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teamgrumman(at)YAHOO.COM
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 Posted: Wed Jun 16, 2010 10:39 am Post subject: Windshield |
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Sorry I got so condescending about windshield. No excuse.
By my count, I've installed 43 windshields since 1984. I've made a lot of mistakes and learned a lot of 'tricks' to getting the windshield square with the bow and getting the correct thickness of RTV.
I built my jig in 1984 in an attempt to simulate the location and shape of the windshield as installed. At the time, I was trying too imagine how they were done at the factory. I figured they had some sort of jig to put the windshield on the bow. The jig has gone through 2 revisions. mostly to provide better access to the underside. The version I have now guarantees an absolutely flat windshield bow to which the windshield is bonded. I have a set of blocks of wood to put under the forward edge of the windshield. These blocks locate and lock the forward edge such that when the windshield is set into position, it always falls on the same position at the windshield bow edge. The jig has dowels that locate the holes to be drilled at the lower corners. Before the holes are drilled, I tape a strip of .020 aluminum to the bow to simulate the thickness of the RTV when installed. The holes in the lower corners are drilled with the windshield in its final location. With those holes drilled, the windshield can be positioned and the two holes on top drilled. It's at this point that I use a feeler gauge the determine the gap between the windshield and bow. Where it's too tight (meaning: places where the forward edge of the windshield bow would project into the RTV making the RTV too thin, <.020, in that area), I mark the windshield so that any clamps in that area are not over tightened. I use two types of shims to space the windshield from the bow and maintain the spacing during assembly.
Shims I've tried:
(1) self sticking foam that compresses to approx .025 inches. I punched out dots using a hole punch. It worked, but left the dots showing. I did one like this.
(2) .020 safety wire clips at the forward edge of the bow. It worked, but left little holes when I removed the clips. The holes couldn't be filled with RV. I did two like this.
(3) I made a spacer, .050 thick, the shape of the windshield bow, attached to the bow through the holes used to hold the double bow seal on, that stuck up .030 above the aft edge of the bow (same surface the seal uses).
The idea here was to hold the windshield .030 away from the bow uniformly from one corner to the other. At first, this sounded like a great idea (it wouldn't work with an LP Aero windshield because
there is no lip at the bow). The biggest problem was: the bows are not all the same shape. I used this for 4 or 5 windshields before it became obvious this was not practical. I kept filing and adjusting the shape to get them to fit.
(4) Then, I made little "L" shaped shims that can be placed under the aft edge of the windshield between the bow and windshield. The long side is flush with the windshield bow face.
The long side is 1 inch long and is .063 inches thick. The short side is .050 inches long and several thicknesses. I have 10 sets in sizes from .025 to .040 inches.
These work pretty well. At first, I clamped them into place. Then, screws through the holes that hold the double bead seal to the windshield bow. Then tape. All work pretty well.
The gap can be filled with RTV after the shim is removed.
(5) My favorite is just too simple to believe. Again, using the holes that attach the double bead seal to the windshield bow, I use a #6 screw onto which I put a wide area #10 washer plus a wide area 5/16 washer.
I'd use just the wide area 5/16 washer but the hole is too big; the #6 screw won't hold it by itself. With the windshield in place, I can adjust the gap between the bow and windshield with the washers tightened against the bow.
When bonding, I tighten the clamps, located at the shims, until the washer just shows through the RTV and just touches the windshield. (NA for LP Aero windshields)
After the RTV is applied to the windshield bonding area, the windshield can then be set into place and located over the dowels on the bottom corners, the holes line up on top for the top two screws and special washers. Clamps are applied until I get either the "L" shim showing on the edge of the windshield or the washer showing through the windshield. At this point, I know the gap at the forward edge of the bow is about .020 inches. The gap is kept as uniform as possible. After it's all done being bonded, I let the windshield sit for a week before moving it. The maintenance manual says 3 days but I've found the RTV to not be totally cured at 3 days.
The windshield in the $80,000 Cheetah was done in 2003 when John Rodgers owned the plane. It has always been parked outside. It's a C.Bailey windshield. The bond is still like new.
I've attached two pics of the jig after bonding the windshield. In the background you can see my work bench on wheels. I keep all the tools I regularly use on this bench. I also have safety wire, nylon ties, gloves, lube, and rulers on that table. In the upper left you can see a couple of wheel pants for testing.
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flyadive(at)gmail.com
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| Posted: Thu Jun 17, 2010 4:28 am Post subject: Windshield |
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Gary:
What's the apology for? You did not hurt my feelings.
I was once condescended, but now I am convince.
I have not had the time to read and digest your posts, but I will.
After all I have only done 2 windows and I do respect my elders 
I am impressed with your jig - Working out the size is quite an
accomplishment. I would have like to have been there as you designed
and manufactured it.
