Today's Message Index:
----------------------
1. 06:54 AM - Re: star washers (Robert L. Nuckolls, III)
2. 08:22 AM - Poor Man's Battery Capacity Tester (ROGER)
3. 08:57 AM - Re: Poor Man's Battery Capacity Tester (user9253)
4. 09:01 AM - Re: star washers (Ken Ryan)
5. 09:17 AM - Re: star washers (user9253)
6. 10:24 AM - Re: star washers (Robert L. Nuckolls, III)
7. 10:34 AM - Re: Re: star washers (Robert L. Nuckolls, III)
8. 10:44 AM - Re: Re: star washers (Ken Ryan)
9. 03:03 PM - Re: Re: star washers (Richard Girard)
10. 07:30 PM - Re: star washers (user9253)
Message 1
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| Subject: | Re: star washers |
At 03:21 PM 12/13/2018, you wrote:
>Bob,
>
>In the recent weeks/months I "think" I saw what
>appear to me to be contradicting posts regarding the use of star washers.
>
>In one discussion I thought you said that star
>washers are never used in the current path on
>any certified airplanes. I think the reason was
>that they prevent the gas tight seal that will inhibit corrosion.
>
>Then, in a second discussion about bus bar
>construction using brass bars, I thought you
>said to be sure to use a star washer under each terminal.
>
>Could you clear up my confusions as to your
>approach to using star washers in an aircraft electrical system?=C2
>
>Thanks,
>
>Ken
I spent a few minutes searching the term
'star washers' in the list archives. Generally,
the use of star washers in the electrical path
was discouraged. If used at all, they were
for mechanical security (i.e. used under a nut).
Couldn't look at all the search hits, but the
few I found were consistent with the above.
Just for grins, I checked a Brand-C parts
catalog for battery contactor installations
and found this image:
Emacs!
Here we see a lockwasher called out as part
of the assembly. It's used under a nut that
secures a terminal post to the 'wing' of
an H6041 mil-style contactor. It doesn't
have a numerical call-out meaning its not
a cataloged spare part as far as Cessna
is concerned. In fact, it's part of the
contactor assembly as supplied by Cutler-Hammer
(item 15). I'm not sure why the catalog
illustrator chose to explode these parts
off the as-supplied assembly. From an OEM
service manual perspective, there was no
reason to disassemble that stud.
I also found some un-flagged star washers
on vendor-supplied assemblies but in each
case, the washer was under a nut . . . not
part of the current path. As a factory
policy, metal locknuts were the
preferred anti-loosening technology for
threaded fasteners.
Electrical conductor pathways were made
up with flat, clean and sometimes malleable
conductors (crimped terminals) being brought
together in gas-tight union with no
intermediate enhancements. Sometimes a
service manual would call out moisture
proofing by painting the finished joint
with some suitable coating . . . these
were joints located out on structure subject
to moisture incursion by drip, splash
or condensation.
B&C supplies star washers with the firewall
forest-of-tabs ground block. All the circuit
breaker manufacturers supply lock washers under
the heads of their screws for terminal attachment.
Again, these are intended to enhance mechanical
integrity of the fastener outside the current
pathway.
An interesting aside . . .
While cruising through the electrical installation
data I found this image I had forgotten
about . . .
Emacs!
Somewhere in my archives, I have a letter from
the head-shed of single engine electrical systems
rejecting my proposal for replacing the too-warm,
panel dimming rheostats with a remotely mounted
array of power transistors on heat sinks. This
would have been about 1964 or thereabouts.
He offered a litany of down-sides . . .
A about 5 years later, the same idea cropped up
across town on the light twins . . . a short
time later, solid state dimming migrated into the
single engine airplanes. We COULD have beat
the twin engine line to this enhancement by
several years. Oh well . . .
Bob . . .
Message 2
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| Subject: | Poor Man's Battery Capacity Tester |
Recently built the tester described in "Battery Replacement: A Plan for Throwing
in the Towel".
Then I tested it with a one-year old battery (PC-680). It operated 2.25 hrs. before
the light went off. I thought this was pretty good.
I read 12v. at the battery immediately after test completion. That surprised me,
I had expected it to be lower...maybe 10 or 11 volts before the light would
go out.
But since the relay used was a 12v relay, I should have known a 12v relay would
drop out at 12 volts! I learned something most of you probably already knew!
Roger E.
Have a blessed Christmas!
