Heekscnc method of getting data to the python script

In my last post, I talked about how Heekscnc uses a master python script to coordinate the generation of g-code. In this post, I will try to convey how data is translated from the gui to this python script.

1. Look at the layout of HeeksCAD with the HeeksCNC installed :

Notice that there is an Objects tree on the left side. This is how all the data for the cnc program is graphically represented. Double clicking in items in this tree usually causes the parameters of that particular item to be displayed and editable.

To create a toolpath in Heeks, you need a 'sketch' (geometry), a 'tool' (end mill, drill, etc...) , and an 'operation' (profile, pocket, drilling...). So the first thing needed to get this ball rolling is the 'sketch'. Here I select the face of a solid and right click on it. A dialog pops up and allows me to create sketches from the face.

The representation of the 'sketch' (or two sketches in this one)  appears in the 'Objects tree':

Notice that in my Objects tree there are already some tools listed. I have a tool table file stored on my hard drive with these tools in it.
I next select a sketch and one of the tools from the tree and then create an operation:

I selected a 'Profile' operation because I want to cut around the outside profile of this part.















I also did the same thing with the inner sketch, but this time used a smaller tool and then selected the 'Pocket' operation. In Heekscnc, the pocket operation dialog looks like this:

When I have a few operations set up, I usually get curious and want to see some results, so I usually post process what I have do far to see what the resulting tool paths look like:

Pressing the 'Post-Process' button causes the master python script to be built and placed in the 'Program' panel:

This is the same type of script that I blogged about last time. This script is run and creates a gcode file in the 'Output' panel.

So, there you have it- that is a basic rundown of how Heekscnc operates.

The thing that I want to stress in this post is that anything that is represented in the Objects tree will be translated to the master python script and later converted into gcode.

Python toolpath generation -HeeksCNC method

In this post, I want to explain the basics of how HeeksCNC uses python to generate toolpaths. The method that Dan Heeks came up with for doing this was brilliant. I have used bits and pieces of this method with different applications a lot and am just starting to use it with FreeCAD. Here is a python script (Dan Heeks named it post.py in HeeksCNC) that is the main script for a gcode file.
post.py : 

import area
area.set_units(25.4)
import kurve_funcs
from nc.nc import *
import nc.emc2

output('/tmp/test.tap')
program_begin(123, 'Test program')
absolute()
imperial()
set_plane(0)

comment('Feeds and Speeds set for machining Please select a material to machine')

tool_defn( id=3, name='1/4 inch Carbide End Mill', radius=0.125, length=1.25, gradient=-0.1)
#(0.188 inch Carbide End Mill)

workplane(1)
comment('tool change to 1/4 inch Carbide End Mill')
tool_change( id=3)
spindle(7000)
feedrate_hv(33.07086614, 7)
flush_nc()
clearance = float(0.1968503937)
rapid_safety_space = float(0.07874015748)
start_depth = float(0)
step_down = float(0.035)
final_depth = float(-0.07)
tool_diameter = float(0.25)
cutting_edge_angle = float(0)
#absolute() mode
roll_radius = float(0.125)
offset_extra = 0
comment('Sketch')
curve = area.Curve()
curve.append(area.Point(1.25, -0.7))
curve.append(area.Point(-0.65, -0.7))
curve.append(area.Vertex(-1, area.Point(-1.4, 0.05), area.Point(-0.65, 0.05)))
curve.append(area.Point(-1.4, 0.45))
curve.append(area.Vertex(-1, area.Point(-0.65, 1.2), area.Point(-0.65, 0.45)))
curve.append(area.Point(1.25, 1.2))
curve.append(area.Vertex(-1, area.Point(2, 0.45), area.Point(1.25, 0.45)))
curve.append(area.Point(2, 0.05))
curve.append(area.Vertex(-1, area.Point(1.25, -0.7), area.Point(1.25, 0.05)))

roll_on = 'auto'
roll_off = 'auto'
extend_at_start= 0
extend_at_end= 0
lead_in_line_len= 0.25
lead_out_line_len= 0
kurve_funcs.profile(curve, 'left', tool_diameter/2, offset_extra, roll_radius, roll_on, roll_off, rapid_safety_space, clearance, start_depth, step_down, final_depth,extend_at_start,extend_at_end,lead_in_line_len,lead_out_line_len )
absolute()
program_end()  

