Re: [CAD_CAM_EDM_DRO] Re: Leadscrews, PCB router experiment

Hi, and if you want to get the oil off after scrub them with Dawn
dishwashing liquid,then with Windex w/ammonia or pearsons ammonia soap. a
quick rinse in hot water running and your done. cul brian f.

----- Original Message -----
From: <cncdxf@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Wednesday, July 25, 2001 7:50 AM
Subject: [CAD_CAM_EDM_DRO] Re: Leadscrews, PCB router experiment


> Hi,
> I just tested the 60 degree mechanical etching bits from
> Think and Tinker. They are micro grain carbide, and they stick
> to a magnet. T&T told me to use 30,000 RPM at 16" per minute
> when milling. I am running the bits at about 8,000 RPM with
> a feedrate of 5" per minute. My boards take around an hour to
> cut at that rate. For wider isolation paths a carbide drill bit
> is a cheaper option. I do IC boards. This is Kleinbauer's
> method. He also told me to coat the board with motor oil before
> milling. I find this keeps the dust down.
>
> Bob
>
>
>
>
>
> --- In CAD_CAM_EDM_DRO@y..., Jon Elson <elson@p...> wrote:
> > JanRwl@A... wrote:
> >
> > > In a message dated 24-Jul-01 02:21:40 Central Daylight Time,
> > > elson@p... writes:
> > >
> > > > The experts can tap the shank on their fingernail and listen
> for the ringing
> > > > of the cantilevered drill bit. If it rings with a very high
> pitch, close to
> > > > 10 KHz, then it is carbide for sure. HSS is magnetic, of
> course, but some
> > > > other cutter steels are not.
> > > >
> > >
> > > The most OBVIOUS way to tell "in an instant" is to "weigh" the
> piece in your
> > > delicate fingers! If it is OBVIOUSLY heavier than steel --- like
> LEAD would
> > > be, only even heavier, yet! --- it is solid-carbide! Dull grey,
> not shiny,
> > > like HSS.
> >
> > Unfortunately, the drill bits in question are quite small, and the
> shanks are
> > often HSS or similar material, so the tiny drill bit's weight is
> lost in all
> > that.
> >
> > > Carbide is even MORE magnetic than HSS!!! NOT a useful test!
> >
> > I find this hard to believe. At least, PURE WC (Tungsten Carbide)
> is not
> > magnetic at all. The various commercial formulations often have
> large
> > amounts of Cobalt and other magnetic metals alloyed in them, which
> makes
> > them mildly magnetic. I just went into my shop to check this, and
> found
> > most of my "solid carbide" tools to be very slightly magnetic,
> although the
> > shanks of many of them were much more strongly magnetic than the
> > cutting end. I didn't fina any where the cutting end was strongly
> magnetic
> > at all, but the HSS tools definitely were.
> >
> > Jon
>
>
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