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Full Lexan Doors

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Posted

Hi Guys,

I was out flying this morning after synchronizing my carbs and adjusting for the warmer weather and she was running great. A friend in the circuit with a PA22 described my climb out like I was riding an elevator. :)

While flying I noticed that it would sure be nice to get rid of the aluminum bottom door half and it just so happens that I picked up some .060 lexan the other day.

I'm wondering if I should make the doors all one piece of lexan or a two piece like someone on the forums here mentioned a while back. Also, if anyone has any pictures of the doors with the full lexan that would be a great help. Thx

Darcy

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Posted

While on the topic of lexan, I would sure like some input on how to make windows that don't crack out. I have tried .093, .060, in both standard and chemical resistant varieties. I've melted the rivet holes with a soldering iron, drilled them with a special plastics drill, and my last attempt used oversize holes (melted with soldering iron) and screws with rubber washers under the heads. So far, it has been a frustrating annual replacement chore. Windshields last a little better, but still not great.

Tips and Tricks?

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Posted

While on the topic of lexan, I would sure like some input on how to make windows that don't crack out. I have tried .093, .060, in both standard and chemical resistant varieties. I've melted the rivet holes with a soldering iron, drilled them with a special plastics drill, and my last attempt used oversize holes (melted with soldering iron) and screws with rubber washers under the heads. So far, it has been a frustrating annual replacement chore. Windshields last a little better, but still not great.

Tips and Tricks?

A builder with more experience than me might give you a better answer.

Are you sure about the quality of your Lexan? The reason I asked is because we cold-bent Lexan in a vise to 90 degrees without cracking it when I was in AMT school. We were also told that if you heated Lexan it would have about the same cracking qualities as Plexiglass. I never tested that theory. Bubble door Lexan is made by heating - don't know of any cracking.

We put the round vents in a Cessna window outside in 30 degrees, or less, by using a dremel tool grinder, with no cracking.

Oversize holes and rubber or soft plastic (cant remember alphabet name) are standard, and back off 1/2 to 1 turn after tightening slightly.

Guess you have to get a very accurate fit, and allow for expansion / vibration. Sorry I couldn't be more help.

ED in MO

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Posted

I tried to do mine in one piece.. It was a bit of a disaster. unless you make some sort of a mold, heat the crap out of it and get it to form, you wont be able to lay it on in one piece.

To get away from the cracking on the doors, I started using SS sheet metal screws so I could really control how tight they are. I use over sixe holes, and a plastic washer under the head. Make replacement a snap when the drains on the wing tank decide to leak and the gas hits the lexan! I just replaced my passenger door lexan in about an hour start to finish.

:BC:

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Posted

I replaced my Model III windshield/skylight (.060) and did some research at the time. GE, the manufacturer of Lexan brand polycarbonate says controlled and uniform heating of the entire polycarbonate sheet is a critical factor for hot bending, as slow heating rates will balance out hot spots and allow the sheet edges to reach the required forming temperature. After attaching to the butt ribs, on a suggestion from a fellow Avid builder, I hooked a 1000w halogen work light to the headrack inside as a heat lamp and my twin halogen stand positioned outside so as to shine not only on the bend area but to warm the entire sheet for a period before getting started.

So I think this approach has merit and, like super smooth edges, may help reduce future crazing. Time will tell but I figure it can't hurt. I also used a heat gun on low setting for extra stress relief while forming the acute, compound curve in the pre-warmed sheet. Blasting the acute curves only with high heat certainly makes the bending process easier but, unless you heat the entire sheet (or as much as possible around the target work area), you have not done everything you can do to help reduce crazing. Good info about hot and cold bending, tips working with poly etc. can be found HERE.

Recommended cleaning agents are noted on the Lexan protective film, see attachment. Other cleaning agents that have been found to be compatible with polycarbonate under laboratory conditions include Brillianize and Windex with Ammonia D, and mild (low-alkaline) Liquid soap or detergents including Dawn and Palmolive. Maintain with Cleaner/polishers compatible with polycarbonate: Meguiars Mirror Glaze Clear Plastic Polish, Cleaner & Detailer, Novus Plastics Polish #1, #2 and Plexus Plastic Cleaner and Polish. I can vouch for Plexus, anti-static to repel dust and dirt, works well on acrylic too.

Tip: If you want to test a cleaner/solvent, cut a few thin strips of scrap Lexan. Ever notice how you can fold polycarbonate back on itself without it breaking or cracking? Now dip it in some solvent, as briefly as you can. Wipe it off and try to bend it over on itself. If the cleaner/solvent is incompatible and induces chemical stress, instead of bending the strip will snap like hard plastic.

post-53-13376219217354_thumb.jpg

post-53-13376219397425_thumb.jpg

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Posted

Here is what I use to clean the windshield (and the blades of my propeller)

pliz_fee_du_logis.jpg

it's very good to clean the "mosquito" even if they are dry from the last flight

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Posted (edited)

We use this acrylic with real good results on the other projects around....like drag cars. It seems to resist crazing from UV and is pretty tough material. Pretty reasonable prices too.

http://www.eplastics.com/Plastic/Plexiglass_Acrylic_Sheet_Clear

You said "Acrylic" - Think that is your problem: Lexan is not acrylic, Plexiglass is. Lexan is Polycarbonate.

Put a scrap piece in a vise, and try to bend it 90 degrees without heating - if it breaks, it is acrylic and not Lexan.

