Phil,
You could have your vendor use a smaller diameter cutter, say 0.063" or
smaller.  Would that help (might increase cost a little)?
Otherwise, are the dimensions on your drawing for the cutouts to the center
of the 0.043 holes, or to the edge of the holes?  Using such a small hole
with a large routing tool will create "scallops," which you probably don't
want.  You could create an outline of your intended "square" cutout, and
have a hole a few thousandths larger than the router tool diameter drilled
at the intersection of each corner to relieve the corners, drilled before
the routing process.
Makes you sort of yearn for the days of the small fab shops that used manual
punches for holes and board outlines to make square corners, doesn't it?

Roger M. Stoops,  CID   [log in to unmask]
TRIMBLE NAVIGATION LLC
Engineering and Construction Division
5475 Kellenburger Rd.
Dayton, OH   45424-1099      USA
Telephone:  937 233 8921      800 538 7800      ext. 288
Facsimile:  937 233 7511

http://www.trimble.com


 -----Original Message-----
From:   Phil Nutting [mailto:[log in to unmask]]
Sent:   Wednesday, May 01, 2002 12:56 PM
To:     [log in to unmask]
Subject:        [TN] Hole routing in PCBs

Hi all,

I wanted to tap into your collective knowledge (opinions).  We have a small
circuit board that is supposed to have a rectangular cutout to accept
ferrite cores.  My board house used an 0.093 diameter cutter with the
argument that it cut through the "corner holes" specified on the print.  He
says that I need to add a radius spec to my board drawing.  My board
designer (and I) have reviewed this board and think that it is clear what
should be done [we need the 0.043 (0.0215 radius corners) holes for
clearance].

I have asked Steve Gregory to post a JPEG file of the board. It can be found
at;

http://www.stevezeva.homestead.com/ and click on "Routing", or

http://www.stevezeva.homestead.com/files/Routing.jpg

How do you think this should be specified/machined?

Thanks in advance.  Thanks Steve for posting the file.

Phil Nutting

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