linuxcnc blogs

Shaped cutters

2010-09-02T09:18:16+00:00

For making 60-degree dovetails, and R=2mm rounded edges.

tkemc: visual improvements

2010-08-31T14:34:50+00:00

tkemc: visual improvements

* get rid of undesirable ridge border on jog speed controls
* align jog controls to the top of their area, not center
  (better appearance when there are no angular axes)

[D H] tcl/tkemc.tcl

tkemc: show work offsets for all axes

2010-08-31T14:30:16+00:00

tkemc: show work offsets for all axes

[D H] tcl/tkemc.tcl

Short trip to Buzias this saturday

2010-08-31T12:43:44+00:00

Close to my home town (Timisoara) there's a smaller city called Buzias..

Equatorial wedge – top plate

2010-08-29T19:33:35+00:00

This is the top plate of the wedge which will be tilted so that the alt/az mount which is bolted to it has its azimuth axis pointing towards the celestial north pole. The side-plates will have to wait until next weekend.

Merge branch 'v2.4_branch'

2010-08-29T18:56:22+00:00

Merge branch 'v2.4_branch'

[D H] docs/README
[D H] docs/src/config/lathe_config.lyx
[D H] docs/src/config/stepconf.lyx
[D H] docs/src/config/stepper.lyx
[D H] docs/src/hal/basic_hal.lyx
[D H] docs/src/hal/halshow.lyx
[D H] docs/src/lathe/lathe-user.lyx
[D H] src/emc/rs274ngc/tool_parse.cc
[D H] src/emc/usr_intf/pncconf/pncconf.py

interp: Get rid of tortured code

2010-08-29T17:47:36+00:00

interp: Get rid of tortured code

This
	b = (x != 0) ? 1 : 0;
is really just a tortured way to write
	b = x;
so do the simple thing.

Thanks to cradek for pointing these out.

[D H] src/emc/rs274ngc/interp_convert.cc
[D H] src/emc/rs274ngc/rs274ngc_pre.cc

interp: use true, false instead of ON, OFF

2010-08-29T15:37:14+00:00

interp: use true, false instead of ON, OFF

[D H] src/emc/rs274ngc/interp_convert.cc
[D H] src/emc/rs274ngc/interp_cycles.cc
[D H] src/emc/rs274ngc/interp_execute.cc
[D H] src/emc/rs274ngc/interp_internal.cc
[D H] src/emc/rs274ngc/interp_internal.hh
[D H] src/emc/rs274ngc/interp_read.cc
[D H] src/emc/rs274ngc/rs274ngc_pre.cc

interp: get rid of the ON_OFF typedef

2010-08-29T15:24:53+00:00

interp: get rid of the ON_OFF typedef

This typedef dates to the same era which provided us with the much-reviled
IS and SET_TO and is about as beneficial.

[D H] src/emc/rs274ngc/interp_internal.hh
[D H] src/emc/rs274ngc/rs274ngc.hh
[D H] src/emc/task/emctask.cc

interp: prefer boolean tests to == ON tests

2010-08-29T15:19:29+00:00

interp: prefer boolean tests to == ON tests

In idiomatic C++, the right way to check the truth value of a boolean
is to simply use it in a boolean context, not compare it to the ON
or OFF (true or false) value.

This change was performed mechanically by executing the following
commands in src/emc/rs274ngc:
  sed -i 's/\([-a-zA-Z_0-9>]*\) == ON/\1/g' *.cc
  sed -i 's/\([-a-zA-Z_0-9>]*\) != OFF/\1/g' *.cc
  sed -i 's/\([-a-zA-Z_0-9>]*\) == OFF/!\1/g' *.cc
  sed -i 's/\([-a-zA-Z_0-9>]*\) != ON/!\1/g' *.cc

[D H] src/emc/rs274ngc/interp_check.cc
[D H] src/emc/rs274ngc/interp_convert.cc
[D H] src/emc/rs274ngc/interp_cycles.cc
[D H] src/emc/rs274ngc/interp_execute.cc
[D H] src/emc/rs274ngc/interp_find.cc
[D H] src/emc/rs274ngc/interp_internal.cc
[D H] src/emc/rs274ngc/interp_inverse.cc
[D H] src/emc/rs274ngc/interp_read.cc
[D H] src/emc/rs274ngc/interp_write.cc
[D H] src/emc/rs274ngc/rs274ngc_pre.cc

interp: add t_flag

2010-08-29T13:59:34+00:00

interp: add t_flag

For symmetry, all words should be a combination of a number and a flag.

[D H] src/emc/rs274ngc/interp_execute.cc
[D H] src/emc/rs274ngc/interp_internal.cc
[D H] src/emc/rs274ngc/interp_internal.hh
[D H] src/emc/rs274ngc/interp_read.cc

interp: add s_flag

2010-08-29T13:56:22+00:00

interp: add s_flag

For symmetry, all words should be a combination of a number and a flag.

