Sunday, October 31, 2010

Passenger Car Window Covers (For passenger cars with sliding windows)

How often have you acquired a passenger car, complete with sliding windows with the glass all intact at the railway yard, only to discover a few days later that every glass pane in the car has been smashed by the vandals?  Or, if you have a passenger car that you want to cover the windows so that they don't get smashed, the only way to fasten the plywood covers is with screws or nails through the side of that beautifully crafted window.  
First developed by Ross Robinson back in 1992 for his GTW caboose, here's a method that requires no screws or nails into windows, frames, or beautiful mahogany wood.  If you know you are getting a passenger car ahead of time, you can fabricate the window covers in advance and install the window covers in the railway yard. 

Elements of The Window Cover
For passenger cars with sliding windows, the window rests on a steel sill and slides up into a cavity inside the wall of the passenger car.  Our window covers make use of these two facts - the steel sill and the cavity inside the wall. 
 The window cover consists of 3 pieces plus 8 carriage bolts and nyloc nuts:
  • A 1/2" plywood panel that completely covers the opening of the window frame - typically 271/2"x 34"
  • A fabricated piece of 22 gauge sheet metal fastened to the top of the plywood panel with four 1/4"x 3/4" carriage bolts and nyloc nuts
  • A fabricated piece of 22 gauge sheet metal that resembles a piece of eavestrough fastened to the bottom of the plywood panel with four 1/4"x 3/4" carriage bolts and nyloc nuts.     
For installation, with one person working on the outside and another working on the inside of the passenger car, window covers can be installed or removed in less than an hour.    Installed from the outside of the car, first, the person inside opens the window to about 9".  Second, the person outside inserts the top piece of sheet metal into the top of the window frame.  Third, they then push the bottom piece of sheet metal into the bottom of the steel window sill.  Fourth, the person inside lowers the window onto the bottom piece of sheet metal.  The window holds the window cover securely in place. 


Fabricating The Plywood Panels
By setting up an "assembly line", window covers can be readily manufactured in short order.   

The first step is to fabricate the plywood panels.  The width of the panel is the complete width of the window opening.  To this measurement, add 1" to account for the window track on each side of the window opening.  For the height of the panel, measure window opening from the top of the steel panel to the bottom of the steel window sill.  To this height, add 1" as the window cover will be about 3" away from the window.  You should end up with measurements that approximate 271/2"x 34". 
 
The windows in the bathrooms at each end of the passenger car may be slightly narrower at about 251/2". 

The best size of plywood is 1/2" as 1/4" plywood has no "structure" to it and will quickly warp, and 3/4" plywood results in a very heavy window cover.  1/2" poplar plywood that is used as sheathing or underlay on new houses is about the right density. 

From a 4'x 8'x 1/2" sheet of plywood, you can get three 1-piece window covers (Panel A, Panel B, Panel, C) plus 3 pieces that you can assemble for one extra window cover (Panel D-1, Panel D-2, Panel D-3), and two pieces of scrap as shown in the cutting diagram below. 
These 3 extra pieces (Panel D-1, Panel D-2, Panel D-3) will have to be joined together to produce the 4th panel.  An air-powered brad-nailer will quickly do the trick. 
On a passenger car with 44 windows, 11 sheets of plywood will produce 44 window covers.
You may be tempted to try and truck 11 sheets of 1/2" plywood away from your local lumber centre on the top of the car, in the back of the pickup truck, or minivan.  
 
Please don't.  Lumber centres like Home Depot, Rona, Home Hardware, etc have specialized saw service departments.  Wheel the sheets of plywood over to the saw service and have them cut up the plywood for you.  This will save you lots of time. 


It can be quite a job trying to get 11 sheets of plywood cut, painted, sheet metal pieces installed all at once.  Break up the job so that you purchase and cut 3 - 5 sheets of plywood at a time.  Once you have completed the window covers for these 3 - 5 sheets of plywood, return to your local lumber centre and purchase another 3 - 5 sheets of plywood.  


The cost of a 1/2" sheet of exterior sheathing plywood will cost about $20 - $25 per sheet - about $5 - $6 per window cover.  If you aren't in a rush to finish your window covers, lurk around the cull bin of your building material store.  Or, take a look at that stack of plywood to see if there are any sheets that have been damaged by the forklift or the metal straps.  Over a period of weeks, you may be able to find small sheets of plywood culls, or plywood with the corners smashed.  If you are sharp with your negotiations, you may be able to pick up damaged sheets for $10 or half sheets of culls for about $5.  This can reduce the cost of plywood to about $2 per window cover.


Painting The Plywood Panels
With the rain, snow, and sun, unpainted plywood will deteriorate, de-laminate, and look ugly in very short order.  Two coats of exterior gloss alkyd or urethane rust paint will protect the plywood panels and make your passenger car look better than what it currently is.  Paint the plywood panels the same colour as your passenger car so that the window cover becomes an integral part of the car. 


