On Sunday 11 March 2018 05:54:08 Andy Pugh wrote:
> > On 11 Mar 2018, at 06:03, a k <pccncmach...@gmail.com> wrote:
> > i want reverse tool path.
> No, you don’t.
> A reversed tool path will still put the tool outside the part
> Just use a 3D printer slicer and configure your machine with a dummy
> extruder axis that does nothing.
That to me, still doesn't quite get the job done. He needs to hook up the
extruders wire feed to the plastic feed, and some way to turn off the
fire when jumping across an opening in the pattern, and restarting the
fire when its moved across the empty opening. The fact that the machine
can lay down a much thicker line of metal in one pass than the 3d
printer can should just be a matter of programming the slicer for a
thicker slice. In fact it may be worthwhile in reduced "finishing" work
to design a new smaller "extruder like" mechanism to handle say .015"
diameter wire, as that would reduce the final pass to size to a single
pass, possibly with EDM if its a thin walled and easily distorted item..
It might even be helpfull to replace the drive motor on the "extruder"
with a reverseable motor so that the wire can be withdrawn far enough to
extinguish the arc. The rest of this I see as a hal file composition
exercise, hooking up SSR's to control the arc, and some sort of a THC
like arc starter. In fact, let the THC output control the x/y feed speed
as a way of laying down a consistent thickness of metal.
It would also be a good idea to have the workspace flooded with the near
inert CO2/Argon atmosphere. The CO2 adds carbon to the puddle, making
the resultant metal layer much harder than straight argon by itself
would. It wouldn't matter if it leaked, as long as the working envelope
was flooded to keep slag at bay because that would make the arc restart
simply a matter of fireing the SSR and extending the wire until contact
was made again, letting a feedhold hold the starting position until the
arc was started, long enough to make sure the metal was being
transferred. The flooding gas would ensure a clean, oxide free
interface, making the arc so much easier to restart you'd wonder why you
ever bothered trying w/o it. The initial startup might need a delay
after gas turnon to assure its well flooded else the weld would slag
over once the head had moved on, at least long enough for the weld to
Or perhaps I don't fully understand the problem. Its certainly something
LinuxCNC can do once the slicer has created the laydown paths from the
Aram hasn't given us any hint at how big the working envelope of the 3d
metal printer might have to be as that will determine the gas economics.
In the size bottles I use, a big box can get expen$ive to flood.
Cheers, Gene Heskett
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>
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