Bill Clark tells us [120921 MMDigest] that his trial violin pipe
plays its fundamental but lacks the characteristic harmonics of
the true violin pipe.  What he doesn't tell us is what design he
is using for his violin pipe.

Violin pipes are not simply flute pipes with the added harmonic
brake (frein).  The pipe must be designed specifically to give the
desired range of harmonics and this is done predominantly by having
a much smaller cross section for any given length than on other pipes.
The pipe must also be of the open variety as these have a different
harmonic range to stopped pipes.  The frein is there for a purpose,
that is, to prevent over-blowing as without it the pipe would never
sound its fundamental.

I suggest that Bill starts by copying the scales of a rank of violins
that he particularly likes, but do not try too early to make violins
with a very narrow scale.  Violin pipes are the hardest to make and
get to speak effectively.  Not only is the cross section design of the
pipe critical but also things like the mouth design, cut-up and foot
hole size.  In fact, I have seen adjustable foot windways used in the
thinnest of the voix-celeste pipes made by Arthur Bursens, where he has
inserted a large machine screw across the windway in order to adjust
accurately the airflow whilst voicing.

The design and positioning of the frein is also very critical.  It
takes many years of pipe making and voicing to be able to make good
sounding violin pipes and very few amateurs get anywhere close to it.
This is why most home-built organs do not include violin pipes.

Good luck,
Nicholas Simons, GB