Today's Message Index:
----------------------
1. 05:27 AM - Re: Inst GND Bus and 18 AWG wire (Robert L. Nuckolls, III)
2. 05:31 AM - Wrong pins shipped in 37-Pin Panel Ground Bus (Robert L. Nuckolls, III)
3. 07:02 AM - wire squash connections (Bob Marshall)
4. 07:42 AM - Re: wire squash connections (Robert Borger)
5. 02:26 PM - Re: wire squash connections (Robert L. Nuckolls, III)
6. 03:37 PM - Re: wire squash connections (rayj)
7. 05:12 PM - Re: wire squash connections (Robert L. Nuckolls, III)
8. 05:44 PM - Re: wire squash connections (Robert Borger)
9. 06:15 PM - When is a 'ground' not a 'ground' (Robert L. Nuckolls, III)
10. 06:24 PM - Re: wire squash connections (Robert L. Nuckolls, III)
11. 06:27 PM - Re: wire squash connections (Robert L. Nuckolls, III)
12. 07:56 PM - Re: wire squash connections (Don)
13. 08:09 PM - Re: wire squash connections (Don)
14. 08:26 PM - Re: wire squash connections (Robert Borger)
15. 09:27 PM - Re: wire squash connections (Robert L. Nuckolls, III)
16. 09:34 PM - Re: wire squash connections (Bob Marshall)
17. 09:46 PM - Re: wire squash connections (MikeRV6-A)
18. 09:56 PM - Re: Re: wire squash connections (Don)
19. 10:23 PM - Re: Re: OT-potting with RTV silicone (rayj)
Message 1
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Subject: | Re: Inst GND Bus and 18 AWG wire |
At 11:31 PM 2/1/2011, you wrote:
>
>I bought the AEC Instrument ground bus, which is a Dsub 37 pin
>connector. In looking at my instrument panel items the radios have
>18 AWG wires for the power and grounds.
>The Dsub standard density pins only take up to a 20 AWG wires, so
>how to deal with the 18 AWG wires. should I solder a Y of 20AWG to
>the 18 AWG wire to go into the ground bus or should I just run the
>wires all the way to the forest of tabs on the firewall. One fella
>on another site said this would work but you can't guarantee the
>flow of power would evenly split down the "Y". The radio is on a 10
>amp breaker to protect the 18 AWG wire but how does this work if you
>slit to smaller wires, to share the load so to speak.
Peel out enough strands from the end of the 18AWG
wire to allow remaining strands to fit into the
20AWG pin.
>I assume it would be bad grounding practice to just bolt these 18
>AWG wires to the cross beam behind the panel?
No, but neither is is bat practice to trim
the wire down until it fits the pin.
Bob . . .
Message 2
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Subject: | Wrong pins shipped in 37-Pin Panel Ground Bus |
It has come to my attention that a number of
37-pin ground bus kits were shipped with female
as opposed to male d-sub pins. I had a note from
one builder . . . I also found some kits in inventory
that were incorrectly pinned
If anyone finds that they have the wrong pins, drop
me a note. I'll forward a correct set of pin along
with a pre-addressed and stamped envelope for
returning the incorrect pins.
I guess that's what I get for playing around in
the shop when I probably should be in bed!
Bob . . .
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Subject: | wire squash connections |
I plan to use p-mags and the installation instructions show the connections made
to the controller are simply striped wire leads placed under screws. Since
this is under the cowl, I was hoping that there was a better way. Is there a
crimped terminal that could be used along with some heat shrink tubing?
My first post here though I have been reading for a while. Thanks,
Bob
I would post a photo but I cannot figure how to do it.
--------
RV-6A construction resumed. Planning electrical and building wing.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=329292#329292
Message 4
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Subject: | Re: wire squash connections |
Bob,
Interesting. I plan to put a pair of P-Mags on the Lycoming for my Toot.
Rather than bare wires under a screw, I'd think about crimping a suitably sized
ring terminal onto the wire with proper shrink tube and placing the ring under
the screw along with a lock washer.
Others, please chime in if there's an error in my thinking as it's info I'll eventually
need.
Thanks,
Bob Borger
Europa Kit #A221 N914XL, XS Tri-Gear, Intercooled 914, Airmaster C/S Prop
http://www.europaowners.org/forums/gallery2.php?g2_itemId=60232
http://www.biplaneforumgallery.com/index.php?cat=10046
Europa Flying!