Anyway, whos feeling did you think you hurt? Hell, let them grow some
thicker skin.
Barry
"Chop'd Liver"
On Wed, Jun 16, 2010 at 2:28 PM, Gary Vogt <teamgrumman(at)yahoo.com> wrote:
| Quote: | Sorry I got so condescending about windshield. No excuse.
By my count, I've installed 43 windshields since 1984. I've made a lot of
mistakes and learned a lot of 'tricks' to getting the windshield square with
the bow and getting the correct thickness of RTV.
I built my jig in 1984 in an attempt to simulate the location and shape of
the windshield as installed. At the time, I was trying too imagine how they
were done at the factory. I figured they had some sort of jig to put the
windshield on the bow. The jig has gone through 2 revisions. mostly to
provide better access to the underside. The version I have now guarantees
an absolutely flat windshield bow to which the windshield is bonded. I have
a set of blocks of wood to put under the forward edge of the windshield.
These blocks locate and lock the forward edge such that when the windshield
is set into position, it always falls on the same position at the windshield
bow edge. The jig has dowels that locate the holes to be drilled at the
lower corners. Before the holes are drilled, I tape a strip of .020
aluminum to the bow to simulate the thickness of the RTV when installed.
The holes in the lower corners are drilled with the windshield in its final
location. With those holes drilled, the windshield can be positioned and
the two holes on top drilled. It's at this point that I use a feeler gauge
the determine the gap between the windshield and bow. Where it's too tight
(meaning: places where the forward edge of the windshield bow would project
into the RTV making the RTV too thin, <.020, in that area), I mark the
windshield so that any clamps in that area are not over tightened. I use
two types of shims to space the windshield from the bow and maintain the
spacing during assembly.
Shims I've tried:
(1) self sticking foam that compresses to approx .025 inches. I punched
out dots using a hole punch. It worked, but left the dots showing. I did
one like this.
(2) .020 safety wire clips at the forward edge of the bow. It worked, but
left little holes when I removed the clips. The holes couldn't be filled
with RV. I did two like this.
(3) I made a spacer, .050 thick, the shape of the windshield bow, attached
to the bow through the holes used to hold the double bow seal on, that stuck
up .030 above the aft edge of the bow (same surface the seal uses).
The idea here was to hold the windshield .030 away from the bow
uniformly from one corner to the other. At first, this sounded like a great
idea (it wouldn't work with an LP Aero windshield because
there is no lip at the bow). The biggest problem was: the bows are
not all the same shape. I used this for 4 or 5 windshields before it became
obvious this was not practical. I kept filing and adjusting the shape to
get them to fit.
(4) Then, I made little "L" shaped shims that can be placed under the aft
edge of the windshield between the bow and windshield. The long side is
flush with the windshield bow face.
The long side is 1 inch long and is .063 inches thick. The short side
is .050 inches long and several thicknesses. I have 10 sets in sizes
from .025 to .040 inches.
These work pretty well. At first, I clamped them into place. Then,
screws through the holes that hold the double bead seal to the windshield
bow. Then tape. All work pretty well.
The gap can be filled with RTV after the shim is removed.
(5) My favorite is just too simple to believe. Again, using the holes that
attach the double bead seal to the windshield bow, I use a #6 screw onto
which I put a wide area #10 washer plus a wide area 5/16 washer.
I'd use just the wide area 5/16 washer but the hole is too big; the
#6 screw won't hold it by itself. With the windshield in place, I can
adjust the gap between the bow and windshield with the washers tightened
against the bow.
When bonding, I tighten the clamps, located at the shims, until the
washer just shows through the RTV and just touches the windshield. (NA
for LP Aero windshields)
After the RTV is applied to the windshield bonding area, the windshield can
then be set into place and located over the dowels on the bottom corners,
the holes line up on top for the top two screws and special washers. Clamps
are applied until I get either the "L" shim showing on the edge of the
windshield or the washer showing through the windshield. At this point, I
know the gap at the forward edge of the bow is about .020 inches. The gap
is kept as uniform as possible. After it's all done being bonded, I let the
windshield sit for a week before moving it. The maintenance manual says 3
days but I've found the RTV to not be totally cured at 3 days.
The windshield in the $80,000 Cheetah was done in 2003 when John Rodgers
owned the plane. It has always been parked outside. It's a C.Bailey
windshield. The bond is still like new.
I've attached two pics of the jig after bonding the windshield. In the
background you can see my work bench on wheels. I keep all the tools I
regularly use on this bench. I also have safety wire, nylon ties, gloves,
lube, and rulers on that table. In the upper left you can see a couple of
wheel pants for testing.
|
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teamgrumman(at)YAHOO.COM
Guest
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| Posted: Thu Jun 17, 2010 11:07 am Post subject: Windshield |
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It's been one of those weeks. Seems like everyone wants their plane yesterday, the parts I get are either poorly manufactured, don't fit or both, the workmanship of some mechanics is appalling, and I am constantly amazed how plane owners accept 'good enough.'