ED in MO

Edited by Ed In Missouri

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Posted (edited)

I installed full Lexon doors which are two pieces and made my skylight and windsheild in two seperate pieces also. Still dealing with cracking problems though.

post-56-13376546115929_thumb.jpg

Edited by Bandit

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Posted

A friend of mine sent one of the door frames of his Avid Mk IV to LP Aero-Plastics and they made a mold for solid plexiglass bubble doors.

They are available from them.

(Bad photo, I know, but it's all I have.)

post-36-13376558281894_thumb.jpg

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Posted

A friend of mine sent one of the door frames of his Avid Mk IV to LP Aero-Plastics and they made a mold for solid plexiglass bubble doors.

They are available from them.

Will these fit the "B" model by chance?

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Posted

Thanks for the replies, i'll be working on the doors today or more likely tomorrow and i'll post some pics.

Darcy

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Posted

Will these fit the "B" model by chance?

I don't know what models they would fit, other than the Mark IV, sorry.

I just spoke with Brett (Airdale) today and found out he is a dealer for LP Aeroplastics, too. He may know what they would fit.

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Posted

Thanks for the info I will give Brett a call, I need to order some wing tanks anyways

-Robert-

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Posted

I installed full Lexon doors which are two pieces and made my skylight and windsheild in two seperate pieces also. Still dealing with cracking problems though.

Bandit could you please post up some pics and info how you transitioned the windshield and sky light together, I'm wanting to use clear for the front and smoke gray on top so I will need to do two piece as well.

also I'm thinking of attaching it all with small machine screws and nylock nuts so I can adjust the amount of pressure it has anyone else done it this way if so what size of screws and how long did you use

Thanks Robert

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Posted

Bandit could you please post up some pics and info how you transitioned the windshield and sky light together, I'm wanting to use clear for the front and smoke gray on top so I will need to do two piece as well.

also I'm thinking of attaching it all with small machine screws and nylock nuts so I can adjust the amount of pressure it has anyone else done it this way if so what size of screws and how long did you use

Thanks Robert

One of my books says to use 8-32 machine screws with rubber under steel washers or nylon washers. Make holes at least 1/16th oversize and back off screws one turn after tightening to just touch washer.

Books show an aluminum angle riveted to crosstubes and both pieces bolted to it, with a flat or slightly bent aluminum strip on top. The rear is about the same, except you do not bolt your turtledeck.

Whatever you can dream up will probably work.

ED in MO

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Posted

Hi Guys,

I was out flying this morning after synchronizing my carbs and adjusting for the warmer weather and she was running great. A friend in the circuit with a PA22 described my climb out like I was riding an elevator. :)

While flying I noticed that it would sure be nice to get rid of the aluminum bottom door half and it just so happens that I picked up some .060 lexan the other day.

I'm wondering if I should make the doors all one piece of lexan or a two piece like someone on the forums here mentioned a while back. Also, if anyone has any pictures of the doors with the full lexan that would be a great help. Thx

Darcy

Think it might be easier and cheaper to just replace the lower half with Lexan. You could add an angle inside and a strip outside of the edges where they meet if necessary. Later on, if you replace, you could do half, or go one piece.

ED in MO

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Posted

Sorry it took forever to get an update to this post. I tried to make the full lexan doors in one piece using a mixture of pressure and heat to form the door over the frame. That was a fail. So I made the doors in two pieces.

I took the doors off and cleaned then primed and painted them. Then using the old lexan and lower door half as rough templates drew the outlines on the lexan. The .060 cut easily with some large smooth tin snips I have for making nice straight cuts in aluminum. A regular file and emery cloth helped smooth the edges and make a nice radius on everything so hopefully there are no sharp areas for a stress crack to start. I also bought a special $9 bit for drilling the holes in the lexan for the rivets. It was just oversize of the rivets and should give a expansion and contraction buffer. Now I just need to hide where the old metal door half was rubbing on the cowling. Anyways, here's the final product installed on the pilot side. Its so clear compared to the old glass that you can barely tell its there. Its an amazing view sitting in the plane looking down at the wheel and everything below.

Darcy

post-263-1346126285584_thumb.jpg

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Posted

Darcy, Very nice :buttrock: thats one of the beauty's of these planes is the ability to see everywhere. I'm planning to do my doors soon as well. One question- what is the small round thing on the center bar near the front of the door? I have the same doors but do not have this. should I?

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Posted

Those clear doors sure do look great, nice job!

"small round thing on the center bar near the front of the door?" is a magnet to hold door open. You can see Darcy has no door lift struts installed. I've seen clips used before, never magnets, how's it work Darcy?

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Posted

The magnets work great. It takes a good tug to get them to release and they hold the door at maximum open. I've been contemplating putting the struts on but that takes effort.

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Posted

The magnets work great. It takes a good tug to get them to release and they hold the door at maximum open. I've been contemplating putting the struts on but that takes effort.

RE MAGNETS: Amazing how much we can learn from each other. And,,what does it stick to - steel on spar? Thanks.

NOW, if we could just figure out how, or get AKFLYER to fix it, we could enlarge the photo by your handle and get a better look at that nice bird.......same goes for other's photos.....would be nice to see them enlarged.

ED in MO

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Posted

There's a magnet attached to the spar that it grabs when you open the door. Its great cause it works right through the wing covers. I'll get a better picture of it open and closed for you.

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Posted

There's a magnet attached to the spar that it grabs when you open the door. Its great cause it works right through the wing covers. I'll get a better picture of it open and closed for you.

Please give us more details about the kind of magnets, where purchased, and how it is attached to spar. Much easier to copy success than stumble around trying new things on your own.

Thanks,

ED in MO

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