3705 Lynchburg Dr.
Corinth, TX 76208
Home: 940-497-2123
Cel: 817-992-1117
On Feb 2, 2011, at 8:58, Bob Marshall wrote:
>
> I plan to use p-mags and the installation instructions show the connections made
to the controller are simply striped wire leads placed under screws. Since
this is under the cowl, I was hoping that there was a better way. Is there
a crimped terminal that could be used along with some heat shrink tubing?
> My first post here though I have been reading for a while. Thanks,
> Bob
> I would post a photo but I cannot figure how to do it.
>
> --------
> RV-6A construction resumed. Planning electrical and building wing.
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=329292#329292
>
>
>
>
>
>
>
>
>
>
Message 5
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Subject: | Re: wire squash connections |
At 09:58 AM 2/2/2011, you wrote:
><marshall6916@sbcglobal.net>
>
>I plan to use p-mags and the installation instructions show the
>connections made to the controller are simply striped wire leads
>placed under screws. Since this is under the cowl, I was hoping
>that there was a better way. Is there a crimped terminal that could
>be used along with some heat shrink tubing?
Yeah, my biggest disappointment with that product.
Their service experience with that configuration must
be okay . . . that's what they've used since day one.
Crimping the appendage of some sort of terminal in
those connections might be a bit better than just
crimping the wire . . . but not much.
My best suggestion is to strip leads (20AWG)
to proper length and then 'comb' them such
that they all lay parallel to each other. Then
connect with as much torque on the screws as
you dare.
Try to support the bundles within a few inches
of where they connect with the ignition modules.
Bob . . .
Message 6
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Subject: | Re: wire squash connections |
do not archive
General question on wires under screws. Is there any benefit in using
an antioxidant similar to what is used on Al wire in electrical panels.
Perhaps not best but better than without?
Raymond Julian
Kettle River, MN
On 02/02/2011 03:22 PM, Robert L. Nuckolls, III wrote:
> <nuckolls.bob@aeroelectric.com>
>
> At 09:58 AM 2/2/2011, you wrote:
>> <marshall6916@sbcglobal.net>
>>
>> I plan to use p-mags and the installation instructions show the
>> connections made to the controller are simply striped wire leads
>> placed under screws. Since this is under the cowl, I was hoping that
>> there was a better way. Is there a crimped terminal that could be used
>> along with some heat shrink tubing?
>
> Yeah, my biggest disappointment with that product.
> Their service experience with that configuration must
> be okay . . . that's what they've used since day one.
> Crimping the appendage of some sort of terminal in
> those connections might be a bit better than just
> crimping the wire . . . but not much.
>
> My best suggestion is to strip leads (20AWG)
> to proper length and then 'comb' them such
> that they all lay parallel to each other. Then
> connect with as much torque on the screws as
> you dare.
>
> Try to support the bundles within a few inches
> of where they connect with the ignition modules.
>
>
> Bob . . .
>
>
Message 7
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Subject: | Re: wire squash connections |
At 10:26 AM 2/2/2011, you wrote:
>
>Bob,
>
>Interesting. I plan to put a pair of P-Mags on the Lycoming for my Toot.
>
>Rather than bare wires under a screw, I'd think about crimping a
>suitably sized ring terminal onto the wire with proper shrink tube
>and placing the ring under the screw along with a lock washer.
>
>Others, please chime in if there's an error in my thinking as it's
>info I'll eventually need.
Just so we're all on the same page . . .
The twist-n-squash terminal strips featured in this
thread are probably the best there is for taking
wires to etched circuit boards with convenience,
minimum cost and reliability . . . UNDER CERTAIN
CONDITIONS. Here's one example of the technology:
Emacs!
Here's one of my favorite $100 data acquisition modules that
uses the same terminal strip.
Emacs!
Note that the bared end of a wire is NOT captured by
a head of the mash-screw . . .
Emacs!
But by the END of the mash-screw. Further, there is a buffer
strip between the wire strands and the end of the screw. If one
REALLY needs to use a twist-n-squash technology, this is one of
the best.
Legacy design goals for aviation (and other disciplines)
have adopted processes that offer gas-tightness in the
metallic joints of the current carrying pathway along
with wire support immediately adjacent to the gas-tight
joint that prevents failure of the wire under vibration.
