Question Questions regarding PCB milling

Hey.
I have read the existing posts in this forum and still have issues.

I have an SC 420/2 and Windows 7 64-bit, WinPC-NC Starter (Basic version).

What have i done..

In Eagle i run the pcb-gcode tool and generates a gcode script.
Next step is to use g-code ripper so i can generate a dxf file.

Now i use winpc-nc and load the dxf file. All looks fine, except that it looks
lika a two year old Child has made the drawing.
I guess this is caused by some cheap Viewer code in the basic version, because the milling machine behaves perfect.
Anyway, i start the milling and discoveres that Z-axis is not used, and i also have an scaling issue.
To get Close to what i need i have to rescale in winpc-nc with 25.
And winpc-nc ignores the Z-axis data in the dxf file.
I have tryed to use different values in parameter tool depth. But is allways stays at the value for tool 2 even while moving between the milling Points.

I also tryed to convert the dxf to R12 using QCAD with the same results.
Since i have issues with the scaling, i also made the lifting height of the tool in g-code-ripper larger.
No luck at all.

I'm starting to Think that the Z-axis is disabled in the basic version. Or am i wrong?

Does there exist an software which automate this? To an affordable price.. $100-$200??

I'm adding my last attempt for this night. It is a single-sided pcb in dxf R12.

BR
Terje.

Sjömark wrote: Hey.
I have read the existing posts in this forum and still have issues.
...

Did you also read the following topics?
https://www.stepcraft-systems.com/en/service-and-support/stepcraft-forum-uk/show-us-your-stepcraft-creations/2142-my-first-pcb
https://www.stepcraft-systems.com/en/service-and-support/stepcraft-forum-uk/milling/2117-winpc-nc-usb-2-50-02-not-working
https://www.stepcraft-systems.com/en/service-and-support/stepcraft-forum-uk/milling/2230-first-steps-towards-pcb-s
Don`t know about WinPC-NC Starter and full version possibilities, but for other software you probably have to replace your USB with a parallel module. Your computer and 64bit system might require some additional stuff, like an external motion controller (UC100 for example).

Usually g-code is the data you send to machine controlling software, exept in the case of some programs.

Yepp. Read them all

I found a youtube clip made by stepcraft. It looks like the basic version won't accept gcodes, but other versions will.
So I Think i have to upgrade. But need to be 100% sure Before i throw out any more cash.

The basic version accepts plt files. I read on internet that plt files is the same as prn. An HP plot printer format. Another idea is autocad. But I'll guess i will probably loose the third dimention during the convertion.

Need to check the formats of Solidworks as well.

BR
Terje.

I have set myself up with the ability to "etch" prototype pcb's on my 420/2 machine. Like you, Eagle has been my vehicle for preparing both the circuit schematic and pcb layout. My interface between PC/Laptop and the 420/2 uses UCCNC and the UC100 usb to parallel "dongle". The UC100 relieves the PC of all the critical timing tasks associated with moving the steppers, and personally I am indebted to Rory for suggesting this route right from square one.

Conversion of the Eagle ".brd" to G code is accomplished via a ULP. This converts the Eagle file to a Gcode file that can run directly in UCCNC with no changes/edits as all!! It also provides full Z axis control for tool changes when drilling the final board.

To the best of my limited knowledge most of the lower end CAD/CAM packages will generate their output either directly in Gcode format or in ".dxf" format. Using formats which have to rely on third party software to provide ".plt" files is fraught with pitfalls and in my opinon should be avoided if at all possible.

Here are some representative pictures of what I have achieved with a trivial "pcb" task - I can cee from the end result that the X axis backlash needs a little tweaking, the holes a little off centre relative to the milled lands.

Vaccum table





Eagle ".BRD" layout.





Final "PCB"

Hey peterg1000

Nice work

UCCNC it is. The price is OK.

I really like your vacuum table.. Nice.

Are you using a vacuum pump from ebay?

What is the size of the mill tool? 0.1mm ?

BR
Terje.

Hi,

Glad you like the vacuum table - milled out from hardwood on my mini mill and then capped with a sacrificial MDF top. This was milled flat in-situ and then drilled through. It looks like this underneath the MDF.



I've tried a couple of router bits - both being carbide types. A 60 degree one from StonyCNC does a good job, but is very critical of flatness of pcb (FR4). Mine tested out at better than .0005" (12 microns) on a dial gauge over the whole surface with vacuum applied. The second is a 30 degree one, again from StonyCNC - rather more delicate, but it is less critical in Z!! I guess the tip is around .004" (100 microns).

