On Wednesday, January 22, 2014 1:26:06 PM UTC-8, Cydrome Leader wrote:
I've tried to look this up and found no real answers so far.



Is there any sort of standard for cutting the chamfer on a thread lead-in?



Say I'm just threading the end of a 1/2" Al rod. The start of the thread

at the end will be jagged and weak. Cutting a 45 (I found 60 does nothing

useful) degree chamfer helps and makes thing far prettier, and for

anything I've done you can just eye-ball this and it really doesn't matter

too much how you do it for my uses.

Cut lead in chamfers slighty smaller than the tap size diameter.

IE 1/2-13 = .421 tap dia. .5-.421= .079 / 2 = .0395 chamfer
so .04 - .045 X 45 chamfer cut on before the threads will be fine.

Same kind of deal for taping. C-sink slighty larger than major thread diameter.






What's done in the production world for stuff like this where looking

pretty is key? Is there a special angle and distance to cut this chamfer?



Would it be measured as distance into the thread, or the diameter of the

end of the fastner once cut?

either way
.040 X 45deg chamfer
or
..42 dia. plus 45 deg.






Last question- how does one really measure a chamfer anyways? There's no

real surfaces to measure off.

chamfers are one time everybody can:
scale & eyeball vernier tips


The real c-sink question is :
Why are Flat Head Screws c-sink at 82 deg? (41 deg / side)
The heads of FHS are 45 deg.?

any takers?