Today's Message Index:
----------------------
1. 07:57 AM - Vacuum vise (Robert L. Nuckolls, III)
2. 08:35 AM - Re: vhf transponder interference (jappie)
3. 09:10 AM - Cessna Switch Bulletin CE-09-42 (Jeff Page)
4. 10:10 AM - Re: Vacuum vise (Y! edpav8r)
5. 12:53 PM - Re: Work bench cord clutter solution (eschlanser)
6. 02:31 PM - Re: Cessna Switch Bulletin CE-09-42 (Vern Little)
7. 07:59 PM - Re: Vacuum vise (Robert L. Nuckolls, III)
Message 1
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On several occasions I've thought it would be nice if a
vacuum vise I inherited from my dad would 'stay put'
better on the workbench. Seems it's difficult to pull a
lasting vacuum on a wooden surface.
A solution occurred to me a couple of days ago.
I used some E6000 to bond a 7 x 7 inch piece of copper
clad to the bench thusly.
Emacs!
I weighted it down well and gave it 48 hours+
to get bonded. E6000 is a solvent based adhesive
and I wanted to give the solvents plenty of time
to escape from under the sheet.
This produced a smooth, vacuum friendly surface . . .
Emacs!
. . . yet thin enough not to be in the way when
the vise was not in service. You could do the same thing
with a piece of aluminum or perhaps some plastic that
was impervious to the effects of the E6000's solvents.
A thin steel sheet might be even better. Time tell how
well the copper clad stands up to the rigors of bench
surface before it too becomes 'leaky' . . .
By the way, the surface under the copper clad is tempered
Masonite. I use this to surface many of my benches attaching
it with flat head screws. When it gets too beaten to
clean up I can easily replace it for a whole new work
surface.
Bob . . .
Message 2
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| Subject: | Re: vhf transponder interference |
what is the importance of the Impedance bushing inside this connector TED 9-30-10
?
I've been told to use use it only with a certain type of cable ...
My old one had none, maybe one of the many reasons I have interference...
JP
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=396657#396657
Message 3
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| Subject: | Cessna Switch Bulletin CE-09-42 |
The FAA released a Special Airworthiness Information Bulletin CE-09-42
advising that the landing, beacon and taxi light switches have been
overheating in the field resulting in smoke or fire in the cockpit.
This apparently occurs after approximately 4000 operations.
The design of the switches is less than ideal, since it is just a
slider with no over-center snap action.
Since the landing light switch in my Cessna 172 has been in operation
for 43 years and 6500 flight hours, it could have as many as 10000
operations. So I decided that I would replace the switch and tear
apart the old one to investigate its condition.
It was in better shape than I expected. The contacts are large rivets
of copper, still firmly attached to the chassis. The slider plate has
very thick paths of copper - it is not just an etched circuit board.
As the plate slides, the paths make contact with the rivets and that
is where arcing occurred. However, the sliding action of the switch
cleans the contact points, so during use the current is passing
between the contacts and the plates in a different location than where
the arcing occurred.
The contact operation of the switch is very dependent on the strength
of the spring that pushes the plate against the contacts. If the
spring weakened or broke, switch operation would be dangerously
degraded. The spring in my switch was stronger than I would have
expected.
Conveniently, the spring also functions for the detent positions of
the switch. So if one of these switches seems loose and doesn't click
into position, it is time to replace the switch.
The switch I replaced is Cessna 0713035-1 and cost me $45 Canadian.
Jeff Page
Dream Aircraft Tundra #10
Message 4
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Bob,
Great idea! Very nice to be able to have a vise front and center when you n
eed it and get it out of the way when you don't.
Re workbenches. I've made a couple of benches using a plain-front solid cor
e interior door as the top. They're rigid, flat and stable, and come with a
nicely finished surface. It's easy to fab and attach a simple support fram
ework and legs with a few dollars worth of lumber and hardware.
Unfortunately, the nicely finished surface doesn't hold up very well to gara
ge bench use. I'll try your idea and screw down a sheet of Masonite next ti
me my bench needs a refinish. Thanks for the tip.
Eric
On Mar 20, 2013, at 7:55 AM, "Robert L. Nuckolls, III" <nuckolls.bob@aeroele
ctric.com> wrote:
> By the way, the surface under the copper clad is tempered
> Masonite. I use this to surface many of my benches attaching
> it with flat head screws. When it gets too beaten to
> clean up I can easily replace it for a whole new work
> surface.
