[Shop-talk] Helicoil in aluminum

[Randall]

> I'm about to install a helicoil in an aluminum block.   The 
> tap calls for
> drilling a 21/64" hole.  Since it is aluminum should I drill 
> the hole just a tad smaller?  If so how much?

I don't think it matters much.  The tap seems to ream the hole out if it is
undersize.  I've even been known not to drill, if the hole is completely
skinned out (and the base metal is soft).

-- Randall