[AR] Re: Electroforming Experiment
- From: "Ray Rocket" <dmarc-noreply@xxxxxxxxxxxxx> (Redacted sender "ar0cketman" for DMARC)
- To: <arocket@xxxxxxxxxxxxx>
- Date: Sun, 14 Jul 2019 18:28:51 +0000 (UTC)
Even the CNC axis that I'm making is really just a stepper motor with
a jeweler's chuck on it. It is mounted to the 3D printer to replace
the Y axis with a pen plotting head in place of the extruder. It's kind
of the reverse process from PCB etching. Ink is placed where you don't
want additional material plated. Most of the parts for this are 3D
printed.
You are using one of the commercially available "wax" filaments to form the
coolant channel features?
Any trouble getting the conductive paint on it?
If somebody wanted to duplicate your results, a modified Eggbot may be an
inexpensive method to apply a resist/filler layer for the coolant channels. It
even has an optional hot wax pen and is all open source.
http:////www.egg-bot.com
On Saturday, July 13, 2019, 1:50:55 PM GMT, Ed LeBouthillier
<codemonky@xxxxxxxxxxxxx> wrote:
On Fri, 2019-07-12 at 18:16 -0500, Elliot Robert wrote:
I take it this is the process that you and the late Charles Pooley
talked about in the later chapters of your book?
Yes. This is the thrust chamber talked about in the Soda Can tank
section.
Compliments on an excellent basic introduction to those competent in
the basic prereqs btw. I'm about to drop a trivial amount of money on
a custom built 4-axis cnc machine so maybe now is a good time to ask,
what exactly is the advantage to this process if you have a 4-axis
cnc that can produce regen cooled liquid rocket engines in far less
time? You seem to indicate a cnc is required anyway.
The largest benefit of this approach is the elimination of the minimum
gauge issue. As shown, making a 0.0025" thick shell is trivial. So, for
example, a low pressure propellant tank which needs to be 0.005" thick
(say in nickel instead of copper) is quite feasible. The engine walls
could be made thinner if it were a two-step process of electroforming a
copper chamber and then adding over a nickel closeout (because the
nickel is substantially stronger than copper (e.g. higher yield
strength)).
Even the CNC axis that I'm making is really just a stepper motor with
a jeweler's chuck on it. It is mounted to the 3D printer to replace
the Y axis with a pen plotting head in place of the extruder. It's kind
of the reverse process from PCB etching. Ink is placed where you don't
want additional material plated. Most of the parts for this are 3D
printed.
The recurring cost to produce additional parts is also quite cheap.
But, ultimately, the benefit relates to the scale of the activity
you're involved in. This process is not so useful for larger scale
engines because they can be machined or 3D printed more easily.
However, even then, the unit material costs can be quite low with
electroforming. Electroforming is still one of the processes used for
making larger scale rocket engines (or has been).
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