Re: [CAD_CAM_EDM_DRO] EMC and Rounded Corners

Yes the g61 mode looks interesting. I have not used it.
There might be some problems with chip load (in routers)
and heat (in plasma) when slowing down though.

I have thought before about changing spindle speed with
feed for constant chip load. I think this is done a lot in high performance
systems.I don't know much about plasma
torches, but I wonder if some parameter will give you the same cut at lower
speeds.

I am definitely in "turn it up and see how fast it will go"
mode with my new machine.

Might allow the whole thing to go a good bit faster, without
sledgehammer blow accelerations.


EMC certainly has the crunch capability to do stuff like this..
but a little code might have to be written, Alternatively a system that
controls rpm or some torch parameter based
on servo back emf or stepper pulse rate would be very easy
to do as a black box. Since the axes are orthagonal just the
square root of the sum of the emf or pulse rates would do it.
I might figure something up for this.
It could be very cheap if there is already a triac or vfd or
something already there to control the parameter.

Perhaps someone on the list has already done this.

Les
Leslie Watts
L M Watts Furniture
Tiger, Georgia USA
http://www.rabun.net/~leswatts/wattsfurniturewp.html
engineering page:
http://www.rabun.net/~leswatts/shop.html

----- Original Message -----
From: "Toddy, Terry L CUBA" <tltoddy@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Monday, April 08, 2002 12:55 PM
Subject: RE: [CAD_CAM_EDM_DRO] EMC and Rounded Corners


> Les, Thanks for the quantitative analysis. The 3/8" rounding was a wild
> guess, not an actual measured radius. It could well be more like 1".
Here's
> the qualitative analysis: My parts look like marshmallows.
>
> It is a stepper system.
>
> Tonight I will try to find my max accel values. Yes, plasma and routers
need
> high accel values to run at high feedrates. Keeping the gantry mass down
> helps with plasma but the routers need the rigidity.
>
> I think the G61(exact path mode) will eliminate the tool path variation
and
> maximizing acceleration will minimize the slow motion around the corners.
> The EMC apparently defaults to G64(continuous mode)where tool path
accuracy
> is compromised to optimize velocity. That's probably a great feature for a
> mill cutting a mold cavity at 10 or 20 IPM, and making slight changes in
> direction, not so great for a plasma machine running 200 IPM trying to cut
> square corners. Actually G64 may be useful with the plasma for curves
> generated from small line segments as long as you go back to G61 to make
> sharp corners.
>
> Terry