Sent from Xfinity Connect Application
Message 3
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| Subject: | Re: Poor Man's Battery Capacity Tester |
A relay will drop out at a MUCH lower voltage than its pull in voltage, perhaps
one half or less. The battery tester relay drop out voltage is determined by
the transistor base circuit. Very soon after the battery circuit is opened,
the battery voltage starts to recover.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=486300#486300
Message 4
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| Subject: | Re: star washers |
Thanks. I now understand how a star washer under the nut is not in the
current path (a concept that had eluded me). As an aside, is there any
preference as to inside vs outside teeth on the washer?
On Fri, Dec 14, 2018, 06:02 Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com wrote:
> At 03:21 PM 12/13/2018, you wrote:
>
> Bob,
>
> In the recent weeks/months I "think" I saw what appear to me to be
> contradicting posts regarding the use of star washers.
>
> In one discussion I thought you said that star washers are never used in
> the current path on any certified airplanes. I think the reason was that
> they prevent the gas tight seal that will inhibit corrosion.
>
> Then, in a second discussion about bus bar construction using brass bars,
> I thought you said to be sure to use a star washer under each terminal.
>
> Could you clear up my confusions as to your approach to using star washer
s
> in an aircraft electrical system?=C3=82
>
> Thanks,
>
> Ken
>
>
> I spent a few minutes searching the term
> 'star washers' in the list archives. Generally,
> the use of star washers in the electrical path
> was discouraged. If used at all, they were
> for mechanical security (i.e. used under a nut).
>
> Couldn't look at all the search hits, but the
> few I found were consistent with the above.
>
> Just for grins, I checked a Brand-C parts
> catalog for battery contactor installations
> and found this image:
>
> [image: Emacs!]
>
> Here we see a lockwasher called out as part
> of the assembly. It's used under a nut that
> secures a terminal post to the 'wing' of
> an H6041 mil-style contactor. It doesn't
> have a numerical call-out meaning its not
> a cataloged spare part as far as Cessna
> is concerned. In fact, it's part of the
> contactor assembly as supplied by Cutler-Hammer
> (item 15). I'm not sure why the catalog
> illustrator chose to explode these parts
> off the as-supplied assembly. From an OEM
> service manual perspective, there was no
> reason to disassemble that stud.
>
> I also found some un-flagged star washers
> on vendor-supplied assemblies but in each
> case, the washer was under a nut . . . not
> part of the current path. As a factory
> policy, metal locknuts were the
> preferred anti-loosening technology for
> threaded fasteners.
>
> Electrical conductor pathways were made
> up with flat, clean and sometimes malleable
> conductors (crimped terminals) being brought
> together in gas-tight union with no
> intermediate enhancements. Sometimes a
> service manual would call out moisture
> proofing by painting the finished joint
> with some suitable coating . . . these
> were joints located out on structure subject
> to moisture incursion by drip, splash
> or condensation.
>
> B&C supplies star washers with the firewall
> forest-of-tabs ground block. All the circuit
> breaker manufacturers supply lock washers under
> the heads of their screws for terminal attachment.
> Again, these are intended to enhance mechanical
> integrity of the fastener outside the current
> pathway.
>
> An interesting aside . . .
>
> While cruising through the electrical installation
> data I found this image I had forgotten
> about . . .
>
> [image: Emacs!]
>
>
> Somewhere in my archives, I have a letter from
> the head-shed of single engine electrical systems
> rejecting my proposal for replacing the too-warm,
> panel dimming rheostats with a remotely mounted
> array of power transistors on heat sinks. This
> would have been about 1964 or thereabouts.
>
> He offered a litany of down-sides . . .
>
> A about 5 years later, the same idea cropped up
> across town on the light twins . . . a short
> time later, solid state dimming migrated into the
> single engine airplanes. We COULD have beat
> the twin engine line to this enhancement by
> several years. Oh well . . .
>
> Bob . . .
>
Message 5
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| Subject: | Re: star washers |
Inside or outside teeth do not matter as long as the teeth are under the nut.
But some outside star washer diameters are big enough so that the teeth are outside
of the nut circumference. For that reason, I prefer inside diameter teeth.
Speaking of lock washers, what we know as split ring lock washers are not really
lock washers at all. In fact, they allow fasteners to loosen sooner than
plain flat washers. There is a YouTube video by Nord Lock demonstrating this.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=486302#486302
Message 6
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| Subject: | Re: star washers |
At 11:00 AM 12/14/2018, you wrote:
>Thanks. I now understand how a star washer under the nut is not in
>the current path (a concept that had eluded me). As an aside, is
>there any preference as to inside vs outside teeth on the washer?
