Dear Kathy,
> Just as an aside -- I like you guys much better when you say what you
> think.
> I realize now that when I first introduced myself, all of you were
> thinking
> "Oh Gawd -- she's got one of those awful kits. We'll just be polite and
> not
> say anything." Well how the hell am I supposed to learn anything that
> way?
I think perhaps we were trying not to scare you away. ;-) It's pretty
discouraging to post on a new group and have people be mean to you right
away,
yes?
> Second aside, for those of you who missed the first post: this kit was
> a
> gift from my husband, and part of the gift was his manpower and skill
> to do
> most of the building. Now, my husband is an attorney and works about 80
> hours a week. Whatever time and skill he devotes to this he is
> basically
> taking out of his sleeping time. He is doing it because he wanted to
> give me
> something I've longed for, but he also wanted to make it himself, so
> that
> when I played it, he would part of it. If the gurdy never plays a
> goddamn
> note, that's a better present than a five figure custom built
> instrument.
>
> Now, down to brass tacks: Alden says:
>
>> The Musikits instrument, for example, has a piece
>> of 1/4" cold rolled steel rod threaded on each end
>> for the shaft. In the time I have before I go to bed,
>> I can't really even start to outline the mechanical
>> problems with this choice in terms of stability,
>> repeatability, precision and longevity.
>
> OK, fine -- so what is an acceptable modification? Why does this not
> work? I
> can understand that Alden,
As noted, Cali on average spends more time in the shop than I do. I'm
the
more public face of OMI, but we're a team.
> who after all makes and sells a very desirable
> line of hurdy gurdies, is not obligated to help me salvage an
> instrument
> from a different maker, but if someone else wants to, for the sake of
> intellectual exchange, clarify what is wrong with this material and how
> someone reasonably adept at fiddling with wood and metal could improve
> the
> design (without access to a machine shop, I suppose I should add.)
I'll try for the short version.
The shaft and wheel are the heart of the instrument - if they don't work,
nothing else will. With that in mind, we'll concentrate on those for the
moment. Before identifying the problems with the Musikit and any
possible
solutions, I'll define the engineering problems and goals.
Your goal is to have the wheel surface remain in constant contact with
the
strings with no variation in pressure or position. The system needs to
have
no runout either radially or axially - in other words, the wheel needs to
be
completely concentric with the shaft, so that the wheel surface doesn't
move
in and out (high spots and low spots) as the wheel is turned, and the
wheel
surface can't wobble from side to side.
The shaft needs to be held in the body so that it allows the wheel to
turn
relatively freely, but doesn't move from side to side in the body, or in
and
out of the body. Both of these parameters are parts of the goals stated
above: if the shaft moves from side to side or up and down, the wheel
surface
won't be in consistant contact. If the shaft moves in and out, the wheel
surface will wobble (and you'll get nasty knocking sounds also). In
addition,
we want a shaft and wheel system that adds no noise to the sound of the
instrument, and ideally it will be durable as well.
So there are the problems. Now let's look at the Musikit's "solutions".
It's been a few years since I last looked at a Musikits (MK) instrument,
but I
doubt they have changed much in that time.
The shaft material is 1/4" cold rolled steel. This material is
intrinsically
non-concentric - in short, it's not round. When I say "not round" I mean
it's
not round enough for our purposes. The HG wheel is sensitive to
variations of
less than 1/1000th of an inch, so having a shaft that varies by 10 or 20
thousandths is problematic.
The HG shaft is usually secured by two bearings, one at the head end and
one
at the tail block. MK chooses to simply use holes drilled in the tail
block
and the tail brace (on the tail side of the wheel hole) for bearings.
While
there's a long tradition of wooden bearings, in this case they are
inadequate,
partially by their design, and partially by the placement of the headward
one
under the bridge instead of on the headward side of the wheel.
The shaft is secured in position with some nuts and washers. While the
shaft
and wheel are removable, this means that if the wheel is ever removed
(assuming it is scraped to roundness) it is most unlikely that the wheel
will
ever be replaced to the exact same position.
In a nutshell, there are the problems with the shaft and bearings - the
shaft
is too short to go into a non-existent bearing on the head side of the
wheel
hole, and it has no distinct stop collar or shoulder for the wheel to
butt up
against, and the addition of such a stop collar would necessitate the
tail
hole being larger, and being filled in with a tail bearing.
As to solutions for the home builder with no metal lathe: I really can't
think
of any. We've pondered this question for many years, trying to find a
sufficiently precise but simple and inexpensive solution, and so far we
have a
big "nothing". For bearings you might try roller bearings, as used on
model
cars and such. The same source might have shaft material for you. For
cutting and threading it, you really need a metal lathe. I'd suggest
asking
around on rec.crafts.metalworking for a hobbyist in your area who would
like
to help out on an interesting project. (Early in our career we tried
making
the shafts and wheels without a metal lathe. The results were disastrous
and
frustrating.)
> Oh, and I can't pass on this, from JULIE BARKER:
>
>> respected UK maker Chris Eaton had a career making
>> high-precision parts for missiles before becoming a
>> hurdy-gurdy maker.
>
> That's really impressive, and really interesting. But the character I
> play
> was born during the reign of Henry VII. I'm fairly sure the luthiers of
> the
> Tudor era did not have the technology to machine metal parts to NATO
> Mil
> Spec. What did they use?
Forged steel.
> How did they do it? What is a reasonable
> approximation in the 21st C.?
We've moved on from that sound. Listen to field recordings of French
players
from the 30's - they're interesting, fascinating even, but not desirable
listening unless I want a lesson in a particular style and sound. I
don't
doubt that the early HG's were as bad most of the time - it's just the
nature
of the beast when it was played in that time and place. There's a reason
the
HG was banned in so many cities. We know now that if it's well built and
well
maintained that it can have a lovely sound. Conversely, if it's not,
then it
sounds dreadful. If dreadful is authentic, I'll choose a little more
modern
sound that has some refinement.
OK, it's 0200, time for bed. I hope that was helpful.
Alden
> And speaking of that -- I won't even ask if any of you have ever worked
> a
> RenFaire. Have any of you ever been to one, and seen the conditions
> under
> which the entertainers work? The weather can be anything from 45 to 105
> degrees, Rain, wind, mud, dust. Little kids putting their sticky hands
> on
> your stuff. Would any of you take your expensive, touchy instruments
> into
> such an environment six weekends in a row, for fifty dollars a day and
> tips
> from passing the hat? I won't take my best harp to a RenFaire, that's
> why
> I've got two backups. (One of which my husband built. From a kit.)
>
> Kathy Hutchins
> [EMAIL PROTECTED]
>
>
>
