Custom Harmonica Comb - Andrew's method
I learned how to make combs from friends with over 100 cumulative years of machinist experience! This is my low-tech, high-precision method of making exquisite harmonica combs. You can use this method to flatten the stock comb on your harmonica to make it play better.
The diatonic harmonica is made of solid pieces that must fit together in a way that is airtight. Mass-produced harmonicas often are not airtight and can be improved with a few minutes work.
This process is usually a little faster but the using a camera slows things down a bit.
Use this process on Hohner Bamboo Laminate (Crossover and Thunderbird) combs or the stock Suzuki Manji comb. You can also flatten a comb made of Corian or any other solid-surface material using this method. Be careful not to drop Corian combs - they shatter.
Wooden combs will swell. To flatten wooden combs like the Seydel 1847 or Marine Band Deluxe/1896 combs, I recommend you seal the surface after you flatten. Check for flatness after you seal, too.
Do not use this method on recessed-type harmonicas like the Special 20, Session or HarpMaster harmonicas. Those harmonicas use a different design concept. Checking and adjusting flatness on those combs requires a different strategy. Straightening and flattening the reed plates will make the best of the thin plastic combs in those models and will offer you great results. For perfectly flat reed plates, use The F Tool™.
This is the comb tool™. I meticulously flatten the top edge. *Only* the top edge is flat - we will be using that edge as a reference.
My comb tool is a working copy of a high-precision straight-edge (some call this a machinist square) precise to .000025" per 6" (25 millionths of an inch). The original stays in a drawer! If I were to use it on every comb I make, it would eventually wear out.
You can get a set of my comb tools here: Comb Tool™.
We will be measuring flatness along the left-to-right axis.
We will be measuring flatness along the up-and-down axis. That means in between every tine.
We will be sanding the comb surface. Tape a piece of 220 grit sandpaper to a flat surface. I use a granite surface plate but any flat surface will do. Don't obsess about the flatness of your working surface. The only thing you need to make your comb perfectly flat is a flat reference.
Place the comb tool over the comb to distribute the weight of your fingers evenly over the surface of the comb.
Move the comb around in circles in both directions until it feels smooth. This usually takes a few seconds. Flip it over and do the other side.
Place the reference along the surface of the comb and hold it up to the light. Hold it only on one side so that you can see how the other side behaves.
Switch sides. this gives us a good clue as to where the comb is bowed and where to flatten.
Put the comb down on the flat sandpaper and apply finger pressure where you want to flatten. Drag the comb along the sandpaper. Check flatness and repeat until it's flat.
Rotate the comb so that you are checking the tips. One tine is leaky here. Flatten the other tines to fix this.
Check in between each tine.
Switch your grip from side to side to reveal where the curve is.
Apply finger pressure and drag the comb to fix.
This is flat.
You can use the tool to apply even pressure to a portion of the comb - just like you used your finger. If the comb was unflat in this area, I would apply pressure like this:
Use this technique on both sides to fix a curve that is concave downward.
In summary, the hard part is measuring flatness. Once you can tell where the comb is not flat, it's easy to fix.
Here are some extra tips on using my comb tool: