Re: The Stronalacher Saga
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From what I have seen and heard, a lot of etchings that have been done in
the past, they have tried to use too thick of a material which means it is very
hard to get folds correct, all of the etching I do is designed to use .4mm.
brass sheet, sometimes after spending countless hours designing the artwork, the
first test etch will reveal some problems, mainly because I got mixed up with
which side some fold points had to be on. Take a look at the photos of a 91
Class SAR loco I am building, and study the steps, one photos shows both sides
of the steps as etched and also what the steps look like after being folded, all
one piece each.
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Brian
Rawbelle
County Workshops
Qld. Aust.
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Sent: Wednesday, October 12, 2016 1:11 AM
Subject: Re: [O14] Re: The Stronalacher Saga
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Very true.
Producing a working CAD drawing that can be turned in
to a pattern or an etch takes a bit of doing for 3D parts you need to add
shrinkage factors these change depending on the material being used to cast the
item.
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For etches you have to flatten the part add bending
lines which change depending on thickness of material and the level of
distortion you need.
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I have lost count of the number of etches I have
ditched and started again with.
And if you want to just produce a 3D
print all parts have interlock or be drawn from a solid as if it's just touching
and unioned the printer will see two parts not one.
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I produced our first kit in 1999 and I'm still
getting things wrong on test etches and you would never know until you build the
prototype.
Marc
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Colin,
I think
you'll find a major difference between a drawing of a loco even in CAD and
what is needed for an etched kit. The 7mm Narrow Gauge Association has books
of drawings but most predate home CAD systems and were probably done
originally by someone to scratch build a model. A lot of the ones published in
NG&IRMR are proper works drawings. Both sources need treating with care,
in the former case one doesn't know how much information the draughtsman had
and in the latter you need to watch what was actually built as opposed to what
was designed. All of course, thanks to someone's, efforts far better than
nothing at all.
Nothing like
publishing anything for some further information to crawl out of the woodwork
and make a fool of you.
Frank
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I
might be wrong in thinking this, but for me an 014 loco kit will need to have
weight, I would guess that if I had a half decent computer and the Auto Cad
programme I would have a go at producing 7mm drawings to make up brass etched
kits and to also make the masters for the 3D Cad castings as
well.
I
think 014 has a lot going for it, and if I had the space then I would consider
building a model in this size, One thing which I am surprised with and that is
the lack of narrow gauge loco and rolling stock Cad drawings which are
available (you watch, some one will come on here now and tell me where I can
find them), but why stop there? as you are half way to getting an etch of that
item done.
May
be it is just me getting older and trying to cope with all this new
technology.
----- Original Message
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Sent: Tuesday, October 11, 2016 12:20
PM
Subject: Re: [O14] Re: The Stronalacher
Saga
There was a kit actually for the Darjeeling
Garratt in 7mm scale and I have seen the etchings and resin castings, now in
the possession of a friend and 7mm NGA member.? BUT this was, I gather,
one of just two test etches and has never been released.? If anyone can
track? down its heritage then the possibility remains!!
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