Step 17: Build the hatch
Building the hatch is not nearly as hard as some people make it out to be. The biggest problem building the hatch is springback. Springback is where the hatch tries to straighten back out. This can be caused by not using enough ribs, or by using a skin that is too thick or heavy.
I’ve built two hatches for two different teardrops, and never had a problem with springback. I’ll share that design with you now!
It’s time to layout one of the ribs. Grab that notch template that you created in step 5. Trace the outer profile of the notch on a piece of ¾” Baltic birch plywood. Using a jig saw, cut the outside radius and the two straight edges, making sure to cut away the waste so you can create an offset in the next step.
Using a marking tool, or an adjustable square, offset a line 1 ½” from the outside radius to the inside. Finish cutting out the rib. This will be your template for the remaining ribs. Using your new rib, mark and cut 5 more ribs. You should now have 6 identical ribs.
The two outside ribs need to be cut back ¼” at the top and 1/8” at the bottom to allow for the hurricane hinge.
The 4 inside ribs need to be cut back 1” at the top and 7/8” at the bottom, because they will fit inside the main frame.
Create the main frame. Cut 2 spars, 1 ½” wide x 56 ½” long. Glue and screw the ribs to the ends of the spars. Your main frame will be 58” wide. That will leave a ¼” gap on each side. If you insulated your walls or built a different width teardrop, adjust the size of your main frame accordingly. The key is to leave a ¼” gap on each side.
The next two ribs are positioned so that they can be used to mount your tail lights. I positioned the next rib so that I had an opening of 9 ¼”. I later came back and added another ¾” piece against the outer rib so the my finished opening was 8 ½” wide. Adjust this dimension to suit your tail lights.
Finish framing in your tail lights with pieces of 1 ½” spars. My finished opening height was 5 ½”, but again, adjust this to fit your tail lights.
Space the remaining 2 ribs equally as shown.
Place a backing plate for your license plate light and holder in between the two center ribs as shown.
Place another backing plate at the bottom for a handle.
Glue a bunch of 1 ½” wide spars across the width of the hatch. The placement doesn’t need to be exact, just do it roughly as shown. This creates a torsion box effect, which helps prevent the hatch from twisting.
All the joints are held together with water resistant glue like Titebond III and galvanized drywall screws. Drill and countersink with a bit like this to keep the wood from splitting.
(picture of combo bit)
Skin the hatch with 1 layer of 1/8” Baltic birch plywood, or two layers of 1/8” luan. Allow 1 ¼” overhang on each side. Glue and fasten the skin to the ribs with staples or nails. Be sure to set the heads below the surface of the skin. You will come back later to patch the holes with a fiberglass putty.
The aluminum trimwork will be added later after the hatch is painted. Right now lets temporarily install the hurricane hinge and see how things fit. Install the hurricane hinge to the hatch with 3 screws as shown. The hinge should hang over the body by 3/8”, and over the hatch skin by 1/8”. Then install the hurricane hinge with the hatch to the roof with 3 screws.
Check the fit. The bottom of the hatch should have 1/8” to ¼” clearance with the floor. If necessary, clamp a guide board on the hatch and trim off 1/8”. Check the fit again. Repeat until you have 1/8” clearance.
With a router and a laminate trim bit, or a jigsaw, cut out the opening for the lights.
Congratulations on successfully building your hatch. That wasn’t so bad, was it?
The quality is remembered long after the price is forgotten, so build your teardrop with the best materials...