How to make a proper hammered sound post...
{revised 11/2017
Page V_82
...There are just a few preliminary steps. First we would like to use the same wood as that used for the top plate (scrap wood left over). [on Wood Tone Scale and having a #22 Rub Tone...]
..If that is not possible, then find good quality spruce wood [ having the wood properties of exactly on the Wood Tone Scale and having a # 22 Rub Tone.] of about 6 grains in 1/4" diameter. {Please see articles and videos on Wood Tone and Rub Tone wood selection elsewhere on this web site...}
..Here we have the material needed to make 'hammered wood spruce sound post stock'.
..In the photo, I am splitting out a section of proper rub tone spruce wood as similar to violin top plate wood as possible and with about 6 grains in 1/4" growth ring density.
..On the work bence you see my wood mallet for driving wood through increasingly small holes.
..I make the steel plate our of oil hardening stock of about 3/8" but you could make yours out of 1/4" mild steel plate (or thicker) .
...The holes are drilled from a 1/64" drill set with our 1/4" diameter goal hole the third smallest and the holes increasig up by 1/64" sizes for six or seven sizes larger.
..The idea is to drive our sound post stock through smaller and smaller holes until we get to the 1/4" final size (for full sized violins).
.. It might be a good idea to harden the steel plate before use (heat to cherry red and then water quench to preseve hardness. followed by grinding surface flat for a sharp edge at surface to shear off wood as post stock is hammered through.
..To get started, round off the square
 edges of the split wood blank.
..Take short taps with the wood mallet; while steadying the wood with the other hand.
..Support the wood die so that both sides are supported, here with an opening in the bench vice.
.To finish tapping through, use another piece of scrap wood. You can prevent the piece falling on the floor each pass by holding the underwood to the side of the bench vice with the small fingers of the left hand.
..The completed stock is often not perfectly straight because the grain of the tree wanders about as it is growing. However, the sound travels so much better along the grain; use the stock as hammered out, curves and all and you will have better sound transmission as the result!
..Of course if these is a serious curve over the length of the finished sound post, that piece will have to be rejected!