Re: Σχετ: CNC isolation routing


There is nothing to transform to metric. It is simple trigonometry, whatever units the numbers are you put in is the units they will be output. The only ‘fixed’ unit is the angle, which is in degrees. If you use type in mm for the tip diameter and depth of cut then you get mm output.


Jeff Birt


From: pcb-gcode@... [mailto:pcb-gcode@...]
Sent: Monday, July 06, 2015 2:16 AM
To: pcb-gcode@...
Subject: Re: Σχετ: [pcb-gcode] CNC isolation routing



Hi Jeff

Thanks for the spreadsheet. It is nice of you. I will transform it into metric and for sure I will be using it.


Am 06.07.2015 um 00:12 schrieb 'Jeffrey Birt' birt_j@... [pcb-gcode]:


Figuring out the resulting width of cut based on the bit angle, tip diameter and depth of cut just requires a bit of trig. A few years ago I put this all into an Excel file: to make it easy. As I recall someone took the calculations and made a plug-in for OCB-GCode from them.


Jeff Birt


From: pcb-gcode@... [mailto:pcb-gcode@...]
Sent: Sunday, July 05, 2015 4:48 PM
To: pcb-gcode@...
Subject: Re: Σχετ: [pcb-gcode] CNC isolation routing



Why do you set  a Ø0.33 when your effective engraving has a flat tip of 0.2mm? On one of your bad boards remove a bit of copper and measure the thickness of the copper free board with a caliper, then deduct its measurement from the thickness of the board with copper and you know know the minimum depth you have to engrave. After you can measure on your bit at which width it will remove the copper when its depth is set to this measure.

Drawing the bit on a CAD programm would also be easy to get all the information needed.

Is it sure that 0.2mm will give you the width of the trace you want to have?

Art is more than correct when he says that a bit calibration is needed.


Am 05.07.2015 um 20:19 schrieb 'Alex P.' poupakisalex@... [pcb-gcode]:


A small correction, it's 0.2mm (sorry for that) and I have set the diameter to 0.33mm

I lowered the depth and will see how that goes



Στις 7:43 μ.μ. Κυριακή, 5 Ιουλίου 2015, ο/η "Art Eckstein art.eckstein@... [pcb-gcode]" έγραψε:



I have come back to your first post and re-read it again and also the
compilation of posts especially the last one by Jean-Claude.

You reference that if you go deeper, your traces become to thin. But what
you do need to do is mill deeper to cut through the copper.

Trying to read between the lines, is it possible that you have entered in
the Machine tab of the setup ulp a diameter of 0.1 for the cutting tool
If so that is your problem because of the 15 degree taper causes the
"effective" diameter of the cutter to be larger the deeper you go. That is
why I suggested the "bit calibration" reference for you to look at and
possibly use. This is a method of determining the actual width of cut
based on the depth of cut. It will not only eliminate any tolerance in the
actual diameter of the flat on the bottom of your engraver, but any
intolerance in the slope of the angle and any runout that you may have in
your spindle.

country bubba

At 09:45 AM 7/5/2015, you wrote:

>Hi all,
>I have a CNC 3040 and 15 degree 0.1mm engraver. I want to isolation route
>a pcb but the problem is that the copper is too thick. It's more than
>0.1mm thick and if I set a lower depth for the engraver, the traces will
>be too thin. Is there anything that can be done about that? I have
>discarded many boards because of this reason. Does anyone have a similar
>Thanks in advance,




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