Thread: How to stabbing motion?

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Hi, I just wondered if anyone had any ideas on how to make an arm move up and down - I have an idea of making sort of an animatronic person stabbing. Any ideas? Thanks

A stabbing motion is not unlike a wiper blade. Can you use a wiper motor?

My thoughts also, wiper motor.

Some sort of cam with a wiper motor, I'm sure would work as mentioned above.

Ok i'll try to find one, at a car wreckers I guess, we don't have much in the way of Halloween stores in country NSW! Also, could you give me some ideas how to make it work, given that I am a technologically challenged female with great ideas but useless hands. Thankyou for your answers.

Originally Posted by Pumpkinzilla

Ok i'll try to find one, at a car wreckers I guess, we don't have much in the way of Halloween stores in country NSW! Also, could you give me some ideas how to make it work, given that I am a technologically challenged female with great ideas but useless hands. Thankyou for your answers.

At the below link you'll see a gif image of what I mean about making a cam. Hopefully it can help you see what I mean.

http://auto.howstuffworks.com/wiper1.htm

Ahhh, pictures are good! I am very visual - thankyou for that. I guess I have to get a motor of some sort to power it? Sorry about all the questions, I really have no idea - so if you dumb it down to the extreme, I am sure to get it. Thank you very much.

Well that sounds like the route I would take. If you go with a windshield wiper motor, remember its 12V. You would have to use a car battery or something alike. I used one with my monster in a box in 2010 and ended up using my dad battery charger with plugs into a 110v, converts it to 12v and clipped the alligator clamps on to the wires of the motor. I just remember as I'm typing this a sort of circular type of cam.. I'll find the video. As you can see he has a sort of circular cam like the picture I have attached. Turns smoothly then with a sharp drop. Take the smooth motion to lift the knife up and the sharp drop off for the quick stabbing motion.

http://www.youtube.com/user/denha#p/.../5/tdDCywscfNU

Wow, that's really clever - I guess I will see what I can come up with. Thank you so much for all of your help.

Yep - no problem. I'm sure you could figure out how to make this work. Fiddle around with different size cams (the second one I show you) perhaps to get the speed you want. If you can't find a way to use a wiper motor, but find a faster one, you can reduce it's rotations by using the motor to spin a small pulley or gear, then with a chain or pulley rope turn a bigger pulley or gear. Something like on a bike.