CNC vrtanje lukenj - CNC Hole Drilling

[simpilot]

PCB Drilling after milling on CNC can be done easily. Drilling BEFORE chemical etching is also not a problem,
But I did not know how CNC drilling could be done AFTER chemical etching.
While searching for a solution, I came across the Youtube video of “Darko Volk:

https://www.youtube.com/watch?v=zZRHaZjGWq4

In the video @12:36 you show how you drill holes on the PCB after etching, with the CNC machine using the camera to initialize the coordinates of the location where the PCB is fixed. I was fascinated by this method and wanted to know how it was done.

I followed the link mentioned viewforum.php?f=95
and viewtopic.php?f=95&t=1634
(Izdelava tiskanega vezja v lastni režiji)
Unfortunately, the sub-title --CNC vrtanje lukenj was not continued with a link.
Above topics are locked.

You write that the software used is Planet-CNC. TNG or CNCUSB? Can you please publish the step-by-step procedure how you set up the software with the camera so that Drill Coordinates of the Excellon file generated by the PCB-Software is modified to match the placement of the etched PCB.
It will help me and all those members interested in this subject.

Thank you.

[JernejL]

I believe that the camera mounted on the head and is offset by known amout of X, Y like height probe on a 3d printer.

camnhere.png

After camera is centered, the locations are used to callibrate and adjust location of drilling holes into final spindle drill coordinates.

[Dorijan]

This is usually used when high position precision is required. eg. Led center position in reference to focal point of reflector.
Since during soldering the components drift a bit in reflow Owen.
Then after soldering machine vision is used for precise measurement of final position and CNC is then used to drill the positioning holes.
End result can reach precision within 0.001mm across production run.

[Kroko]

Here are some links for CNCUSB but TNG does this even better:
https://www.youtube.com/watch?v=JJnenOsbCzU
https://planet-cnc.com/how-to-mill-and- ... -and-warp/

[simpilot]

Hi Kroko,
Thank you for the links. That is the method exactly what I was looking for. I guessed that Planet-CNC should have the solution because Darko mentions under the Youtube video.
I had already heard about Transformation Matrix. But I did not want to "re-invent the wheel" by trying to develop the software.
I just started using a 3018 CNC machine and also made a PCB prototype by milling and drilling. But as I mentioned in my inquiry I wanted to use chemical etching and then drill.
With my own method I drilled another prototype after etching. I did it by placing my own "Reference Holes" as Pads (with a unique drill size not used elsewhere) on layout within the board edge on the four corners e.g. as mounting holes but using pads configured for both sides. Although a single sided board, FlatCam was configured as double-sided, my four Reference Holes were the only Pads on Top Layer. Using FlatCam, it's Alignment holes were placed outside the board edge and generated the G-Code files for drilling my Reference Holes and FlatCam's Alignment Holes. Using GrblControl, the Home point was set on 3018 CNC and my Reference Hols and Alignment holes were drilled. Then I placed my layout film exactly to coincide the drilled "Reference Holes" on Copper-clad board for photoresist development and etched. Then I flipped and fixed the etched board using the Alignment Holes of FlatCam with pegs and drilled with the G-Code generated by FlatCam by mirrored Excellon drill file from the bottom layer side. Of course the initial Home location of the CNC was not touched since the first setting.
The above method was tried on a small board with a few holes. I had to make a big effort to place the film on the board to match my reference holes. Therefore, in my opinion it is very tedious and likely to result in errors if the board is populated with a large number of holes. That is why I was searching for a less tedious and a precise solution.
Now coming back to Planet-CNC. It seems that their software is proprietary and requires license fees. Also I suppose their own Hardware has to be used. I have to ask them if they have special offers for non-commercial use for Makers and Hobbyists.
I will contact them for information.

[simpilot]

I believe that the camera mounted on the head and is offset by known amout of X, Y like height probe on a 3d printer.

camnhere.png

After camera is centered, the locations are used to callibrate and adjust location of drilling holes into final spindle drill coordinates.

Thank you for your suggestion. But it is not as simple as that.
X, X coordinates can be adjusted with fixed offsets only if the PCB is placed exactly matching X, Y at 90deg without any rotation.
To fix the etched PCB at a random location at any orientation on the CNC bed, a complex mathematical calculation is required to modify the original g-code drill file.
See reply from Krako.

[JernejL]

You can just do a general interpolation on a grid and interpolate any points to another set of points on same plane.

That's kinda like perspective correction with 4 points in common phone apps ( https://pyimagesearch.com/2014/08/25/4- ... m-example/ )