QCad CAM

I just drew up a bunch of shapes in QCAD and it suddenly occurred to me that I did not allow for the diameter of the router bit. (oops)

I've never used the Tool Table in Linux CNC. Will that provide the proper offset or do I need to redraw everything?

(Lesson learned!)

>>> Sterl

Sterling wrote:

I just drew up a bunch of shapes in QCAD and it suddenly occurred to me that I did not allow for the diameter of the router bit. (oops)

I've never used the Tool Table in Linux CNC. Will that provide the proper offset or do I need to redraw everything?

(Lesson learned!)

>>> Sterl

You need to provide properly placed lead-in and lead-out moves to be able to use
cutter radius compensation, and then add in the G41 or G42 commands after
placing the cutter at the safe starting point, and a G40 before moving to the
safe stopping point. If you are cutting an outside shape, your safe starting point
is slightly less than the expected cutter radius outside a line extending from
the part outline, and at least a cutter radius beyond the part along that line.
Pretty much the same for the safe stopping point. When the cutter radius
comp. is turned on, what would normally be an angled line toward the part
becomes a nearly straight line tangent to the part outline as the cutter
comp in interpolated in along the length of the move.

LinuxCNC is very picky about there not being an inside corner when cutting
the OD of a part with radius comp. so the selection of the start and stop
point is pretty tricky. Once you've done it a couple times, it gets easier.
There is some info in the docs at :

linuxcnc.org/docs/html/gcode/tool_compen...:cutter-compensation

Jon

Groovy, thanx!
Yes - it's all outer diameter stuff. It is more time consuming and embarrassing really...I will most likely re-draw the shapes in QCAD, adding .125" (I'm using a .25" bit)

>>> Sterl

BigJohnT wrote:

You can use the Parallel with distance line tool to offset both lines and arcs. I like to create a new layer for tool path and offset to that layer. This way if I want to use a different tool I just create a new layer for that tool.

JT

Hmmm...That's a new one. I'll check it out, thanx.

It appears that I ought purchase that help-book I saw on-line. After all, I'll be turning 50 in a few weeks, this might be an excellent present to myself!

Thanx -

>>> Sterl

Sterling wrote:

Groovy, thanx!
Yes - it's all outer diameter stuff. It is more time consuming and embarrassing really...I will most likely re-draw the shapes in QCAD, adding .125" (I'm using a .25" bit)

>>> Sterl

Based on my experience with machines with Fanuc controllers, I can tell you that the learning curve will be well worth it. Imagine you set up a toolpath, and half way through you break the only 1/4" tool you have. Using the tool table, you can swap out the tool for a 3/8" and be cutting with the same gcode within moments.

Sterling wrote:

Groovy, thanx!
Yes - it's all outer diameter stuff. It is more time consuming and embarrassing really...I will most likely re-draw the shapes in QCAD, adding .125" (I'm using a .25" bit)

>>> Sterl

Generally, you don't have to redraw the shape, there ought to be a feature
in the software to automatically create a new outline that is offset from
what you drew. They call this a different thing on every package, so
I can't tell you the exact name of the command.

Jon

Need some help here -

I just bought, downloaded and installed the Pro version of QCAD. I installed it on my Windows machine, QCAD version 3.4.7.0.
I wanted to put in your Linuxcnc Cam export, but when I opened up the file location, I discovered that the path...

BigJohnT wrote:

Place in the scripts/Cam/CamConfigurations directory.

...does not exist...

There is a directory
\Program Files (x86)\QCAD\scripts\
that contains *.js files, but...I'd rather not experiment and just drop the file a folder and hope it works!

Thoughts?

Thanx -

>>> Sterl

Oh drat!
I purchased the QCAD PRO not the QCAD +CAM version. And I do not see a +CAM add on.
I will be sorely disappointed if a re-purchase is required and they not allow for an upgrade!

>>> Sterl