Without getting in too much of a dither about new design
goals, I think the best application of this process calls
for parallel strands of wire pressed into the lower
concave surface of the cavity with force from above
offered by the screw. Then supply bundle support within
a couple inches of the squash-joints.
Note that is NOT what I did on this particular example . . .
but then this DAM isn't expected to be in place and
functioning after what we hope is decades of otherwise
unattended service.
Bob . . .
Message 8
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Subject: | Re: wire squash connections |
Bob,
Oh, OK. Now I see (literally) what was being talked about.
Not the "wrap the wire around the screw and tighten" kind of under screw.
Would crimping a D-Sub female connector pin onto the end of the wire and adding
a couple layers of shrink tube over the junction for some stress relief provide
a better item to be pressed under the screw? Again assuming you would provide
some wire support close to the box.
Thanks,
Bob
On Feb 2, 2011, at 17:25, Robert L. Nuckolls, III wrote:
> At 10:26 AM 2/2/2011, you wrote:
>>
>> Bob,
>>
>> Interesting. I plan to put a pair of P-Mags on the Lycoming for my Toot.
>>
>> Rather than bare wires under a screw, I'd think about crimping a suitably sized
ring terminal onto the wire with proper shrink tube and placing the ring
under the screw along with a lock washer.
>>
>> Others, please chime in if there's an error in my thinking as it's info I'll
eventually need.
>
> Just so we're all on the same page . . .
>
> The twist-n-squash terminal strips featured in this
> thread are probably the best there is for taking
> wires to etched circuit boards with convenience,
> minimum cost and reliability . . . UNDER CERTAIN
> CONDITIONS. Here's one example of the technology:
>
> <1e81a25b.jpg>
>
> Here's one of my favorite $100 data acquisition modules that
> uses the same terminal strip.
>
> <1e81a2d8.jpg>
>
> Note that the bared end of a wire is NOT captured by
> a head of the mash-screw . . .
>
> <1e81a345.jpg>
>
> But by the END of the mash-screw. Further, there is a buffer
> strip between the wire strands and the end of the screw. If one
> REALLY needs to use a twist-n-squash technology, this is one of
> the best.
>
> Legacy design goals for aviation (and other disciplines)
> have adopted processes that offer gas-tightness in the
> metallic joints of the current carrying pathway along
> with wire support immediately adjacent to the gas-tight
> joint that prevents failure of the wire under vibration.
>
> Without getting in too much of a dither about new design
> goals, I think the best application of this process calls
> for parallel strands of wire pressed into the lower
> concave surface of the cavity with force from above
> offered by the screw. Then supply bundle support within
> a couple inches of the squash-joints.
>
> Note that is NOT what I did on this particular example . . .
> but then this DAM isn't expected to be in place and
> functioning after what we hope is decades of otherwise
> unattended service.
>
> Bob . . .
>
Message 9
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Subject: | When is a 'ground' not a 'ground' |
At 09:58 PM 1/30/2011, you wrote:
Bob N., et al,
I have run a bunch of additional tests of my antennas in various
configurations to see what effect they had on VSWR readings. The raw
data and VSWR results are pretty variable (to my eyes) and not very
encouraging.
But my immediate issue is the one that Bob N. focused on shortly
after my original post -- the quality of the ground between my
antenna base and my ground plane. At the time I did the original
tests, it tested out at ~0.1 Ohms on my digital VOM.
But I dug out the four-wire ohmmeter that I build years ago based on
Bob N's directions in the AeroElectric Connection and soldered in a
fresh "D Cell" battery. The meters (especially the voltmeter)
fluctuated quite rapidly and over quite a range so I'm not sure my
data are accurate (although it did come close to the calculated
resistance of a hunk of 18 AWG wire that I used to check the
four-wire ohmmeter for accuracy).
While based on solid physics, THAT test tool was a
hurry-up jury-rig that helped me make some good
measurements in the field with locally acquired
materials. It had no constant current generator
and therefore taxed the operator to visually integrate
voltage/current readings to deuce resistance value
with something like 10% accuracy. The test current
was not REAL stable. Further, using 'shorted'
Adapter I'm offering from the website. I mention
this because one should approach low-ohms measurements
with some degree of caution. Be aware that SOME
devices may not tolerate so high a test current.
