Taps for galvanised hole

[Gregwalker1981]

Anyone help me out on what to use?

i have welded nuts to the back of a PFC and sent it to the galv

but once it is back i will have to tap the nuts again

doses anyone know what size of tap i should use for

M20 nuts for galvy set screws

 

[Welderpaul]

Trick question? M20 tap surely?

 

[Hitch]

There are special oversized taps for using with galv bolts. Use a normal tap and youd have a job to get a galvy bolt in it.

 

[Hitch]

Heres one....http://www.orbitalfasteners.co.uk/e...econd-threading-tap-for-galvanised-fasteners#

 

[brightspark]

1st second or 3d cut tap m20 which one

 

[wyn]

As Hitch says, galv bolts don't fit well with standard nuts or tapped holes.

 

[Rig Pig]

Galvanised set screws or BZP set screws?

 

[Gregwalker1981]

Ok Guys

spoken to MSC today

the tap ive to use is M20x2.5 0.015 2nd tap to re cut the thread on the nut for galv set screws

 

[overload]

A spiral point tap is what you need. Cleans the thread no probs and easier as well, using less effort than a standard tap.