Painting the plywood panels is the type of work that can be done in your basement workshop at home over several evenings.  It doesn't require special equipment or space. 

Don't paint the plywood window covers white with black outlines of passengers sitting inside the car.  Plywood panels painted white or any other light colour is an invitation for vandals to have a go at the car.  

We used Home Hardware rust paint because it is a high gloss exterior urethane paint that can be tinted into our favourite railway colour.  We applied the paint with a 4" roller.  Make sure the plies of the plywood are well sealed with paint.  Paint one side of each panel and let it dry. Turn the panel over and paint the other side.  Repeat this process until two coats of paint have been applied to each panel.  Make sure you paint the edges so that the plies of the plywood are well sealed.  

In some cases, the middle plies along the edges of the plywood may be hollow, creating a space between the plies that is weak.  Mix up some auto body filler and stuff the body filler into this space.  Sand and apply paint.  Do this kind of work outside as it smells up the place and gets very dusty when sanding.  An angle grinder with a "flap-disk" will do the sanding real quick.

Painting the plywood panels is a job that can be done in the basement - either at your museum or at home.  When painting a large number of panels at once, you will quickly run out of space to hang the wet panels.  Before you start painting the panels, drill two 1/8" or slightly larger holes in each corner about 1" in from the top edges.  Hang the plywood panels on a "wire chain" from the joists in the basement.

Making "Chain Hangers"
I purchased several pieces of "wire chain" - each length about 24" long.  I cut the link at each end as shown below and then unravelled and bent the link at each end so that I had a 90 degree hook at each end.  These hooks fit into the 1/8" holes drilled into the top edges of the plywood panel.  As I finish painting  one side of the panel, I slip the hooks into the holes and hang the panel from nails I hammered into the floor joists in the basement. The chains and holes can also be used to store the window covers when they need to be removed from the passenger car windows for the season.
Here's one panel that I've just finished painting with the hooks inserted, ready for hanging to dry.
For those of you who are Canadian National Railways fans, here's the colour formula for CN #11 Green at Home Hardware - in the gallon size and in the quart size.  


CNR #11 Green
Home Hardware (Beauti-Tone) Exterior/Alkyd/ Rust Coat
Gallon Formula:
Base # 64-03 Clear Base, 1 gallon size
Colourant B: 4 ounces + 26 shots
Colourant C: 4 ounces + 14 shots
Colourant G: 16 shots
Colourant Z: 8 shots

Quart Formula:
Base # 64-03 Clear Base, 1 quart size
Colourant B: 1 ounce + 6 shots + 1 half shot
Colourant C: 1 ounce + 3 shots + 1 half shot
Colourant G: 4 shots
Colourant Z: 2 shots

Fabricating The Sheet Metal Pieces
There are two ways to fabricate the sheet metal pieces.  Purchase some 22 gauge sheet metal and fabricate the pieces yourself.  OR Take these diagrams to a sheet metal shop and ask them to fabricate the sheet metal pieces.  I chose to visit the sheet metal shop.  To save some money, I drilled the holes and snipped the corners, saving about $2 per window.  My cost on sheet metal for 44 windows on one passenger car was $250 for one 44-window passenger car - about $6 a pair.

If you fabricate the pieces, you will have to purchase the sheet metal, cut it into strips, drill and bend the sheet metal on a sheet metal brake.  This will take time, experience, and expertise. Which route you take will depend on the money available to you (this will be a good fund-raising project!), the expertise in your organization, the workshop and tools available to you.

Here are the diagrams for fabricating the pieces of sheet metal.
Top Sheet Metal Piece
The top piece is a piece of sheet metal 24" wide by 4" long with a 3/16" bend in the middle.  The top corners of the sheet metal piece are clipped so that the edges are flat (pound the corners with a hammer after clipping the corners with your tin snips). 

And here's what the top piece looks like with the holes drilled and the top corners clipped.

Bottom Sheet Metal Piece
If you decide to fabricate the sheet metal pieces yourself, the bottom piece requires a bit more thought and work.  First drill the holes before you start bending the sheet metal.  It will save you time and effort.   
Here's a photo of the bottom piece.  
For locating the drill holes, here's a graphic of the 2" side of the bottom piece.  
And here's a photo of the back of the bottom piece with the holes drilled.  
Drilling The Holes In The Sheet Metal - Some Hints
If you have the sheet metal shop fabricate the pieces for you, you can still save money if you drill the holes yourself.  At $0.50 per hole, you will save about $4.00 per set.
 
Mark off the holes at the distances shown in the above diagrams.  Centre punch the location of each hole.  Drill the holes out with a 9/64" drill bit.  We drilled the holes a bit oversized to allow a margin of error in drilling the holes in the plywood.  

In drilling the bottom sheet metal piece, fabricate a piece of wood with the same cross-sectional shape as the sheet metal.  Insert this into the "eavestrough" before you centre-punch and drill the holes. 

