Homebrew PCBs

Has anyone tried attaching a very fine pen to a cnc then etch the pcb
board?  Right now I'm using pcb-gcode but it's a pain because it takes
so long to remove all the material when 95% of the board is empty
space and 5% traces.  Also until I get my vacuum holder, it is hard to
be quick with the setup.  I'm thinking a pen mounted in the holder
will be able to write the traces better perhaps then I can chemically
etch them.  Has anyone tried this?  Thanks.
Henry

At 11:30 AM 10/3/2008, you wrote:

>Has anyone tried attaching a very fine pen to a cnc then etch the pcb
>board? Right now I'm using pcb-gcode but it's a pain because it takes
>so long to remove all the material when 95% of the board is empty
>space and 5% traces. Also until I get my vacuum holder, it is hard to
>be quick with the setup. I'm thinking a pen mounted in the holder
>will be able to write the traces better perhaps then I can chemically
>etch them. Has anyone tried this? Thanks.
>Henry
>

I have not tried it but the pen should have some kind of spring 
pushing it into the PCB at a constant pressure rather than ridgedly mounted..



Cecil
K5NWA
www.softrockradio.org  www.qrpradio.com

"Blessed are the cracked, for they shall let in the light."

2008/10/3 k5nwa <k5nwa@...>:
> At 11:30 AM 10/3/2008, you wrote:
>
>>Has anyone tried attaching a very fine pen to a cnc then etch the pcb
>>board?

is it not then a plotter............

----- Original Message ----- 

From: "Henry Liu" <henryjliu@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Friday, October 03, 2008 5:30 PM
Subject: [Homebrew_PCBs] attaching a pen to a cnc?


> Has anyone tried attaching a very fine pen to a cnc then etch the pcb
> board?  Right now I'm using pcb-gcode but it's a pain because it takes
> so long to remove all the material when 95% of the board is empty
> space and 5% traces.  Also until I get my vacuum holder, it is hard to
> be quick with the setup.  I'm thinking a pen mounted in the holder
> will be able to write the traces better perhaps then I can chemically
> etch them.  Has anyone tried this?  Thanks.

It's similar to using an etch-resistant pen in a plotter. That works quite 
well.

Leon
--
Leon Heller
Amateur radio call-sign  G1HSM
Yaesu FT-817ND transceiver
Suzuki SV1000S motorcycle
leon355@...
http://www.geocities.com/leon_heller

Henry Liu wrote:
> Has anyone tried attaching a very fine pen to a cnc then etch the pcb
> board? Right now I'm using pcb-gcode but it's a pain because it takes
> so long to remove all the material when 95% of the board is empty
> space and 5% traces. Also until I get my vacuum holder, it is hard to
> be quick with the setup. I'm thinking a pen mounted in the holder
> will be able to write the traces better perhaps then I can chemically
> etch them. Has anyone tried this? Thanks.
> Henry

Can you use the CNC to remove the 'border' of the tracks instead of the 
majority of the copper?  We achieve this by making the majority of the 
board a ground plane and expanding the power/ground lines to fill gaps.

Stuart

>Has anyone tried attaching a very fine pen to a cnc then etch the pcb
>board? Right now I'm using pcb-gcode but it's a pain because it takes
>so long to remove all the material when 95% of the board is empty
>space and 5% traces.

(mechanically) etch only isolations, not entire  copper.
Google for "mechanical etching" to see what's about.
Cristian

Yes, in fact it has been done usually using plotters. Look in the
Links, Photos, and Files sections of the group here.

Some have reported issues with the pen crossing over previously drawn
tracks.

You might also check those same areas of the list, and search the
archive, for "scratch and etch" or "scratch 'n etch". An idea that
John Kleinbauer came up with. Coat the blank board with a metal
marking fluid, let dry thoroughly, then with a carbide or diamond
scratch tip mounted in a plotter (or CNC, I suppose), scratch off the
borders of all the traces.

<http://tech.groups.yahoo.com/group/Homebrew_PCBs/files/Scratch_And_Etch/>

Steve Greenfield

--- In Homebrew_PCBs@yahoogroups.com, "Henry Liu" <henryjliu@...> wrote:

>
> Has anyone tried attaching a very fine pen to a cnc then etch the pcb
> board?  Right now I'm using pcb-gcode but it's a pain because it takes
> so long to remove all the material when 95% of the board is empty
> space and 5% traces.  Also until I get my vacuum holder, it is hard to
> be quick with the setup.  I'm thinking a pen mounted in the holder
> will be able to write the traces better perhaps then I can chemically
> etch them.  Has anyone tried this?  Thanks.
> Henry
>

I have tried this. Not using PcbGcode, since I use DeskCNC. I output a dxf file from DipTrace. Input the .dxf file into DeskCNC. Use the pocket command to pocket all selected closed entities in the .dxf drawing. I set the tool width to the width of the pen in my CNC machine. This allows me to create any trace width I used on the pcb.

Hope I am not violating the premise of this group, by the above. I do value the expertise in this group.

Instead of a spring loaded pen I use a weight system. I made a round block of wood the same diameter as my router motor. This allows me to clamp it into the same mount as my router motor. Thru the center of the round wood bock I drilled a 1" hole. The 1" hole is for a 1" UHMW rod. A washer screwed onto the top of the UHMW rod keeps it from falling thru the wood block. I drilled a hole in the bottom of the 1" UHMW rod the same diameter as the Steadler Lumicolor pens. A set screw holds the pen in the UHMW rod. I set "zero" on the CNC such that the pen is slightly lifted up. The weight of the UHMW rod gives sufficient pressure on the pen.

