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Subject: Re: [Homebrew_PCBs] Drilling circuit boards on the cheap:

From: Stefan Trethan <stefan_trethan@...>
Date: 2016-02-14

You can easily resharpen HSS bits, even the very small ones. Don't fuss about the correct geometry, almost anything will melt through FR4. You can just touch them against a dremel wheel or grinder at what you imagine might be the correct angle and you are good to go for another couple dozen holes. I didn't even take them out of the drill to sharpen, gives you something to hold onto.

As for carbide, they do work great in a fast running drill in a precision stand. There are several ways to make a stand using a pivoting arm or flexures. Highly recommended if you make a lot of PCBs because of the clean holes they cut.

BigClive (.com and youtube) uses carbide drills handheld, but then he has hands the size of manhole covers, and is a scot....


ST

On Sun, Feb 14, 2016 at 7:59 PM, bobledoux@... [Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:



 While I can find resharpened carbide bits, those cheap, bench drill presses tend to have too much runout. They also run too slow for carbide.  As a result carbide bits tend to break.

I prefer to use high speed steel bits. They don't break.  They do wear quickly, but I can finish a typical board with just one bit.  My preferred size is 1/32 (.032) inch as these tend to cost less than numbered bits. Places like Enco sell these at 65 cents a piece in lots of a dozen plus postage, of course.

Looking for a local, and lower cost supply, I looked to Harbor Freight.   They sell a 30 piece drill bit set for $3.99. The set is metric sized, but very useful.  Converted to inches the set includes five each of .020, .024, ,031; three size .039; and two each of .047, .059, .071, .079, .093 and 118.

For circuit board work, the 18 bits less than .040 size are a bargain at 22 cents each.

 In keeping with the K7QO experimental mindset, I'll buy some tomorrow and report back.

bob-N7SUR