In 1984, a few days after I bought my first Cheetah (which had been sitting in the desert sun for 2 years), a 77 Cheetah with 714 TTSN, I went to the local FBO to find someone to do an annual. I knew nothing about planes. In the FBO, two A&Ps were installing an O360 into a Cessna 172. I watched while preformed aluminum parts, included in the STC, were being bent and deformed to force them to fit. Over the next hour or so, I watched them forcing parts together that simply did not fit. Their reasoning was, "the owner will never look under the cowling." By 1984, I had built 2 hot rods and restored a 69 Corvette and a 66 Chevy II Super Sport. It was then I decided that I would be the only one working on my plane. I found a mentor I could trust and began my tutelage.
I've turned away two potential customers in the last 2 months that actually asked for me to do half-assed work and just get it signed off. Their logic: my regular mechanic does it all the time but he's busy right now. So can you do it?
Windshield: I've heard about installing windshields in the plane. I've never seen how that could be done. Just getting the windshield into the coving the windshield needs to be warped a bit. To keep the bow square with the canopy, it would need to be clamped to the canopy with 1/4 inch spacers to get the proper gap. That means there would be no way to clamp the windshield in place. The windshield would need to be held in place with the mounting screws. That being the case, how is the proper gap held around the windshield bow? Where does the excess adhesive go?
Rear windows: Getting the old sealant out sometimes requires sanding it out. That means there is a whole lot of bare metal on the mounting surface. Now, two things, either the old sealant is completely removed by sanding and new strip caulk or RTV is applied on the bare metal, or strip calk or RTV is applied over the old sealant. When I install rear windows, I sand out all of the old sealant, alodine, prime, and paint the mounting surface with Imrom. Then I let it sit for 7 days to properly cross-link before installing windows.
Canopy windows: I've seen it recommended to use the foam tape on the canopy windows. There is just no way to install the canopy windows with foam tape around the perimeter without tearing the foam tape to shreds. There is a reason the factory used the felt tape: IT ALLOWS THE WINDOW TO SLIDE INTO PLACE. The canopy windows are designed to leak. They are designed to leak to the outside.
1348: cabin prepared for a new headliner
1334: typical avionics wiring. Nice huh. The glide slope receiver was mounted on the bottom of the glare shield.
From: FLYaDIVE <flyadive(at)gmail.com>
To: teamgrumman-list(at)matronics.com
Sent: Thu, June 17, 2010 5:20:20 AM
Subject: Re: Windshield
--> TeamGrumman-List message posted by: FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)>
Gary:
What's the apology for? You did not hurt my feelings.
I was once condescended, but now I am convince.
I have not had the time to read and digest your posts, but I will.
After all I have only done 2 windows and I do respect my elders
I am impressed with your jig - Working out the size is quite an
accomplishment. I would have like to have been there as you designed
and manufactured it.
Anyway, whos feeling did you think you hurt? Hell, let them grow some
thicker skin.
Barry
"Chop'd Liver"
On Wed, Jun 16, 2010 at 2:28 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:
[quote] Sorry I got so condescending about windshield. No excuse.
By my count, I've installed 43 windshields since 1984. I've made a lot of
mistakes and learned a lot of 'tricks' to getting the windshield square with
the bow and getting the correct thickness of RTV.
I built my jig in 1984 in an attempt to simulate the location and shape of
the windshield as installed. At the time, I was trying too imagine how they
were done at the factory. I figured they had some sort of jig to put the
windshield on the bow. The jig has gone through 2 revisions. mostly to
provide better access to the underside. The version I have now guarantees
an absolutely flat windshield bow to which the windshield is bonded. I have
a set of blocks of wood to put under the forward edge of the windshield.
These blocks locate and lock the forward edge such that when the windshield
is set into position, it always falls on the same position at the windshield
bow edge. The jig has dowels that locate the holes to be drilled at the
lower corners. Before the holes are drilled, I tape a strip of .020
aluminum to the bow to simulate the thickness of the RTV when installed.
The holes in the lower corners are drilled with the windshield in its final
location. With those holes drilled, the windshield can be positioned and
the two holes on top drilled. It's at this point that I use a feeler gauge
the determine the gap between the windshield and bow. Where it's too tight
(meaning: places where the forward edge of the windshield bow would project
into the RTV making the RTV too thin, <.020, in that area), I mark the
windshield so that any clamps in that area are not over tightened. I use
two types of shims to space the windshield from the bow and maintain the
spacing during assembly.
