Re: [CAD_CAM_EDM_DRO] Re: Simple Vector Feed Rate Setting Question

This seems to be exactly what is happening. Is it very difficult to look at
both axes movements and calculate the feedrate based on not exceeding the
designated rate for either axis, even if one is a rotational axis? This
seems like it would be a common problem since most people with a rotational
axis connected to their CNC will use it concurrently with a linear axis.

How can I get around this problem? Does it matter what order the axes are
identified in a G01 move as to which axis gets the feedrate control?

My current work-around method is to set the maximum speed of the rotary axis
to the rate at which I want to cut, but this makes rapid moves anything but
rapid.

Dan.

----- Original Message -----
From: "alenz2002" <alenz@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Thursday, June 06, 2002 6:17 PM
Subject: [CAD_CAM_EDM_DRO] Re: Simple Vector Feed Rate Setting Question


> --- In CAD_CAM_EDM_DRO@y..., "Dan Statman" <dan.statman@r...> wrote:
> > There must be an error in the TurboCNC program then.
> Intermittently,
> > depending on the relative contributions of the angular and linear
> axes, the
> > movement speed will far exceed the speed if only the linear axis is
> moved.
> > This occurs without changing the feedrate.
>
> Dan,
> A while back I tried this with CNCPro, NOT TurboCNC, but thought the
> similarities might give you an insight. This is a snip of code to
> cut a gear tooth generated by GearGen set to .001 increments. I
> intended to cut one tooth, jog the rotary, cut the next tooth, etc.
> Then thought it would be cool to just leave the Y at zero and let the
> X and rotary (A) cut the entire gear. Wrote a routine to calculate
> the new X, A and feedrates. CNCPro uses only the X (and ignores the
> A) if there is both an X and an A in the same line, so the new
> feedrate for each step is based on the X component of the X-Y
> vector. However if there is NO X in the line, then it uses the A,
> which is in deg/min. Now on my Sherline, there is a 100:1 ratio
> between steps/in and steps/deg, so you get some strange looking
> feedrates, depending on the radius. Note lines N100 and N110 in the
> converted code.
>
> (original gcode)
> N70 G00 X3.3312 Y0
> N80 G00 A0.
> N90 F8
> N100 G02 X3.3305 Y-0.0711 I-3.3312 J0.
> N110 G01 X3.3298 Y-0.0713
> N120 G01 X3.3288 Y-0.0717
> N130 G01 X3.3277 Y-0.0721
> N140 G01 X3.3267 Y-0.0725
> N150 G01 X3.3257 Y-0.0728
> N160 G01 X3.3246 Y-0.0732
> N170 G01 X3.3236 Y-0.0736
> N180 G01 X3.3226 Y-0.0740
> N190 G01 X3.3215 Y-0.0743
> N200 G01 X3.3205 Y-0.0747
>
> (After converting to X and A)
> N70 G00 X3.3312 A0
> N80 G00 A0.
> N90 F8
> N100 G01 A-1.2229 F137.6 (8 in/min at this radius)
> N110 G01 X3.3305 A-1.2266 F7.6
> N120 G01 X3.3295 A-1.2339 F7.4
> N130 G01 X3.3284 A-1.2412 F7.5
> N140 G01 X3.3274 A-1.2484 F7.4
> N150 G01 X3.3264 A-1.2540 F7.6
> N160 G01 X3.3254 A-1.2613 F7.5
> N170 G01 X3.3244 A-1.2685 F7.4
> N180 G01 X3.3234 A-1.2758 F7.4
> N190 G01 X3.3223 A-1.2814 F7.7
> N200 G01 X3.3213 A-1.2887 F7.6
>
> BTW this did work, but it wasn't totally reliable. I don't
> remember the exact problem, but thought at the time the federates
> were somehow getting tangled up. Needless to say if the rotary is
> used as a linear, then the feedrate is astronomical, and if vice-
> versa, it comes to a dead stop. Never followed up on it, but if
> anyone is using this method with success, I would be interested in
> hearing from you.
> Al Lenz
>
>
>
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