While exploring 'hardware' it's not a concern but
be cautious with the measurement of electro-whizzies.
As best I can tell, the resistance between my antenna mounting screws
and the ground plane are in the 250 milli-Ohm range. This seems to
be way too high. Is it? I believe you said that resistance should
be in the very low milli-Ohm or even micro-Ohm range.
Yes . . . and forgive me, I need to interject another
simple but significant idea into this discussion.
Using the DC ohmmeter to evaluate the metallic
connection between two components is a legacy
standard examination of the joints between ground
straps and the airframe. These investigations are
concerned with predicting performance of a high
current ground like a cranking battery or a bond-
strap for lightning protection.
The DC measurement offers SOME insight for grounding
antennas when the base of the antenna is brought
into forceful proximity with the belly skins
and structure of an airplane. But as soon
as we insert a gap between the base and ground plane,
the reliability of a DC resistance begins to fail
for predicting performance of the joint at very high
radio frequencies.
For example, We could set the comm antenna up on a
22" tall pedestal of copper tube. The DC resistance
of that tube may still be in the low milliohms but
because its LENGTH is exactly 1/4-wave at 126 Mhz,
the ground IMPEDANCE at the top of pedestal would
be THOUSANDS of ohms.
This is why I made the statement earlier this
week that the "quality" of your antenna grounding
was more of an "art" borne of experience and
command of simple-ideas than a matter of measuring
milliohms from one point to another.
I've got one of your newer low resistance testers on order and as
soon as I get it, I'll measure the resistance again.
I'll probably just have to pull the ground plane and re-do the
mechanical mounting again and hope I get a lower resistance.
As stated above, a HIGH DC resistance reading in a
stack up of metallic components is reason for further
investigation, a LOW reading is not necessarily
golden at radio frequencies.
Would it make sense to get some conductive epoxy and bond a ground
strap from the antenna base to the ground plane? I know soldering
copper to aluminum doesn't work and corrodes almost
immediately. I've seen some silver-filled epoxies rated as low as
0.001 Ohm-cm but that stuff is expensive. Could I solder a small
ground strap to the antenna's metal base without damaging the
antenna? I've got room in the hole for the BNC connector to run a
small ground strap up from the antenna base to a ring terminal that I
could clamp under one of the mounting screws. Would conductive gel
under the hardware help?
Yeaaahhh . . . maybe . . . but . . . As a
a practical matter, the TC aircraft industry
has learned to minimize process sensitive
materials that involve pastes, goops, glues, goos
and extraordinary technician's skills.
In addition to the demands of skill and process
to maximize performance, these materials tend
to have a poor service life. They're not even
close to both performance and longevity of a
(1) a single piece of metal or (2)
multiple pieces welded together or (3) pieces
bolted together with enough force to achieve and
maintain gas-tightness between the pieces in
spite the variables of temperature, moisture,
flexure and time.
Since I've got a glass skin between the antenna base and the washer
stack that leads to the ground plane, I didn't "brighten" the
underside of the ground plane -- just the top under each of the four
machine screws. I'm thinking if I brightened up both sides of the
ground plane, there might be some improvement because of the
additional contact between the hardware stack, the machine screws and
the underside of the ground plane.
Okay, if it were my airplane . . .
I'd ditch the aluminum ground plane. Get a piece
of brass sheet, .032 to .040 thick and 1" larger
than extremes of antenna base on all four sides.
Drill #10 close clearance holes and BNC clearance
holes to match antenna base and exactly centered on
the sheet.
Cut 4 spacers from brass. 3/8 to 1/2-inch diameter and
drilled for #10 close clearance. Cut and drill
these on a lathe. By definition, the end of a cylinder
faced in a lathe is perfectly perpendicular to
the axis. Also, the thru holes will be exactly
centered. Make them 1/32" longer than the distance
it takes to come through the thickness of the
composite belly material.
Use 63/37 solder to 'tin' both ends of the spacers
and the area around the bottom side of the brass plate.
Wipe the 'tinning' off with a dry rag while still
hot . . . you don't want any visible 'thickness'
of solder. Bolt the spacers to the plate and solder
to the plate. Tighten the bolts while the solder is
molten to make sure spacers are flat to the plate.
