Milling a No Copper Board

On 4/23/2011 12:11 PM, Thomas W. Gustin wrote:

Dear Experts,

 

All of the board I have developed over the last several years have been

simple rectangular or round boards defined by the Dimension Layer (20).  I

have a new client that wants several boards developed that ALL include

milled slots, and other odd shapes, both as cutouts in the outer edges, and

as cutouts in the interior of the boards.  I have several questions

regarding the development of these boards:

1) Do I use Polygons in the Milling Layer (45) for all of my

non-outside-dimension CNC operations?

2) If so, what "width" do I use?

3) How do I develop a CAM file for Layer 45 that a PC board house can use?

 

Thanks for your assistance.

 

Regards,

 

Hello Thomas,

I'll start the ball rolling and let the experts clean-up the mess.  Ive

used a number of methods from a series of closely spaced drill holes to

drawing the router cutout using "WIRE" and "ARC" in the Milling Layer

(Outline Layer can also work).  Never tried Polygons in the Milling

Layer but I suspect it will work as well, the people that fab the PCBs

are experts at interpreting what we need.  If you use WIRE or OUTLINE it

is more reliable to use 0,2mm thickness.  Sometimes 0 width can generate

questions depending on the service used.  You can designate the Milling

Layer by changing an unused layer in the CAM. Rename the Section to

Milling and rename the File extension to .mll or something similar, turn

on only the Milling Layer then process the CAM job.  Use a Gerber viewer

to check your files and include a .txt file when you send the Gerbers to

define .mll layer.  Your board house may have a preferred bit size for

slots so you will need to contact them.  I use 1mm as a minimum.

Best Regards,

Mike

On 4/24/2011 10:45 AM, Mike Malherbe wrote:

On 4/23/2011 12:11 PM, Thomas W. Gustin wrote:

>> Dear Experts,

>>

>> All of the board I have developed over the last several years have been

>> simple rectangular or round boards defined by the Dimension Layer (20). I

>> have a new client that wants several boards developed that ALL include

>> milled slots, and other odd shapes, both as cutouts in the outer

>> edges, and

>> as cutouts in the interior of the boards. I have several questions

>> regarding the development of these boards:

>> 1) Do I use Polygons in the Milling Layer (45) for all of my

>> non-outside-dimension CNC operations?

>> 2) If so, what "width" do I use?

>> 3) How do I develop a CAM file for Layer 45 that a PC board house can

>> use?

>>

>> Thanks for your assistance.

>>

>> Regards,

>>

>

Hello Thomas,

 

I'll start the ball rolling and let the experts clean-up the mess. Ive

used a number of methods from a series of closely spaced drill holes to

drawing the router cutout using "WIRE" and "ARC" in the Milling Layer

(Outline Layer can also work). Never tried Polygons in the Milling Layer

but I suspect it will work as well, the people that fab the PCBs are

experts at interpreting what we need. If you use WIRE or OUTLINE it is

more reliable to use 0,2mm thickness. Sometimes 0 width can generate

questions depending on the service used. You can designate the Milling

Layer by changing an unused layer in the CAM. Rename the Section to

Milling and rename the File extension to .mll or something similar, turn

on only the Milling Layer then process the CAM job. Use a Gerber viewer

to check your files and include a .txt file when you send the Gerbers to

define .mll layer. Your board house may have a preferred bit size for

slots so you will need to contact them. I use 1mm as a minimum.

 

Best Regards,

Mike

I would not use polygons for the milling layer, they are converted into

a series of tracks in the Gerbers, I would just draw the outlines.

having just been burned by a board house not properly figuring the tool

width in an outline ( they were sure it was good enough, they were

wrong), I would use a width of zero or super small to hopefully make

someone think and ask a question.

bottom line, it's between you and the board house how you want it done.

assume nothing is my advice, they can tell you what size router bits

they will use and much more...