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Hot Topic (More than 10 Replies) DT (Read 11312 times)
Z-man
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Re: DT
Reply #15 - Sep 24th, 2020 at 1:45pm
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I've been curious about how to make a mechanical DT and will revive and old thread to share what I have found.

I was browsing YouTube and found an interesting video on this: https://www.youtube.com/watch?v=6Pv1CLggmVk&ab_channel=SDGG2

When I got looking further I found that the mechanical timer is light and relatively cheap (~$9.00). It appears (based on the video) that it can be modified with a simple shaft inserted in the gear...

The following are links to suppliers I have found:
https://www.acecontrols.com/us/products/motion-control/rotary-dampers/frt-c2-and...
https://www.grainger.com/search?searchQuery=FRT+C2+301+G1&s_kwcid=AL!2966!10!794...

I'm going to get some of these and experiment with them, and maybe others will find these useful, too.

Cheers!
Scott Z

  

( 76 KB | 6 Downloads )
Mechanical_DT_part.jpg

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bigrip74
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Re: DT
Reply #14 - Oct 15th, 2016 at 9:21pm
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Wow! Lots of knowledgeable people here, I may be able to build one of the silly putty DT with all of the diagrams.
  

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Sky9pilot
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Re: DT
Reply #13 - Oct 15th, 2016 at 8:08pm
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Here's a link to some DT's and how to make them on the RCGroups site: Click Here

Here's another link to our Articles section that has articles on Silly Putty Dethermalizers and "how to" build them.
Click Here
Tom
  

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terryman
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Re: DT
Reply #12 - Oct 15th, 2016 at 7:24pm
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Here is a document on building a Silly Putty dethermalizer.  I built one, it worked.  Also some discussion of one here:

http://www.stickandtissue.com/cgi-bin/yabb2/YaBB.pl?num=1443749404/55

Read several replies before and after.

If I were to make another I would use a Tommy Timer instead.

Terry
  

DethermalizerTube.pdf ( 291 KB | 22 Downloads )
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pb_guy
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Re: DT
Reply #11 - Oct 15th, 2016 at 10:25am
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I think that the way of the future is electronic dethermalizers. There are already some on the market. The problem is not weight, but price.
see: http://www.hippocketaeronautics.com/hpa_forum/index.php?topic=20894.0
ian
  
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bigrip74
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Re: DT
Reply #10 - Oct 15th, 2016 at 8:18am
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balsafliesbetter wrote on Oct 15th, 2016 at 2:24am:
Breathing life into this 5yo thread.
I am completely new to ff and would love to see/read more details about dt. Especially the silly putty idea.


"DITTO"

I also would like to see this re: silly putty. I have a formula to make home made silly putty.

Bob
  

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balsafliesbetter
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Re: DT
Reply #9 - Oct 15th, 2016 at 2:24am
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Breathing life into this 5yo thread.
I am completely new to ff and would love to see/read more details about dt. Especially the silly putty idea.
  

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DickA
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Re: DT
Reply #8 - Dec 14th, 2011 at 10:53am
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Thanks for the demo and explanations.  Have a basic question... where do you get the fuse? Huh
DickA
  
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thymekiller
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Re: DT
Reply #7 - Jul 21st, 2011 at 5:52am
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Thank you Ziess.  I hope to have time this weekend to chase those links and a couple others. 
Thanks.
  

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Zeiss Ikon
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Re: DT
Reply #6 - Jul 20th, 2011 at 7:46pm
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Thyme, the Silly Putty does "grease" the tube in tube, but because of the extremely high viscosity, it acts as more of a damper than a lubricant.  If you've never played with the stuff, by all means find the nearest toy or craft store and get an egg -- be sure to get the "original", not any of the kinds that glow or glitter; the stuff inside the egg should be pinkish, almost the color of a "flesh" Crayola.

Here's the build sequence for my first Silly Putty timer.  Here's a link to the improvements I made in the second one.
  
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thymekiller
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Re: DT
Reply #5 - Jul 18th, 2011 at 9:06pm
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Was digging thu old threads and found this link from Papa. 

http://www.vintagemodelairplane.com/pages/Downloads/CRB_Tasters/SillyPutty01.htm...
  

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thymekiller
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Re: DT
Reply #4 - Jul 18th, 2011 at 8:34pm
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Did a vid of my fuse type dt.  There are many refinements that can be added. 

The snuffer tube is also the rear peg.

http://www.youtube.com/watch?v=i_4MA1YKnro

Ziess, I am aware of how a shock absorber works and I am trying to translate that to a circle motion [instead of straight in and out] and I am having trouble with it.   In my limited mind i can only see a tube in a tube and the silly putty would only serve to grease it.   Also of note here is that I have never played with silly putty in my life.  Maybe I should get some. 
If you wouldn't mind, a build sequence would be fantastic or maybe a link.  Sorry to bother you with this.  This is the first time for me and I am lost.   One of the things I enjoy most about this hobby is that there is always another corner to go around.
  

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Zeiss Ikon
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Re: DT
Reply #3 - Jul 18th, 2011 at 3:46pm
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A Silly Putty timer consists of Silly Putty inside a tube, with either a perforated tube or (tiny) paddle on a wire embedded in the Putty (there are more details to it than that; I can post a construction photo sequence if needed); the inner wire or tube is rotated by a string wrapped around, which is driven by a spring (like the rotary damper video you linked) or elastic.  The damping effect of the Silly Putty on the perfed tube or paddle causes the tension to rotate the core very slowly -- my last one does about two minutes for 135º of rotation, driven by a single office type rubber band stretched about double length.

The rest of the setup is the same you'd have with the rotary damper -- some way to let the tension on the drive line hold a flying surface in place, then release it promptly when the tension loop slips off the drive arm, producing the same effect you'd get with a fuse burning through a thin rubber band.

The advantage of Silly Putty over commercial dampers is price -- I spent about $10 on tubing and an egg of putty, added some super glue and bamboo skewers I had around, and have everything I need to make a dozen or more timers; that's less than 1/3 the price of the commercial dampers, and my timers can be customized -- make the tube longer, you get more damping, and the timer runs slower on a given tension.  I could easily make a Silly Putty timer that would run five minutes or more for a 270º rotation, still with a tensioner strong enough to lock a pretty robust DT mechanism...
  
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thymekiller
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Re: DT
Reply #2 - Jul 18th, 2011 at 6:12am
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Any chance you could explain how a silly putty timer works?  I don't have enough details to explain correctly. 
Tonight, I will vid mine in action.
  

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Zeiss Ikon
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Re: DT
Reply #1 - Jul 18th, 2011 at 5:00am
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Yep, it's a commercially made equivalent of a Silly Putty timer.
  
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