Helicoils in Copper

[Rhodrons]

I am trying to bring an old drawing up to date. It shows a copper casting with helicoil inserts to take M10 steel studs. The drawing says "Drill 10.3 dia to suit M10 helicoil 15 long" and it shows the hole depth as 17mm long. Can someone confirm that this hole specification is sensible for a M10 helicoil to take an M10 stud. TO me the 10.3 drilled hole seems too small but perhaps because the copper is so soft it is ok?

 

[drawoh]

Rhodrons,

The notes on my drawings state that thread inserts are to be installed as per the manufacturer's instructions. Other than that, I specify the thread insert and size. On occasion, I have specified the depth of the tap, ensuring that a long screw would clear the insert. Most of the time, this is not necessary.

There are multiple threads on the subject of (not) telling machinists how to tap holes.

JHG

 

[ewh]

Most places I have worked use the method mentioned by drawoh. It simolifies the drawing and lets the machinist know how to proceed.
As far as knowing if the dimensions on your drawing are reasonable, I suggest checking a helicoil catalog, which you can find online.

 

[diamondjim]

The thread depth does make sense that it would
be longer than the length of the helicoil by
1.5 times the pitch as that is the recommended
chamfer at the face of the machined material
to start the helicoil. I assume the bolts are
a very low grade of bolt ie less than grade 5.

 

[MintJulep]

http://www.emhart.com/products/helicoil.html