Holes for countersunk screws
Holes for countersunk screws
(OP)
Hi,
This is a long time misunderstanding on my part..
If for instance I have an M3 DIN7991 screw - what are the dimensions needed for the countersunk part? same dimension as the head? i.e. 6mm x90 degrees?
Thanks
This is a long time misunderstanding on my part..
If for instance I have an M3 DIN7991 screw - what are the dimensions needed for the countersunk part? same dimension as the head? i.e. 6mm x90 degrees?
Thanks





RE: Holes for countersunk screws
This might help
http://books.google.co.uk/books?id=esWtCQuLWtIC&am...
RE: Holes for countersunk screws
Isn't there a table specifically for DIN 7991 etc.?
RE: Holes for countersunk screws
RE: Holes for countersunk screws
http://en.wikipedia.org/wiki/Countersink
If you are working in thin material you need to consider the head thickness also. The "k" dimension here: http://www.dinstock.com/useruploads/files/socket_c...
RE: Holes for countersunk screws
Tunalover
RE: Holes for countersunk screws
John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Holes for countersunk screws
k - height of head = 1.7mm
dk - head dia 6mm max, 5.7mm min
90 deg.
RE: Holes for countersunk screws
What if the screws are going through the part and straight into a threaded hole? In this case the countersink diameter must account for the locus of the mating hole. The minimum LMC countersink diameter is then of diameter H=C+T where C=the MMC diameter of the screw head (across sharps) and T the pt of the threaded hole at MMC. If the minimum clearance hole diameter is F+T then the countersink diameter must be C+T.
Tunalover
RE: Holes for countersunk screws
RE: Holes for countersunk screws
RE: Holes for countersunk screws
I think the better option is to independently control the countersinks with a profile tolerance to control form and orientation as well as locate them. However, few people like doing detailed inspection on countersinks for screws.
RE: Holes for countersunk screws
Scroll to the bottom.
http://www.ifanger.com/fileadmin/Webmaster/Produkt...
RE: Holes for countersunk screws
Therefor the table listed by DINSTOCK seems to be correct.
The c'sink for M3 is as per DIN 74, 9.94 x 90 deg.. 3.4 hole.
Now you need to specify DIN 7991 or EN ISO 10642.
The DIN standard has a tighter limit on the dia. of the screw head. Also the height of the head differs somewhat from EN ISO 10642. This should not be a problem for the c'sink.
RE: Holes for countersunk screws
RE: Holes for countersunk screws
Chris, CSWA
SolidWorks 14
ctopher's home
SolidWorks Legion
RE: Holes for countersunk screws
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Holes for countersunk screws
Where is this countersink going to be located?
If something is sitting on top of the flat head screw, you need the screw to sit invariably below flush. If you are using the flat head screw because it looks cool, you want to set as close to flush as possible. This will affect your tolerances. I do not have any size tables with me at the moment. The size tables I am aware of show that flat head screws, especially small ones, have sloppy diameter tolerances. I have been told my machine shops that if I want stuff like this fabricated properly, I should give them the screws.
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JHG