Re: boat propulsion - miniature computer-controlled steam plant?

"Jim Wilkins" <muratlanne@gmail.com> writes:

"Peter Fairbrother"  wrote in message news:usi5v7$2ea8v$1@dont-email.me...
>
On 07/03/2024 00:51, Jim Wilkins wrote:
>

You machine each blade with two hole saw cuts like this into the rim
of the disk:  ((
with a smaller radius on the back one so the blade has a crescent
moon profile and sharp edges.

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>
I tried that, but couldn't get it to work with a suitable geometry (for
an impulse turbine) - I had problems with the back edge of the holesaw
hitting the workpiece. If the saw was small diameter it would intersect
the workpiece on both edges, and if the diameter was large enough that
it didn't interfere the turbine blade was too straight.

I can visualize what you mean, interference limits the blade
depth. The blades could be cut deeper with a small end mill if the
rotary index holding the disk blank was in a swivel vise (or rotary
table) manually turned only far enough to make the cut. The setup
might be easier if the disk blank was fixed to a drilled index plate
that took up less space, mounted on a vertical surface of a block that
centered (or offset) the blank over the vise swivel axis.
>
I design things like this graphically by drawing the separate shapes
in CAD and moving them to touch, for example the front and back
circles intersecting at the blank edges, then recording the center
coordinates. Trigonometry can refine the precision without much risk
of gross error.
>
I would rough out the gaps first, milling an arc with hand feed
pressure doesn't allow much depth of cut and NO climb milling.

Hi Jim, Peter
This and the previous "machining and eccentric" (with mention of model
aeroplane "peg out of a disc" crankpins) - has really dug up something
from my youth - mid teenage.  Now 60 years of age.
I was obsessed with getting a lathe (how met Tony of lathes.co.uk) - and
wanted to become a machinist.
Word was - no this is not a credible job.
etc.
Thing is - a structured mission is better than "kicking your heels"
ostensibly doing something you have no interest in.
ie. a "lowly" (sic.) mission might get you on a path, where being
defeated out of "wrong choices" and adrift without purpose, structure or
direction is going to put you six foot under.
I am still here - and this is the first time someone has spoken to my
15-year-old-ish self - and I now at 60 years of age see what I was
trying to do.
I would have been drawn in to a world of vast knowledge, been "hot on
the trail" taking-up mentoring, and had a life expanding open from that.
When everything came crashing down, I passed off as a welder and rebuilt
a life.  So I still had to travel a similarish path.
I recently went and for the first time discussed with some family
friends now elderly about their son my contemporary who died by suicide
35 years ago.  I am a living link to their son.  I had to profess I
didn't know much; hadn't seen anything "dark" in the time I was nearby;
have some knowledge of such things yet still was without basis to
comment.
Well; I am here.  And thanks for these interesting responses.
Best wishes,
Rich Smith