# Automate a lid?



## jds10011 (Dec 30, 2021)

Looking for some creative ideas: We are trying to rig up an effect where a large-ish and moderately heavy trunk lid opens and shuts itself several times (and this happens pretty rapidly -- _not_ a very laborious and slow opening/closing). For complicated reasons, nobody can be hidden anywhere near it (or in it), and we need to move it around to various positions while the effect is used (so it can't be physically attached to something rigid). I tried a system with aircraft cable through flexible metal tubing (sort of like a larger version of a bicycle brake cable) but there's way too much friction to make it practical. I would be interested in pretty much any ideas (be they electronic, pneumatic, mechanical) so long as they are safe and not overly pricy (I realize this may not be possible). Any hints about where to source the required items would be helpful, too.

And, before you ask, yes, we are keeping people out of harm's way.

Thanks!


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## RonHebbard (Dec 30, 2021)

jds10011 said:


> Looking for some creative ideas: We are trying to rig up an effect where a large-ish and moderately heavy trunk lid opens and shuts itself several times (and this happens pretty rapidly -- _not_ a very laborious and slow opening/closing). For complicated reasons, nobody can be hidden anywhere near it (or in it), and we need to move it around to various positions while the effect is used (so it can't be physically attached to something rigid). I tried a system with aircraft cable through flexible metal tubing (sort of like a larger version of a bicycle brake cable) but there's way too much friction to make it practical. I would be interested in pretty much any ideas (be they electronic, pneumatic, mechanical) so long as they are safe and not overly pricy (I realize this may not be possible). Any hints about where to source the required items would be helpful, too.
> 
> And, before you ask, yes, we are keeping people out of harm's way.
> 
> Thanks!


* @jds10011* A few queries and thoughts: 
Is the trunk used to contain anything? 
Do patrons see inside the trunk?? 
Do patrons see the rear of the trunk??? 
Is the hinged side up stage / Is the hinged side ever seen by patrons????

Could you use a lever on the up stage / hinged side to gain mechanical advantage and put less load on your enclosed aircraft cable????? 
Toodleoo! 
Ron Hebbard


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## egilson1 (Dec 30, 2021)

I think pneumatics is the way to go. Cylinder to an armature that opens the lid. Run a small hose to a large air tank/compressor. Valve in line. Should give you the speed you need.


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## Crisp image (Dec 31, 2021)

Depending on how creative you are. I have had good effect by using an electric car window winder via radio control. for full travel of the carriage is 2 or so seconds so if it was only half then a limit switch and some mechanical advantage and you might be set to go. 
Low voltage (12V or you could use a 16V battery and get a faster response) very easy to get hold of and with a little bit of electrical/electronic knowledge a simple system.

Regards
Geoff


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## soundman (Dec 31, 2021)

egilson1 said:


> I think pneumatics is the way to go. Cylinder to an armature that opens the lid. Run a small hose to a large air tank/compressor. Valve in line. Should give you the speed you need.


100% this. 

If you have an air source - a new piston (you'll want double acting), solenoid, fittings and mounting you could do this for under $100. Most of these components could be found at a junkyard too if you are into scrounging.


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## jtweigandt (Dec 31, 2021)

I have used hand held battery operated screwdriver opened up and rigged to a transformer wall wart. for various duties... A bolt epoxied in and bolted to a metal arm can work wonders. If you had some sort of sliding crank you can rig a lever arm to open and shut in one full rotation. Have run this arrangement controlled via dmx to open a "drop box" Also used it to power a long chopping axe on a crankshaft on the Dad's contraption in Beauty and the Beast. Hi torque little motors.. had several in storage with bad nicads so the cost was effectively zero. Pays to be a hardware hoarder sometimes


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## TimMc (Dec 31, 2021)

jtweigandt said:


> I have used hand held battery operated screwdriver opened up and rigged to a transformer wall wart. for various duties... A bolt epoxied in and bolted to a metal arm can work wonders. If you had some sort of sliding crank you can rig a lever arm to open and shut in one full rotation. Have run this arrangement controlled via dmx to open a "drop box" Also used it to power a long chopping axe on a crankshaft on the Dad's contraption in Beauty and the Beast. Hi torque little motors.. had several in storage with bad nicads so the cost was effectively zero. Pays to be a hardware hoarder sometimes


Spoken like a true props maker.


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## jtweigandt (Dec 31, 2021)

TimMc said:


> Spoken like a true props maker.


Thats why I adopted the title of Theatrical Howdowe "How do we...........?"


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## Crisp image (Dec 31, 2021)

jtweigandt said:


> Thats why I adopted the title of Theatrical Howdowe "How do we...........?"


I get most of my motors from old cars. Wipers and windows are great motors with gearing.


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## jds10011 (Dec 31, 2021)

soundman said:


> 100% this.
> 
> If you have an air source - a new piston (you'll want double acting), solenoid, fittings and mounting you could do this for under $100. Most of these components could be found at a junkyard too if you are into scrounging.


