Is it possible to install a longer screw and then mangle the first couple
threads on the tip of it so that it cannot back out?
Vern
From: roc-chat-bounce@xxxxxxxxxxxxx [mailto:roc-chat-bounce@xxxxxxxxxxxxx] On ;
Behalf Of Kurt Gugisberg
Sent: Friday, January 20, 2017 1:39 PM
To: roc-chat@xxxxxxxxxxxxx
Subject: [roc-chat] Re: Switch Warning - Schurter 110-220
I think I will get one a little longer. They are 3/16" now and I will get the
1/4". The head needs to make electrical contact with the circuit board below
it so putting anything under the head won't work. I have put something against
the screw from the outside to hold it from moving. Maybe even leave the screw
out completely and install it just prior to launch.
On Fri, Jan 20, 2017 at 11:07 AM, Alexander Jones <uscjones@xxxxxxxxx> wrote:
Maybe get the screw a little longer than the stock one, then put some kind of
tensioner underneath it, like a small spring, a rubber washer, or a little
section of small-diameter silicone hose? Try fuel tubing for nitro RC cars and
planes from the hobby shop. It'll add just enough friction to the screw to
keep if from loosening itself when it's in the "off" position, but still allows
the screw to be tightened down to make the connection...kinda similar to how
they do adjustment screws on some carburetors.
On Fri, Jan 20, 2017 at 10:45 AM, Kurt Gugisberg <kurtgug@xxxxxxxxx> wrote:
One warning about the Featherweight screw switch. I installed one in an e-bay
and this morning I picked it up to work on it some more and the screw was
missing from the switch. This is not the first time I've lost one of those
tiny screws. They vibrate out very easily and they are so small that the
chance of finding one is nil. They are #2-56 stainless. I'm going to buy a
pack of 100 on Amazon for $5 so if anyone needs a replacement, let me know.
I guess the solution is to always keep it snugged down. Not always possible if
you pre-prep your electronics at home before flying. I would try some thread
lock but that defeats the purpose of making electrical contact between the
screw and the board.
Kurt
On Fri, Jan 20, 2017 at 10:03 AM, Brian Home <dmarc-noreply@xxxxxxxxxxxxx>
wrote:
So, as I sit here on an ice pack for the last week, I've been following this
thread with interest because I put the suspicious switch in my new MAC
Performance 75mm Skyscraper. To me, I just didn't like the feel of it. So just
last week I pulled it out and replaced it with the Featherweight Screw switch.
$5. (Featherweightaltimeters.com)
They also have a very cool magnet switch I used in my Mariah.
I tried the wire twist a long time ago on a Black Brandt Terrier two
stage and had a VERY nervous moment when I had to pull it off the pad while the
staging timer was still armed.
On Jan 20, 2017, at 8:54 AM, R Dierking <applerocketry@xxxxxxxxxxx> wrote:
I reached 310 cycles on the test switch with no symptoms of failure. I’ll be
providing some observations as a new post including checking a switch after
being overheated a bit when soldering the wires.
300 cycles doesn’t seem like much until you actually do it btw. I personally
do not have any concerns about these switches in my projects at this point.
However, all switches should be inspected for good soldering connections and
checked for resistance with no intermittent connections before flight.
Richard Dierking
From: Vern Knowles <mailto:knowles.vern@xxxxxxxxx>
Sent: Thursday, January 19, 2017 7:06 PM
To: roc-chat@xxxxxxxxxxxxx
Subject: [roc-chat] Re: Switch Warning - Schurter 110-220
John,
The power dropout duration that electronics can survive is totally dependent on
the design of the electronics. It could range from microseconds to seconds.
I have no idea if the problems seen with these switches are because they are
intermittent or if they fail hard and simply don’t conduct when switched on.
Might even be both.
Vern
From: roc-chat-bounce@xxxxxxxxxxxxx [mailto:roc-chat-bounce@xxxxxxxxxxxxx] On ;
Behalf Of John Coker
Sent: Thursday, January 19, 2017 2:46 PM
To: roc-chat@xxxxxxxxxxxxx
Subject: [roc-chat] Re: Switch Warning - Schurter 110-220
If we really wanted to test switches, what is the shortest length brownout that
would affect electronics during normal operation (i.e., make a flight computer
reset)?
I.e., if you ran a data logger to measure resistance, what sampling frequency
would be required?
John
On Thu, Jan 19, 2017 at 12:55 PM, R Dierking <applerocketry@xxxxxxxxxxx> wrote:
I really wonder about that 300 operations number. It isn’t listed as a MTBF.
It does seem low compared to other switches. Also, keep in mind that other
types of switches (for example, household types of rocker switches) are
intended to be operated many times. So, the statistical number of cycles
before a failure would be very important. Perhaps they just decided to put a
low number of cycles for a lifetime of the switch so people wouldn’t use them
for other applications?
Here’s another important consideration: Say you are planning on using a
Microswitch to arm electronics. Chances are, you will need to create some
mechanism to do this. But, how durable and reliable will your mounting and
operation of the switch be? Would you be able to cycle it 10,000 times? Just
saying that I’ve had the little tube that guides a pull rod on a microswitch
fail when the epoxy came loose.
So, there are many considerations, and we never run out of stuff to cause us to
lose sleep. 😊
Richard Dierking
From: Gregory Lyzenga <mailto:lyzenga@xxxxxxxxx>
Sent: Thursday, January 19, 2017 12:35 PM
To: roc-chat@xxxxxxxxxxxxx
Cc: Allen Farrington <mailto:allen.farrington@xxxxxx> ; Vern Knowles
<mailto:knowles.vern@xxxxxxxxx>
Subject: [roc-chat] Re: Switch Warning - Schurter 110-220
On Jan 19, 2017, at 12:22 PM, R Dierking <applerocketry@xxxxxxxxxxx> wrote:
Now, I think Vern has identified the most likely cause of this problem. The
switches are ‘cooked’ prior to even being used.
You should be careful not to assume there is just one singular failure mode.
Soldering damage doesn’t seem like it would explain the manufacturer’s small
number of rated cycles. There may be more than one factor in play.
- Greg
----------------------------------------------------------
Gregory A. Lyzenga <lyzenga@xxxxxxx>
Dept. of Physics, Harvey Mudd College (909) 621-8378
<tel:%28909%29%20621-8378>
Claremont, CA 91711-5990 mobile (626) 808-5314
<tel:%28626%29%20808-5314>