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If gas mileage is important to you, put a radius
on all edges. photo: Hamilton
Building a Dog Box, Part 2:
Construction and Finishing
by Mark Hamilton
Almost all of the screws in this dog box pass through the plywood and into the framing, which puts those screw heads on the exterior surfaces of the dog box. I countersunk the screws and later filled over them. While there are many commercial wood fillers available, I chose to use Bondo®, an automotive product. Like the high performance wood fillers, Bondo® is a two part polyester material that adheres well to wood and is very dimensionally stable. Don't use Bondo® on any area where structural filler is required or where there will be a stained finish; but under a painted finish it works very well. Here’s another tip, for use when you're working with polyester resins (whether as a filler, a surface coating or with glass cloth) and you don't get the ratio of resin to catalyst just right due to special conditions like high humidity or low temperatures. I'm told that if you're patient and just leave it alone the resin will eventually cure. I've also been told that putting the slow curing resin out in direct sunlight will help it to cure. But, for the rest of us, here's a faster option - apply what is referred to as a "hot coat" directly on top of the slow curing resin. A hot coat is just another batch of resin mixed with a greater than normal amount of catalyst. Caution: be careful not to add so much catalyst to the resin that you don't have enough time to spread it over all the material that is curing too slowly.
Somehow, putting doors into the door holes seems like a finishing detail to me. Maybe it's because, to my mind, the dog box is already built. I took extra time when I cut the door holes into the side panels to label each of the cut out pieces (door panels) so that I knew where each panel came from, which side was up, and which side was the outside surface. That way I knew where each door panel fit best.
There was enough kennel crate material left over after making the box dividers to make a wire insert for each door panel. I cut a 5 in. x 8 in. (12 cm. x 20 cm.) hole - the hole is 1 in. (2.5 cm.) smaller than the dimensions of the wire insert - into each door panel and used a router to create a rabbet around the hole. The rabbet was 0.5 in. (1.3 cm.) wide and 0.25 in. (0.6 cm.) deep, the thickness of the wire insert. Oak strips 0.25 in. (0.6 cm.) x 1.5 in. (3.8 cm.) were glued and screwed around the face of the door to hold the wire in the rabbet. I didn’t want any water getting into that space, so I bedded the wire insert in acrylic latex caulk that, unlike silicone, can be painted. The ventilation/viewing holes in the door measure 5 in. x 8 in (12 cm. x 20 cm.). As the 19 in. bx 24 in. (48 cm. x 61 cm.) divider between the compartments is also made from a section of the same cut up kennel crate as the wire inserts in the doors, the dogs get plenty of ventilation when they are in their boxes. Adequate ventilation is always of concern for us when we build a dog box.
Bondo® is also a good wood filler for projects
with a painted finish. photo: Hamilton
I didn't want rain sheeting down the side of the dog box and into the boxes, so I attached a weather flange made from 0.25 in. (0.6 cm.) luan plywood around the inside of the each of the door openings. An added benefit is that the weather flange gives each door a positive stop in the closed position. The flanges were glued and screwed in place, and then the seams were caulked. I also made drip caps for over the doors out of a little extra spruce. They, too, were installed with glue and screws, followed by a thin bead of caulk.
When I started this project my intention was to apply a coat or two of epoxy to all the internal and external surfaces before painting. I abandoned the idea after speaking with one of the people who actually formulated the epoxy I was about to purchase. He asked me if I knew what was in epoxy. I responded, "Only in a general way. I know that some of the components have to be listed on an MSDS (Material Safety Data Sheet), but I understand that there isn't a problem once the catalyst is added and everything has cured." His response was something to the effect that he had dogs too, and he wouldn't use epoxy on anything his dogs had access to. That ended my plan to use an epoxy coating on the dog box.
PL400 adhesive and screws hold the oak retainers in place on
the door. Grate bedded in acrylic caulk. photo: Hamilton
I had taken our most previous dog box to an auto body shop and had it painted to match our truck. It looked really nice, but I found the automotive paint to be difficult to deal with for the touchups required during multiple seasons of use. This time I decided to use what many wooden boat builders are now using, latex acrylic primer and exterior house paint. If that comes as a surprise to you, you can go here to read an article on the subject. The author is a retired chemical engineer. My choice was to use high gloss paint as they have the toughest surface finish, but semi-gloss does a better job hiding surface imperfections and it’s almost as durable as the high gloss paint.
I used the same brand and type of paint for both the interior and the exterior surfaces although I chose to use a much lighter color on the interior. Before painting the interior I caulked every joint between the framing and the plywood panels to try to prevent the moisture that gets inside the boxes from having easy access to soaking into the wood. With my fingertip I smoothed the caulk into a nice fillet over these seams to eliminate the possibility of water puddling around the caulk.