>
> Bob . . .
Message 5
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| Subject: | Re: Work bench cord clutter solution |
holger-d(at)shadowbrush.c wrote:
> 12 plug strip now on sale (until tomorrow) at Newegg: http://tinyurl.com/ckdgpnq . $36 shipped with promo code EMCXTWL228. That's $3/plug.
>
> Holger
SOLD OUT!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=396681#396681
Message 6
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| Subject: | Re: Cessna Switch Bulletin CE-09-42 |
These are the same circuit functions that failed using Carling switches
after less than 100 operations in my RV-9A. These failures were well
documented on this list several years ago and are in the archives. I've
eliminated switches carrying loads in my Harmon Rocket and I am using relays
controlled by low-current switches. The relays can be replaced when (not
if) they fail in less than 30 seconds, even in flight.
The Vertical Power products do this with automotive-style electronic
switches.
Any electromechanical device, including switches, relays, breakers and
contactors have a lifetime and plans should be made to provide service
access for replacement. The promise of electronic (solid state)
breaker/relays is that there is no practical wear-out mechanism. When a
failure does occur, however, it's quite a bit more complicated to repair.
There are two philosophies at play here: Design so that it never breaks,
and don't worry about serviceability; or assume that it will break and allow
easy service access and low cost maintenance. Sometimes, however, in our
amateur-builts, we get it backwards... sigh.
V
-----Original Message-----
From: Jeff Page
Sent: Wednesday, March 20, 2013 9:08 AM
Subject: AeroElectric-List: Cessna Switch Bulletin CE-09-42
The FAA released a Special Airworthiness Information Bulletin CE-09-42
advising that the landing, beacon and taxi light switches have been
overheating in the field resulting in smoke or fire in the cockpit.
This apparently occurs after approximately 4000 operations.
The design of the switches is less than ideal, since it is just a
slider with no over-center snap action.
Since the landing light switch in my Cessna 172 has been in operation
for 43 years and 6500 flight hours, it could have as many as 10000
operations. So I decided that I would replace the switch and tear
apart the old one to investigate its condition.
It was in better shape than I expected. The contacts are large rivets
of copper, still firmly attached to the chassis. The slider plate has
very thick paths of copper - it is not just an etched circuit board.
As the plate slides, the paths make contact with the rivets and that
is where arcing occurred. However, the sliding action of the switch
cleans the contact points, so during use the current is passing
between the contacts and the plates in a different location than where
the arcing occurred.
The contact operation of the switch is very dependent on the strength
of the spring that pushes the plate against the contacts. If the
spring weakened or broke, switch operation would be dangerously
degraded. The spring in my switch was stronger than I would have
expected.
Conveniently, the spring also functions for the detent positions of
the switch. So if one of these switches seems loose and doesn't click
into position, it is time to replace the switch.
The switch I replaced is Cessna 0713035-1 and cost me $45 Canadian.
Jeff Page
Dream Aircraft Tundra #10
-----
No virus found in this message.
Checked by AVG - www.avg.com
Message 7
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At 12:07 PM 3/20/2013, you wrote:
>Bob,
>
>Great idea! Very nice to be able to have a vise front and center
>when you need it and get it out of the way when you don't.
>
>Re workbenches. I've made a couple of benches using a plain-front
>solid core interior door as the top.\
Hmmm . . . I've used doors for drafting tables.
That was back in the days when the Bruning broken-arm
drafting machine was king. Bought one used at
Cessna and built a drafting table from a door.
Used it a lot of years until the first time I
loaded AutoCAD 1.17 onto a PC-XT with a monster
20 Meg hard drive. The Bruning, table and all
those tools went into the next garage sale! That
was 30 years ago!
>Unfortunately, the nicely finished surface doesn't hold up very well
>to garage bench use. I'll try your idea and screw down a sheet of
>Masonite next time my bench needs a refinish. Thanks for the tip.
Yeah, beat-n-bash benches need some mass. The
last one I built was when we were operating the
Benton Airport (1K1). I used a two-layer
3/4" MDF top covered with Masonite. You can
plunk a V8 block down on it . . .
Bob . . .
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