Even after all this I had some pretty dismal results. The finest point Steadler pen will only do .020 traces. The pen tip is not very tuff. Part way thru an fairly small board the tip tends to flatten/flare and the traces progressively get wider. I also had to run the CNC code twice to get enough ink on the board to get good etching results. 

If any one has better suggestions, I'm listening.

RD

[Non-text portions of this message have been removed]

I'd try Rapidograph pens

http://www.dickblick.com/zz210/03/

If I remember right they are basically a hollow tube with a wire in them.  The wire actuates a  valve, thus you would have to be able to lift the pen to stop the ink.  Extremely light touch and very fine lines.
 
	 
	
	








	


	
	


      

[Non-text portions of this message have been removed]

I've even tried those carbide tip cross groove plotter pens (basically what
was said to be the best). It didn't work either, the trailing edge scratched
too much ink away from the copper. It might work great on paper, but wasn't
so good on copper.

Overall, the whole plotter ordeal was a huge waste of time and money.
Compare that to toner transfer, where i can consistently get much better
results, and i really can not recommend the plotting method. Sure, it
probably can work under certain circumstances, but you'll still be left with
many limitations.

ST

On Sat, Oct 4, 2008 at 5:52 AM, KeepIt SimpleStupid <
keepitsimplestupid@...> wrote:

> I'd try Rapidograph pens
>
> http://www.dickblick.com/zz210/03/
>
> If I remember right they are basically a hollow tube with a wire in them.
> The wire actuates a  valve, thus you would have to be able to lift the pen
> to stop the ink.  Extremely light touch and very fine lines.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> [Non-text portions of this message have been removed]
>
>
> ------------------------------------
>
> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>
>


[Non-text portions of this message have been removed]

----- Original Message ----- 

From: "KeepIt SimpleStupid" <keepitsimplestupid@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Saturday, October 04, 2008 4:52 AM
Subject: Re: [Homebrew_PCBs] Re:attaching a pen to a cnc?


I'd try Rapidograph pens

http://www.dickblick.com/zz210/03/

If I remember right they are basically a hollow tube with a wire in them. 
The wire actuates a valve, thus you would have to be able to lift the pen to 
stop the ink. Extremely light touch and very fine lines.

Ceramic-tipped pens might be better. You will get very rapid wear with the 
ordinary ones.

Leon






















[Non-text portions of this message have been removed]


------------------------------------

Be sure to visit the group home and check for new Links, Files, and Photos:
http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links

I have done some various experiments with engraving (isolation milling) 
or plotting of resist lines using CNC machines. I do not feel this is a 
good approach, I have much better end products using toner transfer 
with a clothes iron and etching in ferric chloride.  

Isolation milling has several issues going against it even with a 
perfect machine:
1) Milling copper is not good process, even under ideal conditions
(outside the pCB industry).  Copper does not machine well.

2) An engraving cutter has to cut with near zero surface speed because 
you are cutting with the point of the tool.  Again, not a good 
condition.

3) Spindle run-out + cutter tip size controls the smallest distance 
between traces.  Dremels and other similar tools can easily have .010" 
of spindle run out which results in a minimum isolation groove of .020" 
plus tool bit tip diameter.

Plotting of the resist lines also is not very ideal.  Making a pen that 
is rigid enough to NOT flex while plotting is a challenge.  Then making 
a holder to hold the pen which also does not flex adds to the issues. 

Trace width is limitted to the minimum width of the pen which is often 
thicker than what is easily attainable with toner transfer.  

While I did not "beat the issue to death" with extensive testing, it 
didn't take long to realize everything I was trying to do with CNC was 
in fact a step back from the reliability and precision I could achieve 
with toner transfer and chemical machining (etching).

If lasers could be adapted for this "cutting", then I think I would try 
it again. However, I don't know nearly enough about electronics to even 
attempt a laser at this time.

Chris







--- In Homebrew_PCBs@yahoogroups.com, "Henry Liu" <henryjliu@...> wrote:

>
> Has anyone tried attaching a very fine pen to a cnc then etch the pcb
> board?  Right now I'm using pcb-gcode but it's a pain because it takes
> so long to remove all the material when 95% of the board is empty
> space and 5% traces.  Also until I get my vacuum holder, it is hard to
> be quick with the setup.  I'm thinking a pen mounted in the holder
> will be able to write the traces better perhaps then I can chemically
> etch them.  Has anyone tried this?  Thanks.
> Henry
>

----- Original Message ----- 

From: "lcdpublishing" <lcdpublishing@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Saturday, October 04, 2008 2:11 PM
Subject: [Homebrew_PCBs] Re: attaching a pen to a cnc?


>
> If lasers could be adapted for this "cutting", then I think I would try
> it again. However, I don't know nearly enough about electronics to even
> attempt a laser at this time.

Lasers work very well  for drilling micro-vias, but just removing copper is 
very difficult.

Leon
--
Leon Heller
Amateur radio call-sign  G1HSM
Yaesu FT-817ND transceiver
Suzuki SV1000S motorcycle
leon355@...
http://www.geocities.com/leon_heller