You need just enough solder to form a small fillet
around the spacer.
When you're done, you'll have a one-piece of metal
that can be installed in the airplane. The four
spacer holes need to be enlarged to about 1/8"
larger radius than the spacer diameter. Put some
10-32 screws in the holes, nuts against the plate.
Tape over the bottoms of the four spacer holes in
the belly skin. Fill the holes about 1/2 with
catalyzed resin. Paint the underside of the plate
with catalyzed resin. Press the assembly into the
final resting place and fixture with sand bags,
shot bags, etc.
When the resin has set up, remove tape and temporary
screws. Clean up any resin that would interfere
with seating the antenna on the ends of the
spacers. Make sure the tinned ends of the spacers
are clean.
Fabricate at least 4 but no more than 8 'radials'
from copper foil. 3/4" to 1-1/2" wide and 21" long.
these can be multiple strips spliced together by
soldering to get desired total length. Lay these
out in as uniformly circular pattern around antenna.
Length can curve up the sides and 'hop' over
ribs, stringers, stiffeners, etc. Solder end of
radials to the brass sheet using 63/37 electronic
solder. Heavy duty iron will flow these joints
one at a time and with minutes between joints to
keep from heating the whole thing up and putting
resin at risk. Put strips of glas and resin over
the radials to keep them in place and protect from
damage.
Brighten under-surface of antenna base before
installing antenna using 10-32 grade 8 or stainless
cap head screws. Screw heads against antenna base;
MS20365 or equal metallic lock nuts over washers against
the plate. Caulk around base of antenna with RTV.
There are no doubt other ways to get an RF-SOLID
installation but this one is based on materials
and tools I have. I know too that the processes
and configuration would produce an installation
with robustness and performance difficult to
improve upon. A DC ohmmeter test of this installation
would be superfluous.
Bob . . .
Message 10
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Subject: | Re: wire squash connections |
>
>Would crimping a D-Sub female connector pin onto the end of the wire
>and adding a couple layers of shrink tube over the junction for some
>stress relief provide a better item to be pressed under the
>screw? Again assuming you would provide some wire support close to the box.
That might 'protect' the wire but now you
have a single, solid, small diameter being
captured between two surfaces having a larger
radius. I.e., potentially less contact surface
area than one could get with a compressed
stack of wire strands (19 of them when it
comes to legacy standard wire).
The guys who designed this terminal strip
were no dummies. It's really a pretty well
thought out product. But I'd bet that they
would not recommend that it be used under
the cowl on any vehicle. Not recommending
doesn't make it automatically "bad" . . .
just not the best we know how to do. I
think the risks are low.
One could use PIDG 'pins' . . .
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=165168-ND
Bob . . .
Message 11
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Subject: | Re: wire squash connections |
At 06:12 PM 2/2/2011, you wrote:
>
>do not archive
>
>General question on wires under screws. Is there any benefit in
>using an antioxidant similar to what is used on Al wire in
>electrical panels. Perhaps not best but better than without?
Probably wouldn't hurt . . . but unless
we're talking about a really bad@#$@
environment (salt air on sea-going boat?)
I can't imagine that it would help.
Bob . . .
Message 12
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Subject: | wire squash connections |
Or you could use ferrules. When they are crimper down the contact is flat.
See
http://www.alliedelec.com/search/searchresults.aspx?N=0&Ntk=Primary&Ntt=ferr
els
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Wednesday, February 02, 2011 5:21 PM
Subject: Re: AeroElectric-List: wire squash connections
<nuckolls.bob@aeroelectric.com>
>
>Would crimping a D-Sub female connector pin onto the end of the wire
>and adding a couple layers of shrink tube over the junction for some
>stress relief provide a better item to be pressed under the
>screw? Again assuming you would provide some wire support close to the
box.
That might 'protect' the wire but now you
have a single, solid, small diameter being
captured between two surfaces having a larger
radius. I.e., potentially less contact surface
area than one could get with a compressed
stack of wire strands (19 of them when it
comes to legacy standard wire).
The guys who designed this terminal strip
were no dummies. It's really a pretty well
thought out product. But I'd bet that they
would not recommend that it be used under
the cowl on any vehicle. Not recommending
doesn't make it automatically "bad" . . .
just not the best we know how to do. I
think the risks are low.
