Wendy and CNC Builders... Question on PCBs

[Buddym]

I direct the post towards all, but I saw that Wendy had displayed a nice PCB for her build in a previous post.


Have you used your cnc for making PCBs? I ran a test using Eagle and a freeware conversion to take the pcb to g-code using the isolation-routing method. I had the depth set wrong on my first test, but the first trial results were VERY encouraging. I was curious to see if anyone had made any circuit boards for things like EFIS, FCU, etc....?

Thanks,
BuddyM
A320 Builder
Tampa,Fl US

[Wendy]

Hey Buddym,

The PCB I showed you was a rather simple one which I made in a normal cad-drawing as part of my panel design. Until now I have not made PCB's designed in Eagle on the CNC.

Regards, Wendy

[Redbird]

I've been pondering the very same thing. I'm about half done building a CNC and am thinking about making my own open cockpit cards. Shipping costs about the same as cards lol and the gerber files are freely available

[Buddym]

I made a couple of very decent first-attempts, but then I found a company to make my boards at such a low price it's not worth the wear on my machine, or the price of blank PCB material.

[Redbird]

Care to share the company name :)

[Buddym]

no problem, it's accutrace (pcb4u.com). They have a deal where you can get 10 boards (2 layers) that are up to 20 sq inches each, for $10 each, plus $10 shipping. Boards up to 40 sq inches are $15 each. It's a great deal, no tooling charges, and no gotchas. The only real gotcha is that you have to order 10 identical boards. The deal loses it's appeal quickly when you look at only doing 1 or 2 boards. Also, for that price I am sure that there's not a great deal of design review, so make sure you have the board perfect before sending the files!!

I bought single-sided copper-clad at $3 each for 6x6 inch boards.... by the time I ruined 2 of them getting the CNC setup correctly, and broke 2 bits, it just makes more sense to me to buy the OC cards from them, and only send my production boards, like the IP-8, out to be made. I think If I needed smaller boards and no double-sided ones that I would keep doing it, but at this point buying the OC cards made more sense for me.

Buddy

[Perik]

Hello Redbird.

I have made (milled) most of my OC-board myself including:
MasterCard, Display-II, Servo, Stepper/DC-motor and Encoder-II.
And a lot of other and more specific PCB's for my B767.
Have a few images on my web-page: http://www.hoddo.net/ocboard.html

To be able to make PCB's in a clean and low-cost way was for me very import part
of my own CNC project and I do whatever to keep the cost down!!
At the same time have fun, learn and master new techniques and keep the brain "spinning".

If you don't have a loaded bank account, the CNC unit is the best investment you ever can do!!

[Buddym]

Hey Perik, nice work...those are some great looking boards. Did you use the isolation routing method on those?

Buddy

[Perik]

Thanks, Buddy

Yes, isolation all the way (60 degrees V-cutter).
I have a small section where I try to describe the PCB milling
in a little bit more detail: http://www.hoddo.net/technical.html#pcb

At the bottom line you need to try and you'll really fast catch the limits
of the machine if any. My homemade CNC rig is NOT rocket science for sure
and PCB's are really achievable.
You may need some software though - like Eagle and Diptrace.
It all depends of how complicated PCB's you want to make.
You can do a lot with just a drawing tool.

Happy milling and go for it.

[BABA767]

Hi Erik,great work!!!...I follow closely your progress; very nice your MIP!!cheers, Valerio

[Wendy]

Hello Per-Eric,

Just visited your website. Very nice and a lot of information. I have played the video about making buttons in 3D, great, have to try this sometime.


Regards, Wendy

[Perik]

Hello Wendy,

Yes, milling 3D is fun and rewarding - you should really make a try!
You seem to be capable of whatever you want - great work I must say!

And you are lucky - if you need some practical advice you have Hessel and
Rob Jansen around you. Rob and his "El Animal" show some really great 3D work (http://www.myvoice.nl/freesmachine/?lang=en)
and Hessel is at the moment drawing 3D stuff like a hero.

Talks soon!

[Redbird]

Perik, site bookmarked :D Very nice work, gives me some inspiration in completeing my own project.

[flatlandpilot]

Yes, thanks Perik,
that prints are really motivating.

[Wendy]

Hey Per-Erik,

If milling 3D is triple the fun of normal milling I have to start with it very soon.;)


Regards, Wendy

[homecockpitbuilder]

Hello all,

Just finish the tutorial on my site about making a pcb. The pcb that i want to make is the stepperpcb from Fsbus.

Software use is sprintlayout and ramsgold.

