RE: [CAD_CAM_EDM_DRO] Re: EMC Newbie

Hi Jerry,

> My EMC computer is not hooked up to anything at this time, and if I
> hit the home button, the axis indicator goes to zero. Can I assume
> that there being a lack of homing switches, if I hit "home", the
> present machine position will be considered home?

The way the .ini file is set it thinks the home switches are already closed
so if you hit home it becomes where you are at. If you change the
HOME_SWITCH_POLARITY setting you will then get the machine to take off in
the direction set by the HOMING_POLARITY setting at the rate set by the
HOMING_VEL setting. It will continue in that direction until the home switch
is hit or you hit a limit switch.

Here is what Fred Proctor sent me when I was confused on the homing action:
The way homing works is that motion proceeds at the [AXIS_#] HOMING_VEL
speed in the direction specified by [AXIS_#] HOMING_POLARITY until the
home switch trips. The polarity of the home switch is set by [AXIS_#]
HOME_SWITCH_POLARITY. Then, the axis position at the trip point is saved
and motion is aborted. Once the move stops, a move back to the saved
trip point plus any offset in [AXIS_#] HOME_OFFSET is done, and the axis
position is set to the value specified by [AXIS_#] HOME.

With HOME_OFFSET and HOME set to 0, the homing sequence would look like
this:

1. slow jog toward home switch.
2. switch trips.
3. jog decelerates and move terminates shortly after home switch.
4. jog back to switch trip position.
5. position set to 0, and digits turn green.

With HOME_OFFSET set to -0.1 (sign depends on value of HOMING_POLARITY),
and HOME set to 3.0, the homing sequence would look like this:

1. slow jog toward home switch.
2. switch trips.
3. jog decelerates and move terminates shortly after home switch.
4. jog back to point 0.1 units past switch trip position (to get off
switch if you need to)
5. position set to 3.0, and digits turn green (lets you specify 3.0 as
home for this axis).

> Can I create macros written in "G", and give them a button, (create a
> button), on the GUI or assign them to certain keys on the keyboard?
> Seems this would eliminate a lot of loading of files, or typing as
> the
> case might be.

Your machine is setup with Ray Henry's extensions. You will find a script
entry on the menu and the backplot function in the View (?) menu. I think
Ray has some documentation on the scripting on the linuxcnc web site.

> I'm not sure I understand when the "Feed override" setting takes
> effect. Can you explain.

Feed override modifies the feedrate by the percentage you select. The
maximum override value is determined by the setting MAX_FEED_OVERRIDE in the
ini file. As an example, if your feedrate is 10 ipm and you select an
override of 50 (50%) your actual speed will be 5 ipm. If you select an
override of 125 (125%) your actual speed will be 12.5 ipm. Override will not
increase a feedrate beyond what is set as the maximum velocity on either a
global or a per axis basis.

> If I set the jog button increment to .100 and hit the + button five
> times quickly, I would expect that the machine would advance, at the
> axis speed, a half inch, but instead the indicator shows some
> intermediate number. Can you explain what is going on.

The GUI is a little odd in how it recognizes key presses. I am assuming that
you are ending up on a multiple of .100". Try letting it finish the move
before you make the next key press and I think you will find it moves the
proper amount. I don't remember who (Matt, Jon, Ray??) has written about how
the key presses are recognized and how that is different from in other
applications.

> What is the list of "G" and "M" codes under the MDI line in the TKEMC
> GUI?

Here is the list I got from somewhere of the codes EMC understands:
G0, G1,G2,G3,G80,G81,G82,G83,G84,G85,G86,G87,G88,G89
G17,G18,G19
G90,G91
G93,G94
G20,G21
G40,G41,G42
G43,G49
G98,G99
G54,G55,G56,G57,G58,G59,G59.1,G59.3

M26,M27
M0,M1,M2,M30,M60
M6
M3,M4,M5
M7,M8,M9
M48,M49

Tim
[Denver, CO]
http://www.ktmarketing.com