Re: Tool tables

[Dam <damg-at-1st.net>]

Being new to EMC I haven't had time to try all this stuff but here are my
thoughts.

Ethan Vos wrote:

> And now for the next problem:
>
> If I understand correctly, the G43 only works in the Z axis and the G41 and
> G42 will only work in the XY axis.
>

I believe that is correct. G43Hn is tool length comp. G42Dn is tool Dia. (in XY
plane only).

>
> I need to make tool length adjustments in the X axis both positive and
> negative as well as tool diameter adjustments in the Z axis (Horizontal
> spindle along the X axis)

You might be able to use variables in your program that act on the programmed
tool path rather than the tool offsets.

> Could I write to a variable and add the variable (either positive or
> negative) to the tool length and diameter?
>
> Is it only the offset that is called up during the G41,2,3 or the entire
> tool table?
>

It should read just the offset called by either Hn for tool length or Dn for
tool diameter.

>
> Where is an example of a widget that writes data to a variable? I'd like to
> play with that for a bit. I have about 200 programs that I need to use and
> they are identical except for the start position, end position and arc
> radius. I think it'd be easier to fill in those parameters and have the
> program pick up on those rather than write 200 or so programs.
>
> Also, where is the file that has all the Tkemc information. I'm going to
> have to add some widgets to it.
>
> Thanks.
>
> Ethan
>

That's about all the help I can offer at this time.

Dale

>
> -----Original Message-----
> From:   Ray [SMTP:rehenry-at-up.net]
> Sent:   Thursday, August 23, 2001 6:03 PM
> To:     Multiple recipients of list
> Subject:        Re: Tool tables
>
> On Thu, 23 Aug 2001, you wrote:
> > Has anyone modified the Tkemc to allow for changing the tool table data
> on the fly?
> >
> > Does the program need to be reloaded to take the new settings into
> account after tool table changes have been made.
>
> Yes the EMC program reads from the tool file when you ask for the tool
> length offset using g43 or the radius offset using g41 or g42.  The length
> offset does not show up until it is commanded with g43 hn.  The radius
> offset never shows up, it is an offset between the tool path programmed and
> the actual tool path computed.
>
> -----handbook snippet-----
> Tool length offsets are given as positive numbers in the tool table.  A
> tool length offset is programmed using G43 Hn, where n is the desired table
> index. It is expected that all entries in the tool table will be positive.
> The H number is checked for being a non-negative integer when it is read.
> The interpreter behaves as follows.
>
> 1. If G43 Hn is programmed, A USE_TOOL_LENGTH_OFFSET(length) function call
> is made (where length is the value of the tool length offset entry in the
> tool table whose index is n), tool_length_offset is reset in the machine
> settings model, and the value of current_z in the model is adjusted. Note
> that n does not have to be the same as the slot number of the tool
> currently in the spindle.
>
> 2. If G49 is programmed, USE_TOOL_LENGTH_OFFSET(0.0) is called,
> tool_length_offset is reset to 0.0 in the machine settings model, and the
> value of current_z in the model is adjusted. The effect of tool length
> compensation is illustrated in the screen shot below. Notice that the
> length of the tool is subtracted from the z setting so that the tool tip
> appears at the programmed setting.  You should note that the effect of tool
> length compensation is immediate when you view the z position as a relative
> coordinate but it does affect actual machine position until you program a z
> move.
> -----end of snip-----
>
> Try this.  First set tool 1 to 2" length and 0.5 diameter by clicking on
> offset or the number widget after it.  Call up tool 1 (M6 T1) then activate
> length compensation (g43 h1) and you should see the 2" offset in the number
> window.  If you plot moves using both no offset and tool length offset you
> should set the display to machine rather than relative so that you will
> see the differences in the path made.
>
> You can do the same with radius compensation by following the examples in
> the handbook.  This is a little bit trickier to figure out the start move.
>
> HTH
>
> Ray