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proper procedure for tapping flanges

Cutting Iron

Plastic
Joined
Sep 3, 2009
Location
Louisiana
I need to tapper tap a carbon steel blind flange to 1/2". After trueing the flange in my lathe I drill a 27/64" hole then I want to ream the hole in order to tap with a interrupted 1/2" tapper tap.

What type of reamer do I use?
Do i use cutting oil with the reamer?
 
OK, then your drill size is wrong for 1/2" NPT,......... reamers?....... Greenfield comes to mind but there are others which I can't remember,............. I'm in the UK.. try googling NPT reamers
 
Reamer?? why bother it's a waste of time
Milions of hydraulic manifold blocks are just drilled and then tapped... never used a reamer.
 
sorry 45/64th inch hole for a 1/2" tapper tap.....not sure where I got that 27/64" hole from..... that would be hard tapping...my bad
 
McMaster-Carr has taper-pipe reamers

As they typically have anything you want. :D

At the bottom of catalog page 2462. Enter that page number in the search box at upper left.

Direct link to catalog page: http://www.mcmaster.com/#catalog/116/2462

Drill a hole slightly larger than the small end of the reamer.

Operation of a taper (not tapper) tap is very different from a straight-bore tap. Every tooth of the taper tap cuts on every turn. If you try to tap a straight hole, the required force increases with each turn, rising to an extremely high level.

- Leigh
 
Reamer?? why bother it's a waste of time
Milions of hydraulic manifold blocks are just drilled and then tapped... never used a reamer.

I'll second that.

PVC, Kynar, Cast Iron, Brass, A36, 1018, 302, 316, Titanium, Zirconium, Hastalloy, Inconel, Stellite ...

I've never, ever, taper reamed a hole for an NPT.
 








 
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