[Morane]

Hi,

I'm a beginner with a few questions.

I just built my first CNC (Chinese) it's a Woodpecker 3018. Running with GRBL 0.9
and controled under windows with the software GRBLControl v 0.8. Bough it one week ago.

My first goal is to make my own PCB and I will see after for small wood engraving.

It's my first CNC so first time for a lot of stuff like: GRBL, G-Code and Eagle

I'm using Eagle to make the PCB and I take PCB_G-Code to generate the G-Code.

The CNC is moving in the right direction, I installed limit switch and activated the hard limite
and the home option. All the controls are working fine including the Z probe so I can use it
to prob my blank PCB before milling to create a height map.

Position

I have a position problem.

I create my board in Eagle. The origin (Mark) is on the bottom left corner.




When I import the G-Code into GRBLControl, I can see that the tool
is pointing the "Mark" but if you look the the XYZ arrows, we can see
that the red arrow is pointing to the right (outside my draw)

If I do I single board I work around the Work Coordinates so I can milling it ok
but I would like to find how to fix that. Because it's not natural and it's a real
problem with a double side board.

Bottom Side






Top side

This is the same board but the top side
Look the tool and arrow are now on the bottom left and this time the
X Arrow is pointing to the direction of my draw.


I cannot make the double side board because it's not the same position
for the tool so I wont be able to start at the same position as the bottom side.





This is my small CNC. I made an enclosure for the Arduino controler
and I installed a small PC (Pipo) on top of it. It runs under Windows 10
so I don't need to take my laptop when I have a long job to do.


A very nice setup for a first machine but now I need to make it work thethe good way.

How can I make my Eagle draw to be always on the right side of my tools in GRBLControl ?

[Bubba]

Hi,
You don't always get it that way. Think about it this way. Take a piece of paper say 3"x5" and label it as "Top" and put a "0" in the lower left corner of the page.
Now, flip the paper over using the right side as the axis and note where the "0" is. It is on the right side of the paper and all of your directions to the positions you want will be -X positions. Y positions will still be positive.

This is exactly how it works. When milling/etching/drilling on the bottom, you will be working in the -X direction. When milling/etching/drilling on the top of the board, you will be using +X +Y directions.

Hint, use fixture offsets for the top and bottom. I personally use G54 for the top and G55 for the bottom.

HTH

[Morane]

Ha OK

So I I was bouncing my head to the wall for no reason.

But like I said I 'm new in this so can you explain a little more about what I can do with G54 and G55 ?

Also, do you know a good link that point to a site on how to do a double side board without losing the good coordonates ?

Thanks

[Bubba]

Glad to hear my sorry explanation cleared it up for you.
The way I have it setup (and this is no means the only way it can be done) is that I have a permanent fixture on my machine. I use vacuum to hold down the board and there is a pocket or recess that is cut into the fixture. The lower left corner is designated as G54 X0 Y0 and when I flip the board, the lower right corner of the recess is designated as G55 X0Y0. These locations are saved to a fixture offset file so all I have to do is home the machine and load the offset file and I am good.

You are using the same corner of the board as reference origin.

Other people use pins in the boards and reference off of that. If you do a search on YouTube, you will find several different ways.

The thing to do is find a "system" that makes sense to you and works with the equipment that you have on hand.

[Morane]

Hu,

Yes I saw some video with four pins but I prefer a fixture also.

I built some supports with my 3D_Printer to maintains the pcb. I'm going to make a fixture probably in a L shape
to do like you. It's better than pins because I don't want to have a wood base fixed on the top of the aluminium table.

To prevent the drill bit to hit the aluminum table, I cut small pieces of thin wood of the same size of my blank pcb
so I just have to put it under a board while working on it.

I'm going to read a little bit more on how to register coordinates in G54 and G55 and how to call it back when need it.

I'm sure that I will have more questions with that new toy :-)


Thanks