Bill:

That is an excellent suggestion!  We have a small daughter card that 
will need to mate perpendicular to a mother card.  We will have 2 
alignment tabs on the daughter card that must go though the mother 
board, and the daughter card must be flush to the surface of the 
mother board.  Everything is tight and critical, so designing in 
loose tolerances to compensate is not acceptable.

I'll look at putting a hole in the corner so when they route through 
it, there will not be a radius.  My original thought was to just 
overshoot the route so it will be square, but I need to know what 
size bit to specify so I know how much to overshoot.  I didn't want 
to specify something too small, as this will be somewhat high volume 
and I need most board shops to be able to manufacture it.

Thanks for your input and great suggestions!

Dave


At 04:06 PM 8/2/2007, you wrote:
>David,
>
>Typical note we use for manufacturability reasons is
>
>  .06 Min Radius on all inside corners...
>
>However... that does not mean that someone can't make a sharp corner for
>you... it just means we save money on our boards by not designing in sharp
>inside corners...
>
>In the old days we used a corner notcher shear to do sharp corners.. there
>are also NC nibblers out there that are used for sheet metal that could
>punch out a sharp inside corner... but I have not tried that for  various
>reasons... best way to deal with it is not to design them in...
>
>Perhaps you relieve the corner with a drilled hole in the exact corner and
>then route up to it with a standard .125 inch dia router bit... allowing it
>to not actually contact the pin point corner of whatever you are mating with
>it?
>
>Why do you need a sharp inside corner?
>
>Bill
>
>
>-----Original Message-----
>From: David Baldwin [mailto:[log in to unmask]]
>Sent: Thursday, August 02, 2007 3:46 PM
>To: [log in to unmask]
>Subject: [DC] Typical Routing Bit Size - Critical Corner
>
>DC Members:
>
>I am designing a board that has a critical inside corner.  Can anyone
>tell me what the typical minimum routing bit that a board shop
>uses?  I need a perfect corner so I believe we will need to overshoot
>the routing to eliminate the radius, but I need to keep it at a minimum.
>
>Thanks in advance for your input.
>
>David Baldwin C.I.D.+
>
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