Airframe Tube Fiberglassing Rotisserie Stand

This is an idea shamelessly stolen from my rocket buddy Marc Casanova. He claimed it worked great, so when it came my turn to glass my first airframe tube I first built the fixture to make the job easier.

It was really inexpensive for me to build because I borrowed the rotisserie motor from my gas barbecue. I had purchased it at Wal-Mart for less than $20 about four years previous. The motor itself is unmodified, but I didn't want to use the same metal spit on the glassing stand that I use for cooking (too short anyway) so I had to find a replacement. Home Depot has square metal rods and angle iron, and I bought two 3-foot sections. One 3' x 5/16" solid rod to fit the 5/16" square drive, and one 3' x 1/2" square tubing to extend the rest of the way. The mid-span end of the rod fits inside the mid-span end of the tubing. I drilled a hole in the 1/2" square tubing where the to join together and tapped it out to accommodate a thumbscrew so I could tighten the assembly in place.

The only other materials I needed were two 8-foot 2x6's, one 6-foot 2x4's, lag bolts, washers, and some miscellaneous screws to mount the rotisserie motor.

Cut the 6-foot 2x4 in half. Cut both 8-foot 2x6's into a five-foot and 3-foot piece. Bolt the two 5-foot pieces together lengthwise to form a T shaped beam. Lay the T upside-down.

Mount the 3' pieces to the end of the inverted T as shown in the illustration to form the uprights. Mount the 2x4's to act as legs.

Drill a 1/2" hole in one of the uprights, centered 1 1/4-inches from the top edge. Make two saw cuts from the top edge of the upright down the each side of the hole you just drilled to form a notch. Figure out a way to mount your motor drive hole over the base of the notch (I used screws). Your mounting method should allow you to slide the motor up and off the stand while the rod is inserted into the drive. Drill a " hole in the opposite upright, same position as the last hole. I chose not to turn this hole into a notch.

At this point I drilled another hole in the 1/2" square tubing, this time just inside the upright opposite the motor. I put a hitch pin in this hole to keep the rod from working its way out of the motor drive, and spaced the pin away form the upright with a couple of washers.

To mount your tube on the spit, make two bulkheads to fit your tube. They need to have a tight friction fit so the tube doesn't slide around while you are working with the Fiberglas and the spit is turning. In one bulkhead, make a 0.6" square in the center using a 1/2" wood chisel to fit the 1/2" square tubing. In the other make a 0.3" hole using a 1/4" wood chisel to fit the x 5/16" solid rod. A set of calipers works really well for helping to measure and draw your square holes to these exact measurements. Install one bulkhead into one end of the tube and insert the spit though tube and through the center hole. Then install the other bulkhead by sliding the spit through the center hole and pushing the bulkhead into the tube.

The stand works well for both glassing and sanding.

Here are some hints for glassing a tube using the Rotisserie Stand:

1. Practice on some spare tubing first. Try a piece of spare tubing, mailing tube, QuikTube or something, just to get the hang of it. My first tube glassing experience was on a $40 section of LOC 5.38" tube, and half-way through I thought to myself, "What in the world am I doing?". It was scary there for a while. But it isn't nearly as difficult as I thought it would be.
2. Don't cut the fin slots before glassing if you have a choice. Use a Dremel tool afterward.
3. The glass will shrink some after the resin is added. Cut your glass oversized.
4. Mark a straight line the length of the tube to line up the glass when you start off.
5. Put a plastic grocery bag over your rotisserie motor before you start to keep the goop off.
6. Get a package of disposable vinyl gloves (I buy them by the 100). Put on two pair before you mix the resin. This allows you to peel off a pair if you need to handle tool, etc.
7. Use 20 minute resin minimum. You don't want it to harden before you're done.

When it's time to glass:

1. Turn on the rotisserie motor
2. Mix the resin thoroughly
3. Mix it again
4. "Paint" the resin on the tube with a cheap brush - wet but not sloppy
5. Apply the glass cloth
6. Paint more resin onto the cloth so it is completely translucent
7. With the motor turning, work the extra resin out of the cloth and off the ends of the tube. Use a spatula or your gloved hands. My hands seem to work better for me than the spatula because of the curvature of the tube, but you may have a gift when it comes to working with spatulas. One never knows these things.
8. Keep the rotisserie rotating while the glass hardens
9. If needed, apply an additional coat of resin mixed with microballoons prior to sanding to fill in the cloth texture after the first coat hardens. The rotation of the motor will prevent drips or pooling and the finish will be extremely smooth.
10. Sand smooth after the resin completely cures. Wear a mask, eye protection, and long sleeves & pants. The fiberglass dust really itches, and you DON'T want it in your eyes or lungs.