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

A small shop vac with the hose attached to your Z axis is a better way do
deal with the dust than to coat your board with motor oil. A

How wide are you milling your isolation paths? I normally mill 10 mill paths
and have absolutely nothing but great results with the Think and Tinker
bits.

If I ever need isolation paths wider than 10 mills I move up to a .032 end
mill. This is better for rub out operations.

There's no way a carbide drill bit would work for isolation cutting at the
speeds I run my router at. The bit would snap on the first move. I have no
idea what my real feed rate is but the settings are 60 IPM for rapid moves,
40 IPM cutting and 5 IPM slow jog speed. Of course all the pad circles that
are cut slows down the effective rate. I'm currently using a Ryobi trim
router and I don't know the top speed but I'm sure it's real close to 30K
RPM.

I rarely have a board that takes an hour per side to mill. 10 to 30 minutes
is more common. But even at an hour per side to mill and about 10 minutes to
drill ( most of this time is changing bits ), that to me is a lot more
preferable than trying to do double sided boards via chemical etching.

later,
Larry E.

----- Original Message -----
From: <cncdxf@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Wednesday, July 25, 2001 5:50 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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