Re: [CAD_CAM_EDM_DRO] Re: EMC and Taig w/ MicroProto

John Stevenson wrote:

>Lester,
>Can EMC2 run a lathe as yet ?
>
>

Yes, I saw this work at the CNC Workshop last month. Very exciting. I
haven't
quite gotten it working with my controller boards yet, but it is just a
bit of software
to tweak. It does the electronic gearing part OK, it is just waiting
for the shift from
spindle sync to gearing that needs some more testing.

>Also with the original EMC there was an issue with 4th axis control,
>When Art ported the EMC core over to Mach2 the 4tha xis didn't work
>correctly.
>It took Art about 4 goes to get this running.
>has this been fixed? I ask because you may not be aware of it.
>many don't use all the features in a package and assume that because
>they are there, they work.
>
>

There is a 4th axis quandary in all machines with a rotary axis. G-code
doesn't
define a way to know the distance from the center of the rotary axis, so the
toolpath velocity can't be computed directly. The workaround that will
almost always
work on any control is inverse time feedrate. Instead of specifying
feedrate with the
F word, you specify the time to complete the motion. This works
perfectly on EMC,
and always has.

There was a problem on earlier EMC versions where some combined axis
motions could
require the rotary axis to spin VERY fast, since the rotary was not
included in velocity
calculations. I'm pretty sure this has been fixed, at least in EMC2.

Jon