Given that the locking effect is really
just a 'friction enhancement' it stands
to reason that you want the greatest
practical torque moment as measured from
the center of rotation. It follows that
external teeth would offer the greatest
impediment to rotation.
Bob . . .
Message 7
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| Subject: | Re: star washers |
At 11:16 AM 12/14/2018, you wrote:
>
>Inside or outside teeth do not matter as long as the teeth are under
>the nut. But some outside star washer diameters are big enough so
>that the teeth are outside of the nut circumference. For that
>reason, I prefer inside diameter teeth.
> Speaking of lock washers, what we know as split ring lock washers
> are not really lock washers at all. In fact, they allow fasteners
> to loosen sooner than plain flat washers. There is a YouTube video
> by Nord Lock demonstrating this.
Many, if not most joints on electrical system
threaded fasteners are made up with only
flat washshers. Given aviation's preference
for fine pitch threads, taking a nut up to
design specs for torque probably makes it
as 'locked' as it will ever be.
The #1 antagonist to make up pressure is
rotational vibration imparted by the WIRE
crimped into the terminal under the nut.
This is why I've been partial to welding
cable for fat wires. VERY flexible and
minimal transmission of wire motion
to the threaded fastener.
Most of this is pretty academic. I've
opened joints that had been in service
for decades that took significant break-away
torque to move the fastener. This in spite
of no 'locking' feature on or under the nut.
I.e. the original installer was paying attention.
Bob . . .
Message 8
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| Subject: | Re: star washers |
Thanks. Although "academic" I have found the responses quite educational.
Ken
On Fri, Dec 14, 2018 at 9:39 AM Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 11:16 AM 12/14/2018, you wrote:
>
>
> Inside or outside teeth do not matter as long as the teeth are under the
> nut. But some outside star washer diameters are big enough so that the
> teeth are outside of the nut circumference. For that reason, I prefer
> inside diameter teeth.
> Speaking of lock washers, what we know as split ring lock washers are
> not really lock washers at all. In fact, they allow fasteners to loosen
> sooner than plain flat washers. There is a YouTube video by Nord Lock
> demonstrating this.
>
>
> Many, if not most joints on electrical system
> threaded fasteners are made up with only
> flat washshers. Given aviation's preference
> for fine pitch threads, taking a nut up to
> design specs for torque probably makes it
> as 'locked' as it will ever be.
>
> The #1 antagonist to make up pressure is
> rotational vibration imparted by the WIRE
> crimped into the terminal under the nut.
> This is why I've been partial to welding
> cable for fat wires. VERY flexible and
> minimal transmission of wire motion
> to the threaded fastener.
>
> Most of this is pretty academic. I've
> opened joints that had been in service
> for decades that took significant break-away
> torque to move the fastener. This in spite
> of no 'locking' feature on or under the nut.
>
> I.e. the original installer was paying attention.
>
> Bob . . .
>
Message 9
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| Subject: | Re: star washers |
Joe, What about the Rotax split washers that have both ends turned the same
direction?
Rick
On Fri, Dec 14, 2018 at 11:23 AM user9253 <fransew@gmail.com> wrote:
>
> Inside or outside teeth do not matter as long as the teeth are under the
> nut. But some outside star washer diameters are big enough so that the
> teeth are outside of the nut circumference. For that reason, I prefer
> inside diameter teeth.
> Speaking of lock washers, what we know as split ring lock washers are
> not really lock washers at all. In fact, they allow fasteners to loosen
> sooner than plain flat washers. There is a YouTube video by Nord Lock
> demonstrating this.
>
> --------
> Joe Gores
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=486302#486302
>
>
===========
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===========
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>
>
--
=9CBlessed are the cracked, for they shall let in the light.=9D
Groucho Marx
<http://www.goodreads.com/author/show/43244.Groucho_Marx>
Message 10
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| Subject: | Re: star washers |
> Joe, What about the Rotax split washers that have both ends turned the same direction?
I am not familiar with Rotax split washers. Where are they used on the Rotax?
The prop bolts on my Rotax have wedge-lock washers, no safety wire required. Matco
breaks also use wedge-lock washers.
When wedge-lock (Nord Lock) washers are used, it is actually harder to loosen a
fastener than to tighten it.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=486317#486317
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