Fixing comb-plates leakages
Tue, 08/23/2011 - 07:26
I used to use micropore between plates and comb in order to fix leakages, but someone advice me not to use micropore with wood combs.
I don't think is a good idea to sand a sealed comb (crossover one) and I was wondering if you know about any other material i can use to fix that.
Any alternative?
Thanks , Kinya.
Hey Sergio--how ya doing brother?
Having flat mating surfaces between the reed plates and comb surfaces is an extremely important detail when building a high performance harmonica.
Rather than using the 3M Micropore tape (or any other material for that matter) as a gasket material, focus your efforts on the following technique:
1. Tape down (or rubber cement) a sheet of 400g or 600g "wet or dry" sandpaper onto a sheet of perfectly flat plastic, tempered (safety) glass, or better yet--a granite slab used by machinists (with only a .001 deviation).
2. Apply a few drops of clean (bottled) water onto the center of the sandpaper.
3. Place your DRAW reed plate into the pool of water (you will not be able to do the BLOW reed plate unless you remove all the reeds--bad idea!)
4. Spread your fingers "evenly" across the reed plate and apply even downward pressure--try to avoid pressing on the reeds, or you will distort your reed profiles.
5. Slide the reed plate in a few figure eight patterns, then alternate with a forward~back motion.
6. Stop, dab the water and black residue off the reed plate and examine the sanded areas--the "high" spots will be identified by the bright polished sections you had just sanded.
7. Repeat steps 3~6 until the entire reed plate mating surface is polished like a factory reed plate--nice!
8. Similar to the the DRAW reed sanding method, you will now adhere a sheet of "non-clogging" 400g sandpaper (used by cabinet makers) onto a flat surface, etc. DO NOT APPLY WATER FOR THIS STEP.
9. Place your comb onto the sandpaper and apply the same technique in step 4,5.
10. Occasionally examine the pool of sawdust that has accumulated onto your sandpaper--this will show you the high spots from your comb. Repeat on the opposite side of your comb.
11. Be mindful about applying even "top down" pressure onto the comb, otherwise you will create a lop sided comb. Hint: place a 3lb weight (fisherman's sinker works well) on top of the comb, then push and pull your comb across the sandpaper. When satisfied, dust off the comb with a damp rag and let the comb dry. Note: This step may raise the wood grains a bit and make the surface feel stumby--don't despair, lightly sand and all will be well.
12. Hohner does not seal the mating surfaces of their combs--only the perimeter and slots--so don't worry about sealing after you completed sanding. Having said that, if you prefer the way a harmonica plays with a denser comb, then spray 2~3 coats of Zinsser "Bulls Eye Shellac" onto the surfaces you had just sanded.
When the above techniques are executed properly, the only time you will need Micropore tape, is to hold done the IV needle down on your next hospital visit ;o)
Let us know how it goes.
Your Harpsmith,
Kinya