[D H] src/emc/rs274ngc/interp_check.cc
[D H] src/emc/rs274ngc/interp_execute.cc
[D H] src/emc/rs274ngc/interp_internal.cc
[D H] src/emc/rs274ngc/interp_internal.hh
[D H] src/emc/rs274ngc/interp_read.cc

interp: add f_flag

2010-08-29T13:49:10+00:00

interp: add f_flag

For symmetry, all words should be a combination of a number and a flag.

[D H] src/emc/rs274ngc/interp_check.cc
[D H] src/emc/rs274ngc/interp_convert.cc
[D H] src/emc/rs274ngc/interp_execute.cc
[D H] src/emc/rs274ngc/interp_internal.cc
[D H] src/emc/rs274ngc/interp_internal.hh
[D H] src/emc/rs274ngc/interp_read.cc

add info on smart quotes

2010-08-29T13:37:16+00:00

add info on smart quotes

Signed-off-by: John Thornton <jthornton@gnipsel.com>

[D H] docs/README

typo's submitted by KimK

2010-08-29T13:30:45+00:00

typo's submitted by KimK

Signed-off-by: John Thornton <jthornton@gnipsel.com>

[D H] docs/src/hal/halshow.lyx

typo's submitted by KimK

2010-08-29T13:29:40+00:00

typo's submitted by KimK

Signed-off-by: John Thornton <jthornton@gnipsel.com>

[D H] docs/src/lathe/lathe-user.lyx

typo's submitted by KimK

2010-08-29T13:28:16+00:00

typo's submitted by KimK

Signed-off-by: John Thornton <jthornton@gnipsel.com>

[D H] docs/src/hal/basic_hal.lyx

typo's subbmitted by KimK

2010-08-29T13:27:05+00:00

typo's subbmitted by KimK

Signed-off-by: John Thornton <jthornton@gnipsel.com>

[D H] docs/src/hal/halshow.lyx

typo's submitted by KimK

2010-08-29T13:20:05+00:00

typo's submitted by KimK

Signed-off-by: John Thornton <jthornton@gnipsel.com>

[D H] docs/src/hal/basic_hal.lyx

typo's submitted by KimK

2010-08-29T13:18:45+00:00

typo's submitted by KimK

Signed-off-by: John Thornton <jthornton@gnipsel.com>

[D H] docs/src/config/stepper.lyx

typo's subbmitted by KimK

2010-08-29T13:14:27+00:00

typo's subbmitted by KimK

Signed-off-by: John Thornton <jthornton@gnipsel.com>

[D H] docs/src/config/lathe_config.lyx

note that no hardware needs to be connected to run the latency test

2010-08-29T11:27:23+00:00

note that no hardware needs to be connected to run the latency test

Signed-off-by: John Thornton <jthornton@gnipsel.com>

[D H] docs/src/config/stepconf.lyx

On random tc, correctly skip invalid tool table entries

2010-08-28T23:51:35+00:00

On random tc, correctly skip invalid tool table entries

This fixes an error case on random tc when a tool table entry
described a pocket that was out of range.  This printed an error
message but then if there were subsequent valid words on the line,
the entry was incorrectly marked as 'valid' again, and the invalid
pocket number caused the array to be written out of bounds.

To reproduce, on a random tc config, use a tool entry such as
T1 P99999 Z1.0

With this change, the invalid entry is skipped when reading, so
when the tool table later gets rewritten it's gone.  I think this
was the original intent.

[D H] src/emc/rs274ngc/tool_parse.cc

Equatorial wedge – base plate

2010-08-28T19:26:17+00:00

I’m building an equatorial wedge which will transform my new alt/az goto-mount into an equatorial mount. This is the first part which attaches to the tripod. Two smaller side plates will be bolted to this plate and support a similarly shaped tilted plate to which the alt/az head attaches. The design is similar to the “mega wedge pro” (how about that for a product name!).

complete installation of gladevcp

2010-08-28T13:52:52+00:00

complete installation of gladevcp

[D H] src/Makefile

remove file added by mistake

2010-08-28T13:34:44+00:00

remove file added by mistake

[D H] configs/plasma-thc/mp1000_serial.py.threadedNonSafe

remove execute bits that don't belong

2010-08-28T13:31:49+00:00

remove execute bits that don't belong

[D H] src/emc/kinematics/gantrykins.c
[D H] src/hal/classicladder/configplc
[D H] src/hal/classicladder/projects_examples/IndexedVar_used_in_function.clp
[D H] src/hal/classicladder/projects_examples/example.clp
[D H] src/hal/classicladder/projects_examples/modbus_rtu_serial.clp
[D H] src/hal/classicladder/projects_examples/test_call_subroutines.clp
[D H] src/hal/drivers/opto_ac5.c
[D H] src/hal/drivers/opto_ac5.h

add gladevcp.py for gladevcp component

2010-08-27T23:17:04+00:00

add gladevcp.py for gladevcp component

somehow this got missed

[D H] src/hal/user_comps/gladevcp.py

addbasic man page for gladevcp

2010-08-27T22:47:14+00:00

addbasic  man page for gladevcp

[D H] docs/man/man9/gladevcp.9

add gladevcp to emc

2010-08-27T22:21:16+00:00

add gladevcp to emc

This allows virtual control panals to be made
using GTK and the GLADE UI editor. At this point
system links need to be added to use GLADE. see
the READ_ME