This script is processed like this:

post.py reaches out to other scripts/modules in the heekscnc world for processing and formatting. These other scripts need to be in the python path, as you would expect.
libarea can be had from many places now, although I prefer to use the 'New BSD' licensed version that can be found here.

kurve_funcs.py is used for processing toolpaths for milling profiles. It depends on libarea too. I think we could probably untangle the dual dependency of calling 'import area' in post.py and in kurve_funcs.py, if we looked into it.

the line 'import nc.emc2' calls upon a user editable script that formats gcode for the emc2 (linuxcnc now) milling machine. There are a lot of other scripts in the nc directory that let one format the gcode for other machines.

Here is a summary of the components of this system again:

 

Our book on FreeCAD has been published

Brad and I have been working on a small book on FreeCAD for Packt Publishing, since February of this year. It has now been published and can be purchased through Packt and Amazon. It was an interesting experience writing the book. I think we initially wrote the whole thing in the span of two weeks and spent the remainder of our time until August editing it. I think we learned a lot about writing and a lot about FreeCAD itself.

Experimental Online APT360 Processor

Edit-I have disabled the server for this, since I needed it for something else. This doesn't work anymore.
I have been playing with websockets and a Linode server. A friend of mine, Brent Muller, set up APT360 on the linode server and I created a python-tornado websocket interface to it.

Paste Apt code in the top text box and press the Post Code button. If there are no errors (be careful to make sure the first line of code begins on column one and that there is a line after 'fini') you should get gcode in the bottom pane. For those of you who know what APT360 is, have fun.

Available Post Processors: a1100m, cent1, cent2, dmb, dmb2, e4axvt, e5axtr, e5axvt, emc, webgl2

PARTNO N/C 360 APT SAMPLE PART PROGRAM machin/emc clprnt print/on SP = POINT/ 0, 0, 0 L1 = LINE/ 4, 0, 0, 4, 8, 0 PT = POINT/ 4.0, 8.0, 0 L2 = LINE/ PT, ATANGL, 45 L3 = LINE/ 8, 12, 0, 12, 12, 0 L4 = LINE/ 14, 5, 0, 14, 10, 0 L5 = LINE/ 0, 2, 0, 10, 2, 0 C1 = CIRCLE/ 12, 10, 0, 2.0 C2 = CIRCLE/ 14, 2, 0, 3.0 INTOL/ 0 OUTTOL/ .005 CUTTER/ .25 SPINDL/ 2000, CLW COOLNT/ ON FEDRAT/ 20.0 FROM/ SP GO/ TO, L1 TLLFT, GOLFT/ L1, PAST, L2 GORGT/ L2, PAST, L3 GORGT/ L3, TANTO, C1 GOFWD/ C1, TANTO, L4 GOFWD/ L4, PAST, C2 GORGT/ C2, PAST, L5 GORGT/ L5, PAST, L1 GOTO/ SP COOLNT/ OFF SPINDL/ OFF FINI

Javascript post processing

This is a test to see how javascript could work for post processing. In the left textarea, add terms like 'g0(0,0,0)' for rapid moves, 'g1(1,0,0)' for feed moves and then press the 'Post' button to get some GCode in the right textarea box. Some of you might wonder why? This is just a test for something bigger.

g0(x,y,z) - rapid

g1(x,y,z) - feed move

g2(x,y,i,j) - clockwise arc - i,js in absolute coordinates

g3(x,y,i,j) - counter clockwise arc

feedrate = 33.0 - feedrate

I tried to make things modal, so that unneeded terms aren't repeated. At some point the post processor needs to reside on a client machine as an html5 local file. I have a lot to learn...

JavaScript Post Processor

Program Data feedrate=44 g0(0,0,0) g1(1,0,0) g3(0,1,0,0) g3(-1,0,0,0) feedrate=22 g1(0,0,0)

GCode output

Javascript blogger test

I just want to try something out with this blogger software. I want to see if I put inline javascript in a post. This post might be deleted later, after the test.

