Introduction: Cat Flap in a Baby Gate

About: I am a graphic art hobbyist, web cartoonist, and wannabe electronics hobbyist. Other hobbies: cooking, baking, exercise, computers, video games, trivia, and some more I'm probably not remembering.

Good day!

My wife and I live in a 3-level townhome. We have a cat and two dogs. The cat has run of the house- and in fact needs to have access to the 3rd floor. However the dogs should not be up there! My challenge: take a baby gate that we already own, and make a cat flap so the cat can go up and down the stairs without letting the dogs through.

We already had the extra-tall walk-thru baby gate that you can get at Babies 'R' Us. We had it at our old home, where we used it for the same purpose - but there, the cat was able to get around the gate by going through the railing bars. Here in our new home, the bars are too close together, and the cat can't fit through.

Ready... Go!

Step 1: Supplies (and a Comment on Safety)

Stuff I needed to do this project (your supplies may vary):

Copper pipe holders (1/2 inch) -- not sure if that's the official name, they're u-shaped with tabs on either side, and holes for screws or bolts to pass thru.
Four Round-head bolts, four washers, and four nuts for the bolts. I used #10 coarse thread bolts.
1x2 wood. This wood is poplar, inexpensive at Home Depot or Lowes. I used 20 inches (2 x 10" lengths).
Screen material (I already had this from repairing window screens)
Packing tape (you can use any durable tape, ie. Gaffer's, Electrical, Duct...)

Tape measure or ruler
Needle nose pliers
Regular pliers
Flat-head screwdriver
Staple gun
Drill and drill bits
Dremel tool with jigsaw attachment, or reciprocal saw, or hacksaw
Dremel tool with barrel sander bit, or sandpaper and lots of patience
Metal blade for the saw of choice above
Clamps (I use quick-clamps)
Razor, scissors or box cutter
White semi-gloss or gloss enamel spraypaint

Probably more stuff I'm forgetting.
Ah, well. I'll add them in later if I remember more.

A Note About Shop Safety, aka I Am Not Responsible If You Sever A Limb Or Injure Yourself In Some Other Grievous Manner:

Saws are loud, sharp, and create sawdust. They can cut off body parts, and cut holes in bodies. The dust that a saw makes can fly around in the air getting into eyes, mouths, ears, and skin. Saws are also loud and can damage your hearing. Electricity can also kill you.

Please wear EYE and EAR protection at all times. You may consider wearing a dustmask and work gloves, to prevent any metal shavings from becoming splinters or being inhaled into your lungs. Also please keep electric cords out of the path of saw blades.

Thank you.

Step 2: Remove the Door From the Gate

To make this project easier, we need to remove the actual door from the gate.
This isn't difficult. The door is held in by a spring-loaded hinge pin with an E-clip on the bottom.

Push on the hinge pin and the E-clip becomes visible. Grab the clip with your needlenose pliers, and yank it off. The spring will push the pin past the top of the hinge, and you can pull out the whole assembly.

The door will then lift right off. Bring it to your workspace.

Step 3: Cut a Hole in the Bars

Anchor your gate door to your work surface with clamps, and measure out the space you want to open up for your cat flap. I measured across 3 bars (four spaces) to get 10 inches. So I wanted a 10x10 square hole when I Was done, about 9 inches off the ground (the rise of one step, so the cat could get through the gate - if I put the hole at ground level, the first step would block the hole).

I marked the cuts with pencil on the bars, and used the dremel saw with a metal jigsaw bit to cut the bars out.

Save the bars for future projects, or at least keep one nearby to verify the size of the holes you'll drill in the one-by.

Step 4: Cut and Drill the Cross-Braces

You may come up with a better idea than this, but here's what I did....

I took a length of one-by-two wood and cut two pieces an 8th of an inch shy of 10 inches, the width of the hole I have just made in the gate door. An experimental and adventurous person could cut it wider, and then dremel out the ends so that they're concave and will slide in-between the bars. I thought of that only after I used something else to secure the cross-braces to the outside bars (in the next step).

using the ends of the cut bars ON THE GATE as a guide, mark the 1-inch side of the board to drill some holes. The pipes in this gate are 1/2" outer diameter, plus a few 64ths of an inch. I would recommend tapping a nail or screw into the center points where you would like to drill, so that the drill bit itself doesn't slide along the surface of the wood before it bites. It's not bad if they're a little off-center but you don't really want them too far off.

When the holes are drilled, use a piece of scrap pipe from the last step to test-fit the hole. I used a 1/2" twist-bit to drill a hole about 3/4" deep (since a 1x2 is really only 1.5" wide). The holes were just a smidgen too tight, so I used a drum sander bit on my dremel to widen them ever so slightly. After a few minutes' work, the holes were a good fit.

