2011/5/3 Steve <[email protected]>:
> Stuart Stevenson replied "agreed - the "kinematics" is in the g code program
> - just having the machine control the axes is enough to be able to cut 5
> axis parts"
>
> I was under the impression that the kinematics had to be written in EMC2 for
> the coordinated movement between all the axes to function properly?  However
> what you say seems to make more sense.  When the tool path is generated by
> the CAM software, off the surfaces of the 3D model, the software uses the
> user selected post processor to output the G code for the desired tool path.
> So it is the writer of the post processor that will have to know the
> orientation of the axis of the machine being used (hence the kinematic
> calculations) so that the G code is correct to produce the desired tool
> path.

I think that You are on the right track. Sophisticated postprocessor
and kinematics module in EMC2 basically does the same thing - takes
the initial code and treats the kinematics specifics (adds different
compensating moves), and I think that it can be considered as a code
for a joint mode.
My personal opinion is that treating the unique machine-specific
kinematic calculations in a kinematics module is more desirable than
in a postprocessor because of 2 reasons:
1) cost perspective - AFAIK producers of CAM applications enjoy
charging their clients for development of postprocessors for
particular machines (I have been asking these questions to authors of
CAM applications for 5axis waterjet cutting), EMC already provides
kinematic modules for most popular types of machines and it is easy
(and almost always does not cost anything) to tweak them to suit
particular machine. With an exception - I have not been able to get
genserkins work with linear joints and unfortunately have not received
any support from mailing list members on this matter, although I tried
to ask for it;
2) ease of use - user can overview, adjust and/or correct the code, if
it is necessary, when it does not contain information about
kinematics. But I do not see it possible to review and understand code
for a puma arm, where axis commands actually are joint positions. User
of those postprocessors is bound to them, it is very difficult to do
anything with their machine without it.

Viesturs

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