This free script provided by
JavaScript Kit

Cloud CADCAM via twisted python

I have been working a bit with Julian Todd of FreeSteel . We have started working on a way of serving out toolpaths, using his 'Slicer' routine from a server. The server takes triangle vertices in and returns tool location paths, for waterline type machining. Julian is very familiar with twisted python and plans on using it for his own server. At the moment, I am running his library locally.

Here is an image of a part that I designed in FreeCAD and applied this 'Slicer' scheme to:



The python code that I used for this doesn't post process into actual g-code, but it could.

import Mesh
import Part,FreeCAD
from FreeCAD import Base,Vector
import freesteelpy as kernel

s=Gui.Selection.getSelectionEx()
s1 = s[0]
m1 = s1.Object
m1.Mesh.write("/home/danfalck/mesh1.py") #write the triangle list to a file
f1 = m1.Mesh.Facets #returns out a list of facets

fssurf = kernel.FsSurf.New()
for f in f1:
fssurf.PushTriangle(f.Points[0][0],f.Points[0][1],f.Points[0][2], f.Points[1][0],f.Points[1][1],f.Points[1][2], \
f.Points[2][0],f.Points[2][1],f.Points[2][2])

def doit(fssurf, z , rad):
fssurf.Build(1.0)

fshoriztoolsurf = kernel.FsHorizontalToolSurface.New()
fshoriztoolsurf.AddSurf(fssurf)
fshoriztoolsurf.AddCylinder(rad, z, 10.0, 0) #cylinder radius, lower Z, upper Z, how the cylinder is connected to the rest of the tool -tangential etc.
fsimplicitarea = kernel.FsImplicitArea.New(0)
fsimplicitarea.AddHorizToolSurf(fshoriztoolsurf)
fsimplicitarea.SetContourConditions(0.99, -1.0, 0.002, 2, -1.0, 0.9)
fsweave = kernel.FsWeave.New()
fsweave.SetShape(-25, 25, -25, 25,.1) #(-x, -y, x , y of bounding area, last arg is granularity of path)
fsimplicitarea.GenWeaveZProfile(fsweave)
fsweave.GetNContours()

fspath2x = kernel.FsPath2X.New(0)
fspath2x.RecordContour(fsweave, False, 0, 0.0)

fspath2x.GetNpts()

[ (fspath2x.GetD(i,0), fspath2x.GetD(i,1)) for i in range(fspath2x.GetNpts()) ]

[ (fspath2x.GetD(i,0), fspath2x.GetD(i,1), fspath2x.GetD(i,2)) for i in range(fspath2x.GetNpts()) ]

pt0 = (fspath2x.GetD(0,0), fspath2x.GetD(0,1), fspath2x.GetD(0,2))

#FreeCAD.ActiveDocument.addObject("Part::Feature","rapids)\n")
c = Part.Compound([])

for i in range(fspath2x.GetNpts()-1):
line = ( Part.makeLine( (fspath2x.GetD(i,0), fspath2x.GetD(i,1), fspath2x.GetD(i,2) ) , ( fspath2x.GetD(i+1,0), fspath2x.GetD(i+1,1), fspath2x.GetD(i+1,2) ) ) )
c.add(line)

c.Placement=Base.Placement(Base.Vector(0.00,0.00,z),Base.Rotation(0.00,0.00,0.00,1.00))

Part.show(c)

rad = 1.0
startdepth = 2.5
zdepth = -3.0
stepdown = .25
steps = startdepth

while startdepth >= zdepth:
z = startdepth
doit(fssurf,z,rad)
startdepth =startdepth-stepdown


Sorry for the poor formatting of the source code- I need to figure that out soon.

Demo of Profiling

More Progress

I was able to hack together a crude 'Profile Operation' dialog and connect it to heekscnc and libarea functions this weekend. Now I can bring up the dialog, select the edges of a solid, and then backplot the code.
It's definitely a rough hack, but it shows some potential.