Helicoil Length?

Im guessing its 1.5 times the dia. Or 2.5 times the dia.

So in this case 4mm times 1.5d would be 6mm long.

Ive always grabbed them from a bin and never had to pay attention to spec.
 
DanGT86 said:
Im guessing its 1.5 times the dia. Or 2.5 times the dia.

So in this case 4mm times 1.5d would be 6mm long.

Ive always grabbed them from a bin and never had to pay attention to spec.

What is the logic in that? why not mention length in millimeters?
 
It's not logical, but...here we are.

As far as logical goes, the USA still uses 12 inches to the foot, and 16 ounces to the pound.

My ebike is not allowed to ride on the sidewalk, but...I'm only legally allowed to use 750W on the streets to keep up with (and dodge) the 4,000-lb cars that are driven at 35-MPH by texting car-zombies.
 
General guidelines for thread strength are based on how many time diameter the threads are engaged. Its probably just easier for them to call them out like that rather than listing a specific dia on every size.

If you are installing a helicoil into a blind hole you are likely not going all the way to the bottom anyway. So calling them out as times diameter give a user a general idea how much thread engagement they will have without requiring too much thought about specific dimension.

Lots of cutting tools are like this. When we buy endmills and drill bits they are called out the same way. The stability of the tool is based on how many times dia it is long. It could be a holdover from the days when mfg. manually stamped the size on the tool. Maybe it was cheaper to just stamp 2xD or 4xD rather than specific numbers.
 
It does make sense. You now know how long any size of helicoil is in both standard and long length without having to look it up.
 
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