I tried with a single-acting piston I had just for a proof of concept. Definitely works, although of course then I must let the air out for it to close again -- very humorous at present. I don't know much about this area. I can certainly source a double-acting piston (e.g. from McMaster), but could use a little help with navigating what sort of solenoid setup to get. Ideally not every opening/closing would be identical, and perhaps we could even close partway and reopen from that position -- so any help in figuring out controls would also be very useful. Thanks!

Edit: Might I be better off with a manual valve like this one (McMaster 3368K24, linked below), rather than a solenoid setup, if we are ok being tied to operating from the location of the other end of the hose? (Or, would that not let me "pause" partway?)







McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.



www.mcmaster.com


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## soundman (Jan 1, 2022)

jds10011 said:


> Ideally not every opening/closing would be identical, and perhaps we could even close partway and reopen from that position -- so any help in figuring out controls would also be very useful. Thanks!
> 
> Edit: Might I be better off with a manual valve like this one (McMaster 3368K24, linked below), rather than a solenoid setup, if we are ok being tied to operating from the location of the other end of the hose? (Or, would that not let me "pause" partway?)
> 
> ...



That is not a device I have used before but judging by the spec sheet I think that would be a good way to achieve the effect. You could also restrict the flow of the exhaust to change the speed of motion, something to play around with and extra pneumatic parts are always handy to have around.


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## kicknargel (Jan 4, 2022)

Here's a couple sources for pneumatics:

https://www.automationdirect.com/adc/home/home



AllScare.com


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## Ted jones (Jan 5, 2022)

Also, take the exhaust thru a hose to a room or outdoors to keep the exhaust sound to a minimum. You can also buy or make an exhaust line muffler.

T


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## RC4Wireless (Jan 5, 2022)

RC4 Wireless dimmers are designed to handle all kinds of DC motors, including automotive motors.

I think I would use a DC-powered linear-actuator. You could set it up to run full length end to end, or use limit switches to set stop points in each direction. Use one dimmer for motor speed, another for a relay to reverse polarity and change motor direction. It's very simple, I'm happy to share a diagram with you of how to hook it up.


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## RonHebbard (Jan 5, 2022)

RC4Wireless said:


> RC4 Wireless dimmers are designed to handle all kinds of DC motors, including automotive motors.
> 
> I think I would use a DC-powered linear-actuator. You could set it up to run full length end to end, or use limit switches to set stop points in each direction. Use one dimmer for motor speed, another for a relay to reverse polarity and change motor direction. It's very simple, I'm happy to share a diagram with you of how to hook it up.


A lubricated length of all-thread rod + a freely travelling nut can equal a poor man's linear actuator and a pair of locked nuts at two points can equate to a poor man's fail-safe EOT limits. 
Toodleoo! 
Ron Hebbard


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## RC4Wireless (Jan 5, 2022)

RonHebbard said:


> A lubricated length of all-thread rod + a freely travelling nut can equal a poor man's linear actuator and a pair of locked nuts at two points can equate to a poor man's fail-safe EOT limits.
> Toodleoo!
> Ron Hebbard


Yes, absolutely -- this is, in essence, what's inside a commercial linear actuator.

One more thing that is tricky but doable is to file away the threads for a short section right before the 2 locked nuts for EOT. This lets the shaft spin freely without the drive nut jamming and binding against the locked nuts. It helps to also add a spring that helps catch the nut back on the threads when the shaft rotates in the other direction and needs to grab back onto the not.

All that mechanical complexity goes away, and adjustability is much easier, if you use limit switches. Common types of switches for this are microswitches, optical (beam-break), and magnetic (proximity to a magnet or to a ferrous metal pad). A simple microswitch on a springy arm to absorb small amounts of overrun is probably the easiest to undertstand and implement, and is very low cost.


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## Ted jones (Jan 5, 2022)

Agreed. If the visuals work, a linear actuator is a great machine. Better than hydraulics in the case.


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## RonHebbard (Jan 5, 2022)

Ted jones said:


> Agreed. If the visuals work, a linear actuator is a great machine. *Better than hydraulics* in this case.


And no hazardous accumulator to leak, mess up your floor, and cut your fingers off. 
Toodleoo! 
Ron Hebbard


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## Red_Carpet (Jan 6, 2022)

I can't help with the mechanics but I could offer this suggestion for the electronics.
Depending on how quick you need this operational you could get the following devices from AliExpress.com or ebay (I see you are from USA so your link will be ebay.com).
*Wireless DMX *could be a way to go. (So you can operate this from your control booth)
If you are not already using a DMX wireless transmitter device they are around 25 GBP and you just plug it at the end of one of your DMX cabling.
Even though your trunk needs to be transportable you will need to be having some sort of mains feed to it for your:-

