how do you size Crack stop holes?

[Chinaman]

what is a simple way to calculate the size of a "crack stop hole"?

[PinkertonD]

I may be wrong here, but I have always just grabbed a drill that looked about right. If it is a cell phone sized thing then a 1/8" hole looks about right. If it is in a 10" Pipe flange then 1/2" looked about right.

I am not sure there is a science to it, but I have been wrong before.

[Kelly_Bramble]

Bigger is better - larger radius distributes the stress better...

[PinkertonD]

Bigger is better - larger radius distributes the stress better...

Hmmm, now that could open a whole can of Academic discussion Kelly.

[jackkingsford]

There’s actually a way to calculate the size of the crack stop hole. I just forgot about it. You don’t just go for a bigger one.

[Dwight Politte]

Hi pinkertonD! Don’t you agree with what Kelly said? I actually think that Kelly is right. :3

[RWOLFEJR]

The key is finding the end of the crack... From there I doubt it really matters? When in doubt go stout...!! If you're not 100% on the end of the crack's location then drilling a little bigger will likely catch it.

Reason I doubt it matters is... The part cracking tells me it has already been underdesigned or simply run it's course for the parameters it had to be built within. To stop the crack from spreading is a temporary fix until a stouter piece can be integrated into the system?

But then after looking a this again... Do you mean a radius at corners for the prevention of cracks? If that's the case then as big as you can afford. Like Kelly said... Bigger will better distribute the stress.