On 9/15/25 22:02, ken.stra...@sympatico.ca wrote:
Understood!
If you need only an estimate of the time rather than super accuracy you could:
Calculate the circumference of the smallest circle (3.142 x diameter)
Calculate the circumference of the largest circle (3.142 x diameter)
Average the two circumferences
Multiply the average circumference by the number of complete rotations
Divide the total of the circumstances by the feed rate.
And that can be done in a single pass at servo-thread rate , although I
might consider an even slower thread, like the 200 hz I use for some of
the hand input stuff on my Sheldon which eases the load on the rpi4b
that runs it. I do see a bit of a problem in the ratio from the 1/4mm
starting circle radius to the 8mm radius for the final, minus of coarse
the working diameter of the electrode. The z feed is to equalize the
erosion of the electrode. The steel sewing cutter whose central hole I
am expanding is only .3mm thick. But I still need to know how long the
input pulse has to be in order to capture every arc discharge. I'll have
to wind that transformer as I already have sample ferrite cores and
enough stuff to make the RC circuit come Wednesday.
Thank you Ken.
-----Original Message-----
From: gene heskett <ghesk...@shentel.net>
Sent: September 15, 2025 8:27 PM
To: emc-users@lists.sourceforge.net
Subject: Re: [Emc-users] EDM auto advance Q's
On 9/15/25 11:49, ken.stra...@gmail.com wrote:
I think that you need to calculate the length of an Archimedean spiral
to determine the time to move along it. This page provides a general
formula for arc length using calculus for spirals expressed in
parametric or polar form.
https://www.mathsisfun.com/calculus/arc-length.html
Unforch Ken, while the above is no doubt correct, I still have 2 problems. Not
your fault, mine, as my math education stops with simple 8th grade algebra, (I
quit school and started fixing the first 30 tube tv's in '48) is problem #1, #2
is I haven't a clue where to find those characters on my utf-8 keyboard. I have
done some work with
cateranary's(sp?) but not since the '70's to check guy wire tensions on a 1000'
Stainless tower after a legendary Nebraska blizzard left several tons of ice on
the antenna, using the rifle scope derived intercepts on the wires. Had to
make a homemade TDR to tell the tower crew where to take it apart to find the
first of the line burnup that caused. Tower was a bit crooked but straightened
as the weight went away as the ice ablated. Took around 11 days to thaw it all.
I was caught at the site for 3 days w/o any food in the fridge, when I got
plowed out I went to the drug store for my youngest's special formula and some
eats for the rest of us, and drug it all the last mile to the farmhouse we were
living in at the time, on a 2x6 throw rug slogging thru 2 to 4 foot drifts.
Obviously I was a bit younger then. Now I'll be 91 in about 2 weeks.
Thank you Ken.
-----Original Message-----
From: gene heskett <ghesk...@shentel.net>
Sent: September 15, 2025 11:37 AM
To: Enhanced Machine Controller (EMC)
<emc-users@lists.sourceforge.net>
Subject: [Emc-users] EDM auto advance Q's
Actually 3 Q's, two of which Peter may be able to answer.
1; in a 7i76D, the 12 volt inputs need a signal of what duration to
reliably detect that a signal has occurred? And what is the maximum
voltage that can be applied to a 12 volt input?
2; how can I determine the predicted elapsed time for a 10 spiral
g2/g3 move which will expand in time as the diameter of the spiral grows?
Thanks everybody.
Cheers, Gene Heskett, CET.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
_______________________________________________
Emc-users mailing list
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_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
.
Cheers, Gene Heskett, CET.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
.
Cheers, Gene Heskett, CET.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
