2014. május 13., kedd

3D toolchain - bitmap

And we arrived to the first CNC work.
How will a bitmap image (in our case a jpg) to turn to a usable result.
When I started to work on it it was obvious that I'll need to following elements:
Some image manipulation software. For this I use paint.net for years. I was thinking it will be sufficient here. I need it to setup the parameters (contrast, brightness, sizing, etc.) of the source image.
I need something what is able to turn raster image to vectors. Looking around I fond the InkScape because it is able to export to CAD format (like DXF) and it's free.
I need a CAM software indeed. I was fighting a lot with the HeeksCNC, so I'll check if I can use it for the task.
And finally the Machine Controller what is the LinuxCNC.
Here is the source what will be the starting point:

For first trial I thought that no modification is needed on it. Looked around the net to find out how can I convert it to vectors with the InkScape.
Loaded it into the InkScape and given an A4 size for reference. After this I used the Path/Trace function it with the original settings. It created a vector format. There was a recommendation about the Simplify function, but it wasn't working correctly on this image.
I saved the result and given to the HeeksCNC.
The thing was known to me that I need pocket operation for the letters and profile for the edges. The thing what I wasn't know how to leave out the "islands" of the e and a letters. After a long struggling I found the solution. The two sketches must be combined after the island sketch order changed to counter-clockwise.
Its finished (as I believed)
I went with the finished file to the machine. I started a dry-run (the spindle switched off, no cutter bit installed). First it stated that I've no tool on the tool table in the 4th position. Ok, I created one for the 4.8 mm cutter in the LinuxCNC. Secondly it stated that I'm out of the dimensions. Looked into the G-Code, one of the values in the beginning was someting above 500mm movement. And yes, I don't fit in. This is fundamentally bad.
Back to the InkScape. Now I tried to put the image to the A4 sheet watchfully. I wasn't able to do it correctly. From the page settings I found out that the whole thing works with 90dpi. This is a fixed value. The dpi value of the source image doesn't count.
Opened the paint.net and resized the image to 20x20 cm and 90dpi. InkScape once more. It looks good. I created the vector format. Instead of the svg used before I saved it in dxf.
HeeksCNC. I went through the process with checking the sizes. Not good. The coordinate system is not in its place. Recreated it in InkScape with care of the origin point what should be at the lower left corner (I already know this step was unnecessary, because the HeeksCNC is able to move the object into its place with a well done transformation).
HeeksCNC once more. Now I like the result:

Back to the machine. I reconfigured the machine itself. I set that the whole size should be available both in the positive and the negative scale. This gives me the freedom to put the origin at a given job anywhere I like.
Starting to set the origin. I found out that the X axis works in the reverse direction (my guess is it is a reverse connection problem in the hardware). Back to the mahine configuration. Reverse the X axis polarity from software.
Now it's good. Dry run starts correctly. Material tighten, cutter bit in place, spindle to full throttle. Lets run...
And the result after a few hours:

After some post processing (sending and lacquering):

Unfortunately the letters of the lower line are not perfect because I haven't got thin enough cutter bit.

Nincsenek megjegyzések:

Megjegyzés küldése