Yes, I think a heat sink would probably help. I would use needle nose pliers
tightly gripped to the terminal right where it enters the switch body. The
idea being to prevent heat conducted into the internals of the switch.
However, it would probably require three hands to hold the soldering iron, the
solder and the pliers. Some sort of locking needle nose pliers like “micro
vise grips” or perhaps medical forceps might work better with two hands.
Vern Knowles
From: roc-chat-bounce@xxxxxxxxxxxxx [mailto:roc-chat-bounce@xxxxxxxxxxxxx] On ;
Behalf Of John Coker
Sent: Thursday, January 19, 2017 11:27 AM
To: roc-chat@xxxxxxxxxxxxx
Subject: [roc-chat] Re: Switch Warning - Schurter 110-220
Interesting observation. Many of us who are not hardware people by trade could
probably use a good primer on soldering.
Would it help to use an aluminum heat sink between the switch body and the end
of the pin? (There's not very much room, but one might be able to fit a small
heat sink in there.)
I like these switches too, so I'd like to understand the cause of the failures
people have experienced.
John
On Thu, Jan 19, 2017 at 9:56 AM, Vern Knowles <knowles.vern@xxxxxxxxx> wrote:
I have used many Schurter switches over the years and not had any issues. I
am wondering if maybe the problems some people have had with them is related to
soldering. I just did a quick test and discovered that the surface finish on
the internal switch contacts does change visibly if a terminal is heated to
soldering temperature for more than a few seconds. With the soldering iron I
used, a couple seconds is okay but at about 4-5 seconds there was enough heat
conducted into the switch to change the contact surface finish. I have no
proof the change in surface finish is detrimental to the operation of the
switch but frankly, under the microscope, it does look somewhat “degraded”.
The finish is not as nice and smooth. It would not surprise me if the number
of reliable switching cycles is significantly reduced by this but I have not
tested it. (By the way, the switch is very easy to take apart for inspection.
Just squeeze together the two plastic posts sticking out the bottom. It is
also very easy to re-assemble. Just push it back together.)
It would be easy for someone to do some testing to see if this is a problem.
(hint, hint!).
Vern Knowles
www.multitronix.com
From: roc-chat-bounce@xxxxxxxxxxxxx [mailto:roc-chat-bounce@xxxxxxxxxxxxx] On ;
Behalf Of R Dierking
Sent: Wednesday, January 18, 2017 7:35 PM
To: kurtgug@xxxxxxxxx; roc-chat@xxxxxxxxxxxxx
Subject: [roc-chat] Re: Switch Warning - Schurter 110-220
I think the 3D printed switch arrangement that Mike brought to the meeting is
better. So are the screw-type Aerocon switches, and the one that holds the PCB
switch that someone posted. I’m doing this mostly for people that have the
110-220 switches already in their rockets. Also, of course, I’m looking for a
reassurance for the switches I’m using in my L3 project.
I’ll definitely take the test switch apart after the testing concludes. I’m
not sure what number of cycles to stop, but I’m thinking about dropping the
test box on the garage floor every 100 cycles after 500. Really give the
switch a shock to see what happens.
I’ll be taking one of the new switches apart too. I want to see if I can pot
one of the Aerocon PCB switches inside the 110-220 switch case. So, retrofit
with no re-wiring.
From: kurtgug@xxxxxxxxx
Sent: Wednesday, January 18, 2017 5:27 PM
To: roc-chat@xxxxxxxxxxxxx
Subject: [roc-chat] Re: Switch Warning - Schurter 110-220
Hey Richard. Great work you are doing there. You should also dissect the
switch at the end of the testing to see if you can see any wear and tear on the
housing or the contacts.
I'm also interested in making a switch like what Kramer came up with, a micro
switch and screw. That could also be a viable solution.
Kurt
Sent from my iPad
On Jan 18, 2017, at 2:37 PM, R Dierking <applerocketry@xxxxxxxxxxx> wrote:
After the group of posts on this switch and other types used to arm
electronics, I wanted to run a simple test. Maybe to provide some reassurance
to people that already have this switch installed for their project. On the
other hand, there’s no way I can guarantee a favorable result.
There were a couple of concerns voiced during the last thread for the 110-220
selector switch. One was the lifetime specified in the manufacturer’s
documentation: 300 operating cycles (without load). The other was reports of
failures including high resistance, unreliable connection, and switches
actually cracking during use.
I believe that at least some failures could be attributed to installing what is
intended to be a flat panel mounted switch on curved airframe tube. I’m
thinking that some switches are being over-tightened creating stress on the
rotatory selector.
Please see the attached photos.
Installation:
The hole for these switches is not ½”, but it is close. The manufacturer’s
dimensions for installation are metric. If you just drill a ½” hole, the hole
will probably be too large to use the small protrusion that should be used to
prevent the switch from rotating. Please see the arrow on the first photo.
The switch doesn’t have to be tightened much at all on the mounting panel.
Unfortunately, I’ve never seen any documentation on installation when you buy
them. Anyway, you should drill a smaller hole, and gradually increase the size
until the treads just clear. Also, the notch needs to be filed for the small
projection to prevent rotation.
Durability:
To test the lifetime, I installed a new switch that powers a small light bulb
(9 volt battery for power) and also has posts to check the voltage. I’m
keeping track of how many times I cycle this switch on-off. I’m occasionally
operating the switch 10 times when I go out into the garage. I observe the
light for intermittent connection, occasionally tap the test box, and jog the
selector. So far, I’m at 80 cycles. Again, looking for any problems. I’m
keeping the box on my clothes dryer because it vibrates when operating, and
even the temperature varies. This morning it was 45 F in my garage, and after
operating the dryer for a couple loads of laundry, the test box was 80 F.
So, we’ll see how many cycles I get from this switch. Please keep in mind that
this simple test is not designed to check mean time between failure (MTBF)
because those tests are a lot more involved.
Questions and comments are appreciated.
Richard Dierking
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