Sound Post Fitting... page two...
...After about thirty minutes, remove the tool from the instrument by gently tipping the bottom of the sound post shape gently away toward the center of the instrument, turning and then with with-drawing through the sound hole.
...Here the center-line length of the needed sound post is being measured with a dial vernier caliper and this length is written down for reference. Be sure to measure in the center of each angled end both now and when measuring the sound post as it is 'cut' to size. (that is the 'center line' length).
...Once the length is established, then the end angles are measured with an angle protractor (this one is made by General Tool) and noted down. {You may have to change the length setting of your sound post tool before being able to measure the top angle, but since you already have the length needed recorded this is O.K.
...The sound post stock should be first quality spruce, round and 0.250" in diameter or slightly smaller. It should have 5 to 7 growth rings across the width of the end. Shape the sound post so that the grown rings run at 90 degrees to the centerline of the instrument (from side to side). Set the first end angle (as determined above) and clamp the sound post in position with the thumb screw and the grain horizontal (as viewed from the end).
  After setting the sound post end angle on the mitre gage (as measured above); the end is sanded by moving the mitre gage back and forth while feeding the sanding disc (not rotating) toward the sound post. Use light pressure, letting the sand paper do the wood removal. As soon as the end is sanded flat, then remove the sound post stock from the tool.
  Measuring up from the center line of the just sanded end, mark the length of the sound post allowing extra for fitting and the slope of the end cut. Saw the excess material off with a fine saw blade.
Back to page one of sound post fitting...
...The other end of the sound post is now locked in the sound post end sanding tool with the growth rings horizontal. After setting the end angle for this end of the sound post on the mitre gage, this end is hand sanded by moving the mitre gage back and forth along its guide while slowly advancing the stationary sanding disc out against the spruce sound post. ...When this formed end is straight and smoothly cut (sanded), lock the spindle that feeds the sanding disc in this position {that is with the sound post against the sanding disc.
...The sound post tool is basically a block of hard wood with a 1/4" hole drilled (and then reemed) straight through.
...Here, a 1/4" steel rod is pushed down this bore until it concacts the sound post stock (which is locked in place with the side mounted thumb screw.in the step above).
...A flat is gound / filed on one side of this steel rod so that the set screw on the locking collar does not create a 'burr' which would interfere with the movement of the locking collar in the future.
...With the set screw wrench, loosen the set screw on the locking collar and slide the locking collar down firmly against the wood block of the ' tool. Lock it in this new position.
...Next, remove the sound post from the tool and measure its center line length. Subtract the recorded corrrect (goal) length from this measurement to discover the amount that remains to be removed still.
...Re-install the sound post in the tool (seen here as viewed from above) pushing it in too far, then slide the steel rod back into postion so that the locking collar is once a gain up against the wood block of the tool. Now lock sound post in position with the thumb screw mounted on the side (not too tight, just firmly so as not to dent the soft spruce wood). Be sure the sound post is oriented correctly (a reference pencil mark on the sound post is a good idea).
...Next, select a number of steel blades of the 'automotive feeler gage set' to equal the amount of material that must be removed from the sound post to make it the correct length.
...The locking coller is loosened and moved back on the steel rod (which is up against the sound post inside the tool). The feeler gage blade set is put up against the wood block and against the steel rod and then the locking collar is slid firmly toward the wood block and against the feeler blade set and locked with the set screw.
...The final step is to loosen the thumb screw holding the sound post and then move the mitre gage back and forth against the sanding disc while gently pushing in on the steel rod.until the locking collar is up against the wood block of the tool.
...At this point, the post should be the correct length and with the correct end angles,
...Measure the centerline length of the sound post again and make corrections if necessary. Adjust the Tap Tone along its vertical axis to match the rib structure's side tap tone of: (227 1/2) HZ.
..213 HZ (from the side) tap tone all along its length evenly.
See separate instructions...
...I like to rub the ends of the sound post with white black-board chalk and then rub the ends on a piece of newspaper to remove excess chalk before installing the new sound post. (to help keep it in position).
...In this photo, the sound post installer tool is pushed in to the sound post between the grain lines and is ready to be installed in the violin.
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Modified 10/2020
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