After trying a couple of alternatives, I eventually went for a proper single stage vacuum pump - its reasonably quiet and pulls down to 20 - 30 pascals if the workpiece is sealed properly onto the table. I use ordinary masking tape as this holds the workpiece firmly located laterally even when the vacuum is off.

Here is a link on ebay for the type I bought, The only snag with this type is the oil mist it produces - I'm probably going to fit a filter to deal with this once I have located one at a reasonable price in the UK.
link

Peter

The latest creation on the pcb front!!

Milled with 30 degree carbide cutter set to 0.2mm depth. Spindle at 18000rpm. Gcode file straight from Eagle pcb2gcode ULP - no edits. Running on UCCNC of course!!

Nice work.

On Friday I get my UCCNC software and a two carving bits (from Stepcraft Germany).

BR
Terje.

Once you get running, don't forget to compensate for backlash otherwise 0.4mm tracks will end up almost non existant!!

I used a piece of scrap FR4 with a depth setting of 0.05mm (barely scratched the surface) and fortunately had a small microscope with a calibrated graticule. A good magnifying glass, a steel rule and plenty of time will help!!

Here is a section from one of my early test pieces - lines are set 1mm apart, but milling depth is too great.

Have you had any success with SMD ?
SSOP, QFP .
I'm using FPGA chip now and then. But in worst case I can use an adapter QFP to DIL.

Where do you adjust the backlash? in pcb2gcode or in unccnc ?

I try to use sensible sized components where possible - I guess that you might be lucky with QFP - I did a trial with 0.5mm QFP some time ago, but it wasn't very promising so I abandoned the idea for now. I've not tried smd's so far either, but guess they might be ok as the larger sizes are relatively easy to handle.

If I need to use a high spec QFP processor chip then I opt for a breakout board - no problem for hobby use.

You set up the backlash on the UCCNC /Configuration / Axis / pages - next time I have my machine active I'll take a couple of screen shots so you know what to expect. It's lots of fun !!!!!

One point - make sure you use UCCNC revision 1.1027 or later, there was a bug in the earlier versions and I don't know at what revision it was corrected. I know that 1.1027 works OK for me.

Peter

Here are the screen captures I promised. All the parameters relate to my SC420/2








Peter

Hi Peter.
I got the software today, and have downloaded the version you recomended.
I have entered your configuration settings and the axis moves

But i have a problem.
Y-axis is inverted.

Any idea. I have tested with softlimit +415.

Well that's odd !! Never had that sort of problem at all - haven't needed to fiddle with soft limits at all. If rotation of stepper is inverted and everything else is the same as in my config file then it's worth checking the the stepper wiring.

I suspect that if one of the windings is connected the wrong way round then the stepper rotation will reverse - I'll need to do some sketches to get my head around this possibility!!! This might be the problem if the config settings are identical

By the way, my backlah settings will not be correct for your machine unless you are extraordinarily lucky.

Peter

Inverted movement can be caused by mistakes in the wiring of the stepper. Either the connection from motor to board is wrong or the wires are mounted totally wrong to the motor by the manufacturer.
But don't worry, most driver software allows to invert directions in software. Just change the "direction positive" setting.

I tested to modify the direction checkbox too with the same results

The wiring is done according to the assembly instructions, and has worked perfect and correct with WinPC-NC.

I will continue tonight with more tests. Yes, last option is to switch two cables.

I'm about to mill my first pcb-board.
PCB-GCODE produces bottom layer and drill holes.
But how do i get gcode for milling layer (large holes in different shapes) and dimention (boards outline) in gcode?

One option is to write my own.

No need to do that - capability is already available in Eagle!!

Draw the outline of your board using the "wire" command and place on layer 46 (milling). You could also add text to the board in the same way if neccessary.

Configure the Pcb2gcode to generate a milling file and set a suitable milling depth as shown in the screenshot below :-




You've done well to get so far already - hope you have set the backlash, otherwise the result might be rather poor.

Peter

Here is my result.
Have to buy a massive wood board and mill down so I get a leveled surface.
And some adjustments. Need larger via hole.

Sadly the unccnc crashed at 90%. (Lost connection between PC and CNC.)
I'm using the provided UC100 usb interface and a laptop, Asus I7 8GB.
I guess I will move over to a real hardware parallel port if I get more problems.

Backlash. No. I have not locked at that yet.
Backlash is the extra movement needed when direction is changed? I guess so.
Will try that later next week. I will do a similar pattern like yours.

BR
Terje.

Here is my solution: PCB Table

So, everything is flat. But still .. if you want to have same thickness, you have to do a test in X and in Y direction. I do the leveling by adding a sheet of paper in the lower corners.
On the next page of that thread you see some images of my results and of the special PCB mills I use.