Home

Go to Beginning

Building an 8" Closed Tube Reflector

Construction Pictures
Building Tube and End Pieces

Laying out parts on MDF or plywood

The first step is to carefully measure the inside diameter (ID) of the tube. With that information, and the dimensional information on the plan drawings, you can being to pay out the parts on either MDF (medium density fiberboard) or good quality plywood. MDF can be gotten at any chain hardware store but good quality plywood must be gotten at a specialty lumber yard. I do not recommend buying any good quality wood at large chain home improvement stores. Using a compass, square and ruler carefully study the plans and lay out the  parts to be cut out. beginning this project I can not over-emphasise the need to go slowly and think a lot about what you are doing.

Cutting Out End Cap, Cell and End Ring

Once the parts are laid out and holes are marked cutting and drilling can begin. Use paper tape to hold parts in place as shown and mark orientation of parts so they will always fit properly. At the beginning use pencil to make orientation marks, later these can be replaced with drill indentations when paint is applied.

Before you measure the ID of the tube for the end rings remove the flocking paper to the depth of the rings so you will get a good glue base.

A small drill press is very useful for making accurate right angle holes. Test fit on tube to make certain everything is right. 

Preparing the Tube 

The tube I used is the 9.9" diameter phenolic resin impregnated kraft board tube sold by Protostar. This tube comes with a black flocked interior. The exterior is smooth except for the spaces between the wrappings. The depth is quite shallow but the spaces need to be filled for a good appearance. Various autobody repair materials can be used. I used the red stuff in the tube you just squeeze in and smooth over. It sands very easily with 200 grit and then with 400.

Make a cap out of cardboard and tape it over the end when sanding to keep dust from entering the tube and getting into the flocked lining.

Keep sanding and working on the tube until it's smooth. Any missed areas and gaps will only show up later on when you apply the finish.

Before inserting and gluing in end rings make sure you have cut out the flocking material so you will get a good glue base.

NOTE: Resin and acetone should only be used in an open and well ventilated area and not where there are children. Read the instructions on the resin and acetone containers and use good sense and take precautions in their use.

Make sure everything fits snugly. I use polyester resin the glue in the end rings. Use more hardener than recommended so it dries quickly. Small clamps are useful here to hold things together. Use wax paper between resin and clamps or anything else. Resin will not stick to wax paper.

After the resin is dry sand the ends smooth. Sand with the tube horizontal so dust will not get deeply into the tube. A vacuum cleaner is useful for cleaning out the interior. Don't worry if the flocking is discolored, later on we will paint the interior with flat back to additionally deaden the walls.