Mar 3, 2014

Banjo Boys - Chapter 30

Bob's partly assembled banjo -- neck and rim now fit together
Clint and I haven't gotten together for several weeks because of many different conflicting activities and business travel.  So today was special and the weather forecast was promising with only a 20% chance of rain and highs in the 60s.  Clint got up here around 8:30, accompanied by Zoe.  Naturally, Sheila and Goldie were excited to see their cousin.  I left them out of their pen all day and they stayed close to the shop.

We first set up to counterbore our holes in the rim and heel into which the dowel rod is glued.  The way this is done is quite clever (I didn't think of this, by the way.).  After shaping the base of the neck where it attaches to the rim, the two major parts, neck and rim, are held in a fixture to maintain their proper alignment.  Then, using an 18" long drill bit, we bore a 1/4" hole in the bottom of the rim, through the opposite side of the rim where it contacts the neck, and a couple of inches into the heel of the neck.  This hole allows the builder to insert a 1/4" steel rod completely through both rim holes and into the neck hole.  The next step is to make a
The Fuller Counterbore
larger hole in the upper part of the rim and the neck.  This hole must have the same axis as the initial 1/4" hole to keep the neck in proper allignment with the rim.  Fortunately, there's a tool that can accomplish this.  It's called a Fuller Type B counterbore bit.  Think of a 5/8" drill bit with a 1/4" hole in its center line.  Add a couple of set screws, and you have the tool needed.  We insert the steel rod into the lower hole on the rim, then lock the counterbore near the end of the rod, then insert the rod into the opposite rim hole, and begin boring.  When the wood chips quit flying, we've bored a 5/8" hole through the upper rim and into the neck.

Next, we shaped the upper 1-1/2" of the square dowel rod into a round 5/8" peg that will be glued into the neck.  The finished product looks like this:

The 5/8" hole in the rim is then expanded into a square just large enough for the tapered dowel rod to slide into.  The square shape keeps the neck from rotating relative to the rim.  We want to keep the fretboard surface transversely parallel to the plane of the banjo head.  The neck will be held tightly against the rim by the attaching hardware we will install later.

The last thing we did today was to cut and install the nut that supports the upper end of the strings.  We are both using black water buffalo horn for our nuts.  The nut groove is trimmed to ensure a snug fit for the nut and then the nut is lightly glued in place.
The finished peghead with nut installed

I spent the last hour or so shaping my heel and staining the entire neck and rim.  As with my previous "Buick" banjo, I used a dark tobacco brown stain.  The amount of "curl" in the maple is really remarkable.  I think it's going to be a very nice instrument.

Clint did most of the same operations I did.  He's trying to finish up his "cherry blossom" banjo as a gift for his father-in-law.  It's really looking spectacular!

'Til next time...