Answers.Body: <p>Ok, I have managed to build a working cam mechanism using LEGO Technic. Only thing missing is a big enough spring or elastic band to pull the entire assembly upwards - Still thinking through that part but sharing in the hopes that others can take my idea further (My current best thought is to have rubber bands on the outside of the mechanism pulling the "clicker" upwards.). Here is a demonstration of the mechanism at work (was difficult to demonstrate with just one hand as I haven't lined the walls of the vertical holder enough and sometimes the up/down motion goes under an angle): <a href="https://www.youtube.com/watch?v=7YUYSS7IRXY" rel="nofollow noreferrer">video on youtube</a>.</p>
  
  
  
  <p>Pictures:</p>
  
  <p>The entire mechanism:
  <img src="https://i.sstatic.net/Yriy8.jpg" alt="The entire mechanism"></p>
  
  <p>Clicker in the "up" position (i.e. retracted pen):
  <img src="https://i.sstatic.net/nMJEh.jpg" alt="Clicker up"></p>
  
  <p>Clicker in the "down" position (i.e. pen out) - my hand is in the picture as there is no spring to provide pressure upwards:
  <img src="https://i.sstatic.net/bImZO.jpg" alt="Clicker down"></p>
  
  <p>The insert with the loop (I believe this is what is called a "cam"). There is a resting point on the top (the "down" position) as well as a resting point on the bottom (the "up" position):
  <img src="https://i.sstatic.net/OqPhX.jpg" alt="Cam inside"></p>
  
  <p>The "ball" - in this case a simple Technic axle with 2 1/2-width bushings on it - is supported in this mechanism, which allows the black part to slide freely from left to right. This "ball" moves around the loop defined by the "cam" from the previous picture:
  <img src="https://i.sstatic.net/MCkle.jpg" alt="The &quot;ball&quot;"></p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2015-01-13T13:48:05.890Z
Answers.Text: This is impressive. Thanks. I was hoping for something smaller and with fewer pieces, but this is definitely an example of a working mechanism.
Answers.UserDisplayName: Jason Swett
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2015-01-09T04:02:26.913Z
Answers.LastActivityDate: 2015-01-09T14:29:29.280Z
Answers.LastEditDate: 2015-01-09T14:29:29.280Z
Answers.UserDisplayName: Phil B.
Answers.Body: <p>What you can do is use an old-style spring loaded missile, the rubber tip is soft enough to let you trigger the launcher without putting the missile back in, and you don't need to trigger the launcher to lock the missile.</p>
  
  <p><img src="https://i.sstatic.net/XPt7n.jpg" alt="enter image description here"></p>
  
  <p><img src="https://i.sstatic.net/xkLEJ.jpg" alt="enter image description here"></p>
  
  <p>I you press the flat bar at the top it works about 90% of the time.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2015-01-02T15:29:43.750Z
Answers.Text: Thanks for the response, but it seems like a solution should be possible without special parts (I don't own this missile part) and it seems like a solution should be possible that works 100% of the time.
Answers.UserDisplayName: Jason Swett
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2015-01-02T18:04:35.937Z
Answers.Text: Fair enough.  I'll have another think.
Answers.UserDisplayName: Windfire
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2015-01-02T11:55:41.863Z
Answers.LastActivityDate: 2015-01-02T11:55:41.863Z
Answers.UserDisplayName: Windfire
Body: <p>For no particular good reason, I think it would be interesting to build a Lego button that behaves somewhat like the button on a click pen: as you press it, it alternates between a "down" state and an "up" state.</p>
  
  <p>I've researched how pen buttons work and done a fair amount of Googling. I've experimented on my own. I haven't yet been able to figure out how to build such a thing. It's surely possible. Any advice?</p>
  
  <p><strong>Edit</strong>: OR I'd accept, as a solution, the official (Googlable) name for such a mechanism. If I can find a number of examples online I assume I can figure out the Lego version myself.</p>
  
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2015-01-02T16:36:25.440Z
Comments.Text: The Lego trains have something like 
  [this](http://lego.brickinstructions.com/07000/7939/053.jpg). It's not a solution for your problem yet though, as the actual "clicking on/off functionality is in the battery holder brick.
Comments.UserDisplayName: S.L. Barth is on codidact.com
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2015-01-02T18:17:24.613Z
Comments.Text: And I think the cycling happens electronically as opposed to mechanically since, at least on my train motor, the button always returns to the "undepressed" state.
Comments.UserDisplayName: Jason Swett
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2015-01-08T16:35:56.340Z
Comments.Text: The technical name for what you're looking for is a *latched push button*.  You might try *latching* instead of *latched*, and you might try *switch* instead of *push button*, but *switch* will also give you a lot of toggle switch results, which isn't what you want.
Comments.UserDisplayName: Nick2253
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2015-01-08T16:38:45.390Z
Comments.Text: If you are referring more specifically to the pen mechanism, you are looking for a *bistable cam system*.  You can, of course, also search for *pen mechanism*, which gave me lots of pretty pictures from Google.
Comments.UserDisplayName: Nick2253
Tags: <mechanical>
Title: Two-state clicker button
UserDisplayName: Jason Swett
ThreadText: # Two-state clicker button
  
