[Harp-L] harp-l at xxxxx
Thu Oct 4 10:00:51 EDT 2018
> Your SilverWing system has many desirable features. However, I question a pointed punch for removing rivets. A sharp point tends to spread the rivet. This can make the removal more difficult and alter the hole. Its only advantage is that it is an easy shape to grind.
Hi, Vern! Long time no see. (Also a long time to get my Harp-L digest
so I could reply to your message.) I hope all is well for you and yours.
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 thought the same thing about the value
of the nipple-tipped style punches in the beginning and actually started
with such punches. The hand punch I've used for the last 15 years has
that feature and it works great. But it was difficult for me to heat
harden them. I wanted to keep costs low so I tried a simple tapered
punch and discovered the added time and expense of machining the tip was
not necessary in actual practice. I turns out that if you use very light
force in removing the the affected reed, the punch never needs to
contact the metal of the reed plate. And, even if it does, the effect of
the taper is to put a slight chamfer on the hole, which actually makes
it easier to install the donor reed. It's interesting how something I
thought was an absolute necessity on theoretical ground isn't required
in common practice.
And, from the FWIW column, IMO tapered tips ~are~ more difficult to
machine than nipple tips. They require a special lathe fixture (compound
cross slide table) where machining a nipple does not. Any high school
metal shop student can make nipple-tipped punch with any garden-variety
lathe. It takes additional knowledge and skill to use the more complex
machinery required to make the taper.
> I posit that the optimum shape for the punch point is a cylinder about .035? in diameter (a bit smaller than the hole) and about .050? long ( a bit longer than the plate thickness). This can project from a larger diameter punch shank. This shape is stronger than a point, spreads the pressure over almost all of the rivet face, and won?t damage the hole if it is pushed too far.
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.
Since I no longer use the nipple style punch it's a bit moot. But for
those who want to try it, I preferred the length of the shaft to be just
short of the plate thickness. I did this to keep the rivet attached to
the reed. That way I have the option to re-use the rivet. It is a simple
matter to transplant the reed with the rivet attached. Not so simple
using detached rivets, even new ones. A loose rivet with tiny hole in
it is pretty intimidating to me at least. I never liked using rivet sticks.
> I viewed the video and did not understand how filing the rivet head at an angle can move the reed position. A large part of the video is dedicated to adjustments after the rivet is set. This is what often defeated me when I tried to employ rivets. I?m aware that many technicians use rivets routinely and that my problems may have arisen my lack of skill and experience. I had much better results with screws.
That is Andrew Zajac's technique, and he is rightly proud of it, because
it actually works. In practice, I find it is generally unnecessary as in
my hands the off-center problem occurs infrequently. Gary's results are
more typical. Although I think I understand it well enough to use it,
I'll let Andrew explain his method.
Recognizing the role of screws for reed replacement, I have another
system that uses a drill bit and a tap in small arbors to enable their
use. It uses the same punches in a similar jig to remove the rivet and
prepare the rivet pad. 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 keep using the phrase "in actual practice" for a valid reason. In this
case, using screws is significantly more complicated and time consuming.
In my experience, replacing with screws is usually not necessary except
for plates that have welded reeds. The vast majority of the time the
(properly prepped) "used" rivet still attached to the donor reed works
just great. In instances when that doesn't work I have to start over
using a new rivet. That nearly always works but it is more "fiddly" and
hence more time consuming. Honestly, the only time I need to use screws
is when I am replacing welded reeds from Japaneses or Chinese
manufacturers who use them.
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. They require more sophisticated equipment and
skill. The real problem, though, is the unavailability of replacement
reeds from the manufacturers who use that method. I don't see any causal
relationship that would preclude manufactures like Suzuki and Easttop
(who use welding to affix their reeds) from providing replacement reeds.
But the fact is you need to obtain an entire harmonica or at minimum a
whole reed plate from which to harvest a single donor reed. Clearly,
such manufacturers have a different mindset that doesn't include
provisions for harmonica repair folk. Obviously they want us to simply
buy a new instrument if a reed goes south. That just isn't in my budget.
I ask, do guitar player buy a new guitar when a strings needs to be
replaced? Not hardly.
The screw method does have one distinct disadvantage compared to rivets.
You must ream the hole in the reed pad to be able to pass the screw
through it. Then, unless you are much better at accurately and perfectly
concentrically reaming the hole in a fragile reed without ruining it
than I, the problem is centering the reed in the slot. Sometimes that
can be a real pain and require a lot of time to get it right. And, once
in proper position, there is always some likelihood that it will work
its way loose from the screw's grasp again. I believe it is much better
to have the affixing done mechanically with the rivet matching hole in
the reed plate rather than relying on the friction of the screw against
brass to center the reed positively and have reason to believe it will
stay that way.
> The ideal system would not depend on the location or shape of holes in the reed or plate or on the process of installing screws or rivets, You would locate the reed in the slot and fasten it without any strong forces or torques on the reed base. Welding meets these criteria but welders are very expensive .
No doubt. But I designed this to be a tool for the Everyman. I wanted it
to be both affordable and robust, yet simple enough that technicians and
even players without much experience (or any at all) could achieve a
high degree of success in battling the ever rising cost of harmonicas.
For an outlay little more than a "professional" harmonica costs these
days, one can repair an unlimited number of broken reeds. It takes me
about two minutes start to finish to remove the old one andinstall a
replacement reed and I'm ready to adjust and tune it. That takes maybe
another, say 5 minutes (I'm not the best tuner around). The biggest
problem, quite frankly, is obtaining a replacement reed. Some companies,
to remain unnamed, make it difficult to buy new ones. Companies wo use
welded reeds often proved to replacements. This why I have asked (and
received) "dead" harmonicas from all my friends. I now have 2-3 lifetime
supplies of such donor harmonicas (which often suffered only from an
easily unclogged reed). I usually offer to return a fully restored
instrument as incentive in exchange for a few broken ones to do this.
Happy, happy, all around. I strongly suggest anyone who ever even hopes
at to some point repair broken harmonicas do the same thing.
> In lieu of welding, I experimented with resistance soldering. I use it myself. Although I don?t plan to sell the equipment, I would furnish information to anyone wanting to try soldering. I have illustrated the process in this video:
> https://youtu.be/DOBJCpZQ68Y <https://youtu.be/DOBJCpZQ68Y>
> You can also see my home-grown punch in action.
You are nothing if not an engineer's engineer, Vern. I bow to your
creativity and ability to make difficult things look easy through
technical wizardry. Unfortunately, you are one of a kind. We all don't
possess sufficient technical knowledge and skills to even reproduce your
innovations. That is one reason I am trying to provide affordable tools
for "the rest of us."
I appreciate the time you took to review my post and congratulate you
for designing your novel soldering system. I always ~study~ everything
you write. Honestly you are one of a handful of my harmonica heroes. We
need folks like you and Brendan Power to push the boundaries of
harmonica technology. IMHO, we also need folks who can provide
real-world solutions for the "journeyman" harmonica player who merely
wants to maintain his investment in his personal instruments or to help
a buddy who isn't able to do it for himself. There are a lot of these
players and only one Vern Smith or Brendan power.
I send all my well-wishes, admiration and respect until we meet again,
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