Caution - When drilling holes in sheet metal, make sure the sheet metal is securely fastened to your drill table.  The sheet metal piece may spin and cause injuries when the drill breaks through the underside of the sheet metal. 

Most of the fabricating work, drilling holes, bending corners, etc can be done on an "assembly line" basis in a couple of evenings.  Because the sheet metal shop fabricated my pieces, my work was limited to snipping off the corners and drilling the 8 holes.  

Installing The Top Sheet Metal Piece To The Plywood Panel
Plywood has a tendency to curl.  You will want to take advantage of this curl when installing the sheet metal pieces.  The sheet metal pieces are installed as shown in the diagram below - on top of the curl.  When you install the window cover, you will force the curve to "unfurl", making a nice tension-tight fit. 
  You will need the following tools/ supplies to install the sheet metal pieces to the plywood:
  • Straight Edge
  • Ruler
  • "Fine" tip permanent marker (for marking on the sheet metal pieces)
  • Pencil
  • Two pieces of scrap wood
  • Two C-clamps
  • Two T-squares (optional) (for locating bottom sheet metal piece on plywood)
  • 1/4" drill bit (a Forstener bit will reduce spintering)
  • Eight 1/4"x 3/4" carriage bolts for each panel
  • Eight 1/4" nyloc nuts for each panel
  • 1/2" box wrench
  • Hammer (for tapping the square collar of the carriage bolt into plywood)

The top sheet metal piece is fastened to the plywood panel in two steps.  First, the middle two carriage bolts are installed.  Then the outer carriage bolts are installed. 
  • Place the top piece of sheet metal on the top of the plywood panel so that the sheet metal is centred with equal space of plywood on each side of the sheet metal.  The bend in the sheet metal should be right on the top edge of the plywood panel
  • Place the piece of scrap wood under the plywood, install and tighten a clamp so that the sheet metal piece is held in place on the plywood panel.  Repeat the process at the other end. 
  • From the top of the sheet metal, drill the two middle holes in the plywood
  • Insert the carriage bolt from the bottom
  • Install and tighten the two nuts. You may have to tap the head of the bolt with the hammer to seat the square collar of the carriage bolt into the plywood. 
Insert photo of installing middle carriage bolts.
  • Remove the clamps and pieces of scrap wood from the ends
  • From the top of the sheet metal, drill the two end holes in the plywood
  • Insert the carriage bolt from the bottom
  • Install and tighten the two nuts.
Installing The Bottom Sheet Metal Piece To The Plywood Panel
Installing the bottom sheet metal piece to the plywood panel is a bit trickier than installing the top piece.  In addition to a space of about 3" from the window sash to the outer edges of the window frame, the steel window sill is stepped about 11/2" from the bottom edge of the window.  This means that the bottom of the plywood panel will be about 1½" lower than the bottom of the window sash that sits in the bottom sheet metal piece.  We have to account for this 1½" drop from horizontal when installing the bottom sheet metal piece to the plywood.  
  • Slide the rule of one of the T-squares out to about 6".  Use this T-square to draw a line 6" from the bottom edge of the plywood.  This marks where the top of the bottom sheet metal piece will be fastened to the plywood. 
  • The sheet metal pieces are 24" wide and the plywood panel is 271/2" wide - a difference of 31/2".   Slide the rule of the other T-square out to 13/4" (half of 31/2").  This will mark off the edges on the plywood where the sheet metal pieces are to be installed - ie 13/4" from each edge of the plywood cover. 
  • Place the bottom sheet metal piece on top of the plywood, lining the piece with the three lines drawn on the plywood in the previous two steps.  
  • Clamp the plywood and sheet metal together along the outer edges of the plywood.  
  • (Insert photo)
  • Turn the plywood over and drill the middle two holes in the plywood.  This can get a bit tricky as there's no way for drilling a pilot hole.  It's matter of lining up the hole visually and mentally with a little bit of ESP!  
  • Insert the carriage bolt, screw on the nyloc nut and tighten.  You may have to tap the head of the bolt with the hammer to seat the square collar of the carriage bolt into the plywood.
  •  (Insert photo.) 
  • Remove the clamps and drill the holes for the two outer holes.  Install the carriage bolts and nyloc nuts.  
  • (Insert photo.)

Voila!  You have just fabricated a passenger car window cover.  One done and only 43 more to go!
(Insert photo.)


Paint The Exterior Of The Sheet Metal
If you install  the completed window cover, you will see that the shininess of the sheet metal can "attract attention".  In order to tone it down, paint the sheet metal with two coats of paint.  This will also allow you to touch up any other spots on the window cover that may have been "tarnished" in the fabrication process (eg missed drill holes, etc).  

Here's a couple of photos of a complete set of window covers - one side of the coach.  
and a close-up of a couple of the covers.  
 If you do undertake this project, we'd be interested in seeing the results.   

1 comment:

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