Re: [CAD_CAM_EDM_DRO]Breaking cutters OT

That's great advice for steel- unfortunately AFAIK PCB's are usually clad in copper. Copper is soft and cuts fairly easily but work hardens severely if you try to cut it at too slow of a feedrate (chip load). So the opposite may apply, going faster may actually make the material cut smoother and better with less tool breakage. Shortening the tool or resetting it to have less free extension may also help. I have not tried to mill PCB's at all, so this is just speculayion. I have milled some copper and can't say I can offer a proper feedrate as a result myself from that either. My problem was the copper tried to bend out of the way like a sheet of cookie dough and I had to sandwich it between some corian because the double stick carpet tape I tried to hold it down with was not working- PCB's have the advantage of being attached to a substrate at least!

-Will

----- Original Message -----
From: William Thomas
To: CAD_CAM_EDM_DRO@yahoogroups.com
Sent: Tuesday, November 10, 2009 11:25 PM
Subject: Re: [CAD_CAM_EDM_DRO]Breaking cutters OT



Hi Alan and all:
A year and a half ago I cut a mold cavity in S7 tool steel with 1/16" and 1/32" ball nose cutters. I was able to cut a 1/16" circular groove with the OD being .875" in diameter .065" deep in four cavities with just one four flute solid carbide cutter. The key was using shallow depth of cut and a find feed rate. I was limited to only 2,800 RPM so I had to use a low inches per minute feed rate of around 1/2" or less as I calculated it down to appox. .00008" to .0001" feed per tooth or chip load per tooth. Just email me if you want more info.
GOD'S BLESSINGS
Bill

15:06:19 -0800 (PST), Alan Rothenbush wrote
>
>
> Hmm, EDM in a raster format .. with raster of course being the key ... hmmm
>
> Anyway, thanks to all who responded to my original request about laser "etching", even if I didn't like most of the things that any of you said! <G>
>
> It sounds like I'm back to breaking tiny little cutters until I find the RPM/Feed rate sweet spot.
>
> Alan
>
> --
> Alan Rothenbush
> Client and Research Services
> IT Services
> Simon Fraser University
>
> ----- "Roland Jollivet" <Roland.Jollivet@...> wrote:
>
> > I still think (without trying) that good resolution PCB etching could
> > be
> > obtained using a fine wire and EDM or ECM in a raster format.
>
>

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