Bending Tools/Fixtures
Posted: Sat Jan 15, 2022 11:55 am
Tools and Fixtures 01/15/22
I've built 9 acoustic guitars in a non-humidity controlled former farm shop in southern Michigan.
I carpentered summers for the 18 years I taught in public schools, and contracted finish carpentry in Austin, TX for 4 years (they call it “trim” carpentry in Texas) before putting my Industrial Design undergraduate degree to work doing mechanical design with/for mechanical engineers.
Carpenters make quick and dirty one-off fixtures to complete whatever work that requires something special. Only tools that get used often warrant money spent or time making good fixtures.
I've got a piece of 3” automotive exhaust pipe that serves me as a hot pipe to make waist bends for guitar sides. The photo shows a scrap of red oak clamped to the bench. This mounts a piece of quarter-inch angle. On top of the angle is welded a piece of 1/8” x 1-1/2” angle to make a “Y” to support the exhaust pipe held on with 4 sheet metal screws.
The heat is provided by a $10 electric element designed to start charcoal in a barbecue. You can see the handle protruding from the back. I had to compress the heating loop a little in my welding bench vise to get it to fit in the exhaust pipe.
This heats up very rapidly and cools quickly also since it's thin-wall stuff. I wet a doubled dishrag and drape it on the hot pipe to provide supplemental moisture and steam. The resulting 1-1/2” radius makes useful waist bends and even a Venetian cutaway for my #8 build.
Upper and lower bout bends are made on a quick and crude Fox bender. For 30 years I've had an unused print I bought from Luthier's Mercantile for a deluxe version of one of these. The luthier Charles Fox devised an excellent fixture for doing this. Hard to improve on a good design so I built a quick version using the concept fundamentals.
I bought an inexpensive Chinese scroll saw base, attached a box on the lower stretchers for component storage. On top is another box of ½”plywood lined with roof flashing aluminum to keep it from catching fire and housing 3 - 200 watt light bulbs.
The separate upper compartment that profiles the bout forms for the model being built is also half-inch plywood similarly lined. The curved surface is galvanized sheet metal of a gage that will yield a thickness somewhere between .016-.024”. This is 6” wide and nailed to the plywood sides with 1” nails.
The rest is pretty much self-explanatory. A 6” piece of the same auto exhaust pipe helps clamp the waist bend under a sheet of more aluminum roof flashing material, .012” thick.
The pieces of wood that clamp the sides in place are from an old eight-quarter white ash board that's eaten with holes from the Emerald Ash Borer, which is killing off ash trees here.
I time the bending with a dime store wind-up kitchen timer, though I also look at my watch when I plug the light bulbs in so I can stop at 20 minutes or it tends to start smoldering. I also have fire extinguishers and no one runs this but me.
I build one or two guitars a year, gig with a group, and try to spend time with my granddaughters, here and in Texas. It isn't worth my time to make a sophisticated bending fixture as I don't aspire to go into full-time production at age 78.
I've got no complaint against having expensive tools or carefully and elaborately constructed fixtures or specialized luthier's tools, I even own a couple by necessity. I drool every time I see John Parchem's shop in the background of his photos, hah!
I could also afford Garret Wade, Lie-Nielsen, LMI or Stew Mac specialized tools, but what's shown works fine for me without a great expenditure of time and/or money for what little production I turn out.
And hey, think about what Antonio de Torres Jurado had to work with. Or had to make to use.
I've built 9 acoustic guitars in a non-humidity controlled former farm shop in southern Michigan.
I carpentered summers for the 18 years I taught in public schools, and contracted finish carpentry in Austin, TX for 4 years (they call it “trim” carpentry in Texas) before putting my Industrial Design undergraduate degree to work doing mechanical design with/for mechanical engineers.
Carpenters make quick and dirty one-off fixtures to complete whatever work that requires something special. Only tools that get used often warrant money spent or time making good fixtures.
I've got a piece of 3” automotive exhaust pipe that serves me as a hot pipe to make waist bends for guitar sides. The photo shows a scrap of red oak clamped to the bench. This mounts a piece of quarter-inch angle. On top of the angle is welded a piece of 1/8” x 1-1/2” angle to make a “Y” to support the exhaust pipe held on with 4 sheet metal screws.
The heat is provided by a $10 electric element designed to start charcoal in a barbecue. You can see the handle protruding from the back. I had to compress the heating loop a little in my welding bench vise to get it to fit in the exhaust pipe.
This heats up very rapidly and cools quickly also since it's thin-wall stuff. I wet a doubled dishrag and drape it on the hot pipe to provide supplemental moisture and steam. The resulting 1-1/2” radius makes useful waist bends and even a Venetian cutaway for my #8 build.
Upper and lower bout bends are made on a quick and crude Fox bender. For 30 years I've had an unused print I bought from Luthier's Mercantile for a deluxe version of one of these. The luthier Charles Fox devised an excellent fixture for doing this. Hard to improve on a good design so I built a quick version using the concept fundamentals.
I bought an inexpensive Chinese scroll saw base, attached a box on the lower stretchers for component storage. On top is another box of ½”plywood lined with roof flashing aluminum to keep it from catching fire and housing 3 - 200 watt light bulbs.
The separate upper compartment that profiles the bout forms for the model being built is also half-inch plywood similarly lined. The curved surface is galvanized sheet metal of a gage that will yield a thickness somewhere between .016-.024”. This is 6” wide and nailed to the plywood sides with 1” nails.
The rest is pretty much self-explanatory. A 6” piece of the same auto exhaust pipe helps clamp the waist bend under a sheet of more aluminum roof flashing material, .012” thick.
The pieces of wood that clamp the sides in place are from an old eight-quarter white ash board that's eaten with holes from the Emerald Ash Borer, which is killing off ash trees here.
I time the bending with a dime store wind-up kitchen timer, though I also look at my watch when I plug the light bulbs in so I can stop at 20 minutes or it tends to start smoldering. I also have fire extinguishers and no one runs this but me.
I build one or two guitars a year, gig with a group, and try to spend time with my granddaughters, here and in Texas. It isn't worth my time to make a sophisticated bending fixture as I don't aspire to go into full-time production at age 78.
I've got no complaint against having expensive tools or carefully and elaborately constructed fixtures or specialized luthier's tools, I even own a couple by necessity. I drool every time I see John Parchem's shop in the background of his photos, hah!
I could also afford Garret Wade, Lie-Nielsen, LMI or Stew Mac specialized tools, but what's shown works fine for me without a great expenditure of time and/or money for what little production I turn out.
And hey, think about what Antonio de Torres Jurado had to work with. Or had to make to use.