Wednesday, October 9, 2013

1/12 Scale Clawhammer Banjo (This project is on indefinite hold)

Last month I went to Uke Fest at Ft. Warden in Port Townsend, WA.  During a visit to the local musical instrument emporium I was drawn to a tack head clawhammer banjo for sale.  It turned out to be a Civil War era recreation fretless banjo with a huge 13 Inch diameter calf skin head, oak rim and maple neck.  It is one by banjo builder Eric Prust who specializes in this particular era of banjo.

As it has pseudo gut strings, a through dowel rod that the tailpiece ties onto and friction tuning pegs it might be a candidate for fairly easy shrinkage.

Here is the original on the day I brought it back to Ft. Worden.

The build commences with a thin strip of oak on which I sanded tapers on the end faces, steamed and then bent around a 1inch steel punch handle.  When cooled I slathered Elmer's glue all over it and rewrapped it, clamping it in place with a dozen miniature plastic clothespins. 

When this was dry I was able to mount it to a mandrel on my drill press and sand the outside smooth, and then sanded the inside with paper on the mandrel.  A quick touch of the edges to the belt sander to even up the wrappings produced a plausable and rigid banjo rim.  Final measurements will be approached later.

It is out of scale in thickness, but the unbent strip in the picture above should make one closer to scale.  I will take pix of all the steps with the next rim.   Banjo rims vary in thickness in the real world so it would not be totally out of place if i used the first one.

10 Oct  update - 

I cut a square strip of maple scale 2.5 inches sq, laid out and sawed, filed, whittled, and sanded a neck.  I also cut a scale 3/4 inch sq dowel rod, and rounded off the part that will inserts into the hole in the neck heel.  I still have to drill and file a hole in the dowel stick for the wedge holding the neck to the rim.

That will complete the major big work leaving things like final fittings, ebony pegs to be turned, carved and drilled, and some star branding irons to be made to brand the markings onto the outside of the rim and the peg head and scoop.  I also need to cut out a bridge and tailpiece.

Material for the top is still being debated.  I am not sure what skin would be thin enough to mount and shrink...   mouse maybe?  Think I will call some local taxidermists to see what they would recommend/have available.  I will also have to index drill some 40 tack mounting holes 0.083 inches apart and glue in teensy round head tacks.

It sounds worse than it is, but putting my process into writing helps me concentrate on the project, and you get to see how my mini mind works.

Oct 12 update -

I went back and remeasured and recalculated the shrinkage for the hoop as the first one looks considerably too thick and slightly small.   

I sawed a new oak strip just under 0.02 in thick and steamed and bent it around the same mandrel with enough wraps of blue tape to equal 12 1/2 inches which is the ID of the full size banjo.

Tape around a forstner bit with double sticky tape for outer sanding on the drill press.

A piece of plastic vacuum hose fitting serves as a mount to file the holes square without puncturing fingers on the non file hand...   (lessons learned the hard way are the best retained)

Much closer to true scale now.  The first pot will probably find it's way into a tenor or a bluegrass banjo at some point in the future.

I suppose that I should have used an ink stamp or stencil to do the stars.  The original has them branded in.  I made a little branding iron and went for it.  a couple came out nicely...

And a couple were slightly overdone.  Temperature control at that size gives a very narrow window for getting a clean stamping/branding.

As this is more or less a proof of concept model I will learn my lessons here, and do better on the next one.

Still debating what to use for the head...  it has to be slightly translucent, thin, and apparently taut enough when mounted.   Real hide would be nice, but I fear impractical.

Any ideas out there among the readers?

Off to the watchmaker's lathe to turn some ebony pegs...

20 Oct update -   Did not get to the pegs as expected, however one of my followers here and on CAMP passed a great idea for the head material.  She suggested I use real leather parchment and sent a link to a firm that provides various thicknesses (from apx 0.01" up) of calf, goat, deer etc.  They sell a 1 lb box of mixed scraps with apx 4 sq in ea, and 3 dozen pieces per pound for $25 plus shipping.

While I eagerly await it's arrival I decided to embark on a new project (a gig bag/soft case for the full size banjo)  as follows in the next post.   I will continue this one as it progresses.

6 Nov update...

I received the parchment and while thin, I do not think it is as thin as it needs to be.  I sanded a small piece thinner, soaked it in water and after cutting a hole in the lid of a snaptop container (for air flow for drying) I stretched the skin and snapped it shut.  I think this is going to work.  Photo results follow.

Results were quite promising.  I will have to make a form the same size as the rim with a close fitting outer ring to do the stretching of some even thinner skin.  I am not too concerned about perfect tightness as it will not actually produce audible notes with the strings I have, but this test gave me what I am looking for.

I have been slightly distracted by a new project idea and may be bouncing back and forth a bit.

Stay tuned...