It is essential that you pre-bend your wood binding strips to conform to the shape of your guitar body. The best method for this is to use a Heated Side Bender jig. This will allow you to bend several sets of binding at one time.
If you have decorative purfling on the bottom side of your bindings, pair each set of binding together so these purling strips are facing each other. This will better hold them in place and assure that you are making a “set” of bindings when you bend them. Place masking tape around each pair and very tightly tape each set together at several places along the binding length. Use 2 to 3 revolutions of tape to tightly “sinch” each pair together. I usually make a spare set of bindings because at least one is usually damaged during the bending process.
Wet the Binding:
One of the most critical steps to bending binding is to properly Wet each set of binding strips. Use a spray bottle filled with water and carefully soak all surface of each binding set. Set each bind set aside to allow the water to soak deeply into the wood strips. Just prior to placing the binding sets into the side bender, wet the surfaces one more time.
Placing the Strips in the Heated Side Bender:
You should be pre-heating your side bender by this time to bring it up to temperature. Also you will need to have stainless steel slats to perform this task properly.
On the two strips that will face outward in the bending machine, take a white pencil and mark the centerline of the waist so you have a registration line to work from when adjusting the binding in the bender.
Place all of the strips between the metal slats and place the sandwich in the side bender. Try to spread the 3 strips evenly on the stainless steel slats so there will be even pressure applied to them from the retainers. Place Registration marks t to line up your waist pencil marks with the waist center of the bender jig. This mark should be on the edge of the binding strip that faces toward you when working on the bender. Let the slats cook for a few minutes. When they have heated sufficiently, start to crank down the waist hand screw and stop about 1/8″ to 1/4″ short of having the sandwich tightly secured to the bender.
Be careful to listen for any fibers letting loose or cracking as this may mean the strips have not adequately heated.
Mist the Exposed Binding:
Before you start to bend around the upper and lower bout, it is a good idea to lift up the top stainless steel slat and take a spray bottle filled with water and soak the exposed portions of the strips while you have access to them. You should wear leather gloves to do this as by now the slats are burning hot.
Finish Bending The Strips:
After about 8 to 10 minutes, of heat up time, you can now start to bend the upper bout and with your hands (while wearing leather gloves), bend the slats around the curvature. Take the front retaining block and slide it around the slats smoothly, again, while listening carefully as to what is going on. All the while the slats are heating, keep on working the slats around the curvature, stopping to let the sandwich heat more if needed.
Complete the same procedure with the lower bout and secure the retaining blocks at the very ends of the slats on each end of the guitar bender.
Now it is time to make the final cranks on the hand screw for the waist and crank it down securely until it is tight.
Turn off the bender and let the strips set for a day. If you wish, you can heat it up once more and cook the binding a bit more, but that may be unnecessary and could risk dislodging the purfling.
Leave the strips in the bender as long as you can. If you need the bender for other operations, consider making a binding jig retainer where you can secure the bindings into a guitar shaped mold (even the inside mold works for this). I usually place blocks at the head and tail and a shaped block at the waist to overbend the bindings slightly.
You are likely to experience some spring-back, but don’t be too concerned about it yet. When the binding is dry, compete a dry fit and make sure that you do not have to use excessive pressure to install the binding.
GLS Tip #1: You can make the binding retainers from left-over pieces of wood that you made your inside or outside forms from. Each 3/4″ piece of plywood will handle 2 bindings, so two of them secured together will do an entire guitar. If you use scrap from the inside mold, just overcut the head and tail block areas and overcut the waist about 1/4″.
GLS Tip #2:Don’t have a Guitar Side Bender? You can make your own. We have a great set of plans and instructions for you to make this essential guitar making tool. Here are some articles for your reference:
How to Use the Side Bender Jig:
The Georgia Luthier Supply Heated Side Bender:
GLS Tip #3: You can also use an instrument bending iron for bending your binding strips. It works great and with some practice, it can actually be quicker than with the Heated Bender. You should still tape the pairs of binding strips together and follow the steps outlined in our article – Side Bending – The Hot Iron.