Purchasing a whelping crate (birthing box) for your dog can be quite expensive, however, building one out of wood isn't ideal either. A whelping crate would ideally be light weight, easily cleaned, durable, inexpensive and provide safety for the pups. My solution to this dilemma was to build a whelping tub out of a large plastic water tank. I was fortunate to buy this tank used on Craigslist for only $50. The previous owner had never used it to hold anything but water which is obviously ideal. Tanks which have been used to store chemicals should not be used for this project. Remember the pups will be breathing the bottom of this tank 24/7. The tank measures 42" in diameter and 56" tall.
Step 1: Cutting the Tub
The first step is to cut the tank bottom off at whatever height you'd like. To allow mama to get out, I cut mine at an angle with the short side 11" tall and the back being 22" tall. This allows the mother dog to leave the pool to drink and eat and return to nurse. Sometimes mom needs to get away so we use an x-pen around the tub to give her some private space while staying close to the pups. The height of the tub will vary depending on the size dog you have but this size & height should work for most mamas in the 50-70 lbs range.
To cut the tub I simply marked the cut line with a sharpie and used a jigsaw to make the cut. This tank is 1/4" thick and I used a file and coarse sandpaper to round over the sharp tub edges. This is particularly important in the area where the bitch will be entering and leaving the pool so that trauma to her mammary glands is avoided.
Because the tub is so large it is very handy to have some "handle holes" for moving it. The tub is relatively light, but bulky so without these holes it's hard to do much but drag it around. With the holes, I'm able to lift the tub and carry it by myself.
Step 2: Handle Hole Jig
The handle holes measure 1 1/2" x 4 1/2" and I made them using this jig and a handheld router. The distance from the edge of my 1/4" bit to the edge of the router base was 1 3/4". After marking the hole dimensions, I made another series of marks 1 3/4" away from the edges of the hole. Along these marks I glued some blocks which act as guides for the router base and allows uniform holes with clean edges to be made.
The top of the hole is 1 3/4" away from the edge. The round tub is flexible enough to clamp the jig in place, drill a hole for the bit and then router out the handle. After cutting the hole, I again used a file and sandpaper to round over the edges for comfort.
Step 3: Adding a Pig Rail
The toughest part of this project is making a pig rail for the pups. Pig rails prevent the dam from laying down against the side of the whelping tub and smothering a pup. Mom has to lay in the center and the pups can duck under the pig rail to stay out of the way.
The rail ended up being about 3 1/2" wide which is all you need. To allow for this width, I cut 12 pieces with 15 degree angle cuts on each end to create 30 degree angles between boards. 12 x 30 = 360 degrees. The length of your boards will depend on the diameter of your tub. Although my tub was 42" in diameter, there were indentations around the bottom which required the ring to be slightly smaller. I used a "story stick" to arrive at the ideal diameter for the rail and then used the stick to set the distance on my router circle jig.
The length of my boards worked out to 11 1/4" and the width was 4 1/2". I used a plastic & wood composite deck board for the rail because it is resistant to moisture and odors. I was able to find some leftovers at a salvage lumber yard and purchased them inexpensively. To join the pieces together I used biscuits joints and epoxied the biscuits and wood with PC-7 epoxy. http://www.pcepoxy.com/our-products/paste-epoxies/pc-7.php Composite decking is impossible to glue together, but this epoxy did the trick. Another choice would be using pocket screws on the back side but the decking board didn't want to hold the screws well so I opted for biscuits. I layed the ring on wax paper to keep the epoxy from sticking to the floor and used a band clamp to hold everything in place until the epoxy set (24 hours).
Step 4: Cutting the Pig Rail
I used a circle jig on my router to cut the pig rail. A circle jig allows you to adjust the radius of the circle to any desired length and rotate the router around the center point to cut a circle. This is a jig I purchased but you can make your own by mounting your router to a board and then drilling a hole the correct distance away from the bit. I cut the outside circle first and tested it to make sure it would fit inside the tub. Once I had the outer diameter the proper size I cut the inner circle. Remember when routing the outer edge to go counterclockwise and when routing the inner circle to go clockwise to prevent the bit from grabbing the wood and running away!
Step 5: Rounding Over the Edges
I used a self-guided 3/8" round over bit in my router to remove the sharp corners. I did this on all 4 edges.
Step 6: Giving the Rail Some Legs
The last step was adding legs to the pig rail. To keep from blocking the pups from getting under the rail I tapered the legs to 1" x 1" bottom. The legs are 4 1/2" tall and 2 1/2" wide at the top. I put six legs under the rail and fastened them with two 2" #8 wood screws from the top of the rail.
Step 7: Ready for Puppies
That's it! For about $65 in materials, I was able to make a whelping crate which is light, durable, easy to clean and safe for the pups and mom.
Step 8: Adding a Floor Mat
The plastic tub works beautifully during whelping because it is so easy to clean. The slick plastic is a nice surface for cleaning, but not for pups trying to get to mom for lunch. So after whelping is finished and the tub cleaned, I add a mat to the give the pups better traction and to also provide a layer of insulation between them and the floor. I used an interlocking mat from a big box store ($20) and cut it in a circle the size of the rail. This type of mat is water-proof on the seams and we've not had problems with moisture getting under the mat edge. The translucent white plastic also has an unexpected benefit of adding brightness within the tub. Because some light can pass through the plastic, shadows and darkened corners are minimized. I also prefer the round tub over a square box since there are no corners for pups to get stranded in. All the pups are equidistant to mom's body heat and mammary glands.
We are very pleased with these inexpensive whelping tubs. Our moms have seemed comfy in their nest, the pups have gained weight and thrived, and we have found them very easy to clean and maintain. I hope this instructable has been helpful and given you some useful ideas for making whelping boxes.