For more info, the tutorial is locate on my site under buildertips (http://www.homecockpitbuilder.com/index.php?option=com_content&view=article&id=75:making-a-pcb-with-your-cnc&catid=46:buildertips&Itemid=58).

Regards Bas

[Jan737]

Hello all,

Just finish the tutorial on my site about making a pcb. The pcb that i want to make is the stepperpcb from Fsbus.

Software use is sprintlayout and ramsgold.

For more info, the tutorial is locate on my site under buildertips (http://www.homecockpitbuilder.com/index.php?option=com_content&view=article&id=75:making-a-pcb-with-your-cnc&catid=46:buildertips&Itemid=58).

Regards Bas

Hi Bas,
Thanks for the tutorial!!:D:D
I've watched some of the videos you made.
Can you tell what material you use for the panels and where to buy it?
I live in the Netherlands.

Best regards

Jan Geurtsen

[iwik]

Hi Per-Erik,
Really enjoyed reading your site articles. Very impressed with what you did with O/C pcb. I see you used Sheetcam to produce your Gcode. I had been using Eagle with the appropriate plug in. I know have Cut2d to generate gcode.
Can you explain how you got your gcode from importing the DXF into Sheetcam. I know one has to mill an isolation track.
Look forward to your comments.
Thanks again for a great website.

Regards
Les Barwick.

[Perik]

Hello Les

I know there are some areas badly explained on my site – sorry ;-)

Well, I’m using Diptrace for my PCB schematics and layout. I don’t know Eagle in details and how the dxf-plugin works, but from Diptrace layout I have the possibility to export layers as layers in one DXF-file. Even if that’s not necessary, it makes the next stage in the process a lot easier.

So I select four layers like in the first attached image – Drill_Top, Board_outline, Edge_Top and Edge_bottom – the two last layers are the outline of the top and bottom traces including the pads.

Cut2d is as well unknown for me though I expect you can import dxf with layers. In SheetCam it will look like the last attached image after importing the DXF-file.
BTW – this is the OC Display-II pcb.

SheetCam shows the same layer structure as the PCB layout program.

The next will be to define the needed operations.
I always start with the top side of the PCB and the drilling layer using normally 0,7mm drill-bit. Some features like mounting holes will require a tool change during milling operation. You can of course make a separate operation for each tool. I do that often – having more control while zeroing the Z-axis.

The next operation to define will be the Edge_Top - traces on the top side of the PCB. For this operation I use 60 degrees V-cutter. Set up as an Outside Contour path with a depth of 0,05mm, but you may end up going deeper to get the isolation you want.

Added comment: The cobber layer is approx. 35um or 0,035mm, but cobber is a soft material so you may have to go even down to 0,1mm. And to be sure, I run two passes – one “Up cut” and one “Down cut” or simpler, one run in each direction. That fixes most of the remaining burs you may have in the path. Steel wool in the end makes it perfect:D

The Edge-Bottom operation is the same as Edge-Top and at last the Board Outline operation using e.g. a 2mm end-mill.

So, then select only the Drill operation and hit the “P” button and get ready for some action. This command sends the G-code for the selected operation(s) and in the sequence they are listed directly to Mach. Put in the right tool and of you go! When and if Mach stops for tool-change do as told.

Then back to SheetCam. Deselect Drill and select and send the Edge_top operation to Mach and prepare for a new tool-change – now to V-cutter. After Mach is done, go back to SheetCam and into Edge_top operation (double click) and select Cut Path -then select or deselect Climb-cut to change direction and run the operation again.

When finished you have to flip and line up the board for doing the bottom side. And now it is important to flip/mirror the layout in Sheetcam before you start on the bottom side operations. Do the same for Edge_bottom as for the Edge_top. Last operation is Board Cutout - also mirrored.

That’s about it...

Les, I hope I've not missed your question totally and you got some answers at least.
I’m ready for more questions if needed.
I would believe you are be able to achieve more or less the same with the combination Eagle/Cut2D though I may be wrong.

Happy milling

[iwik]

Hello Per-Erik,
Your website is quite clear and well layed out. The bit i was most interested with was using Contour outside to cut the isolation barrier. Ive had a look at
Diptrace and are experimenting with Academic Version(500 pins and 2l), its a nice package as it handles Schematic Capature/Autorouting and Milling.
The only other package that will handle similar at a low cost is eagle with the plug in. However i find Eagle to complicated for my casual usage.
What version(eg lite,standard Free) are you using?
Thanks for replying with great detail, very much appreciated.

Best Regards
Les

[Perik]

Hi Les.



