holes where I wanted them in the skull first, then line up the lexan inside the skull and mark off where the holes come through.

I didn't even measure. I made the holes about a half inch below the top of the skull and put one near the seam on each side. You can see the seam where the skull is put together if you look close. The holes look like this:

Just remember that the plate fits in at an angle. The back is near the top and the front get's screwed down to the inside of the skull.

Here is the lexan placed in the skull after the holes were drilled in the skull:

Then, with a silver sharpie, I marked the spots where the holes come through the skull:

Then with the spots marked, I put the plate in the vise and drilled a small hole (Which I will later tap for a 4-40 screw) in the edge of the lexan:

Then, as I mentioned, I tapped the hole with a tap made for 4-40 screws, since that is what I will be using to hold the plates in:

If you look close, you can see the hole in the edge of the lexan in this picture:

Next, I will mount all the servos on the new plates, but I can't screw them into the skulls until I finish all the central rods and mount them to the rod ends in the skulls.

I also still need to make the aluminum strips that hold the jaw servos in place.

I'll document that another day.

For the Jaw servo, I did use a different armature. I wanted a longer one, so I used a two part armature that came in the package with the servo. It includes a small square section that mounts right on the servo, then a long adjustable arm slides into that first piece. I set it all the way out. It looks like this:

I will not be using the linkage pieces I got from ServoCity.com for this servo. The jaw is moved by a piece of thin wire that I fit through the outermost hole in the armature. It then goes through a hole I drill in the skull and attaches to another hole I drill in the jaw. You can also see in that picture that I am going to cut off one side of the servo mounting brackets. I am doing this because this servo stands up on end. It needs to be flat on what will now be the bottom as it will be held in place with the aluminum strap I will be making.

I could have cut a slot in the lexan for these mounting brackets to fit in. That would have been a better idea, but I didn't think of it until I was done with the lexan plates. It would not be easy to do that as an afterthought. So it was easier to chop off the brackets. After I cut them off, I filed the remaining stubs off like so:

One of these days, I'm going to spend that nickel!

 

[HalloweenBob]

I mounted most of the servos on the lexan plates and wanted to post a pic of what they look like with the servos attached.

I have not done the jaw servos yet, because I still need to make the aluminum brackets to hold them down.

I wanted to show a picture so that you can see what the default "center" position should be for each of the servos.

The picture below is the view from the bottom of the lexan plate showing the servo arms and linkages. Each of the servo arms is screwed in place as shown with an equal amount of motion possible in either direction. This is so when they get hooked up to the controller board and they center themselves, they should not move more than a few millimeters from where they are now.

If you are following this project, please make note of which end the servo gear is mounted and the direction of each servo arm. They are measured out to meet up in the right places to connect to the center rod, which I will be posting pics of soon.

Here is the pic:

You can also see where I drilled into the edge in two places and tapped the holes so I can screw this to the skull.

 

[bandacoot]

Thanks HalloweenBob... please keep the pics coming.. I appreciate it very much!

So you are attaching the lexan with a screw that goes through the skull??? do you notice those screws?

Is that armature steel or aluminum?

 

[HalloweenBob]

The screws are counter sunk and are towards the back of the skull. I plan to have a wig on one and hats on the others, so for me, they will not show. You could fill in over the screws with some wood putty or even spackle, or just paint the screws to match the skull color. It shouldn't be a problem.

It's much more of a challenge to make the line where the skull cap is cut not be noticeable.

Yes, the small armature is steel, but aluminum would also work fine. I think I did say it was aluminum at the beginning of the thread, but I was wrong. Don't think it makes a difference. It is not under any real stress. If you use aluminum, just be sure it's thick enough to be rigid.

 

[bandacoot]

ok cool.. thanks.

Yes the line on the skull seems to be the hardest to hide....

ya i was thinking alum might be easier to cut also. I'll find out anyways.

 

[HalloweenBob]

Speaking of Aluminum, I did use some here for the clamps that hold down the jaw servo for each skull.

First, since I did not cut a slot into the lexan plate, I had to shave off the mounting brackets on the side furthest away from the servo gear on the servo which will be controlling the jaw motion.

Then, I had to file down the stub that was left so the servo will sit flat on it's edge

Then it was time to make the brackets:

I started with some strips of aluminum I cut out with a hacksaw...(new blade this time)

Then I measured out the dimensions of the servo casing leaving a half an inch on each side for the 'feet' of the bracket.

I cut off the extra length with the hacksaw, then bent the aluminum strips on the marks I made so they would fit tightly around the servo. Here's what they looked like:

I checked them all by fitting them around one of the servos like so:

Then I drilled out the mounting holes. I used 4-40 screws again here to hold the brackets down, so use an appropriate drill bit for the screw you are using. Remember earlier when we made the lexan plates we tapped these holes for a 4-40 screw.

Finally, I mounted the bracket over the servo on the lexan plate.

Here's a couple shots at different angles: