Re: Air hoses and brackets...


Dennis Storzek
 

--- In STMFC@yahoogroups.com, jim peters <mikado2206@...> wrote:


Denny or anyone else . . .

I share in the obsession, but my thought was to fabricate the
bracket in etched brass. To date I have made one inquiry about the
do-ability and cost . . . with a "I don't have the time" response.

My thinking was, the etched brass part would allow variance in
mounting to the car and with a short piece of .006" brass wire
partially wrapped around the air hose (brass of coarse) could be
soldered to the other end of the bracket, giving the appearance of a
U-Bolt attachment.

If anyone on the group is experienced in the brass etching process,
I have all the dimensions worked out and would like to discuss the
project further . . . on or off the list.

Jim Peters
Coquitlam, BC
I was kind of hoping that the gentleman from Free State Systems would
chime in, as I thought he was on this list. I know that that firm does
some small size etched parts sets, such as the Carmer cut levers that
have been discussed.

From the little etching design experience I have, I see two potential
problems that make etching not the most desirable method of production
for these parts:

1) Rule of thumb is that the minimum through hole is 1.5X the material
thickness. It is possible to fudge this a bit, but holes sized at 100%
of material thickness tend to not etch through. Since you want holes
for .006" diameter wire, that means you either keep the material that
thin or less, or the holes will need to be drilled out by the modeler.
Keep in mind, the smallest drill available to most modelers is #80,
which is .0135" in diameter, over twice the desired size.

2) The biggest reason people don't just make these out of flat stock
is the difficulty of making accurately located bends. The standard way
to do this with etching is to include "fold lines" etched half way
through the material thickness on the side toward the inside of the
bend. While .006" brass may be a reasonable thickness for the part,
the .003" left at the bend locations is going to be exceedingly weak.
The bends could be reinforced with solder after bending, but most
people don't want to solder, and CA isn't going to give adequate
reinforcement to these critical areas. This would seem to indicate
that somewhat thicker material would be preferable, but that causes
problems with the holes as stated above.

Biggest problem with photo etching is that the initial development is
not cheap, and if the chosen dimensions don't work out, you scrap that
art and start all over again. It is certainly doable, but If Doc Denny
can get parts cast, they will be not only stronger, but more user
friendly as well.

Dennis

Join main@RealSTMFC.groups.io to automatically receive all group messages.