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DIY Custom Silicone Couplers
DIY Custom Silicone Couplers.
I think I’ve perfected a recipe for custom fiberglass reinforced silicone couplings. This is not a cheap solution and there’s a lot of labor involved, but if you need to get your IC pipe around a tight spot, this may be the answer.
The couplings consist of two wrappings of fiberglass tape coated with silicone adhesive and finished with a layer of self-fusing silicone tape. They are very strong but somewhat ugly. Sculpted foam blocks and scrap tubing are taped together to serve as a mold. Floral foam is very easy to sculpt with a knife and easy to break up afterward.
Working with 30 feet of adhesive coated fiberglass tape may be a challenge for one person. I devised a coating pot that I filled with adhesive and dragged the roll of tape through. Plan on using about 15 feet of 2” fiberglass fabric tape and 1 tube of adhesive for every 1 foot of tubing length that you fabricate.
This type of adhesive (and many others) releases a very strong acetic acid odor. I don’t think it is particularly harmful but it can be overwhelming. Use with adequate ventilation.
Materials Needed
2” fiberglass tape – McMaster-Carr No. 8817K66
Silicone Adhesive - McMaster-Carr No. 7545A662
Self-Fusing Silicone Rubber Tape - McMaster-Carr No. 7643A33
Foam blocks (I prefer floral reservoir foam)
A whole box of latex or nitrile gloves
Duct tape / electrical tape
Scrap tubing or pvc connectors
Tools Needed
Scissors
Knife
Vise (optional)
Pliers
Caulking gun
Oven
Hose clamp
Procedure
Prepare the Form
1. Sculpt the coupler shape from foam block. Floral foam cuts very easy with a steak knife.
2. Adding the proper sized scrap tubing to the ends will assure proper fit when finished and it makes the sculpting very easy. If you use a piece of tubing that is somewhat longer than necessary, it will allow you to clamp it in a vice while you wrap it (much easier).
3. Tape the form together with duct, masking, or electrical tape.
4. Finish by spirally wrapping the entire form from end to end with electrical tape.
The Messy Part-Wrapping the Form
1. Estimate necessary length of fiberglass tape and wrap it onto a spool (1” pvc connector works well).
2. Infuse the entire length of tape with adhesive. This where the coating pot comes in. Reroll the infused tape on another spool.
3. Spirally wrap the mold from end to end and back again. Be sure to overlap at least half the width of the tape to prevent thin spots. This will give your finished coupler four thicknesses of fiberglass.
4. With your gloved hands, smear a good amount of adhesive around the outside.
5. Remove your gloves and wrap the form with self-fusing tape. If you’ve never used it, it may take a little practice. The recommended tape is marked down the center as a lapping guide. This tape is great stuff. You’ll find yourself wanting to use it for everything.
6. Set the finished form aside to cure. The fully exposed adhesive will start to set up in about half an hour. Allow a couple of days before you attempt to unveil your creation.
The Unveiling
1. Preheat oven to 200°F.
2. Tighten a hose clamp around the end of the coupler and use it as a guide to cut off the excess length on both ends.
3. Stick the coupler in the oven for about 20 minutes.
4. Remove from oven. The tape you used for the form will be soft. Pull the tubing ends out with pliers.
5. Break up the foam form. Sticking coat hanger wire all the way through and swirling it around will make this easy. Step on it to break up the stubborn pieces.
6. Grab the end of the electrical tape and pull it all the way out. The inside of the coupler should be hollow and clean.
7. Rinse out any foam residue.
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Ron
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