  (Asked by: username_0 on 2015-01-01)
  
  For no particular good reason, I think it would be interesting to build a Lego button that behaves somewhat like the button on a click pen: as you press it, it alternates between a "down" state and an "up" state.
  
  I've researched how pen buttons work and done a fair amount of Googling. I've experimented on my own. I haven't yet been able to figure out how to build such a thing. It's surely possible. Any advice?
  
  **Edit**: OR I'd accept, as a solution, the official (Googlable) name for such a mechanism. If I can find a number of examples online I assume I can figure out the Lego version myself.
  
  **Tags:** mechanical
  
  > **Comments:**
  > **username_1**: The Lego trains have something like  [this](http://lego.brickinstructions.com/07000/7939/053.jpg). It's not a solution for your problem yet though, as the actual "clicking on/off functionality is in the battery holder brick.  
  > **username_0**: And I think the cycling happens electronically as opposed to mechanically since, at least on my train motor, the button always returns to the "undepressed" state.  
  > **username_2**: The technical name for what you're looking for is a *latched push button*.  You might try *latching* instead of *latched*, and you might try *switch* instead of *push button*, but *switch* will also give you a lot of toggle switch results, which isn't what you want.  
  > **username_2**: If you are referring more specifically to the pen mechanism, you are looking for a *bistable cam system*.  You can, of course, also search for *pen mechanism*, which gave me lots of pretty pictures from Google.  
  
  ---
  
  ## 2 answers
  
  ### Answer by username_3 on 2015-01-09. Score: 3 | Accepted answer
  
  Ok, I have managed to build a working cam mechanism using LEGO Technic. Only thing missing is a big enough spring or elastic band to pull the entire assembly upwards - Still thinking through that part but sharing in the hopes that others can take my idea further (My current best thought is to have rubber bands on the outside of the mechanism pulling the "clicker" upwards.). Here is a demonstration of the mechanism at work (was difficult to demonstrate with just one hand as I haven't lined the walls of the vertical holder enough and sometimes the up/down motion goes under an angle): [video on youtube](https://www.youtube.com/watch?v=7YUYSS7IRXY).
  
  Pictures:
  
  The entire mechanism:
  ![The entire mechanism](https://i.sstatic.net/Yriy8.jpg)
  
  Clicker in the "up" position (i.e. retracted pen):
  ![Clicker up](https://i.sstatic.net/nMJEh.jpg)
  
  Clicker in the "down" position (i.e. pen out) - my hand is in the picture as there is no spring to provide pressure upwards:
  ![Clicker down](https://i.sstatic.net/bImZO.jpg)
  
  The insert with the loop (I believe this is what is called a "cam"). There is a resting point on the top (the "down" position) as well as a resting point on the bottom (the "up" position):
  ![Cam inside](https://i.sstatic.net/OqPhX.jpg)
  
  The "ball" - in this case a simple Technic axle with 2 1/2-width bushings on it - is supported in this mechanism, which allows the black part to slide freely from left to right. This "ball" moves around the loop defined by the "cam" from the previous picture:
  ![The "ball"](https://i.sstatic.net/MCkle.jpg)
  
  > **Comments:**
  > **username_0**: This is impressive. Thanks. I was hoping for something smaller and with fewer pieces, but this is definitely an example of a working mechanism.  
  
  ---
  
  ### Answer by username_4 on 2015-01-02. Score: 2
  
  What you can do is use an old-style spring loaded missile, the rubber tip is soft enough to let you trigger the launcher without putting the missile back in, and you don't need to trigger the launcher to lock the missile.
  
  ![enter image description here](https://i.sstatic.net/XPt7n.jpg)
  
  ![enter image description here](https://i.sstatic.net/xkLEJ.jpg)
  
  I you press the flat bar at the top it works about 90% of the time.
  
  > **Comments:**
  > **username_0**: Thanks for the response, but it seems like a solution should be possible without special parts (I don't own this missile part) and it seems like a solution should be possible that works 100% of the time.  
  > **username_4**: Fair enough.  I'll have another think.  
  
  ---
  
  