Doing Windows...Some Questions for those that have

[scottfromiowa]

Going to replace side windows at annual and have some questions:

Going with Great Lakes Aero, but wondering if most did .187 or .250 replacement?  I was leaning toward .187 in the solar grey.  Anyone do the rear windows in the darker grey tint?  How did it come out?  Photos?

How much Silicone and what brand do you recommend for pilot/door and l/r rear windows in an M20E?

What size drill bit (make/model where?)  What type hardware?  Where did you buy?

Any key do's and don'ts?

I'm pulling interior and re-painting plastic and pulling head-liner for replacement re-glue of cloth.  Any do's and don'ts here too?

Photos of process or direction where they are MUCH APPRECIATED.

[aerobat95]

I am pretty sure my rear windows are the darker tint.  We like them a bunch.  I cant speak as to how the install went as it came that way when I bought the plane.  Good luck with the install sounds like it should be fun.

[N601RX]

PM Sent

http://www.mooneyspace.com/index.cfm?mainaction=posts&forumid=2&threadid=2085

It will take a lot of MEK and scrubbing to get the old headliner and window glue off.

 

[scottfromiowa]

Thanks guys.

[carusoam]

Scott,

Check with the guys selling the windows.  I purchased the proper drill and some other supplies directly from them.  I also sent them a piece of window to determine what color it actually was.  The coke bottle green had turned greyish and I was no longer sure that they were original. 

From my M20C experience...

I went the other way for a test...I bought an extra window with no tint.  I like the brightness and ease of sightseeing through the clear window.  Unfortunately, solar energy passes through clear windows very easily.

I settled for exact replacements: color, tint level and thickness....

I think the gray looks more modern.  If your changing everything all at once...

Best regards,

-a-

[scottfromiowa]

Thanks Carusoam.  Good stuff.

[Clarence]

Hi Scott

I replaced all of my side windows with solar grey 1/4" thick.  I machined a step in the edge of the widows so that they now fit flush with the exterior skin.  It was alot of work but the effect is quite nice. 

I used PRC window sealant as per the Maintenance manual.  It is a bit messy and will take 2 people to install them if yours are held in with screws and nuts.  All of my skins were dimple counter sunk so I had to machine countersink the window to accept the dimpled skin and screw

I found that drilling the window is easier when I used Johnson paste floor wax to lubricate the drill bits and counter sinks and reamers.

Good luck,

Clarence

 

 

 

[MARZ]

Scott - take lots O pictures - Hopefully I'll be doing mine before year end.

[Hank]

Just be careful drilling. Plexi will crack if you try to go through it too quickly [apeed of advance, not RPM] and/or if it is not supported directly underneath the hole. Use scrap lumber and move it to every hole. I can show you a photo of what happens with ~1/8" gap under curved plexi--the crack is about an inch long.  :-(  But it's a wingtip light cover, on the bottom, so I just glued it up and live with it. You don't want that on your windows!

[N601RX]

If you get a bit that has been ground to cut plexiglass it will feed itself into the material very slowly and you will not have any problem. These are available from the window manufactures or Skygeek.  The old timers would just take a regular bit and dull it up by drilling into concrete for a couple of seconds.  I've tried both and like the purchased bits better.  I did a few practice holes on my old windows before drilling on the new ones.  With the purchased bits, I was able to repeatedly drill a hole within 1/8 inch of the edge with no cracks.

[N601RX]

double post

[scottfromiowa]

I plan to take copius photos and maybe some video of the process.  The countersinking is the part that makes me nervous...Thanks for the tips.  I like the wax idea along with the proper drill bits, tape stainless screws etc...

[thinwing]

for the drilling of plexi...get a unibit step drill...these will safely drill through with out risk of cracking...also plexi is much more brittle an easier to crack while cold...warm up your work space to at least 70 f...windows should really be a summer job ,IMO...the largest plexi job Ive done was a Bell 47 bubble....3k that you really didnt want to mistreat..kpc

[thinwing]

oh ..and counter sinking aluminum skin is no problem...prob the easiest part of job...use a 45 degree countersink bit turning slowly with an adj speed hand or air drill..kpc

[thinwing]

and the best back support for plexi is a piece of duct tape...prevents splintering..kpc

[jetdriven]

I thought on thin guage alumunum you use a dimpler?

