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Oak Lane Cemetery
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2,356 Posts
Discussion Starter · #1 ·
First off let me say I'm not the first to do this, there have been several others who have done this same mod to their spiders and I looked at theirs to get ideas on how to do mine. It's a fairly simple mod to make as long as you pay careful attention to the length of both your drive arm and the length of the rods you use to connect the pedipalps to the drive arm. Too long and the rods will buckle some and you get a jerky animation that might bind up and stop from time to time. Too short and the motor will jam and stop on the backside of the rotation. Using a large washer as a swivel like I did in mine will give you a half inch or so of play and add a bit of randomness to the movement, but it's not the only way to go. A secondary pivot point can be used to transfer the animation to the pedipalps or a lever can be set up using the support frame to do something similar. My way was the quick and easy way to do it. Anyways here is my version of how to animate the pedipalps (mouth legs) on the 1st gen home depot Gargantuan spider -
 

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Oak Lane Cemetery
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2,356 Posts
Discussion Starter · #8 ·
Just to update this, after testing it developed an issue caused by me overestimating how long my drive arm needed to be. The legs were maxing out at both the top and bottom of the animation, which was causing the animation to become jerky and created a lot of creaking and other small noises because of the strain it was putting on the motor, hinges and rods. Over the two 6 hour test runs I did on it I had it it stop a few times too due to getting bound up. The problem didn't show itself right away I think because the rods were stiff enough to cope with it for a while, but then started to flex a little as the stress started causing them to start to bow slightly. After trying to make adjustments for a while I took about an inch off of the length of the drive arm, which fixed the binding up issues and got the noise stopped, then added a spring to the mechanism to stop the pivot washer from twisting sharply from side to side when the rods changed their direction of travel. The spring holds it nice and steady so the washer stays even as it goes around. The legs now change direction before the max out and hit the top and bottom of their travel, which looks MUCH smoother. I also added a strip of fur along the front edge of the belly to help conceal the mechanism a little more when viewed from the front as mine will be by 90% of the people who view it. I discovered that staples hold the fur really well so I didn't even have to mess with glue. Going to attach the hair to all of the body joints the same way before I tuck this guy back into storage. That way I won't have to fiddle with covering those joints with the hair strips and zip ties when I set up.

 

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Oak Lane Cemetery
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2,356 Posts
Discussion Starter · #9 ·
Wrapped this project up today with a little more fur work to hide some things and make it easier to set up. I already have fur in all of the leg joints and leave the legs assembled so I don't have to mess with anything, but the body joints did not have permanent hair installed. Instead I had been wrapping a strip of hair around each joint after assembly and securing each one with a zip tie. Turned out to be a bit of a PITA so I went ahead and attached some hair to the body side of the joints to make things simpler. It does not cover quite as well as the strips did, but it covers well enough and now I'll have one less thing to fiddle with up on the roof, which is good. At the hinges I put a small strip over the upper part of the hinges to hide them. I just did the upper part because it's stationary and more noticeable than the moving part on the pedipalp. I felt like covering both with fur would have been too fluffy and might have gotten goofy looking. I didn't add any more fur to the belly for the same reason - didn't want to overdo it. The strip across the front should suffice to obscure view of the moving mechanism when viewed from the front, as mine will be.

 
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