Sunday, April 22, 2012

Archtop Guitar Build - Top Plate and F Holes

I thought long and hard about the "F-holes".  The key points to my thinking are to keep the edges perfectly parallel to the sides and make sure the holes are perfectly round.  From previous experience, I know that your eyes can pick up small imperfections and round holes are prime causes of imperfections.  My options were to cut them by hand or spend time building a jig to cut them by router.  I chose the hand route since it seemed a little quicker since I am making only one guitar.

The book calls for cutting the "f-holes" into the finished carved top plate but once you carve the top plate, you've removed the flat bottom of the plate.   That flat bottom could act as a support during the cutting of the "f-holes" (rather than a narrow perimeter) and also help in layout.  I started by measuring where the centers of the round portions of the "f-holes" were located and I marked them on the flat back of the top plate.  This was much easier than trying to find them on a curved surface.  I then drilled small pilot holes from back to front on these marks using the carving jig as a support.  These pilot holes were used as references for scribing the shape of the "f-hole" onto the top side of the plate.  Next, the appropriate sized forestner bits were used to drill the perfectly round and perpendicular holes (I used a small backing plate to prevent tear-out on the back side).  This is what the plate looked like at this time.

 A scroll saw was used to cut the reminder of the "f-holes" out.
 The plate was now carved just like the back plate, once again the stained area was a test of liquid dye.
 Here it is about half way through.
 I then made a small wooded "L" that I used for sanding up the edges of the "f-holes".  The "L" was used to keep the sand paper perfectly perpendicular to the bottom of the carving jig.   This worked really well to clean up the saw marks, make the curves flow well and keep the side edges of the "f-holes" parallel to the sides.  This is what the plate looked like at this stage.


  1. Very smart. I spent a day making a router jig which scared me half to death, and had to buy a special bit to use it. Wish I'd thought of this.

  2. Yeah, there's nothing like blindly plunging a router bit into the top plate and hoping for the best. The thought scarred me too.

    BTW my bending set up doesn't have enough "guts" to get the job done. It bent thin strips of maple just fine but the sides have more mass and suck the heat out faster than the heat gun can put it in so I popped for the Stew Mac version. I've bent a fair bit of wood over the years (maple, cherry, basswood, mahogany...) but this fiddle back maple is hard to work with. Stew Mac's site said to not soak this variety of wood but rather surface wet it. I can see why because my practice piece which I soaked for 45 minutes in really hot water (near boiling) wanted to "delaminate" on the cross grain flames rather than bend over the arc. We'll see...

  3. I have good luck bending curly maple just spraying it with water to keep it wet when the heat drys it out. and my bending "iron" is an aluminum tube about a foot long and 2 1/2" dia. about 1/4" wall thickness. a piece of 3/8 x1 flat screwed to the bottom to hold it in the vice. and another gizmo to hold the nozzle of the propane torch in one end. also you will have to block off about 1/3 of the "exhaust" end to keep the heat in. use a piece of alum. flashing the same width as the sides to lay over the piece when you are bending it. don`t soak curly maple and make sure it is .080" to .085" thick. good luck.