[D H] lib/python/gladevcp/READ_ME
[D H] lib/python/gladevcp/hal_python.xml
[D H] lib/python/gladevcp/hal_pythonplugin.py
[D H] lib/python/gladevcp/hal_widgets.py
[D H] lib/python/gladevcp/led.py
[D H] lib/python/gladevcp/widget-hal_pythonplugin-hal_led.png
[D H] lib/python/gladevcp_makepins.py
[D H] src/Makefile
[D H] src/hal/user_comps/Submakefile

AXIS with PyVCP jogwheel

2010-08-27T15:12:55+00:00

By popular demand, an example where a PyVCP jogwheel is hooked up to AXIS:

The files needed to make this work are in here: axis_jogwheel.tar

Merge remote branch 'origin/v2.4_branch'

2010-08-27T14:43:30+00:00

Merge remote branch 'origin/v2.4_branch'

[D H] docs/README
[D H] docs/man/man1/halui.1
[D H] docs/src/README
[D H] docs/src/config/ini_homing.lyx
[D H] tcl/tkemc.tcl

Radial tool projection

2010-08-27T11:53:23+00:00

The basic operation when producing waterline-paths is to push the cutter along either the X or Y axis (red and green arrows) into contact with a triangle (cyan lines). That’s done through three different functions, one each for the vertices, facet, and edges of the triangle. The vertex test (results shown as red dots) and the facet test (green dots) are straightforward to implement. The edge-test (blue dots) is more involved. The above figure is for a CylCutter where the edge-test is implemented through the vertex-test (thus red dots along the edges), but this figure for a BallCutter shows the colors better:

Blue dots show edge-contacts with the spherical part of the cutter, light-blue dots show edge-contacts with the cylindrical shaft of the cutter.

The vertex test requires only a radius(h) function that returns the radius of the cutter at height h. The facet test needs three parameters (n, nxy, c) for each cutter, which define where the cutter should be located relative to a point which lies on the facet. From the CC-point on the facet we go a distance n along the 3D unit-normal, then a distance nxy along a unit-normal in the XY-plane to find the cutter center. From the cutter center we go down along the z-axis by a distance c to find the CL-point.

Figuring out the (n,nxy,c) parameters for CylCutter and BallCutter is left as an exercise for the reader.

These points are then hooked up in the correct order to produce waterlines like this (CylCutter on the left, BallCutter on the right).

The edge-test for CylCutter reduces to a 2D problem of line-line intersections, while the edge-test for BallCutter can be done by intersecting a cylinder/tube around the edge with a line. The filleted/toroidal/BullCutter edge-test is much harder. Here I’ve just implemented the special case where the edge is horizontal and the solution is easy to find analytically. The general case where the edge slopes up or down requires an iterative solution to either a quartic or the offset-ellipse problem.

Weekend trip to Vienna

2010-08-24T14:07:00+00:00

Vienna - Schoenbrunn

It's been a long time since we had such a fun weekend in Vienna..

tkemc: fix radiobutton appearance

2010-08-23T20:37:13+00:00

tkemc: fix radiobutton appearance

A difference between tk8.4 and tk8.5 radiobuttons meant that
on Ubuntu 10.04 it was not possible to see whether a radiobutton
was selected or not selected.

After this change, the background of the checkbutton's indicator is
blue and its indicator dot is white.  This seems most in keeping with
the tkemc white-on-blue style.

[D H] tcl/tkemc.tcl

remove unused/mistaken code

2010-08-23T20:08:00+00:00

remove unused/mistaken code

[D H] tcl/tkemc.tcl

make tkemc display only axis needed & show MACHINE from ini

2010-08-23T19:03:49+00:00

make tkemc display only axis needed & show MACHINE from ini

[D H] tcl/tkemc.tcl

Fixed minor typos in docs/src/config/ini_homing.lyx

2010-08-23T12:12:26+00:00

Fixed minor typos in docs/src/config/ini_homing.lyx

Fixed minor typos in docs/src/config/ini_homing.lyx.
This is #3 of 8 minor edits to docs files in this group.

Sent to John Thornton for final approval.