Quote: thinwing

oh ..and counter sinking aluminum skin is no problem...prob the easiest part of job...use a 45 degree countersink bit turning slowly with an adj speed hand or air drill..kpc

[Guest]

 

Scottfromiowa

I did my side grey windows a while back and it's no big deal, shouldn't take more than a day. I marked the location of the first whole while the window was in place then drilled the rest in place installed the screws as i progressed. As far as sealant I'd never use silicon, I myself used pro seal. If you intend on any counter sinking I'd counter sink the windows and dimple the skin. Since I also build experimental aircraft ( currently a RV7 ) I have a very nice set of custome made plexiglass  drill bits  your more than welcome to borrow.  After the plexiglas is warm  I've drilled many many windows with never a crack. Anyway if interested just PM me, good luck.

 

[MooneyMitch]

"Perhaps countersinking the plexiglass was also just another example of his quest for perfection?"

I did countersink the windows to match the countersunk holes in the aluminum skin.  I believe that was advised with the installations instructions from the window manufacturer.  So far so good, after 5 years of new windows being installed.

[Ned Gravel]

For those of you that might not know Clarence I can tell you he is a PERFECTIONIST!!  He is a cook who eats his own cooking and I am glad he looks after my Mooney.

I would venture to guess that countersinking the screw holes had more do with reducing drag than probably anything else. So did bevelling the edges of the plexiglas windows themselves (to make a seamless connection to the window frame along the fuselage).  We all know of a few MSC types that are the same way when it comes to finding more efficiencies in the Mooney airframe.

After all, these are Mooneys and they are comparitavely efficient and relatively fast, are they (k)not?

[jetdriven]

Get some .040 ABS plastic sheet stock, some ABS cement, and some lightweight fiberglass cloth. Every piece of plastic with a crack, or a pulled through screw hole gets repaired and doubled up either with fiberglass or abs pieces from behind.  You can spend a few hours at the house and really fix it up for about 20$.  Generally, repair flat areas such as screw holes with a small piece of .040.   Curved areas or long cracks get fixed with fiberglass cloth. Paint the crack with ABS glue, press a strip of fiberglass cloth into the glue, and then cover with ABS cement. Simply glue on small patches of .040.   After an hour or so, carefully trim away any squeezed out glue on the front side with an X-acto knife as it is still soft. Or squeeze it into the crack to fill.  After drying overnight the plastic is rigid, permanently fixed, and is done right.  I even repaired my glareshield this way.

After painting (Jim R has a great thread on that), repairs are invisible and the plastic isnt cracked up and falling apart.  Screw your interior screws into balsa, paint the heads, and bake in oven 300 degrees for a couple hours for the final killer polished look.  Since you are in DIY mode with windows, freshening up the plastic is going to make your Mooney look awesome.

Quote: scottfromiowa

I'm pulling interior and re-painting plastic and pulling head-liner for replacement re-glue of cloth.  Any do's and don'ts here too?

Photos of process or direction where they are MUCH APPRECIATED.

[scottfromiowa]

Thanks for all the excellent information.  This is awesome.  I have already taken Mike up on his kind offer to lend me his bits for the project that will be completed in a heated hanger during annual.  Good advise on having the plexi warm when working.  Will also use 3M tape front and back.  I'm a visual learner and while the suggestions on labeling the trim piece connectors and process for countersinking  as explained sound straight forward...I have ZERO experience (besides cutting out a window in a tub enclosure on our first house...ledge was a great time) I am a novice on plexi.

If the screw goes through the skin then through the plexi why/how am I countersinking the plexi?  Seriously I am not seeing what everybody means here.

Can somebody give me the exact brand and where to buy and quantity I will need for side windows on sealer?

How long and what type of stainless screws do I need for .250 glass?  I believe they are 100 degree counter sunk screws.  Is the 100 degree the diameter of the screw or having to do with the head?

Any special prayers to be uttered before beginning the task?  (I will have an ANP there, but delicate and finesse are not Iowa gentetic traits) 

Thanks again for the feedback.  If someone has a photo/s of the counter-sinking process I'd love to see it.  I like the idea of drilling one attaching and drilling remainder in place.  Suggestion was to do sides first.

Round/reduce corners with belt sander or dremmel was a previous suggestion.

