tapered hole for taperd pipe tap?

RJT · Feb 4, 2008

Hired a new guy a few months ago (experienced) and he wants me to buy tapered reamers to prepare the holes for 1/8 - 27 pipe tap. I've never used one in 30 + years, but now he'w got me wondering. When are they normally used? RJT

hyskilevel · Feb 4, 2008

I use them anytime I have alot of time in a part and the last thing I do is tap a hole. Tapered reamers limit your mistake factor as well as make a better part. It's not a big deal but it gives you a higher quality thread than a straight hole. I've done both ways and if its a high dollar part I always use a tapered reamer.

L Vanice · Feb 4, 2008

I have the taper pipe reamers and use them before tapping steel. It takes some load off the tap teeth.

Larry

Barry Weeks · Feb 4, 2008

I tap alot of pipe threads on molds, and I usually skip using the tapered reamers on 1/16" and 1/8" NPT, but do use the tapered reamers on 1/4" pipe and anything larger. Seems to make the tapping go easier. Give it a try, the reamers are cheap, last forever, and your new guy will feel like you at least take his opinion as being credible. You might like it.

scollins · Feb 4, 2008

We had a new job recently that called for a 1/4" NPT tapped hole through 10mm steel plate. I enquired about taper reamers to prepare the hole, only to be told by our tool supplier that nobody bothers with taper reamers anymore and that he couldn't supply one other than as a 'made to order special' with a price to match. We did the job drilling a parallel hole and after a bit of experimentation got a reasonably good thread. The customer then changed the part design to totally eliminate the NPT thread! It sounds as though tapered reamers for preparing holes for tapered threads are readily available in the USA.
Stephen

i_r_machinist · Feb 4, 2008

The old guys laughed at me when I ordered the first set for the plant. Now THEY swear by them.
They make life much better. Wonderful tool. Worth every penny.
have fun
i_r_machinist

SND · Feb 4, 2008

I have used them when available. It does make some difference on larger taps or in hard materials.

MagSMC · Feb 4, 2008

Yeah,,,and if you don't taper the hole, you put a really heavy load on the last third of the tap, which can, and does, break taps!!! Don't ask me how I know!

Richard Rogers · Feb 4, 2008

would this be one?

http://tinyurl.com/2mjfls

Richard

Davis In SC · Feb 4, 2008

Proper use of pipe reamers will save you a lot of taps and scrapped parts... Reamers are cheap, buy several of all sizes you tap..

precisionworks · Feb 5, 2008

The tapered reamers really shine when the tap size is above 1/2" NPT. Don't know the exact numbers, but torque reduction is substantial. The threads look better as a bonus, and probably guage better (although I don't have NPT gauges).

huntinguy · Feb 5, 2008

Funny you should mention it...

This has been the discussion around the lathe the last few days.

There are two gauges used for checking pipe, first is for the taper the second if for the thread engagement.

It has to do with the compression of the male to female threads and where that takes place, part of the sealing effect.

In short, when pipe thread is inspected you can have the thread gauge go in properly (yes there is a proper depth) and the thread fail if the taper gauge does not register correctly. (Aircraft inspectors get testy over that sort of stuff, something about ISO standards and all:p)

Charles Dolan · Feb 5, 2008

I put a lot of NPT threads into 316SS and Titanium of all sizes and would never dream of doing it without reaming the taper in first. You eliminate any misalignment, get a much cleaner thread with about half the effort. They make the taps last indefinitely which is why the tool dealers don't want to sell you them!

Charles.

mrainey · Feb 5, 2008

Some more info here.

http://www.sct-usa.com/pt12.asp

Software For Metalworking
http://mrainey.freeservers.com

RJT · Mar 14, 2008

OK it seems this is the way to go. I see two styles, one goes in a tapping wrench and is used by hand, the other is brazed carbide flute with a straight shank which can go in a collet. For occasional use, I am leaning toward the first option at about 20% of the cost of the carbide tipped. Anyone know of HSS straight shank pipe reamers? RJT

Limy Sami · Mar 14, 2008

RJT said:
OK it seems this is the way to go. I see two styles, one goes in a tapping wrench and is used by hand, the other is brazed carbide flute with a straight shank which can go in a collet. For occasional use, I am leaning toward the first option at about 20% of the cost of the carbide tipped. Anyone know of HSS straight shank pipe reamers? RJT

No straight shanks, found MT though
http://www.formrelief.com/Form Relief Catalog 26.pdf

Keith Krome · Mar 14, 2008

I just got a couple of these

Based on this thread, I got a few of these because I was tapping stainless steel (300 series) and I have been frustrated with tapping NPT in the past.

I tried to use the 1/4 NPT by hand. The set up was less than ideal. I had a problem with the reamer "cogging" within the hole, producing a polygonal hole. To correct this, I chucked in an R8 collet and securely fastened my workpiece down. With a now-rigid setup, the reamer cut true.

I ordered my reamers from Mcmaster. The ones I got were made by Alvord-Polk Tool (domestic made).

MechWerks · Mar 14, 2008

I vote for the taper reamers too. The taps last much longer, less chances of threads gauling out during the tapping. Much less force required to turn the tap (explains the other benefits). Then look into some of them intermittent (skip tooth) pipe taps...almost fun to make pipe threads now.

David Carlisi · Mar 14, 2008

When I was in Houston, we ALWAYS used tapered reamers to cut NPT internal threads. Now, I am in Georgia, and it seems that no matter what shop, no one here uses them. I would like to have a set, sure makes cutting them much easier. We also had a set of plug gages. This left no question marks. Flush with the flat plus or minus one thread. I would buy a set of the gages as well if I could get a decent deal.

Mrainey, I like the reamers with chamfer... looks handy.

JMackessy · Mar 14, 2008

I've got to vote for the tapered reamers, too. I spent a lot of years moldmaking, we had a tapping bench set up with tapered reamers and pipe taps. As others have mentioned, using the reamer and then a skip-tooth tap made hand tapping a breeze, especially when you've got several dozen holes to finish in tool steel. Be kind to yourself and spend the extra, your arms will be glad you did!-JM

tapered hole for taperd pipe tap?

Titanium

Aluminum

Diamond

Titanium

Aluminum

Titanium

Diamond

Aluminum

Titanium

Diamond

Diamond

Cast Iron

Hot Rolled

Stainless

Titanium

Diamond

Stainless

Cast Iron

Stainless

Cast Iron

Similar threads