Linkage question

[Indyandy]

I want to build a zombie prop that leaps up and at you from the ground. I have a half torso that will be on the ground looking at you. When triggered it will lunge up and out at you. 4 feet up and 3 feet out. Does anyone have a diagram on how to build the linkage for this? The cylinder that I have is a 8 inch throw double acting. Also, what size of solenoid valve will I need? I am not sure if I will need air to retract the cylinder or if gravity will do it. What do you think? Andy

[DarkShadows]

get yourself a 4 way solenoid valve and get one flow control to control the speed of it coming down.

And your going to want to make one of these mechs, called a 4-bar. Ignore his ghetto use of bike pumps and washing machine valves, use the real deal please. It's just a good how-to on building the mechanism.

http://www.deathlord.net/Exorcist/exorc.htm


most penumatic props are 4 bars.

[BTH]

Here is a link to a 4 bar simulator that should help in defining your dimensions. http://www.boopack.com/software.html Just run the fourbar.exe file and you should be able to plug in different sizes to figure out what you need. Hope this helps.

[Indyandy]

Thanks for the info.

[Indyandy]

Well, after digesting this and talking to a few people, I decided that I need to use a scissor mech. Is there a simulator or a formula that I can use to determine how many and how long each bar should be?

[The Creepster]

I want to build a zombie prop that leaps up and at you from the ground. I have a half torso that will be on the ground looking at you. When triggered it will lunge up and out at you. 4 feet up and 3 feet out. Does anyone have a diagram on how to build the linkage for this? The cylinder that I have is a 8 inch throw double acting. Also, what size of solenoid valve will I need? I am not sure if I will need air to retract the cylinder or if gravity will do it. What do you think? Andy

your going to need more the just one cylinder and one solenoid to make the prop go up 4feet then out 3 feet.

[bourno]

Andy, scissors are typically made to just go out and back in.

Here is something in the works that I started (need to get newer pics of it though).
http://www.teambac.com/web_hall/ground_breaker.html

Mine, does more of a 1 foot up and then arcs back down after 4 to 5 feet out.

A 4-bar mechanism may be more of what you are describing with the vertical height. I would play play with the 4 bar program mentioned earlier in the thread. Here is my 4 bar leaper http://www.teambac.com/web_hall/leaper.html

[The Watcher]

A scissor prop would send it at a angle 3 feet out and 4 feet up in a straight line. But from my scissor props I have learned, You are better off with 2 air valves. One on each side will help to stabilize your prop better. Also if you use 16 inch bars they are stronger with a 6 inch cylinder. The 8 inch cause the to open 50 %, which will cause a lot of sway. None of mine are over 16 inches.But I would thin 5 sets of 16 inches would give you about what you are looking for. A drawer slide will also make it run smoother.

[fritz42_male]

I'm about to play with using a 4 bar to make a skelly leap up from a sitting position and lean forward. Is this good enough?

If yes I'll make a sketch of the linkup.

The cylinder I have only has a 150mm throw - I wanted the skelly to jump up from a sitting position and needed double that. I can't remember where I found it but the 4 bar I saw showed that if the top arm was longer than the bottom arm, that I got forward movement as well which made it ideal as a scarer.

[fritz42_male]

Try this. It uses the fourbar.exe mentioned

[The Watcher]

This is my 4 bar. it goes up about 10 ft high. It will have a Tombstone if front of it. I will also have added sound and will use fog to mask the bars. I built it in January I think. So I have to water proof the electronics and paint it. Before I put it back together. I haven't got my scissor props down yet.

halloween 09 :: New prop in test stage. video by brushe2008 - Photobucket@@AMEPARAM@@http://vid511.photobucket.com/player.swf?file=http://vid511.photobucket.com/albums/s360/brushe2008/halloween%2009/SDC10083.flv@@AMEPARAM@@vid511@@AMEPARAM@@511@@AME PARAM@@s360/brushe2008/halloween%2009/SDC10083

[BTH]

Here is another four bar.
Huge Four Bar video by indianaholmes - Photobucket@@AMEPARAM@@http://vid6.photobucket.com/player.swf?file=http://vid6.photobucket.com/albums/y220/indianaholmes/100_4170.flv@@AMEPARAM@@vid6@@AMEPARAM@@6@@AMEPARA M@@y220/indianaholmes/100_4170

[Indyandy]

I am still thinking this over, just moved on to other projects. I am pretty sure I am going to use a scissor mech. The scare is; there are a couple of animated crawler zombies in the pathway that move when you walk by. But this one with jump out at you as you walk past. The scissor mech will be at an angle to give it the upward projection. Say at 35 -45 degrees. I am concerned about the weight of a wighead and mask. Not sure how much weight I can put on this at an angle.

[DarkShadows]

scissors suck... 4 bars FTW... it's the truth...