I'm not a patient person (and have the scars to prove it). I wanted to be able to paint both sides of the doors in each painting session as a coat of primer and two color coats would otherwise require a total of six painting sessions. I used the cutouts for the door ventilation holes and smaller scraps of plywood to make raised pedestal painting fixtures that I attached to a temporary worktable. The doors rested solely on their wire inserts as they sat on these fixtures. The fixtures made it easy for me to first paint a side, then flip the door over and paint the reverse side and the four edges. Painting the doors was reduced to three painting sessions. By the way, I almost never clean paint brushes during a painting project. I wrap them in clear plastic food wrap and toss them into the freezer between painting sessions. This technique works for me with both latex and oil base paints.
Paint front side, lift door off the fixture and turn
door over. Now paint reverse side and all edges.
Eleven years ago when I built our previous dog box, I used stainless steel piano hinges and galvanized latches on the doors. These materials cost more at the time, but over the years they proved to be worth it by eliminating maintenance or replacement costs. I used the same hinges and latches from the old dog box on the new one I built this fall. Now I think I'm in the area where those hinges and latches have saved us money.
Once the designing, building and finishing processes are done, the dog box needs to be mounted onto the vehicle. The method of attachment will be dependent upon the dog box, the vehicle and your preferences. But I think a word about mounting hardware is in order here. Your dogs are going in those boxes, and we all want our dogs to be safe and secure. I refuse to use ungraded bolts to attach my dog box to my truck. Grade 7 (five lines, evenly spaced around the bolt head) and Grade 8 (six lines on the bolt head) are made from medium carbon steel that has been quenched and tempered. They have high tensile strength (resistance to breaking from force applied along the length of the bolt shaft). Grade 5 bolts (three lines, evenly spaced around the bolt head) are also made from medium carbon steel that has been quenched and tempered. They have somewhat lower tensile strength, but greater shear strength (resistance to breaking along the cross-section of the bolt shaft).
In terms of numbers of bolts and sizing, you likely will not be led astray by being guided by what the manufacturer uses to attach the bed to your truck. Remember, you're not just bolting a light cap onto your truck bed. The weight of you dog box and its cargo is being secured to your truck by those fasteners, and you want it to remain securely attached over rough roads, in harsh conditions and during any emergency maneuvers required driving down the roadways.
Rail boxes bolt to alum. angle on the bed box
and to the bed rails. Turnbuckles and u-bolts
secure the bed box. photo: Hamilton
It occurs to me that some of you may be wondering what my experience has been with this dog box. Do I like it? Would I do it again? What would I change?
First off, kudos to Alex Murphy of MaineMade Dogsleds! This is a stunningly good design for a dog box. Every time I load or unload dogs, I'm struck by what a civilized way this is to carry sled dogs. They walk up into the back of the truck on a leash and step up into their box. Unloading is the same process in reverse and that takes a lot of strain off my back.
Loading and unloading the sleds are much the same. I never have to lift higher than chest high, and at the same time I have one or both runners on the box sliding along, taking the weight off me. That's wonderful too.
I can't tell you how much I enjoy reaching into the closet for the hanging harnesses or the tuglines lying in their plastic container. Having the other supplies organized and available from the shelves in the cabinet (instead of digging wildly through a tack box where everything was piled on top of everything else) is a joy. If I were to build another dog box I wouldn't consider any other design. I would just try to do a better job with my carpentry.
If I wanted to carry more dogs, on a full size truck, I'd just rotate the individual compartments in the rail boxes 90º and build the bed box to the height of the bed rails. Then I could have two compartments in the bed box and five dogs per side in the rail boxes. Or I could have four dogs per side in the rail boxes and a good-sized closet on the back of one rail box and big cabinet on the other. Or I could put the closet and cabinet together on the back of one rail box and a fifth dog compartment into the other rail box (Alex's configuration). So this design, on a full size truck, can be adapted to carry as many as twelve ISDs. That's more of them than I’m ever going to be carrying, but maybe that number works for you. If so, why not give Alex's design a try, then email him a picture when it's done so he can enjoy it too.
Let it snow, let it snow, let it snow! photo: Hamilton
Free CAD/3D Modeling Programs
Google Sketchup 3D, PC or Mac
CadStd Lite 2D, PC only
Waterproof Construction Adhesives
Titebond III & IV
Stainless Steel Hinges and Fasteners
Fore and Aft Marine Supply - pretty good prices on stainless steel fasteners or hinges if local supply isn't available.
Speciality Lumber Supplier
Boulter Plywood - do you need something special, like plywood that will bend around a 12 in. (30.5 cm.) radius?
How To Information
Make a scarf joint jig - for those times when you need something bigger than 4'x8' plywood.
Using latex paint for exterior projects
Got a tip you'd like to share? Email it to email@example.com or snail-mail it to Mark Hamilton, 55 Town Line Road, Harwinton, CT 06791, USA.