Shims I've tried:
(1) self sticking foam that compresses to approx .025 inches. I punched
out dots using a hole punch. It worked, but left the dots showing. I did
one like this.
(2) .020 safety wire clips at the forward edge of the bow. It worked, but
left little holes when I removed the clips. The holes couldn't be filled
with RV. I did two like this.
(3) I made a spacer, .050 thick, the shape of the windshield bow, attached
to the bow through the holes used to hold the double bow seal on, that stuck
up .030 above the aft edge of the bow (same surface the seal uses).
The idea here was to hold the windshield .030 away from the bow
uniformly from one corner to the other. At first, this sounded like a great
idea (it wouldn't work with an LP Aero windshield because
there is no lip at the bow). The biggest problem was: the bows are
not all the same shape. I used this for 4 or 5 windshields before it became
obvious this was not practical. I kept filing and adjusting the shape to
get them to fit.
(4) Then, I made little "L" shaped shims that can be placed under the aft
edge of the windshield between the bow and windshield. The long side is
flush with the windshield bow face.
The long side is 1 inch long and is .063 inches thick. The short side
is .050 inches long and several thicknesses. I have 10 sets in sizes
from .025 to .040 inches.
These work pretty well. At first, I clamped them into place. Then,
screws through the holes that hold the double bead seal to the windshield
bow. Then tape. All work pretty well.
The gap can be filled with RTV after the shim is removed.
(5) My favorite is just too simple to believe. Again, using the holes that
attach the double bead seal to the windshield bow, I use a #6 screw onto
which I put a wide area #10 washer plus a wide area 5/16 washer.
I'd use just the wide area 5/16 washer but the hole is too big; the
#6 screw won't hold it by itself. With the windshield in place, I can
adjust the gap between the bow and windshield with the washers tightened
against the bow.
When bonding, I tighten the clamps, located at the shims, until the
washer just shows through the RTV and just touches the windshield. (NA
for LP Aero windshields)
After the RTV is applied to the windshield bonding area, the windshield can
then be set into place and located over the dowels on the bottom corners,
the holes line up on top for the top two screws and special washers. Clamps
are applied until I get either the "L" shim showing on the edge of the
windshield or the washer showing through the windshield. At this point, I
know the gap at the forward edge of the bow is about .020 inches. The gap
is kept as uniform as possible. After it's all done being bonded, I let the
windshield sit for a week before moving it. The maintenance manual says 3
days but I've found the RTV to not be totally cured at 3 days.
The windshield in the $80,000 Cheetah was done in 2003 when John Rodgers
owned the plane. It has always been parked outside. It's a C.Bailey
windshield. The bond is still like new.
I've attached
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pitts_pilot(at)bellsouth.
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| Posted: Thu Jun 17, 2010 11:38 am Post subject: Windshield |
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flyv35b(at)minetfiber.com
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| Posted: Fri Jun 18, 2010 5:54 am Post subject: Windshield |
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That's probably the worst wiring I have ever seen!
Cliff
[quote] ---
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grumpyparts
Joined: 28 Jan 2009
Posts: 65
Location: EGHH
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| Posted: Wed Jun 23, 2010 3:20 pm Post subject: Re: Windshield |
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Gary said
"I built my jig in 1984 in an attempt to simulate the location and shape of
the windshield as installed. At the time, I was trying too imagine how they
were done at the factory. I figured they had some sort of jig to put the
windshield on the bow."
Yes they did, check out the picture of it on this thread on the TeamGrumman Forum site
http://forums.matronics.com/viewtopic.php?t=71876
Assume that may be the email listing doesn't attach the pictures posted on the forum.
Ian
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teamgrumman(at)YAHOO.COM
Guest
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| Posted: Wed Jun 23, 2010 7:49 pm Post subject: Windshield |
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Look at the fixture in the foreground. That looks very similar to the piece I made to space the windshield. Maybe I gave up on that too early.
From: grumpyparts <i.r.m(at)btinternet.com>
To: teamgrumman-list(at)matronics.com
Sent: Wed, June 23, 2010 4:20:47 PM
Subject: Re: Windshield
--> TeamGrumman-List message posted by: "grumpyparts" <i.r.m(at)btinternet.com (i.r.m(at)btinternet.com)>
Gary said
"I built my jig in 1984 in an attempt to simulate the location and shape of
the windshield as installed. At the time, I was trying too imagine how they
were done at the factory. I figured they had some sort of jig to put the
windshield on the bow."
Yes they did, check out the picture of it on this thread on the TeamGrumman Forum site
http://forums.matronics.com/viewtopic.php?t=71876
Assume that may be the email listing doesn't attach the pictures posted on the forum.
Ian
Read this topic online here:
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