Re: Milling Circuit Boards

>So KellyCAM can do offset on a .DXF file?

If you setup the travel hight and cut depth of your machine
in KellyCam the DXF file is set to those values when you import it
into Kcam. Then just save as Gcode file. Always make sure
you hit update before saving the GCode file.
I am using a Dremel! The problem seems to be the circuit
board material. The board material is glass epoxy. This seems
to be killing the bits. The trick is to only cut the copper.
I ment to tell you. In TurboCad if you click where you want
a hole move the mouse a hair and click again. A dot is left
on the drawing. During the milling process a starter hole is
formed at these locations. Drilling circuit boards is tough
work. I use number 60 drill bits and they have flex and walking
problems. By having the milling bit make a starter hole,
things get easier. Real circuit board companies use a entry
and exit layer over the board during drilling.

John

And

> output Gcode, or cut it? More ways to do things! 5 boards per bit
> sounds a little rough, but then I haven't priced the bits at "think

an

> tinker". Ballendo has posted previously that a Dremel mill can be

used

> to replace the spindle of the Sherline (and provided a drawing), so

that

> might work for you too! I have a pair of 12" ball screws with light
> motors that I'll eventually press into this service, after a few of

my

> "other" projects get done!
>
> Alan KM6VV
>
> kleinbauer@j... wrote:
> >
> > Hi Alan,
> > I laid out my design on .1 grid paper. Then in TurboCad
> > I turn on the grid! I then redraw the traces ending them at
> > the nearest line. All the traces are square in nature. Since I
> > deal with digital signals, the size of the trace can be larger
> > than needed.
> > Like I said, the trick is in the drawing! Make the outline
> > of each trace one continous line. You can click on turns, but
> > don't hit finish until you come back around to the beginning of
> > the trace. Draw the board in four or more sections. Don't jump
> > around, drawing a little here and a little there. If you jump

around

> > your machine will spend more time moving than cutting. If you hit
> > finish several times on one trace, you will be treated by see the

Z

> > axis move up than down for no reason.
> > Save the file in DXF format. Import into KELLYCAM and
> > SCALE and OFFSET the drawing. I also use the FIND and change
> > feature in KCam to fix some rapid speed moves that get mixed
> > in. I am only milling at 5" per minute. I designed my machine to

mill

> > wax and plastic. So far the machine is performing well. I have

made

> > ten six IC circuit boards so far. I am getting 5 boards per

milling

> > bit. I am using the mechanical etching bits from Think and Tinker.
> > They say to run the bit at 30,000 rpm. I am running at 3,000! I

put

> > three drops of motor oil on the board and then spread it around.
> >
> > John
> >
> > --- In CAD_CAM_EDM_DRO@y..., Alan Marconett KM6VV <KM6VV@a...>

wrote:

> > > Hi John,
> > >
> > > Thanks for the update. Sounds like you had best results by

drawing

> > in a
> > > CAD program, doing the outlines as toolpaths? Perhaps you'd

like to

> > > share the .DXF and Gcode files for this or a smaller example?

I'd

> > like
> > > to study it!
> > >
> > > Must have been a lot of work to do the offsets for each "trace
> > island".
> > >
> > > Alan KM6VV
> > >
> > >
> > > kleinbauer@j... wrote:
> > > >
> > > > Hi All,
> > > > Here is an update! After spending countless hours using
> > > > TOPO,TurboCad,Eagle and Target here are my findings. TOPO will
> > > > take a BMP and turn it into a DXF. The problem with using TOPO
> > > > to make circuit boards is, the program adds tons of up and

down

> > > > commands. The conversion is also plagued with the traveling
> > > > salesman syndrome.
> > > > Eagle with it's script looked great until I did a

larger

> > > > circuit board. Three 14pin ICs and some traces resulted in

16,000

> > > > lines of code.
> > > > Target had the same problems as Eagle to a lesser

degree,

> > but
> > > > the program is not a easy to use as Eagle. I went back to

TurboCad

> > > > using a new approach. I found out that when you convert a DXF

to

> > > > a Gcode file, the machine will move the same way as you drew

the

> > > > outlines. The trick is to stay in one area at a time and to

draw

> > > > as much outline at one time as you can before hitting finish.

Make

> > > > each trace of the circuit board one long line. Then hit

finish. If

> > > > you draw each trace as several seperate lines, the machine

will

> > move
> > > > up and down for each line. Jumping around on the drawing to
> > touchup
> > > > or correct will result in a final GCode that will move the

same

> > way.
> > > > I have a GCode file that makes a six IC circuit with
> > twelve
> > > > transistors.(4"X6") My machine takes an hour and twenty-

minutes to

> > > > mill the board. I am hoping to cut this to 60 minutes while

adding

> > > > starter holes for components.
> > > >
> > > > John