[Harp-L] harp-l at xxxxx
Fri Oct 5 19:49:57 EDT 2018
> On Oct 4, 2018, at 7:00 AM, Michelle LeFree <mlefree at xxxxx> wrote:
> ……..I wrote "pointed" as a general descriptor. The punch actually has a flattened tip with the flat just smaller than the diameter of the shaft of a typical harmonica rivet………
I readily admit that my preference for a “nipple” punch tip over a pointed one may be allowing the pursuit of perfection to interfere with good enough. I use a hand drill and a grinder to machine a pointed tip on a punch.
> Then you drill out the hole and tap it to accept a cell phone repair screw. I'll be announcing my all-encompassing "Reed-O-Matic" system to in the coming days.
> I’ll be interested in seeing it.
Cell phone repair screws sound a little exotic and expensive.. I use 0-80 Phillips-head screws from McMaster-Carr, $8.32 for 50. An 0-80 tap is about $13.
> ……..I have a little rant about welded reeds. Welding reeds during manufacture avoids the mechanical pitfalls of using rivets, therefore permitting near perfect placement of the reed in its slot (ergo the quality of the instruments out of Asian manufacturers and the attendant success they are currently enjoying). But welded reeds are no friend to the harmonica technician………...
I agree. Welded reeds are probably more susceptible to automated assembly. For that reason, I predict that we’ll be seeing more of them and not less. Commercial welders are very expensive. Using internet instructions, I made a DIY capacitive-discharge welder. They are intended for battery-cell interconnections in rechargeable batteries that have stainless-steel connections. The much lower resistivity of brass defeated me. The heat isn’t necessarily generated at the interface of the reed and plate. Not enough power resulted in no weld. A little more power blasted a gaping hole in the reed. A copper electrode often welded to the reed. Apparently a tungsten-copper alloy electrode is required. I gave up on welding.
Our methods have not yet caught up to the latest manufacturer’s methods, e.g. welded reeds. Drilling holes to replace a welded reed seems to me to be awkward and error-prone for your “Everyman”. That is what led me to work on soldering.
You can get all of the critical parts (transformer, carbon electrodes, foot switch, and solder paste) from MicroMark for $182. Then you can look at my video to see how to make a soldering fixture. It isn’t complicated.
Any method of replacing reeds is tedious. With rivets or screws, lots of that fiddling occurs after the reed is attached with potential for damaging the reed or plate. With soldering, the fiddling occurs before the reed is attached. If an error occurs, you can have a re-do without risking damage to the plate or reed. Soldering has potential for special tunings. I can’t attach it to a harp-l post but I have a picture of the shortest reed of a diatonic soldered on the longest slot. It plays perfectly.
………..I disagree that the nipple design is stronger than a tapered one. After all, (if you want to be able to see what you are doing in guiding the punch) you start with a tapered end and remove material from there. How could that be stronger? It can't. And without an expensive gas or electric forge that can heat the whole punch uniformly (I use a homemade mini-forge that uses a propane torch for the heat source), that nipple is very difficult to harden (for me anyway). The tip gets so much hotter than the shaft so quickly that you either over-harden or even "burn" the tip and under-harden the shaft or under-harden the shaft for proper hardening of the tip (if you get my meaning). I broke of a lot of tips trying, and forced to use a simple taper decided in the end that the nipple tip isn't really necessary………...
Here is a tip on hardening. I ground my “nipple” tip on a socket-head machine screw. (Not SS) Then I applied a paste of graphite (lock lubricant) and motor oil to the tip. I wrapped the tip (not the head) of the screw in stainless steel foil and heated it to a cherry red in the flame of my propane torch and dropped it in a glass of water. Protected from oxidation by the foil, the carbon of the graphite and oil surface-hardened the tip. It is so strong that it will punch a neat hole in a reed plate where none existed before. I have some foil left that I don’t expect to use. If you are interested, email me off-list and I’ll send you a piece.
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