One could use PIDG 'pins' . . .
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=165168-ND
Bob . . .
Message 13
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Subject: | wire squash connections |
You will need to reattach the "els" to the link on the allied web site
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Don
Sent: Wednesday, February 02, 2011 7:50 PM
Subject: RE: AeroElectric-List: wire squash connections
Or you could use ferrules. When they are crimper down the contact is flat.
See
http://www.alliedelec.com/search/searchresults.aspx?N=0&Ntk=Primary&Ntt=ferr
els
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Wednesday, February 02, 2011 5:21 PM
Subject: Re: AeroElectric-List: wire squash connections
<nuckolls.bob@aeroelectric.com>
>
>Would crimping a D-Sub female connector pin onto the end of the wire
>and adding a couple layers of shrink tube over the junction for some
>stress relief provide a better item to be pressed under the
>screw? Again assuming you would provide some wire support close to the
box.
That might 'protect' the wire but now you
have a single, solid, small diameter being
captured between two surfaces having a larger
radius. I.e., potentially less contact surface
area than one could get with a compressed
stack of wire strands (19 of them when it
comes to legacy standard wire).
The guys who designed this terminal strip
were no dummies. It's really a pretty well
thought out product. But I'd bet that they
would not recommend that it be used under
the cowl on any vehicle. Not recommending
doesn't make it automatically "bad" . . .
just not the best we know how to do. I
think the risks are low.
One could use PIDG 'pins' . . .
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=165168-ND
Bob . . .
Message 14
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Subject: | Re: wire squash connections |
Bob,
Yes, I can see the PIGD pin working.
If contact area is the issue, how about crimp on male spade? Lots of contact area
for the screw to mash into. It has a crimp onto the wire and a crimp onto
the insulation. Add some heat shrink tubing for strain relief and support the
wire.
Bob
On Feb 2, 2011, at 7:20 PM, Robert L. Nuckolls, III wrote:
>
>
>>
>> Would crimping a D-Sub female connector pin onto the end of the wire and adding
a couple layers of shrink tube over the junction for some stress relief provide
a better item to be pressed under the screw? Again assuming you would provide
some wire support close to the box.
>
> That might 'protect' the wire but now you
> have a single, solid, small diameter being
> captured between two surfaces having a larger
> radius. I.e., potentially less contact surface
> area than one could get with a compressed
> stack of wire strands (19 of them when it
> comes to legacy standard wire).
>
> The guys who designed this terminal strip
> were no dummies. It's really a pretty well
> thought out product. But I'd bet that they
> would not recommend that it be used under
> the cowl on any vehicle. Not recommending
> doesn't make it automatically "bad" . . .
> just not the best we know how to do. I
> think the risks are low.
>
> One could use PIDG 'pins' . . .
>
> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=165168-ND
>
>
>
> Bob . . .
Message 15
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Subject: | Re: wire squash connections |
At 11:22 PM 2/2/2011, you wrote:
>
>Bob,
>
>Yes, I can see the PIGD pin working.
>
>If contact area is the issue, how about crimp on male spade? Lots
>of contact area for the screw to mash into. It has a crimp onto the
>wire and a crimp onto the insulation. Add some heat shrink tubing
>for strain relief and support the wire.
I like the pins better . . . or simply
the combed strands.
Bob . . .
Message 16
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Subject: | Re: wire squash connections |
Great suggestions, thanks everyone!! I think I will order the ferrules from Altech
though they come in packs of 100. If I do order, does anyone want a few?
My thinking is that the ferrules will do as advertised and prevent strand breaks
and maybe a bit of oxidation, too. Just seems like a better connection.
--------
RV-6A construction resumed. Planning electrical and building wing.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=329418#329418
Message 17
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Subject: | Re: wire squash connections |
Wire termination ferrules are designed for use in
connectors of the type used in P-Mags.
See digikey.com, part number 298-10044-ND for an example.
These ferrules are tin-plated copper, and they provide
an insulated segment that keeps the wire bend away from
the stripped part of the wire- this helps to prevent
flexing that can break individual wire strands.
The ferrule crimper (yes, another tool...) leaves
flat sides on the ferrule that align with the
clamp action of the terminal into which the ferrule
is inserted.
