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

Alan Marconett KM6VV wrote:

> Hi Jon,
>
> Carbide drills like these:
>
> http://www.thinktink.com/cgi-bin/carbide.cgi?page=imperial&step=10&start=88
>
> It's the Think and tinker URL. They have a $50 minimum, so I'll need to
> get the ME bits too!

Yes, that looks like the thing. But, you can get these somewhat cheaper
at other locations. MSC has them, and so do some other machine tool
catalogs. If you ever catch them on sale, you can get them a lot cheaper.
I have a drawer full of used bits that I get for about $.65 each. They seem
to be quite usable for my purposes.

> I bought some surplus PCB drills at Haltek when they were still there.
> How do I know if they're carbide or not?

Generally, if they have 1/8" shanks and step down to the drill point, they
are carbide. Examination with a 25 x magnifier will often make it obvious.
If you look under strong magnification, ans when the thing looks as big as
a 1/2" drill bit, and the flutes still look like mirrors, then it has to be
carbide.
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.

Jon


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