Sutton 1 in Taper Pipe Reamer BSPT NPT - HSS

The Sutton R108 is a taper pipe reamer (also sold as a pipe tap reamer): a hand reamer used to pre-form the taper before tapping tapered pipe threads, 1:16 taper forms such as BSPT and NPT. It prolongs tap life, especially in tough materials. It is used by hand with a suitable wrench, suits tool rooms and workshops, and is HSS with a bright finish (uncoated and polished) with 15° left-hand flutes.

There are 9 sizes, from 1/8 in to 2 in pipe thread size, with 6 flutes up to 1-1/4 in and 8 flutes on the 1-1/2 in and 2 in sizes. There are two drill sizes for every pipe thread: a larger drill if you drill and tap, and a smaller drill if you drill, then pre-form the taper with a taper pipe reamer. The table below pulls that chart together with the R108 sizes so you can see both at a glance.

Where this product is used

• Pre-forming the taper in a drilled hole before tapping a tapered pipe thread, 1:16 taper forms (BSPT, NPT).
• Tool rooms and workshops, used by hand with a suitable wrench.
• Tough materials, where the reamer prolongs tap life.

Drill sizes for Rc (BSPT) and NPT threads

Taper pipe threads of improved quality are obtained when the taper is pre-formed using Sutton Tools taper pipe reamers.

Rc is the ISO Rc taper series (1:16, 55°) and NPT-NPTF is the National Pipe Taper (1:16, 60°). The "drill only" and "drill and reamer" columns are the published sizes from the Sutton Industrial Catalogue.

Getting a clean taper

• Lubricate generously. A lack of lubricant causes tool wear and a poor finish, and the fix is to increase the supply. Straight cutting oil is the usual choice in reaming, because the aim is finish rather than cooling.
• Start with a good hole. A badly drilled hole is listed against all four problems (breakage, wear, chatter and poor finish) and the fix is to replace the drill.
• Keep it aligned and rigid. Misalignment causes breakage and wear (fix: align the holes) and lack of rigidity causes breakage and chatter (fix: improve rigidity).
• Don't force it. Entering the work too fast is listed against breakage and chatter, and the fix is a slower approach feed.

Key specifications

Related reaming tools

Tapering the hole first is only half the job: browse the taper pipe reamer collection to find the matching taper pipe taps, and see the reamer collection for related precision hole tools. If you need help matching a reamer to a thread form, get in touch.

Having reaming problems? Our Cutting Tool Troubleshooting Guide covers reamers alongside drills and taps.