Ferrules are sized for various wire gauges, the part
number that I gave above is for #18. Ferrules are
available to receive two conductors, having a double-
width insulation sleeve. Catalogs often contain part
numbers that offer various ferrule tube lengths, but
the small connectors that are used on P-Mags would
probably lead to trimming the longer ferrules to fit,
which is OK.
I think that this approach is more desirable than the
PIDG pins, because the ferrule can be trimmed to length
so that the ferrule fits quite neatly into the receiving
area of the connector body, leaving the ferrule's insulator
supported within the box-shaped entry to the connector.
PIDG pins have enough bulk that, in some of these kinds
of connectors, the pin projects outside the confines of
the connector body: This means that the pin is essentially
a miniature cantilevered beam carrying whatever bending
load that might exist in the wire's installation. In the
long run this might result in flexing and breakage of
the PIDG pin.
Mike Linse
Corvallis, OR
>
> Bob,
>
> Yes, I can see the PIGD pin working.
>
> If contact area is the issue, how about crimp on male spade? Lots of
> contact area for the screw to mash into. It has a crimp onto the wire and
> a crimp onto the insulation. Add some heat shrink tubing for strain
> relief and support the wire.
>
> Bob
>
> On Feb 2, 2011, at 7:20 PM, Robert L. Nuckolls, III wrote:
>
>> <nuckolls.bob@aeroelectric.com>
>>
>>
>>>
>>> Would crimping a D-Sub female connector pin onto the end of the wire
>>> and adding a couple layers of shrink tube over the junction for some
>>> stress relief provide a better item to be pressed under the screw?
>>> Again assuming you would provide some wire support close to the box.
>>
>> That might 'protect' the wire but now you
>> have a single, solid, small diameter being
>> captured between two surfaces having a larger
>> radius. I.e., potentially less contact surface
>> area than one could get with a compressed
>> stack of wire strands (19 of them when it
>> comes to legacy standard wire).
>>
>> The guys who designed this terminal strip
>> were no dummies. It's really a pretty well
>> thought out product. But I'd bet that they
>> would not recommend that it be used under
>> the cowl on any vehicle. Not recommending
>> doesn't make it automatically "bad" . . .
>> just not the best we know how to do. I
>> think the risks are low.
>>
>> One could use PIDG 'pins' . . .
>>
>> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=165168-ND
>>
>>
>>
>> Bob . . .
>
Message 18
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Subject: | Re: wire squash connections |
Bob I use them on my P-MAGS. Like Bob N says these will not form gas tight
connections in screw down devices, but they do provide a fairly lagre
contact area and they keep the wire from being stressed. I check mine every
condition inspection. So far I have not needed to replace any wires but it
will be easy when the time comes. I wish that the P_MAGS came with D-SUB
connectors, but I am not holding my breath. Don
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Bob
Marshall
Sent: Wednesday, February 02, 2011 9:32 PM
Subject: AeroElectric-List: Re: wire squash connections
<marshall6916@sbcglobal.net>
Great suggestions, thanks everyone!! I think I will order the ferrules from
Altech though they come in packs of 100. If I do order, does anyone want a
few?
My thinking is that the ferrules will do as advertised and prevent strand
breaks and maybe a bit of oxidation, too. Just seems like a better
connection.
--------
RV-6A construction resumed. Planning electrical and building wing.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=329418#329418
Message 19
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Subject: | Re: OT-potting with RTV silicone |
do not archive
Thanks to all for the info. I'm going to go with a coating of E 6000
and I'll add additional layers of RTV, if necessary.
Raymond Julian
Kettle River, MN
On 01/30/2011 01:15 PM, Robert L. Nuckolls, III wrote:
> <nuckolls.bob@aeroelectric.com>
>
> At 10:30 AM 1/30/2011, you wrote:
>>
>> You can buy silicone without acetic acid at the pet store - used for
>> sealing aquariums. I haven't tried it for potting though.
>
> Thank you! I'd forgotten about that. I think the
> same grade of RTV is approved for situations that
> come into contact with food.
>
> I'm pretty sure this stuff would do the job if applied
> in several layers of 1/4" or less and allowed to cure
> before more is added.
>
>
> Bob . . .
> ////
> (o o)
> ===========o00o=(_)=o00o========
> < Go ahead, make my day . . . >
> < show me where I'm wrong. >
> ================================
>
>
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