Introduction: Window Fly Screens

About: Just your average non engineer in beautiful New Zealand, solving my seemingly unique problems because I cant find any one else that has.

its summer and the fly's and mosquitos want our food.....

So a quick trip down the local hardware store froze our minds - this was going to cost... Until.....

This Instructable tells you how to make simple wooden framed fly screens.

What you will need;
Timber : Width 30mm x Height 20mm x your length ( having the luxury of a band saw i brought cheap concrete edging timber and cut it to re sawed to size)
Bullet head nails: 30mm x 2.0mm (16 per frame)
Wood glue
Pin hammer
Combination square
2.0mm drill bit
Accurate tape measure
Mitre saw
Mitre clamp or jig
Bench sander
Nylon fly mesh ( hardware store)
Staple gun and staples
Counter sunk wood screw: approx. 30 - 35mm( for retaining latch - one screw per side)
Three washers(per retainer)
Length of tube:10mm diameter x your length

Step 1: Measurements

Type of frame
Decide if you are going to have our screens sit in side the window frame, resting on the sill (picture 2) OR

its going be bigger than the window opening and sit against the window frame while resting on the sill(picture 3) (an option I would tend to use if you are going to take the screen down to close the window.)

Take your measurements thus inside the frame or out side depending on which you intend to use. Measure the height and width that you desire the frame to be and add together before mutipying by 2 to give you the length of timber required for the window.

Then add a cutting allowance, 3 times the thickness of your saw blade, multiple this by four and add to the total length of timber required. ( (H + w)x2 )

I will assume that you already have your wood at the correct dimensions, so give it a finishing sanding to the quality that you want at the end now, using your sander and a fine grit. Then run along the edges with the rasp to take off the sharpness and then sand smooth. ( i used the sander in its upside down jig for this, rolling the timber from one flat to the other while moving it along the belt at the same time.)

Ensure that the end of your timber that you are going to start measurements from is nice and square....

Step 2: Marking Up

If you are not hot on mitres you might consider using the weaker Butt joint, or perhaps a halve joint - (all though the can be quite complicated in the marking...)( picture 4) which ever you choose the initial marking up is the same prior to drawing the mitre lines.

Mark up.
Using your tape measure, mark out with the pen on the edge of the wood, the first height length. ( I do this one piece at time to all measurement on the cut edge and allow for mistakes.

Take the combination square and line in the mitre cut lines, (picture 4a,b,c) take care to make sure that the mitre lines always angle inwards to create a shorter opposite side on the timber. (that is the measurement you are marking is the external edge of the finished frame always)

Step 3: Cutting

First test the accuracy of cut from your mitre saw -by cutting a few bits of scrap at 45 degrees and then checking with the combination square angle.(power saws tend to be less accurate in my experience.)

When you cut mitres take time to ensure they ae as good as possible...other wise you will have problems later when you mate the two ends...

Cutting Mitres
Cut the marked mitres, using your mitre saw. (picture 5) As you cut each mitre mark up the surface that will be glued in sequence so that you can match the corresponding piece that you have just cut from - so later you can join them. (ie: 1 and 2 together, 3 and 4 together...)

Lay out the 4 pieces lined up and ensure they all connect properly at the joints.(see picture 6)

Step 4: Assembly

Place two pieces in to the mitre vice, line up and push the mitres together to test their fit.(picture 7 and 7a)
If they don't fit to well - try using other opposing pieces until you get a good match - of course you only have four options - its at this stage that the quality of your mitre is apparent and also crucial.

Now unclamp one piece and take out, apply wood glue to the flat of the mitre still in the clamp (picture 8)

Now put the second length back in to the vice and slide up hard against the glued pieces and clamp position.(picture 8a)

Before the glue sets - nailing must be complete.

Step 5: Nailing


First take your four bullet nails, put the points on a hard object - steel or concrete and give the heads one or two taps with a hammer to take the sharp points off - this stops them from splitting the frames when you hit them in.(picture 9)

Next set your drill bit length so its just about 5mm shorter than length of your bullet nails, and drill the 2.0mm pilot holes for the nails,(picture 10)

The pilot holes are each drilled out of line with each other, one lower than the other. One side wide and one side narrow in spacing to ensure the opposite nails don't clash.(picture 11.)

Place the nails, in the pilot holes and gently tap in with the pin hammer before the glue sets, release the mitre clamp and give both sides another tap to seat.(picture 11a)

Then repeat gluing and nailing steps for all four corners, also before the glue sets so that you can seat them all.(picture 12.)

Step 6: Fitting

Take the frame back to the window and ensure it fits in the orientation that you want, its not uncommon for it to be a bit bigger now - as a result of the mitre alignments.

If this is the case - use a pen to mark how much needs to come off the frame, and take it back to your belt sander ( I am envious if you have a bench mounted one) place the frame in a vice or place your sander in a turn over jig (see my Instructable coming soon) and slowly sand away the extra - checking regularly to ensure you don't take to much off
(picture 13)

Step 7: Apply the Screen

Place the screen over the frame, staple the first edge, pulling the screen tight away from it, repeat for the opposite edge pulling the screen tight.(picture 14)

Then repeat for other two sides - ensuring that in the end the screen is stretched tight in all directions - not crucial but looks better I guess.(picture 14a)

Step 8: Holding Screen In

If you have built your screens to sit on the sill and against the window frame rather than in it, make up two retainers(picture 15) which rotate over the frame to hold in place and back beside it to release.

First cut a small piece of wood form scrape approximately one and a halve times the width of the upright frame ( seen next to the retainer in picture 15)

- smooth of its edges on the sander
- find a wood screw that is going to be long enough to go through the retainer , and the thickness of your frame with still about 10mm of thread exposed.
- Drill a hole in the center of one end slightly greater than the shank of the wood screw ( the no thread part)
- now put the screw through a the first washer, through the retainer, through a second screw and lay it flat in the across the frame and figure out how much tubing to cut to act as a spacer. cut and file off the edges of the tubing.
- hold the retainer in the open position (picture 15) allowing about a 4 mm gap out from the frame, mark and drill a pilot for the wood screw.
- screw the wood screw in just enough to take the slop out of the retainer but not tight.

Once complete simple place the screen between two retainers and rotate them 90 degrees horizontal to retain the frame in place (picture three in the open position)

Step 9: In to the Future....

Since completing that project I have managed to make a really nifty screen for my sliding door. It is just tall enough to allow it to stand with in the groove of the sliding door, but just small enough that when the door is wide open it can be removed or placed by taking it diagonal towards the edge of the door and taking it out of the door slide / putting it in.