WESTport STC thread comparators, frames, bases and dial indicators

EXTERNAL THREAD COMPARATOR

STC Comparators (External)

The STC is a compact external thread comparator using gaging segments (frames STC-101 / STC-201). It shares WESTport's bases and dial indicators with the Tri-Roll line and is set with a master setting plug.

Request a Quote
ISO/IEC 17025Accredited Calibration
ISO 9001Certified Quality Management
ANSI/NCSL Z540-1Accredited Calibration Lab
Made in USASince 1989

What goes into an STC system

  • 1. STC Frame

    Compact external comparator body — Frame STC-101 or STC-201.

    One-time

    Shop STC frames 

  • 2. Gaging Segment

    The measuring element, specific to your thread size and pitch.

    Per thread size

    Shop segments 

  • 3. Dial Indicator

    Reads pitch-diameter variation. Shared with the Tri-Roll line.

    One-time

    Shop indicators 

  • 4. Base & mounts

    Bench base, dual-frame base, mounting bar, hand-held handle — shared with Tri-Roll.

    One-time

    Bases & mounts 

  • 5. Master Setting Plug

    Zeroes the gage before you measure. One per thread size.

    Per thread size

    Setting plugs 
1 5

Choosing your gaging segments

TypeWhat it measuresWhen to choose it
Type 3 — Full ProfileFunctional (assembly) diameter.Pitches coarser than 48 TPI.
Type 4 — Cone & VeePitch diameter, limited flank contact.Pitch-diameter control across all pitches.
Type 5 — Best WirePitch diameter, best-wire radius.Fine pitches (48 TPI & finer).

STC is an external comparator that uses gaging segments. It shares WESTport's bases, mounts, and dial indicators with the Tri-Roll line, and is zeroed with a master setting plug. See the frame product page for STC-101 / STC-201 capacity.

STC buying questions

How is STC different from Tri-Roll?

Both measure external threads. STC is a compact unit that uses gaging segments (Tri-Roll uses three rolls). STC shares Tri-Roll's bases, mounts, and dial indicators.

Can I use my Tri-Roll base/indicator with STC?

Yes — the bench base, dual-frame base, mounting bar, hand-held handle, and the dial indicators are shared between the Tri-Roll and STC lines.

Which setting master?

STC is external, so it's zeroed with a master setting plug (one per thread size).

Calibration certificates & lead times?

A Long Form Certificate is available on most items, and we offer ISO 17025–accredited calibration. For lead times, call 1-888-400-4243.