Signed-off-by: Kim Kirwan <Kim@KimKirwan.com>
Signed-off-by: John Thornton <jthornton@gnipsel.com>

[D H] docs/src/config/ini_homing.lyx

buildslave user now needs sudo apt-get

2010-08-19T17:41:18+00:00

buildslave user now needs sudo apt-get

I changed the buildbot to automatically install build dependencies before
trying to build the non-pbuilder builds.  (pbuilder has always installed
whatever build dependencies it needs.)

This commit changes the buildslave-admin-guide to give the buildslave
user password-less "sudo apt-get", instead of manually installing the
build deps needed at the time the buildslave is created.

[D H] farm-scripts/buildslave-admin-guide.html

BallCutter(d=6) and BallCutter(d=8)

2010-08-19T12:41:55+00:00

Octree animation

2010-08-18T21:15:34+00:00

Update: this figure shows the numbering of vertices(red), edges(green), and faces(blue). The arrows show the direction of the X-(red), Y-(green), and Z-axes(blue).

Here the sides of the cube are not generated with Marching-Cubes, they are just extracted directly from the octree. Nodes are subdivided whenever the signed distance-field of the cutter indicates that the surface is contained within the node, i.e. the distance-field evaluates to both positive and negative at the eight ~~four~~ vertices of a node. This apparently leads to transient holes in the surface when the cutter is just about to enter a coarse node which hasn’t been subdivided very far yet. It should be possible to adjust the subdivision criterion so that the octree ‘anticipates’ the cutter slightly and subdivides ahead of the actual cutter surface.

Holes in plastic

2010-08-17T09:14:05+00:00

CNC-milled three hemispherical (ca 50mm diameter) holes into these bits of plastic yesterday. To fit a steel cup (far left), attached by gluing.

Cutsim progress

2010-08-16T06:37:44+00:00

The speed of the new cutting-simulation code makes it possible to run it at a higher resolution than before. That makes the surfaces look smooth and nice. Alas, some problems still remain with holes in the fabric of reality mystically appearing and disappearing .

There is an edge-flipping paper by Kobbelt et al. from 2001 which improves the jagged/aliased look of sharp edges.

Update: Kobbelt provides a LGPLv2 licensed sample-implementation of the algorithm here: http://www-i8.informatik.rwth-aachen.de/index.php?id=17

OpenCAMLib machining simulation, v.2

2010-08-14T07:23:32+00:00

This is my second attempt at a machining simulation where a moving milling tool cuts away voxels from the stock material. To save space an octree data structure is used to store the voxels, and to produce a nice looking surface you store the signed distance to the exact surface in each vertex of the octree. You then use marching-cubes to extract triangles for a distance=0 isosurface in order to draw the stock.

Unlike my first attempt, this works well enough to warrant further experiments (on the to-do list are: differently shaped tools, colouring triangles based on which tool cut the voxel, lathe operations, material removal-rate, etc.). It should be straightforward to hook this up to the EMC2 G-code interpreter so that any G-code, not just densely sampled CL-points from OCL, can be simulated. You could also flip the sign of all the numbers, and simulate an additive process, like 3D printing (reprap / makerbot).

This approach to machining simulation is described in a 2005 paper by Yau, Tsou, and Tong.

a desk for me

2010-08-13T12:32:13+00:00

We moved a bit over one year ago into this apartment, and I've been meaning to add a desk for my PC + stuff ..

Octree with Marching Cubes

2010-08-09T20:52:54+00:00

Update 3: this leads slowly towards a better and faster cutting simulation. Here’s an example with Tux:

Update2: this looks slightly better now (a ball translated in a few steps towards the right). Image and c++ code by fellow OCLer Jiang from China.

Update: in a cutting simulation the stock is updated by removing voxels which fall inside the cutter. Here I’m trying it with a spherical shape positioned at (0,0), and then moved slightly along the X-axis. The white dots are corners of octree nodes, and the cyan triangles are produced by marching cubes. It works quite well, but on the border between the two cutter instances the distance-field is somehow wrong, and marching-cubes doesn’t come up with the right triangles, leaving gaps instead.

Earlier I was building an octree volume-representation of a shape using a simple bool isInside(Point p) predicate function to determine which cubes are in and which are out. If instead a distance-function double distance(Point p) which is negative inside the volume, zero exactly on the surface, and positive outside, is used, then the Marching Cubes algorithm (this is a better explanation, someone should make the wikipedia page as good!) can be used to triangulate the octree. This leads to much more visually pleasing results at reasonable maximum tree-depths.

The same Hong-Tzong Yau of Taiwan who wrote a very reasonable drop-cutter paper in 2004 has more recently come out with a 2009 paper on cutting simulation using an octree and Marching Cubes.

bubbles

2010-08-04T09:16:48+00:00

Soap Bubbles

Still in Garana, I played a bit with soap bubbles for my son....