Arduino CNC GRBL: using Inkscape to create DXF files

I put this in the Bar, as it primarily involves Inkscape, as the Ardino hardware has not yet arrived.

has anybody used Inkscape to create DXF files? i have a DXF to GRBL converter, but whatever i use to open the DXF file, it shows nothing.

All i want to do is learn how to create the DXF files correctly, so i can convert them to GRBL. I can export from Inkscape to DXF, but i don't think i am doing it correctly. either i have the sizing incorrect, or i really don't know what i am doing (the later is most likely).

Thoughts? ideas? suggested tutorials? Suggested anything, that doesn't include adding the idea to the circular file? :smiley:

I am just trying to make sure i know what i am doing first, while i wait for the parts to arrive.

~Travis

Inkscape can write HPGL files which are very close to GCode. I wrote a Python program to convert from HPGL to GCode.

I wanted to mill some very simple shapes from thin brass sheet on my small lathe. It worked OK but then I discovered electro-etching which is a lot less trouble. I can cut an etch mask from self-adhesive vinyl with my Silhouette Portrait cutter.

...R

Laser sounds good but is very difficult to do well.
Also emits seriously bad gases.

If you don't get a ready made unit, you will be very sorry, but I think this was implied already.

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travis_farmer:
would that just do two vertical points though (pen up, pen down)?

I guess so. But I was working on the assumption that Inkscape just produces a 2D drawing.

It would be straightforward to repeat a movement (or series of movements) at different depths if you could not mill all the way through in one pass.

...R

The motor, drivers and controller is 1% of CNC.
The important part is the lead screws and bearing surfaces and control software is the other 99%.

I have a scope, soldering station, signal generators, powers supplies, analyzes, all purchased.
What you do with them is what DIY is about.
Same with CNC.

Enough said.

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This is nothing to do with you.

Do you think perhaps we are speaking from a great deal of practical experience.

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No disrespect. It's like building your own TV when you only really want to watch Judge Judy.

Mine came in semi-kit form and it was clear that building one from scratch would require a fairly sophisticated shop. But, if your goal is to build a CNC machine and not use a CNC machine it would sure be a challenging project.

These guys have some cool stuff you may find helpful: https://www.8020.net/

Sounds like you are having a grumpy week end. :wink:

Anyway, if you proceed, make sure you use backlash nuts with the lead screws.

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travis_farmer:
I have an old version of SolidWorks that was given to me due to it being outdated. but i have not found a way to generate GRBL code from there.

I know nothing about SolidWorks and I have never put in the time to learn proper 2D Cad, never mind 3D. I do my 2D drawing with LibreOffice 4.3 Draw which I think is better than InkScape and which can export SVG files that Inkscape can use. I had a problem with the SVG files from a newer version of LibreOffice.

I reckon it would help if you explain the sort of tasks you want your CNC to do.

I added 3 stepper motors (X, Y and Z axes) to a small lathe (Sieg C1). I wrote a simple Arduino program to control them. And I wrote a Python program for my PC to allow manual control and to interpret simple GCode and convert it to numbers of steps for the motors (actually the total time for a move and the time between steps for each motor) which it sends to the Arduino. It seems to work properly but I have actually used it very little. I had started adding a sensor to detect the position of the chuck so as to synchronize the feed for screw cutting - but like a lot of my things the need evaporated before I got that finished :slight_smile:

Making a robust machine that can handle the heavy loads for metal cutting would be a major task.

I wouldn't worry too much about backlash. You can make your program allow for that by adding some extra steps when the direction changes - as long as the backlash is consistent.

...R

Lead screws are direct connectable to stepping motors.
You get huge mechanical gain advantages.
Very accurate linear movement, better than 1/2 thou.
With backlash nuts, negligible forward to reverse slack.
Easy to mechanically connect to.
Easy to maintain/clean.
Low wear.
Put a bearing to the frame on the non business end is all the support necessary.
Great for X Y and Z axis.

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This is a family forum. ???

I think a stationary work surface is the only way to go.
That's what mine is, it's 22X22" but I rarely do more than 16X12"

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OOPs
X & Y are reversed. :frowning:

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Zero defection (See diagonal brace).
Some units come with two Y steppers

2017-04-09_15-25-13.jpg

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In your software, you control X & Y cutting speeds, also your Z down speed.

You will also have to adjust the spindle speed per surface you are cutting.

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I use 1/4" trimmer routers (with 1/8" collets as needed), has built in speed control.

Home Depot

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Never needed software spindle speed control in 24 years since I bough my CNC.

You do need to adjust router/spindle speed for types of wood and different kinds of plastics.

When you determine the best speeds to prevent burning/melting, write it down along with the X,Y and Z speeds and bit type used.

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travis_farmer:
I am thinking of starting with just 2D engravings, to begin with.

That should be perfectly possible with GCode derived from HPGL output from Inkscape.

One of the things that has put me off GRBL (and the LinuxCNC etc) is the absence of simple advice explaining how it "knows" where the tool tip is so as not to crash into the work piece and how the zero position is set for measurements against each different piece of material that is to be cut. It has always seemed to me that the authors assumed a level of knowledge bout the process of CNC machining that I don't have. My solution was to write my own Python code.

...R