I wonder what the insulation will look like once I get in there?  Anyone replace theirs while all was out?  Suggestions there for sources?

[scottfromiowa]

Byron:

That is EXACTLY the kind of help I was looking for on plastic.  Thank you much.

[carusoam]

I bought the drill and the countersink bit from the window supplier.  They were a few dollars each and well worth the price. 

First, I tried my skill using ordinary tools on the old window.  The polymer cracks and splits when the drill bites as it exits the backside.  Bought the proper drill bit and turned my amateur skills proffesional.

Second, I originally thought I could do without the countersink.  Bought the proper countersink and turned my amateur skills even more professional.

Additional: Spotting the hole centers as perfectly as possible was a challenge.  Trimming excess polymer off the edge of the windows was an unexpected chore.

The aluminum skins are already dimpled with the perfect countersink for machine screws.

Clarence IS the man for machining the edges.

Best regards,

-a-

[Clarence]

I guess I should have been more clear in posting my reply.  My 1966 E model has all of the windows held in with countersunk  100 degree countersunk screws, not 82 or 90 which are industrial angles.  In this vintage Mooney dimpled the skins and coutersunk the plexiglass to accept the screw and dimpled skin, unlike later versions where most exterior screws are round or pan head style and are some what slower, and still later version where the windows are held in place with clips on the inside of the window.  I used MS 24693 series srcews which are the replacement for the old AN507 with just engough torque to keep them from spinning.  Over torquing distorts the skin and streesses the plexiglass.

The hole in the plexiglass is a few number drill sizes larger than the screw shank,  to allow clearence for the screw shank, most cracks I have seen in 29 years fixing airplanes are caused by screw holes with too little clearence.  I have also reamed the holes after drilling, this leaves a perfectly smooth hole with less chance of cracking from jagged edges.

The windows were reinstalled using PRC sealant per S/B M20-208B not silicone.  Silicone is good for sealing bathtubs and in some versions changing the shape of the human body.

The real mod was maching a step in the edge of all windows, this was for appearence and smoothness of the airframe.  I beleive it helps with speed. After every mod I have done I fly against a buddies very fast Comanche 250.  He can still beat me but has to work harder with each successive mod.  My goal is to match his speed on 50 less HP.

Clarence

[jetdriven]

Plexiglas works like wood.  Just keep it at 70 degrees or more, tape the glass where you are drilling, and always drill with it backed up with something.

The skin is dimpled 100 degrees to allow your screw to sit flush with the outer skin.  That dimple is behind the skin, so you must countersink the plexiglas to allow the skin to nest inside it and all fit together tightly. Same concept with flush rivets. Both skins are dumpled before riveting.

100 degrees is the angle of the underside of the screw head.   explanation here.

insulation should be something other than fiberglass, ours has mylar.  There was some yellow fiberglass by yhr baggage compartment and in the roof there. We are changing that.   I dont know if there is insulation in the cabin by the windows. 

Quote: scottfromiowa

Thanks for all the excellent information.  This is awesome.  I have already taken Mike up on his kind offer to lend me his bits for the project that will be completed in a heated hanger during annual.  Good advise on having the plexi warm when working.  Will also use 3M tape front and back.  I'm a visual learner and while the suggestions on labeling the trim piece connectors and process for countersinking  as explained sound straight forward...I have ZERO experience (besides cutting out a window in a tub enclosure on our first house...ledge was a great time) I am a novice on plexi.

If the screw goes through the skin then through the plexi why/how am I countersinking the plexi?  Seriously I am not seeing what everybody means here.

Can somebody give me the exact brand and where to buy and quantity I will need for side windows on sealer?

How long and what type of stainless screws do I need for .250 glass?  I believe they are 100 degree counter sunk screws.  Is the 100 degree the diameter of the screw or having to do with the head?

Any special prayers to be uttered before beginning the task?  (I will have an ANP there, but delicate and finesse are not Iowa gentetic traits) 

Thanks again for the feedback.  If someone has a photo/s of the counter-sinking process I'd love to see it.  I like the idea of drilling one attaching and drilling remainder in place.  Suggestion was to do sides first.

Round/reduce corners with belt sander or dremmel was a previous suggestion.

I wonder what the insulation will look like once I get in there?  Anyone replace theirs while all was out?  Suggestions there for sources?