A decent drilling machine will make your carbide bits last a long time. HSS or cobalt bits may not break from bending forces, but they will dull very quickly and then break from torsional overload.
If you only drill a few hundred holes in your life, HSS or Co may be sufficient.
Donald.
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----- Original Message -----
> From: "michael tenore" <wb2lcw@...>
> To: "Homebrew PCBs" <Homebrew_PCBs@yahoogroups.com>
> Sent: Thursday, February 24, 2011 3:06:40 PM
> Subject: Re: [Homebrew_PCBs] Re: Carbide PCB drill ?
>
> Its better to use high speed steel or cobalt bits..
> they can be found cheap from Victor machine or travers or on the web!
> The carbide bits break too easy even with a dremel drill press.
> regard
> mike..
>
> --- On Thu, 2/24/11, designer_craig <cs6061@...> wrote:
>
> > From: designer_craig <cs6061@...>
> > Subject: [Homebrew_PCBs] Re: Carbide PCB drill ?
> > To: Homebrew_PCBs@yahoogroups.com
> > Date: Thursday, February 24, 2011, 2:26 PM
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> > I was going to buy some from Drill Bit City:
> >
> > http://drillcity.stores.yahoo.net/
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> > One thing thought, the carbide bits are vary birttle and I
> > found it was not possible to use them with a hand held tool
> > like a Dremel. Not even sure you can use a low quality
> > drill press. The quill runout needs to be fairly good and
> > the down feed needs to be very sensitive or you will snap
> > them. You also need to turn them very fast, they like
> > speeds around 30,000RPM -- some PC drillers use 100,000 RPM.
> > I have had success at 5000 RPM on my CNC Bridgeport mill. I
> > am sure I will snap a few before I get he feed rate dialed
> > in. I have plans for a high speed spindle but not had time
> > to work on it.
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> > Craig
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> > I will be drilling with my CNC bridgeport
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> > --- In Homebrew_PCBs@yahoogroups.com,
> > Cristian <bip@...> wrote:
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> > > > I eventually bought a sharpening machine that
> > had diamond wheels,
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> > > > drill bushings and a microscope.
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> > > Let me know where to buy such tool, Tom, please.
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> > > Cristian
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> ------------------------------------
>
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