When you're done, test-fit the bracers into the gate door itself. It may take a little work but it should pop right in and hold pretty tight.

Step 5: Bolt the Bracers to the Gate (possibly Optional)

This step is possibly optional, but I take no chances!
After lining up the bracers and placing them in the gate, mark which is the top and which is the bottom.

Set the gate aside, and dig out your copper pipe retainer bracket things. If I ever remember what they're really called, I'll fix this instructable up.

Using your needlenose pliers and regular pliers, straighten the tabs so the bracket is U-shaped, not speed-bump-shaped. This takes some practice, and I wish I had a video of this so you don't have to destroy as many of these as I did getting it right, but it's mostly trial and error. Grab the flat tab as close to the bend as you can with the regular plier, then work the needlenose in as close as you can get it to the regular pliers' nose on the other side of the bend. Straighten the bend slightly, then move the needlenose closer to the regular plier. Repeat until straightened.

Because the brackets I got were only 1/2" I had to widen the large curve slightly to fit around the 1" end of the 1x2 (which is really only 3/4"). I could probably have made this look nicer -- instead of straigtening the 90-degree bends, I could have added another 1/8" past the existing ones, so the 1/2" curve bend fit snug to the pipes and then the bracket itself would fit snug to the board. Ah, well.

Test-fit the now U-brackets to the ends of your bracers, and mark the holes for drilling. Try to get the brackets in as close as possible, they should be tight when they're finally attached. And, mark your holes carefully. The U-bracket holes should align on exact opposite sides of the board.

Once that's done, take the boards out, and clamp them down. Drill at the marks holes large enough to accomodate the bolts you got. The bolts themselves should fit thru the holes in the U-brackets, so the hole you drill should be about the same size.

When you're done drilling, re-assemble the hole in the gate, and bolt the U-brackets onto the ends of the boards around the bars, and tighten down. The Hole is now COMPLETE!

Move along...

Step 6: Paint!

This is a no-brainer.

Paint the whole contraption so it's all the same color.
Set up newspapers or dropcloths or plastic to protect your work area. Don't forget to turn the gate door over and around to get paint on all sides and in all crevasses.

Safety note: Always use spray paint in a well-ventilated area unless you enjoy raging headaches. I dunno about you but breathing this stuff definitely ain't enjoyable....

Step 7: Make the Flap

My cat won't go through a flap she can't see through, so I made the flap out of screening material.

Note, if you don't have any other animals small enough to go thru the hole, you don't NEED a flap. We own a dachshund who could fit thru, but is too skittish to press through the flap, so this keeps her out of the forbidden zone.

I started by measuring the opening, and cutting a piece of screen material narrower by a quarter inch than the hole, but longer than the hole is tall. This allows me to attach the screen to the top bracer, and the flap will then swing freely.

Cut the screen with the box-cutter. I placed a piece of scrap wood under the screen to protect both the blade of the cutter and my concrete floor.

Once the screen is cut, "selvage" the edges to prevent them from fraying.
Anyone who's seen my other instructable on Sticking Suction Cups to (some) Non-Smooth Surfaces will know I like packing tape. You could use Duct tape, Gaff tape, Electrocal tape... anything durable. (Gorilla tape is probably overkill.) Black duct tape or gaff tape would probably look better.

Cut the tape to the length of a side, and place the edge of the screen in the middle of the tape. Fold the tape over to seal the edge.

Next, play a little game of "alignment" to get the screening in place against the back of the top bracer so that the flap will swing freely. Use the staple gun to tack the screen in place. If the staples don't go all the way into the wood, tap them in, gently, with a hammer until they're flush. If you tap too hard, the staples will break thru the tape and screen.

Voila, done.

Step 8: Reassemble Gate, and Install

You're done!

Re-assemble the gate hinge by placing the plastic washer, then the spring (narrow end towards the top of the hinge pin) on the hinge pin, then pushing the hinge pin thru the hinge and snapping the E-clip back on.

Install the gate according to the manufacturer's instructions.

After installation, I added a home-made stepstool to the front of the gate so the cat could walk thru easier. On the bottom of the back of the stool I attached magnets with short lengths of chain attached to magnet plates, so that the stool could be loosely attached to the gate door. When the gate is opened or closed, the stool moves with it, making it easier on my wife and me... we don't have to move the stool around to get in and out of the gate, it's just easier.

The stool was a relatively simple project -- a piece of scrap plywood with four holes drilled in the bottom, four table legs bought at home depot screwed into the holes, three pieces of 1x1/4" trim nailed around the edge of the ply (for looks and to prevent delamination), a few coats of stain and seal, then the jerry-rigged magnet contraption to hold it all in place.

Thanks for reading!