What version(eg lite,standard Free) are you using?
Thanks for replying with great detail, very much appreciated.
Les

The version I'm running is:
DipTrace Non-Profit, 1000 pins, 4 signal layers, non-profit use only Cost: €95

I believe this is a better offer than Eagle at least looking at pricing here in Norway.
Nice thing with Diptrace is - no size limit which is usually the case for Eagle (160x100)
Diptrace have a quite steep learning curve though when you've passed those first basic tutorials,
the sky starts to lightning up a bit...

[iwik]

Hi Per-Erik
Thanks for the reply, i agree, Eagles board size limitation is a killer. Will go for the same as you when ive become more familiar with the package. Steep learning curves seem to be norm today with anything that has some sophistication to it.
By the way you did a great service to us all for the rewrite of the Master card Schematic, the original was terrible to read.

Regards
Les

[Perik]

Hi Les,

The diagram didn't become too much better than the original.

As you may have observed, I’ve done a few changes which suites me well.
I’ve reduced the size of External Bus connector – from 40 to 16 pin and removed one of the 259 IC's.
So if you are not going to use some of those old boards, this should be safe.
I believe the only board in general use today utilizing this connecter is the
Display-II board and then only thirteen pins.
BTW, I’ve done the same change on my own Display-II board.
I’ve also replaced the DB-9 with a 10-pin IDC connector.
The connector symbols used can be confusing – it’s more to get the
drawing easier to make/read.

Just tell when you’re ready.;)
I have a couple of libraries which you could take advantage of.
Adapted those few components I’m using to CNC – mainly increased
the size of pads in component pattern.
You can also have the Diptrace files (Schematics & Layout)
for misc. board if you like and do your own customizing very quickly.
It's this possibility which is charming. Make simple changes without breaking the
protocol.

[riche543]

Hey Perik Ive been trying to workout the cnc cutting of the pcb,s. Im trying to figure out what is really happening in the cutting process. Now when etching/cutting the pcbs are you cutting away what is not needed of the copper, or am i missing something else. sorry if this is a dumb question im very thick sometimes :? when i look at the videos of the pcb,s being cut it looks like the tracks are being cut but im then thinking if your removing the copper from the tracks then theres nothing for current to pass??
Cheers
Rich..

[Perik]

Hello Rich

It’s nothing like a dumb question in this “game”.

What we are doing is called “isolation routing”. Search for this topic at
Google and you’ll find a huge amount of information.
When you bring your PCB layout (in my case in DXF format) into your
CAM package all the traces will be shown as they are in the layout program and
with correct width. The traces are continuous curves / line segments – including pads.
I then run “outside contour” tool-path with a 60 degrees V-cutter.
V-cutter for pcb-milling is a science in itself and is available in many shapes and a wide price-range.
Those I’m using are low-cost engraving V-cutters from:
http://www.cnc-plus.de/Fraeser---Bohrer/Single-Flute-Engraving-Router-Bits.html , but any V-shape can be used.
I know somebody using this type as well:
http://www.cnc-plus.de/Fraeser---Bohrer/V-groove-Engraving-Router-Bits-1007.html with 0,1mm tip-diameter.

The depth is another issue which you need to have control over and that’s all the
way from the CAM software. The path distance from the trace edge is calculated
in the CAM package based on the specification of the V-cutter (angle/tip) and the depth set.
The cobber layer usually have a thickness in the range 30-40um.
I mill at approximate 0,1mm depth but I always starting “high” and goes slowly
down step by step (0,05mm) until the isolation is OK. Use a Ohm-meter to verify.
In the end the depth is not critical – just get properly through the cobber and still have some traces left;)
This is something you will master within a very short time.

Happy milling

[iwik]

Hi Per-Erik,
All understood, realised you had done a few changes. Would much appreciate Libraries , misc and yes it would make for easier changes without having to start
from scratch. Im not quite ready yet but like to collect this imfo when i can.
Thanks
Les

[riche543]

Thanks Per-Erik for that. Im understanding that much better now. not 100% but my brain seems to take a long time understanding things :rolleyes: . Thanks Again...

[Rob65]

Wow,

thanks to Per-Erik for your nice words.
I realize that my website is out of date with my current activities - I should really update and show some of my later work.

I recently started to do some PCB work using a very old version of Protel (98) that had a great user interface in the old days ... Need to update to something like Eagle - which a lot of people are using nowadays. A good thing on Eagle is that there is a freeware version for non-commercial use keeping it all legal :o

Coppercam (http://www.galaad.net/coppercam-eng.html) is IMHO the tool to convert PCB layouts into milling data. You can change track width, size of the isles, size of drilling holes and one of the best features is that you can isolate regions of a PCB which is a must for small pitched connectors.

Rob