Your pneumatic feed,
DMX Wireless receiver,
DMX Controller.
You could rig up the trigger to open-trunk and close-trunk with a DMX receiver control board/box.
This would project be easier if your pneumatic trigger requires a 12v supply (low amp) as you can buy these ready made.
The link is to a 12v trigger item you can by in the US if you are in a hurry -> [click here as @ Jan2022] ( Cheaper in AliExpress -> [click here as @ Jan2022] )
If the pneumatic trigger needs mains voltage than a small mains relay will fit the bill.
Hope this helps
_Red.
P.S. Just thought. I am presuming you are using a DMX lighting board, if not you can buy a v.simple version for approx 30GBP
P.P.S. Please excuse rubbishy graphics (I am sure Ron will let me off) :¬)_


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## almorton (Jan 6, 2022)

Using the RC4 solution suggested above with 12V linear actuators would work similarly, with the advantage that the RC4 connection tends to be reliable, even with mobile swash from phones, and they have high current controllers available to control the actuator, just need a relay controlled by one of the "dimmer" channels to reverse the feed to the actuator. Alternatively, a pair of low current dimmers with a high current H-bridge driver to reverse the actuator could work. All powered from easily sourced12V rechargeable sealed cells.


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## Ted jones (Jan 6, 2022)

RonHebbard said:


> And no hazardous accumulator to leak, mess up your floor, and cut your fingers off.
> Toodleoo!
> Ron Hebbard


Details! Details......


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## DBL (Jan 6, 2022)

jds10011 said:


> Looking for some creative ideas: We are trying to rig up an effect where a large-ish and moderately heavy trunk lid opens and shuts itself several times (and this happens pretty rapidly -- _not_ a very laborious and slow opening/closing). For complicated reasons, nobody can be hidden anywhere near it (or in it), and we need to move it around to various positions while the effect is used (so it can't be physically attached to something rigid). I tried a system with aircraft cable through flexible metal tubing (sort of like a larger version of a bicycle brake cable) but there's way too much friction to make it practical. I would be interested in pretty much any ideas (be they electronic, pneumatic, mechanical) so long as they are safe and not overly pricy (I realize this may not be possible). Any hints about where to source the required items would be helpful, too.
> 
> And, before you ask, yes, we are keeping people out of harm's way.
> 
> Thanks!


Look at frightprops.com. If fixed speed is ok, I'd use a pneumatic cylinder with a small CO2 tank (paintball tank?) hidden in the trunk.
Otherwise I'd look at a car window motor or a linear actuator (depending on weight and travel needed). RC4 products are excellent but you may not need that much control. There are some cheap on/off radio links available. Obviously you need to be sure no one can get hurt if the radio link malfunctions.


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## Jay Ashworth (Jan 6, 2022)

Ted jones said:


> Agreed. If the visuals work, a linear actuator is a great machine. Better than hydraulics in the case.


But put a circuit breaker in the drive wire in case it locks up.


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## almorton (Jan 7, 2022)

DBL said:


> RC4 products are excellent but you may not need that much control. There are some cheap on/off radio links available. Obviously you need to be sure no one can get hurt if the radio link malfunctions.


You may not need the control, but you _do_ want a reliable link, which is why, if I have a choice, I go with RC4 (or City Theatrical? I have friends who use them all the time, again, for reliability) as they are proven products, whereas the cheaper stuff _can_ get swamped by cell phone mush, radio mics, you name it. It's part of a risk assessment, of course.


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## RC4Wireless (Jan 12, 2022)

almorton said:


> Using the RC4 solution suggested above with 12V linear actuators would work similarly, with the advantage that the RC4 connection tends to be reliable, even with mobile swash from phones, and they have high current controllers available to control the actuator, just need a relay controlled by one of the "dimmer" channels to reverse the feed to the actuator. Alternatively, a pair of low current dimmers with a high current H-bridge driver to reverse the actuator could work. All powered from easily sourced12V rechargeable sealed cells.


A few years back we offered an RC4 receiver/driver with an H-Bridge built-in. It would have been perfect for this -- directly connect and go, set up and running in seconds, everything you need in one little unit. Unfortunately, we didn't get enough interest in that product to keep it in production. If having this kind of thing interests anyone, be sure to let people like me know. I'd love to see enough interest to put a wireless H-Bridge back into production.

Jim
RC4


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## RonHebbard (Jan 30, 2022)

jds10011 said:


> Looking for some creative ideas: We are trying to rig up an effect where a large-ish and moderately heavy trunk lid opens and shuts itself several times (and this happens pretty rapidly -- _not_ a very laborious and slow opening/closing). For complicated reasons, nobody can be hidden anywhere near it (or in it), and we need to move it around to various positions while the effect is used (so it can't be physically attached to something rigid). I tried a system with aircraft cable through flexible metal tubing (sort of like a larger version of a bicycle brake cable) but there's way too much friction to make it practical. I would be interested in pretty much any ideas (be they electronic, pneumatic, mechanical) so long as they are safe and not overly pricy (I realize this may not be possible). Any hints about where to source the required items would be helpful, too.
> 
> And, before you ask, yes, we are keeping people out of harm's way.
> 
> Thanks!


* @jds10011* How did you eventually achieve your goal and were you and yours happy with it? 
Toodleoo! 
Ron Hebbard


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