On 3/8/26 08:24, Thomas J Powderly wrote:
_
Thx TomP
On 3/8/26 17:40, gene heskett wrote:
On 3/8/26 03:02, Thomas J Powderly wrote:
Hello, I propose a Sink EDM emulator comp.
( Sink EFM is used to make molds,
Wire EDM is used to make dies )
I plan it can evolve into a real Sink EDM controller.
The comp controls EDM motion and spark generator.
It is a python hal component that moves along
a pre-programmed path (parametric).
It also sequencers though power settings,
allowing a single tool to 'rough', 'pre-finish' and 'finish'.
Forward motion uses a predetermined list of positions.
It moves using EXTERNAL-OFFSETS.
The forward path is entirely pre-calculated.
The paths is a list of tuples with XYZ values
measured from starting point ( SPO = [(0,0,0).)] )
Motion is simply moving to an adjacent tuple's offsets.
The process is driven by a fake sensed volatge.
The emulation has no real Pulse Generator
or voltage monitor.
The emulation is driven by a fake
process variable (PV) which is
pv = random.uniform(max,min).
Later, this fake PV can become
real hardware that measures
the voltage between tool; and wok,
and a hardware Window comparator
the output FWD HOD BWD.
How PV causes motion:
If PV evaluates to FWD,
the path list index is incremented,
and the tuple offsets are given to axis.L.eoffset-counts
If PV is HOLD, no new motion occurs.
If PV is BWD, a DETOUR is created.
this list is a path away from stock,
towards a position where bad discharges are unlikely.
DETOURS:
Detours begin and end
at the break point (BP)
( where BWD occurred)
The detour list describes motion away
from stock, usually ending at SPO.
When the DETOUR ends successfully:
If the PV controlled motion returns
the tool to the BP ,
( when FWDs move the tool back to BP)
then the orbital path is resumed.
A succesful detour simply returns to
the main path.
On simple plunge cuts, this is trivial, the detour is the path.
If the detour fails,
the power is reemoved,
the tool returns to SPO,
and the NGC program is aborted.
PECK EDM:
The addition of DETOURS mafe
PECK eddm possible.
The CutTime and JumpDistance are programmable.
The tool always begins at [(0,0,0), ...
and always returns there.
After an EDM cut the sparking generator is disabled.
LinuxCNC poses, SEDM cuts:
LinuxCNC will 'pose' the tool
using Gcode.
Mcodes supply needed parameters
to the comp.
(Later ,Mcodes can be replaced
by LatheMacro style GUIs)
EDM CUT Success or Fail:
A sink EDM cut can fail if:
the process returns to SPO.
or
too many contiguous BWDs occur.
( this is a parameter )
If the cut was successful, the NGC program
takes control of tool position, and continues
( to next EDM cut or to program end)
If the cut fails,
the tool is returned
to the SPO, and
the NGC program is aborted.
The machine is ready for use.
If the cut succeeds,
the tool is returned to SPO, and
the NGC program is resumed.
Many SEDM cuts can be in one NGC program.
The above is the intent,
it already runs,
I have a brand new RIP iwth mnaster from 08.03.2026.
I can populate that local repo with
the developed c ode ( likely in a single day)
This local repo has a SEDM branch.
If idea review says to go ahhaead,
I will add my code
and git commit -m "Description of changes".
and git add .
and git push origin [your-branch-name].
then on GitHub
Open a Pull Request (PR)
then wait for review.
I wont push until comments say to do so.
Please advise
Thanks TomP
( hope this makes sense ;-)
Yes. it does and is something like I've had in mind for expanding a
3d pattern hole until it fits.
I would find something like this useful at some point down the log. I
already have most of the parts on hand to handle the sensing
required, but haven't warmed up the soldering iron yet.
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Cheers, Gene Heskett, CET.
Thnks Gene,
That messgae is step 1 in the how y to contribute to LCNC.
"tel the devs what you're doing"
For yourself, look at
An Electrical Discharge Machining Power Supply Design
https://samblazes.net/posts/2021-04-07-edm-power-supply.html
I've looked at several bits of such but have only actually used RC
discharge supplies in what I've done so far, which pretty limited to the
replacement shaft in the E400 under drive of my 11x56 Sheldon. The
replacement shaft I bought from McMaster-Carr turned out to be made out
of gawd awfull hard steel that just broke carbide bits and I had to edm
the woodruff key sockets in it. I also replaced the bronze/oilite
bushings with torrington needles. Took me about a week a key with a 40
volt supply, a 50 ohm 200 watt R and a 10uf 600 volt paper cap. I also
made custom taperlock hubs into the pulleys too as they were augered out
off center from somebody trying to stop the slippage of a missing key
with the grub screw in the pulley. I learned a few more colorful words
while doing that. So I've no experience with timed pulses, just k2 or
distilled water for electrolyte. Water worked best as it could get bad
and conductive but dump it out & replenish with fresh deionized, worked
slow but well. Noisy as can be, you could hear it running 3 blocks
away. :=)> I have zero experience with anything more complex than
that. That repair will easily outlast me since I'm already 91.
Basically Iowa farm boy shade tree engineering.
( needs OnTime pulse,
and Ionization detector if you'd like Equal energy discharges.
The off time is simple,
Arc detection and truncatin of On time is not simple ;-)
esp. on a per-pulse basis )
Thx TomP
Thnks Gene,
That messgae is step 1 in the reccomended way to contribute to LCNC.
"tel the devs"
For you, look at
An Electrical Discharge Machining Power Supply Design
https://samblazes.net/posts/2021-04-07-edm-power-supply.html
( nneds OnTime pulse,
and Ionization detector if you'd like Euql energy pulses.
The off time is simple,
Arc detection and truncatin Off time is not simple)
Thx TomP
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Cheers, Gene Heskett, CET.
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-Ed Howdershelt (Author, 1940)
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- Louis D. Brandeis
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