I think the best would be to actually use a drill to drill holes, like
everyone else ;-)
Those grinders are meant for very hard material (ceramics, teeth, glass),
not soft epoxy that smears.
Some of the diamont grinding bits don't even have conventional cutters,
they just have a rough surface with diamonds embedded.
What you need is drills, ideally carbide. If you use carbide drills you
need a press or something else they'll break. If you use plain HSS bits
they won't break, but dull after like 15 holes. Carbide bits will not dull
(nobody has ever managed to dull one that is, they will break before that
'cause of mistakes etc.)
You can get them cheap at ebay, like 10eur for 100 is what i'd expect to
pay if i can select the size.
ST
On Sun, 11 Dec 2005 10:21:11 +0100, soffee83 <soffee83@...> wrote:
> Hi again!
>
> I recently received a ridiculous quantity of some suspiciously
> inexpensive 0.9mm diamond burrs I won on eBay.
>
> http://tinyurl.com/cncw6
>
> I don't have any serious board drilling on the agenda, but I tried a
> bunch of test holes and it doesn't look too promising-
>
> On the first couple holes the bit feels as if it's "burning" it's way
> through the PCB with some unfamiliar looking debris being tossed out
> of the cut. I actually had to remove and examine the bit with a
> magnifying glass to see if it had anything that looked like cutters. I
> tried another with the same result. They had to feed extremely slow
> due to the "not so clean" cut and I actually broke two tips by not
> giving them the time to "burn" through. They also leave a nasty raised
> lip around the entry and exit holes, which would imply that they're
> pushing rather than cutting their way through.
>
> I had used a Dremel diamond burr for a long time, but eventually
> dulled it on something or chipped it's cutters. I got another one not
> long ago and did something stupid in a hurry (side to side pressure),
> which broke the ball off. IIRC- They cut quite nicely, however, they
> were around 2.5mm, which wasn't too good for smaller stuff, plus I
> think they were 5 or 6 bucks a pop.
>
> Does anyone else here use dental burrs for their drill work. If so,
> how quick and clean of a cut are you usually getting?
>
> That seller had about 650 profile hits, all positive, and states that
> the bits are all top quality, just with no names. Some of the feedback
> even praised the quality of them. (??)
>
> Regardless of what ends up happening with these, I was sort of in a
> pinch. I don't like the idea of buying one or two non-standard micro
> small bits locally and the 5 pack of mini Dremel drill bits (in a
> glass tube) is no longer around here.
>
> How are the rest of you guys stocking up, and from where?
>
> -Thanks Again!
> George
>
>
>
>
>
>
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> Photos:
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>
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