Re: librecad

[Gene Heskett <gheskett@shentel.net>]

On Friday 07 December 2018 01:39:35 Jeremy Nicoll wrote:

> On Thu, 6 Dec 2018, at 22:32, Gene Heskett wrote:
> > Or is there an even better 2d app for such?
>
> There was a discussion here starting in Nov 2017, entitled
>
>    "software to do drawings of houses, gardens, etc."
>
> where several people bemoaned the difficulty they had in getting
> any GUI-based CAD program to do what they needed, without a
> huge learning curve.

Thats a huge part of the problem, but theres another fence to jump. most 
of these so-called cad programs cannot generate even the most basic 
gcode.  And if you have to hand translate its printouts into gcode, you 
may as well write the gcode to do the job in the first place. First, 
your gcode is 10-5000 times more compact, I have it doing 10 holes in 
the needed pattern in under 90 LOC right now, probably under 150 LOC 
when its ready to be actually carved into the alu back panel of this 
box.

> Someone described how they'd instead used hand-coded PostScript
> (which is in essence a set of drawing commands, normally sent to a
> laser printer) to draw plans for house changes.
>
Never tried that. but my customer is a cnc controlled milling machine. 
Not a printer. This process is subtractive, not additive.

I couldn't get to sleep, so I've been up writing gcode since bout 4am 
local, and have about 75% of it done and working, with the rest being a 
matter of getting some measurements from my as built box so far, and 
setting up 2 more of LCNC's 10 available co-ordinate maps to place an 
already written dsub connector pattern in the correct 2 locations.  Then 
I screw the panel to a piece of sacrificial wood and hit r on the 
keyboard and go take a nap. gcode may look like magic, but its quite 
straight forward once its understood. Then one more hole, for a packing 
gland to restrain the line cord, and I'm done. But not till it gets here 
next week so I can measure what size hole it needs. Might as well do it 
all in one pass.

> Something like that might be easier to get to grips with.   A /big/
> advantage of using scripts is that one gets to place comments in
> the script explaining what's going on, why one did something in a
> particular way etc.
>
gcode allows that.

> Also scripts easily allow parameterisation of values - eg (for the
> house plans) what the thickness of a piece of timber is, or what
> the spacing between regular items should be.

gcode can do that. Also has if/else/endif/while/endwhile/repeat etc 
language constructs. And subroutines. Cuts threads at any tpi or tpmm. 
Imperial or metric, no gears limiting what you can do as the coupling 
between the spindle and the workpiece is electronically geared together 
to submicron accuracy. Whats not to like other than cleaning up the mess 
as its made?

-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>