Re: Modifying EMC interface for lathe (x and z) display Thanks to all.

[Ray Henry <rehenry-at-up.net>]

Howard

I believe that the var file uses tool diameter values but does it's comp 
based on the radius.  This should work as well for lathes as it does for 
mills.

Some of the confusion comes in the fact that lathes run the x value as a 
diameter rather than a direct distance.  A 0.1 move with the handwheel is 
only 0.05 in distance but 0.1 change in diameter for the finished part.  
You can achieve the same effect with EMC if you double the x axis 
input_scale.  You just have to remember that 1 inch isn't an inch anymore 
so you need to set the soft limits and such to account for it..

I have seen a number of Sherline mills and at least one lathe run with 
the EMC software.  Several folk on this list have them and there are a 
couple Sherline dealers hereabout as well.  There is not a great deal of 
cost involved in doing this.  I'd certainly use the Sherline motor mounts 
because they provide good alignment between the motors and shafts without 
any fiddling at all.  

I have run Sherline steppers using "slave mode" on the Sherline index 
controller.  There is a small jitter problem with this because the index 
controller puts out four microsteps for each step pulse put in.   It 
works well when the commands come from the indexer itself because it 
knows how fast to spit out the pulses to match the next step pulse. 
Unfortunately it does not know how to pace these pulses in "slave mode" 
so spits them all out at once.  Hence the bit of jitter and noisy 
stepping when you try contouring with them.

Matt Shaver has added limit and home switches to the NIST mill.  If you 
want these for teaching purposes contact him.  

If that bridgeport clone uses steppers and you can get access to input 
step and direction signals to the drive amps,  it would not be a 
difficult task to set up a parallel EMC to the existing control with the 
"much less efficient and elegant interface."  

Ray


On Sunday 15 December 2002 11:32 am, you wrote:
> Ray,
>
> Thanks for the tips.  Sounds just like what I need.  I noticed the lack
> of cutter comp on the x-z plane and thought about using the lathe in
> the x-y plane to hopefully be able to get cutter comp.  This would
> require programming to a radius instead of a diameter of course.  This
> might be a problem if several people use the machine and they are used
> to standard x-z setups, like in a school setting.
>
> I am trying to push EMC to the local university and I think I have one
> professor convinced to let me do a conversion on a Sherline mill.  I
> just wish I had been knowledgeable enough at the time when they were
> choosing a controller for their Bridgeport clone and went with
> something with a much less efficient and elegant interface.
>
> Thanks again,
>
> Howard Bailey
>
> > Hi Howard.
> >
> > I've got one running here.  The emc does equate axis #0 with x,  #1
> > with Y, and #2 with Z.  There does not seem to be a way around this
> > but you can make the tkemc interface show only x and z by setting
> > your ini file like this.
> >
> > ; Trajectory planner section--------------------------------
> > [TRAJ]
> >
> > AXES = 3
> > COORDINATES = X Z
> > HOME = 0 0 0
> >
> > The reason you can do this is that tkemc looks at the coordinate
> > names variable and creates a position display for each name in there.
> >  Having the three axes defined should be no problem.  This way both x
> > and z words move the correct axis.
> >
> > You will not get tool radius offsets, yet.
> >
> > Hope this helps
> >
> > Ray
> >
> > On Saturday 14 December 2002 11:30 pm, Howard wrote:
> > > John,
> > >
> > > Thanks for the reply.  Set the number of axes to 2 and deleted the
> > > third axis section.  I also deleted Y where it was listed in the
> > > first portions of the .ini file leaving X Z ....  EMC still regards
> > > the second axis as the Y axis, requiring me to do a find and
> > > replace to change all of my z moves to y moves in my Gcode file. 
> > > Any work arounds for this would be welcome.
> > >
> > > Best Regards,
> > >
> > > Howard Bailey
> > >
> > > > It is just a matter of changing the .ini file and you are there. 
> > > > I don't remember the exact items to change but I think it is
> > > > pretty self
> > >
> > > explanatory
> > >
> > > > when you start looking at the .ini file.  Change the number of
> > > > axis to 2
> > >
> > > and
> > >
> > > > delete the extra sections for the unwanted axis.
> > > >
> > > > John Guenther
> > > > 'Ye Olde Pen Maker'
> > > > Sterling, Virginia
> > > >
> > > > > -----Original Message-----
> > > > > From: emc-at-nist.gov [emc-at-nist.gov]On Behalf Of Howard
> > > > > Bailey Sent: Saturday, December 14, 2002 22:58
> > > > > To: Multiple recipients of list
> > > > > Subject: Modifying EMC interface for lathe (x and z) display
> > > > >
> > > > >
> > > > >
> > > > > I was wondering how one would modify TKEMC to only display the
> > > > > readouts for
> > > > > the X and Z axes for a lathe.  I have looked at some of the
> > > > > files and what I
> > > > > needed was not apparent to me.  Additionally, I was wondering
> > > > > how difficult
> > > > > it would be to have one version of EMC set up to run a mill and
> > > > > another
> > >
> > > to
> > >
> > > > > run a lathe on the same computer to be able to choose the
> > > > > proper version for
> > > > > the job at hand.  More specifically, which files I would need
> > > > > two
> > >
> > > versions
> > >
> > > > > of and which references to these files in the .ini files I
> > > > > would need to modify.  Any help is appreciated.
> > > > >
> > > > > Regards,
> > > > >
> > > > > Howard Bailey