How I spent a week lining the F-holes

The top of a guitar is visible. If there's a defect there, people will notice it for sure.

I could have left the f-holes unlined, but I decided to line them for a number of reasons. First, I have to admit, it's classy. Also, I really dislike the look of the end grain of wood. Finally, I think the lining will make the tops a lot more secure from damage. I kept thinking about those tiny softwood tips at the vortex of each of the curliques... had to do it.

Almost all archtops I see these days are lined with plastic strips sold my Stewmac and other places. They're what Bob Benedetto uses in his $40,000 guitars. So I guess there's nothing wrong with them, but I don't want plastic on my guitars at all.

Also, I don't want the guitars to be really "flashy." So I decided to line the f-holes with a single 1/16" strip of African Mahogany, same wood as the sides and back. When I made this decision, I had no idea how difficult it would be, but I remind myself daily that adding new skills is what this project is all about.

 Each f-holes has two tight curllique circles, so the wood would have to  be heat bent to fit. And, of course, I'm going to need a bending iron for the sides. Stewmac sells a bending iron for $189, but there are a couple of things I don't like about it. First, it's horizontal, and I'd rather have it with a vertical element. Second, it doesn't have a way to add small diameter elements like I need for the f-holes. And finally, of course, it's $189, which I hate to part with.

Looking around bins in the shop, I found a cut-off steel section from a lally column I used in the barn, and a heating element from an old electric paint stripper which I hated because it burned my hands and nearly set my old house on fire. Perfect fot this, though. I salvaged the heating element, and bent it in a vice. 

Here's the finished heating element, with a removable small-diameter curlique adapter in place. 5/4 rock maple top and hardware were all in the shop. Total cost $11 to Florence Hardware for the 600-watt dimmer. Notice the "limiter" on the switch. The heating element is 750 watts, and glows red hot after a few minutes. I only want 275 - 300 degrees, since the wood wil char above that. I experimented using the thermometer from my wood stove to find the right spot on the dimmer, then fixed it so it can't go any farther. My hunch is it's not drawing more than 200 watts or so.

I set up in my living room for steam-bending the mahogany strips, so I could use the wood stove to steam the pieces. To that end, I made a "steamer spout" for an old iron kettle. Scooter supervised. Ultimately, though, the steam bending didn't work, and I boiled each of the 8 curlique pieces  for 8 minutes to get it pliable enough to take the small-radius bend without fracturing.

I made 4 bending forms on the router jig out of 1/4" masonite, using the same router jog I used to cut the f-holes in the top. I got thin strips of brass to take some of the stress off the outside of the wood as I bent each piece around the copper pipe, then used these strips in the bending form to protect the wood strips from damage as I lashed them in to cool and dry. This is a closeup of one part of one of the strips, fresh from bending into place.

Here are all the bent strips in their forms, ready for a night in front of the wood stove to dry and set. The circles are for the less radically arced pieces, which still needed some persuasion to bend.

4 days work: the bent, cooled pieces of mahogany, ready for trimming and fitting in the f-holes. 

Before I could install the mahogany lining pieces, I had to trim sharp inside corners on the f-holes, where the 1/4" router bit from the cutting jig wouldn't go. The corner on the right is from the jig, the corner on the left is trimmed.

Gluing the first set of strips. I made little screw clamps to draw the strip tight into the inside corner, and little plugs for each of the holes, which I shimmed against toe strips to push each mahogany strip outwards firmly against the cedar.

Trimming the first strips down to the cedar, inside and out, with a sharp 1/4" chisel. Pencil marks on the cedar indicate the direction of the grain in the mahogany, to keep from digging in. 

Glueup part 2 - the adding the arced strips against the curlique strips. They had to be mitered on both ends, and fitted to be snug. Fussy work, but less risky than the first pieces. Actually a lot easier, since most of the pressure could be applied by little wedges.  I cleaned up most of that squeezed-out clue you see before it dried.

A completed, lined f-hole. I haven't sanded the insides of the strips, and don't intend to until after assembly - less chance for damage.

AI'm really pleased how these turned out. Not perfect, but up to my specs. Those sharp edges will be slightly radiused over when I'm ready to start the finishing.

Still building 2 guitars - no disasters, and looking good. the ops and backs are completed, and ready for gluing onto the sides, which I will bend as the next step.