Arcs

[Anxious]

I have a Vytek 4x8 table router which uses 3D HPGL I downloaded the Vecric trials and carved several samples after cobbling together a pp file for my machine. I got the basic jog speed, carve speed functions working, and the point to point stuff no problem, but when it came to arc support my HPGL control board accepts a point center degrees command:

PAx,y,z; <beginning of the arc (or end of last)
AAxc,yc,degrees; <arc center and +ccw or -cw degrees

to carve the arc but none of the examples seem to introduce the degrees variable. My math is a bit rusty but I'm thinking trig functions to calculate the degress may not be available in a .pp specifiable way.

Anyone have any suggestions?

[ger21]

ask on Vectric's support forum, in the PP section.

[Anxious]

Gerry,

I did post the question to Vectric's customer support email and actually got excellent response, however, it more or less ended with HPGL is a 2D spec and 3D abilities are generally proprietary and I might want to contact the controller manufacturer...

They don't make Vytek routers any longer and while the company is still around and very responsive I might add, Vytek suggested replacing the entire controller board including the stepper controllers, which I will eventually get around to as some positive cash flow begins to trickle in... I was just trying to optimise the current situation to bridge the gap between now and then. First some software to make some product then some cash to upgrade the hardware before production volumes ramp up too high etc...

[ger21]

You should be able to create a post that breaks the arcs into short straight line segments.

[Anxious]

Actually the VCarve Pro does that nicely on it's own. Just use a post that doesn't define arcs and it doesn't use arcs, but rather breaks them into very small line segments that look great.

If I want to mill aluminium parts for my dirt bike or something like that, I might need finer control, but for wooden signs, gates, doors, rocking horses, arts and crafts projects etc the result is fabulous. I thought perhaps specifying an arc might help reduce the cut time and keep the cutter through the material speed more consistent.

Dave

[Kiwi]

Can you post some code of before and after so we can see what's required. (doesn't need to be mathmatically correct)

[Anxious]

Sorry it took so long, but here is the code to cut a couple of circles

IN;PU;PA0,0,-400;
VS60;
PA24716,48835,-400
PD24716,48835,102;
AA25339,24450,86.8782;
PA956,25156,-400;
PA956,23744,-400
PD956,23744,102;
AA25339,24450,86.6834;
PA24633,67,-400;
PA26045,67,-400
PD26045,67,102;
AA25339,24450,86.8778;
PA49724,23827,-400;
PA49724,25073,-400
PD49724,25073,102;
AA25339,24450,87.0726;
PA25962,48835,-400;
VS60;
PA21435,24517,-400
PD21435,24517,102;
AA25444,24517,90.;
AA25444,24517,90.;
AA25444,24517,90.;
AA25444,24517,90.;
PA21435,24517,-400;
PA21435,24517,-400;
PA0,0,-400;
IN;

The first one must be leaving tabs I'd guess

Dave

[Anxious]

So that's the code that implements the AA Arc Absolute command and the process for this table is essentially put the cutter at the starting point for the arc then provide the center and number of degrees the arc should proceed from the current position. - degrees is clockwise and +degrees is counterclockwise...

Trouble is I'm not sure how to get the degrees out of vectric.

One last tidbit, the vectric software does very small line segments such that a circle is a circle it looks good, the cut file is bigger but hey... I researched the implementation specifics of the arc command and essentially the machine gets what they call a default cord setting such that I think the hardware actually implements the arc in a very similar manner when the AA command is physically moving the table so the quality difference may not be noticable anyway. But hey puzzles are fun right?

Thanks everyone who is enjoying this puzzle with me.

Dave

[Kiwi]

I thought I could write you a program, that is why I asked for some code, but there is not much of your code that I can follow, all those AA25339,24450 and AA25444,24517 are confusing me.
I'm now thinking that as you are not completely stuck I might give this one a miss even though I like a challenge:-)

[neilw20]

A picture (or 2 is worth a few hundred words)

[ger21]

So it looks like it draws your arc out of straight segments anyway, with the smallest allowable segment being 1° long?

[Anxious]

I think you've all hit the nail on the head, at least with my HPGL based controller. If I move this machine into a money making endevour, I'll probably need to replace the controller and drivers with mach 3 / gecko or similar to increase its speed but for now even with the 1 degree increments it seems pretty smooth. Perhaps I'll cut a 4' table to see what code it generates and to see if I can detect the flat sections around the circumphrence. From the doc it should be glaring, but from the small amount I've cut I have no indication it will show up as quite such rough chords.

I'll keep you posted when I cut such a piece.

Thanks again!
Dave