Re: Re: CNCPro

Roger Brower wrote:

> From: Roger Brower <rbrower@...>
>
> Jon Anderson Wrote:
> Snip...radius comp at that time wasn't
> as high on the list...
>
> Yeah, I'd love to have radius
> compensation in the controller, but
> that's apparently pretty hard to do,
> programming wise, with the lookahead
> function and all.
> I could be to blame! I probably told
> Doug I'd do that in the CAM step; Ahha
> has it? Does EMC do radius comp?
> reliably?

Absolutely! It works in all movement modes except G00, which
sort of makes sense. So, you can do linear, arc and helical
moves with radius comp. I have never had any trouble with
the radius comp, except getting the lead-in move to not
get a squawk about concave corners. This is a problem with
the way radius comp works, and I went through the same
trouble with the Allen-Bradley control I started with. EMC
is a bit more sensitive about these concave corners, but that
is not really EMC's fault. The 'backplotter' (on screen preview
of programmed moves) makes this a LOT easier and faster
to debug. I pretty much have this down solid, now. I did
some parts with radius comp this weekend, and it worked
flawlessly. I often use it so that I can use the same program
to make roughing cuts (with the tool diameter defined in the
tool table to be larger than the actual tool) and then make
a finishing cut with the tool table set to the actual tool size.

> Anybody know how to program
> it? If we can give Doug something
> useful, I suspect he'd try to use it.

Combining radius comp with alternating linear and arc cuts
and lookahead sounds pretty tough to me. I think I'd want
to spend a week at the blackboard with a colleague to bounce
all the possible cases off of before saying anything with
confidence.

>
> hansw wrote: Snip... home to opto
> switches or promity detectors, not
> Mechanical switches>
> I measured <.003 per axis, havent
> measured since.

When using home switches with shaft encoders that have the
index signal, the home switch just gets you to the right rotation
of the encoder, the index pulse sets the actual home position,
generally to one specific encoder count.

Jon