Re: [CAD_CAM_EDM_DRO] Re: G-Code Arc drawing question

On 11/15/01 7:58 PM, "ballendo@..." <ballendo@...> wrote:

> Dave,
>
> G code is supposed to use "right hand rule" to determine/define
> direction for G02/G03 arc commands...
>
> Right hand rule states that you must "look" at the two ACTIVE axes
> FROM the PLUS(or positive) direction of the UNINVOLVED axis to
> determine CW or CCW.
>
> So in G17 (arcs in XY plane, and the default for vertical mills) we
> look from the plus Z to determine arc direction (above the spindle,
> looking down for a vertical mill).
>
> In G18 (arcs in XZ plane) we would look from the "plus" direction of
> the Y axis.(vertical mill again assumed for the following) Since TOOL
> movement is what defines plus and minus, a tool moving AWAY from us
> is moving in the positive Y direction. (note: It may be the TABLE
> moving TOWARD us, but the TOOL is still moving positive). So we would
> need to get behind the mill to "see" proper CW and CCW.
>
> In G19 (arcs in YZ plane), the uninvolved axis is X, so we need to
> look from the plus side of X to see CW or CCW. Using our vertical
> mill example, we would go around the right end of the table and look
> back toward the mill spindle.
>
> Hope this helps.
>
> Ballendo

Ah! Good explanation....at least it makes sense. I still feel it is
non-intuitive. Breaks of the game. ;-)

Dave

>
> --- In CAD_CAM_EDM_DRO@y..., Dave Engvall <dengvall@e...> wrote:
>> Slightly off topic but emc will use G18 (y-z) plane G2 or G3.
>> However be careful of the sense...i.e....test on foam first as it
>> doesn't seem to cut the way I would expect, seems to interchange G2
>> and G3. Ray tried it on backkplot and agrees that is seems
>> backwards at least to intuition.
>>
>> I've not tried G19 but expect it to work also....and also it may
>> surprise you...test first as going the wrong way into a big chunk of
>> steel can be a shock.
>>
>> Best Wishes,
>> Dave
>
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