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Discussion Starter · #1 ·
I took on the task of making a Leering Larry this year. I had plenty of time until my GF tells me she needs my help with fixing her chimneys on her 100yo house the other week. Then, since she had rented a 50' boom lift for a week, we took two days to cut down, and cut up, a tree in her yard. UGH!!!! Anyway, after all that was done, I was able to put this prop together.......until I got to the mechanism to make him twist!
Out of all the videos I have watched, none of them explain how to attach the first rod to the motor. At first I took some pvc and created some nice pieces that looked great, but they didn't cause him to twist. Then I took a piece of pvc pipe and wired it to the motor so it's movement would be more direct as the motor rotated. Doing this caused the motor to pause and then turn in the opposite direction. I even tried to use my tap and die set to thread the post so I could tighten the pvc to it, but couldn't get it started and then the post started to move when I would get a bite on it.
How do I get this motor to work the right way? I know I am down to the wire, but I had hoped to get this done the other week, had I not had to help my GF, I could have thought this out in time. Now I am having to come to you guys.

This is the post from the motor
Fluid Wood Household hardware Tap Plumbing fixture


Here is the attachment that came on it.
Wood Rectangle Gadget Font Cable


Here they are together.

Wood Table Gas Flooring Serveware


Here are the various extensions that I have tried to get to work.
Musical instrument Wood Wind instrument Flute Recorder

Please, can someone help me figure this out?
 

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Did you see this video? It shows the mechanics pretty well

A motor that pauses and reverses is usually binding in my experience. Can you simulate the motion of all the parts without the motor attached, just to make sure your geometry is all in order?
 

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Looks like that video should get you what you need. Basically, attach one more arm to the motor output, then use your steel strap as a 'connecting rod' between the (new) motor arm and the arm on the 'leering' rod you already have.

Ideally, you could move the center shaft of the motor as close as possible to a 90° angle from the pivot on the leering arm turning the skeleton. That would get you the maximum amount of 'twist' with the motor rotation. Having the motor out in front like in the video isn't necessarily bad, and can even give some slight irregularity to the movement (which may even be desirable), but you may have to experiment with arm lengths a little bit to avoid binding at the extremes.
 

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Discussion Starter · #4 ·
Did you see this video? It shows the mechanics pretty well
[video]
A motor that pauses and reverses is usually binding in my experience. Can you simulate the motion of all the parts without the motor attached, just to make sure your geometry is all in order?
Thanks. Yes, I just saw that video a while ago. I had been watching a few videos; one in particular is the one from Blanck Mortuary. I commented on his asking for help and he led me to the same video you did. But the problem is, that if you look closely, that first bar is screwed onto the plastic arm on the motor, and then zip-tied.
Table Wood Twig Automotive exterior Ceiling


Look at my post; my arm is much shorter and it's not designed for a screw to go down into the top of it.
 

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Could you drill a hole in the motor bracket, counter sink with a larger bit, then install a countersunk screw through it? Then you could drill 2 holes in your first arm and use a nut on your new screw to hold it down. I haven't made this one, but looking at what I have seen so far, that would be my best guess. Glad you are up and going either way!
Wood Font Rectangle Auto part Flooring
 

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Discussion Starter · #8 ·
Could you drill a hole in the motor bracket, counter sink with a larger bit, then install a countersunk screw through it? Then you could drill 2 holes in your first arm and use a nut on your new screw to hold it down. I haven't made this one, but looking at what I have seen so far, that would be my best guess. Glad you are up and going either way!
That is a brilliant idea!! I love it!! I was thinking of trying to tap it a put a small screw into it from the top, but I knew it wouldn't have held. But, coming up from the bottom is a stroke of genius. As long as I could counter sink it enough, it would work. The only thing I would worry about is that little bolt that holds it onto the motor post. It's so small, If it doesn't go down by a just a couple millimeters, I can't run that bolt through.

I did have an idea on my way to my parents to go set up though. My public library has a laser scanner and a 3D printer. I could have them scan this piece and just add another post to it coming out like the screw would. It wouldn't cost but a couple of bucks and I don't have to worry about messing up the original.
 

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If you know the diameter of the shaft, it might be easier to just print an arm! Based on the scale of the screw driver in your photo, I guessed at 8mm and sketched a quick arm which holes every inch for mounting the connecting rod. If the sizes are accurate and something like this works, let me know and I believe I can upload a file you could just 3D print straight away. (I use .stl... believe that is fairly universal?)

(this is 'upside down' for printing)
 

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If you know the diameter of the shaft, it might be easier to just print an arm! Based on the scale of the screw driver in your photo, I guessed at 8mm and sketched a quick arm which holes every inch for mounting the connecting rod. If the sizes are accurate and something like this works, let me know and I believe I can upload a file you could just 3D print straight away. (I use .stl... believe that is fairly universal?)

(this is 'upside down' for printing)
That is great, a perfect use for 3D printing- what app did you use to make that sketch? I bought an Ender printer a few months ago, and imagined using it for scenarios just like this.
 

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Well, I use BobCAD to draw up the parts. Don't use BobCAD. It's pretty terrible... just happens to be what I know and can usually sketch enough to get by. Probably something like sketch up or solidworks would be much better. I just haven't attacked the learning curve on those yet!

I'll attach the .stl file if it is of any use. (OK, stl is not supported. I'll call it .txt and likely it will need to be renamed to an .stl extension once downloaded)
 

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