On Tuesday 09 April 2019 23:40:54 Thaddeus Waldner wrote:

> On Apr 9, 2019, at 10:26 PM, Gene Heskett <ghesk...@shentel.net> wrote:
> > On Tuesday 09 April 2019 23:02:46 Thaddeus Waldner wrote:
> >> Assuming you unplug the rotary axis when you remove it, you could
> >> simply use a normally closed homing switch that unplugs with the
> >> axis. Problem with this is it wouldn’t let you use the fast
> >> approach, slow home sequence with a single switch.
> >>
> >> Thaddeus Waldner
> >> Newdale School
> >> Elkton, SD 57026
> >>
> >> ________________________________
> >> From: andy pugh <bodge...@gmail.com>
> >> Sent: Tuesday, April 9, 2019 9:34 PM
> >> To: Enhanced Machine Controller (EMC)
> >> Subject: Re: [Emc-users] Leaving an axis out of the home sequence
> >> AND (continued:)
> >>
> >> On Wed, 10 Apr 2019 at 02:33, Gene Heskett <ghesk...@shentel.net>
> >
> > wrote:
> >>> out of the logic that determines whether the machine will run
> >>> gcode when that A axis has not been homed because its unplugged,
> >>> off the machine and stored and either is unhomed, or was never
> >>> homed since this power up.
> >>
> >> The simplest is probably to set it for immediate homing (home
> >> search velocity zero) but have it in the homing sequence.
> >>
> >> If you want it to physically home when present, but not home when
> >> absent, automatically, then it's harder. I imagine that some HAL
> >> logic to detect presence or absence and a mux2 to switch between
> >> real and simulated home (wcomp looking at apparent position of the
> >> stepgen?)
> >
> > unplugging it isn't practical without adding a plug in the switch
> > cable, but some timers could simulate that, and a mux2 to steer the
> > timers or the switch could work. I'll have see if I can set
> > something up along those lines.
> >
> > More ideas.  Thanks Thaddeus.
> Another idea:
> Instead of simulating a home switch with a timer, you could use an
> actual home switch from a different axis (eg. z-axis).
Not sure about that one. I'll investigate the "check to use" idea first. 
My homes, except for A are very close to the switches, so a rehome 
doesn't take long. 5 seconds maybe.

One of the things I have planned for A is sharpening/shaping HSS lathe 
tooling, but have not found a mounted CBN wheel of a size suitable for 
spinning in this spindle. Seems to me the CBN people are missing a 
market niche by not making a fairly rigid miniature cup mounted version. 

The diamond wheel dremel now sells for $26, is so thin and flimsy you 
can't accurately maintain a face angle, plus the diamond isn't 
compatible with HSS, so its not a good choice for HSS. I have made an 
arbor to spin a 4.5" CBN cup in the G0704, and have used it a time or 7, 
but even though I've fine tuned the face of the arbor 2 times, it still 
runs out of true by several thou at the cutting face.  Thats hard on the 

And I need to make a base wedge to hold the A nose up (or down) by 7 
degrees for the clearance angles. One almost needs a 2 axis combo table 
for that, at which point LCNC needs a 5th axis.  And that means a 
different interface, like a 7i90HD, or different firmware in the 5i25 to 
put the 5th axis on the p2 connector. The 7i76D only has 4.  Humm, I 
supposed a software stepper could be loaded, and a base-thread setup, 
hal can certainly do that. 2 problems with that though, first, and show 
stopper being the limited Z motion available in a gantry. I bought one 
of those $70 touch probes, and had to make a shorter stylus to get it to 
clear the bed. Piece of fragile plastic junk IMO.  As a probe, its 
usable for xy locations, but will need a round ball tip for z profiles. 
No where near concentric although that can be fiddled with given enough 

I'll probably get a Wild Horse probe before I'm happy. But thats a few 
pages down the log I'm not keeping.

Simple hack-a-day carousel Tool changer first. 6 pocket probably.

With this vfd, I left it running at 675 revs for a few hours yesterday, 
to check out the slow speed burn-up horror stories. At 675 revs, and I 
don't currently have any low speed boost programmed in, in 2 hours the 
motor was up 2C and the coolant tank was up 1C. I can stop it with two 
fingers, so obviously I can add some low speed boost when the new vfd 
gets here. It was back to running the spindle fwd yesterday. Go figure.

Cheers Thaddeus, 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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