Go to Post Forum Anonymity = Rampant Exaggeration, if not outright Blatant Lying. - dsm [more]
Home
Go Back   Chief Delphi > Technical > Electrical
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Closed Thread
Thread Tools Rate Thread Display Modes
  #1   Spotlight this post!  
Unread 27-03-2011, 08:32
Foster Foster is offline
Engineering Program Management
VRC #8081 (STEMRobotics)
Team Role: Mentor
 
Join Date: Jul 2007
Rookie Year: 2005
Location: Delaware
Posts: 1,394
Foster has a reputation beyond reputeFoster has a reputation beyond reputeFoster has a reputation beyond reputeFoster has a reputation beyond reputeFoster has a reputation beyond reputeFoster has a reputation beyond reputeFoster has a reputation beyond reputeFoster has a reputation beyond reputeFoster has a reputation beyond reputeFoster has a reputation beyond reputeFoster has a reputation beyond repute
Cable to switch covering - use RTV or something else?

I have a project that part of it is a double pole double throw switch. The connections go into a covered cable (CAT5) and then to a molded on connector. Wires are soldered onto the switch. Once assembled there is no need to get to the connections again.

I'm looking for ideas on how to close up the back of the switch and protect the pins. In the prototypes I used Silicon RTV to cover the 1/4" high pins. I bend the cable down so it comes out the end of the switch. RTV between the switch and cable to hold it down, and then more RTV to cover the pins. Due to my amazing lack of eye / hand coordination the RTV has bumps and swirls in it.

I need to create ~50 of these switch / cable combinations. I'm looking for something easy and simple to do that looks reasonably nice.

Switches are 1 1/4" by 1/2" and are slide switches. They do not have mounting holes on them so a case or a box adds a new layer of problems.

I thought of trying to use small icecube trays as a form, but I'm not sure that the RTV will pop out of them.

Thanks for your ideas!
__________________
Foster - VEX Delaware - 17 teams -- Chief Roboteer STEMRobotics.org
2010 - Mentor of the Year - VEX Clean Sweep World Championship
2006-2016, a decade of doing VEX, time really flies while having fun
Downingtown Area Robotics Web site and VEXMen Team Site come see what we can do for you.
  #2   Spotlight this post!  
Unread 27-03-2011, 15:06
RyanCahoon's Avatar
RyanCahoon RyanCahoon is offline
Disassembling my prior presumptions
FRC #0766 (M-A Bears)
Team Role: Engineer
 
Join Date: Dec 2007
Rookie Year: 2007
Location: Mountain View
Posts: 689
RyanCahoon has a reputation beyond reputeRyanCahoon has a reputation beyond reputeRyanCahoon has a reputation beyond reputeRyanCahoon has a reputation beyond reputeRyanCahoon has a reputation beyond reputeRyanCahoon has a reputation beyond reputeRyanCahoon has a reputation beyond reputeRyanCahoon has a reputation beyond reputeRyanCahoon has a reputation beyond reputeRyanCahoon has a reputation beyond reputeRyanCahoon has a reputation beyond repute
Re: Cable to switch covering - use RTV or something else?

Would heat shrink tubing work?
__________________
FRC 2046, 2007-2008, Student member
FRC 1708, 2009-2012, College mentor; 2013-2014, Mentor
FRC 766, 2015-, Mentor
  #3   Spotlight this post!  
Unread 27-03-2011, 15:49
DonRotolo's Avatar
DonRotolo DonRotolo is offline
Back to humble
FRC #0832
Team Role: Mentor
 
Join Date: Jan 2005
Rookie Year: 2005
Location: Atlanta GA
Posts: 7,019
DonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond reputeDonRotolo has a reputation beyond repute
Re: Cable to switch covering - use RTV or something else?

Normally I'd say hot-melt glue, but 50 of them?

If an ice-cube tray size is not too large, then you can use any of several substances, first choice in my mind would be liquid epoxy potting compound, just pour and wait. The downside is that it's difficult to remove if repairs are ever needed.

To have any substance release easily from an ice-cube mold, use silicone spray liberally. This is how it is done in industry. An alternative would be to get a flexible silicone ice-cube tray so it can be peeled off instead (but still use the release spray!)

Silicone "caulk" is not an ideal substance. As part of the curing process it releases acetic acid (vinegar), which attacks electrical connections. In electronics, it is used only as a mechanical connector to hold heavy components in place on a PC Board, and should never come in contact with metal connections. You CAN buy silicone potting compound which uses a different chemistry and is safe for electronics, but it isn't cheap.

If you do use epoxy, consider a custom mold that creates mounting ears for your switch, or some other mechanical features that will improve the device. Molds can be made from hard plastic (polyethelyene), metal, or even machinable wax (Google it, I use Freeman Supply for mine).

Good luck!
__________________

I am N2IRZ - What's your callsign?
  #4   Spotlight this post!  
Unread 27-03-2011, 15:57
Mr V's Avatar
Mr V Mr V is online now
FIRST Senior Mentor Washington
FRC #5588 (Reign)
Team Role: Coach
 
Join Date: Feb 2011
Rookie Year: 2009
Location: Maple Valley Wa
Posts: 997
Mr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond reputeMr V has a reputation beyond repute
Re: Cable to switch covering - use RTV or something else?

RTV is not a good idea to insulate electrical components, most formulations are corrosive to copper. If you do want to try an RTV make sure you find something that won't cause corrosion and if you do I think the ice cube tray would be perfect. All the automotive formulations pop right out of the supplied extension tube when allowed to properly cure.

Another option to look into is the silicone used to make castings, don't know if it will cause issues with corrosion or not. But it is designed to work with a release agent coating the part being replicated. I don't see a reason the release agent couldn't be applied to the ice cube tray.

The last option I can think of is to use a rubber based potting compound designed for circuit boards that will be located in high moisture environments.
  #5   Spotlight this post!  
Unread 27-03-2011, 16:51
Gene F's Avatar
Gene F Gene F is offline
FIRST Fanatic
AKA: Gene Falendysz
#0343 (Metal in Motion)
Team Role: Engineer
 
Join Date: Mar 2002
Rookie Year: 2001
Location: Oconee County, SC
Posts: 218
Gene F is a splendid one to beholdGene F is a splendid one to beholdGene F is a splendid one to beholdGene F is a splendid one to beholdGene F is a splendid one to beholdGene F is a splendid one to beholdGene F is a splendid one to beholdGene F is a splendid one to behold
Send a message via AIM to Gene F
Re: Cable to switch covering - use RTV or something else?

How about epoxy putty?
__________________
- Gene Falendysz
Closed Thread


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 19:03.

The Chief Delphi Forums are sponsored by Innovation First International, Inc.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi