Actuator Project with Solanoid latch - :)

Discussion in 'The Projects Forum' started by Leckyuk, Mar 28, 2013.

  1. Leckyuk

    Thread Starter New Member

    Jan 1, 2011
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    I'm wondering if someone could help me out with my current project? It's a simple threaded bar attached to a 12v motor with a bearing on the opposing end that will have a Nut welded to some box section in the middle which will be on runners. I bassically need a two way rocker switch to initially activate the solanoid to release the latch and then after a time delay of around 5 seconds, the motor to start turning to move the middle bar. Once the bar reaches the furthest distance It should travel i want it to hit a microswitch to disconnect the circuit. It's a bit of a crude way doing it but i think it will work. Ive put the solanoid latch on a seperate circuit via a relay to try to keep everything seperate. Any feedback would be great, will this work? PS I haven't even looked at polarities yet :D just wanted to get what was in my head on paper and get some advice. Cheers all.
     
    Last edited: Mar 28, 2013
  2. Leckyuk

    Thread Starter New Member

    Jan 1, 2011
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    Has anyone had a chance to take a look at this?

    I'm pretty stuck ha ha! I don't want to start buying parts if it 's not going to work. Many thanks.
     
  3. bance

    Member

    Aug 11, 2012
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    What is this for? Looks a bit like the x-axis of a CNC machine, I don't really understand what purpose the solenoid serves, maybe a little more information would help.

    HTH Steve
     
  4. Leckyuk

    Thread Starter New Member

    Jan 1, 2011
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    Hi Steve,

    Thanks for the reply. This is a device for a fold up / Rock and roll bed. I've attached a very rough image for you which gives it a bit of life anyway. It will be fitted in a Campervan so the solenoid latches will basically hold the two section together quite strongly. where the solonoids are there would normally be a manual catch so i want the whole operation to be automated. It will just be a nice touch seeing the Seat turn in to a bed without having to do it manually.

    Thanks again.
     
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  5. Leckyuk

    Thread Starter New Member

    Jan 1, 2011
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    Oh and just to correct my mistake, the solenoid latch will be attached to the stationary frame, not the moveable section as the will only be required when the unit is in the seated position, therefore not having to move.
     
  6. bance

    Member

    Aug 11, 2012
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    Wow !!! what a lousy drawing.:p

    I had to look-up rock and roll bed .... But I think I know what you mean now.

    Yes I suppose that would work, some things to think about...

    I think a pull type solenoid is better for this application, it will only consume power for a few moments to release the seat section. The rest of the time, while in the lock position, no juice required.

    You will have to think carefully about the motor and how it drives the screw rail, you will need enough torque to move the mass involved as well as overcoming friction etc. But it also needs to be not too fast, think gearing etc.

    Maybe think about how the mechanics of how the seat moves...

    Try to do some (more technical) drawings or sketches to get things clear before you start, it's much easier to change things with a rubber!!!

    HTH Steve
     
  7. shortbus

    AAC Fanatic!

    Sep 30, 2009
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  8. Leckyuk

    Thread Starter New Member

    Jan 1, 2011
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    Thanks guys, if I'm honest the drawings are about as technical as it gets ha! As for the solenoid, it is a pull one! It will only draw power when the relay is latched. The seat is on ball bearing runners so it is literally as simple as opening a draw. It requires absolutely no force to open and close. The mechanical side of this project I am fine with, I have 2 motors in mind that are geared nearly perfectly for the job. The bit I'm not ok with is the circuitry. My first idea was to use two motors, one at each end of the threaded bar so I could keep the two circuits completely separate. I thought this might be overkill and that there must just be a simple way if running two independant circuits in to the same motor (with opposite polarities on each circuit)! My idea is that when the switch is turned to "open" the positive circuit turns the motor one way, thus opening the bed until the frame hits the micro switch and breaks the circuit, and releases the solenoid also. The negative circuit is still active as its micro switch is on, the switches then flicked to "close" which turns the motor the opposite way until again it hits the micro switch and kills the circuit and drops the solenoid in to the latch hole! I just really need some advice if my theory should work. I don't want the circuitry to be off and just start shorting out!!
     
  9. shortbus

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  10. Leckyuk

    Thread Starter New Member

    Jan 1, 2011
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    That is absolutely amazing :) I was hoping to build the circuitry myself but I just don't think I have the skills to do it, I just don't understand the components If im honest! The remote control unit looks fabulous for what I need. The only problem is they are only available in the US. I might just take a punt and get one shipped. How do I go about getting the solenoid latch in to this circuit though?
     
  11. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Limit switches usually have two sets of contacts in them, normally closed(NC) and normally open (NO). When the seat is at the upper limit the NC contacts open and shut off the solenoid and it drops in place.

    But if you use a screw for an activator, why do you need a solenoid? The mechanical advantage, of the screw, will keep the seat in what ever position it stops in.
     
  12. Leckyuk

    Thread Starter New Member

    Jan 1, 2011
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    I want the solenoid because of the seat going in a van. The force of people sitting on it and the vehicle breaking and accelerating will put unecessary pressure on the assembly. Especially as I intend to fabricate an Acetal nut which I don't want to be stripped. The latch will prevent this. Do you think this is wise or is it just overkill?
     
  13. shortbus

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    To me, over kill. The weight of a person will be against the seat back keeping it in place. Unless I'm not understanding the design. Plus like I said before the nut and screw will keep it from moving. If you mean by Acetal, what is known in the US as Delrin, there isn't a much stronger plastic for some thing like this.
     
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