Friendly Plastic - Luthier Tips du Jour Mailbag
In this episode, Robbie O’Brien shows how to use Friendly Plastic as a clamping caul for sound ports.
Video Transcription
[on-screen text reads: Luthier Tips du Jour Mailbag]
Mailbag question: What is the best way to glue a sound port into a guitar?
Robert O'Brien: Today's Tips du Jour Mailbag question comes to us from Florida. "Robert, I want to put a sound port in my next guitar I build. I understand I need to glue some reinforcement veneers on the inside to help support this area. What is the best way to glue this? Thanks, Joe, in Florida."
For those that don't know, a sound port is a hole usually cut in the side of the guitar that allows some of the energy, some of the sound, to escape and therefore allows the performer or the artist to hear the instrument better. There are also other benefits to having a sound port, and I won't go into that at this point.
Joe is correct. When I do a sound port I usually make a veneer sandwich. I have a side and then two pieces of veneer on the inside, and you need to glue those pieces of veneer in that area. A lot of times that area is rounded, it's in the upper bout. So how do you clamp it? Well, one way of doing that is using a product that I got from LMI, called Friendly Plastic. Let's go over to the bench and I'll show you how I use this product.
Friendly Plastic
This is a product called Friendly Plastic. It's a malleable plastic that comes in beads. Drop it into a little bucket of hot water, 140 to 160 degrees Fahrenheit. Once the beads become transparent just take it out of your little cup of water and now you can shape it to any shape you want. And once that cools down then you've got a hard piece of plastic that you can use for a clamping caul.
So, Joe, here's the piece of Friendly Plastic I used to make a template for clamping the veneers in that upper bout where I'm going to do the sound port. It's radius or contoured and it fits perfectly right in between the kerfing. Now I do recommend that if you're going to place this on the wood to get the shape that you put a piece of plastic or Saran Wrap or something between it and the wood, so it doesn't stick to that. I had a friend once that that happened to.
So, Joe, I hope this answers your question. And keep in mind there's a million and one uses for this friendly plastic. Not only can you use it for clamping cauls like in contoured areas, but also for inside the guitar. If you need to clamp around braces and things like that and you need to get a better toe hold with your clamp Friendly Plastic is a great way to do this. So be creative. I'm sure you'll find a lot of uses for it.
[on-screen text reads: More Luthier Tips and online courses available at www.obrienguitars.com. Private and small group guitar building and finishing instruction available.]
