Lead Gages

Thread Lead

Gagemaker-Lead-GagesThread Lead is probably one of the most important thread elements if not the most important in the thread cutting industry.  Lead error (which often leads to standoff error on tapered threads) is the most common error generated by manual and CNC lathes not cutting properly.  Worn ball, lead screws, Z axis servo drives and spindle encoders on threading lathes will permit the cutting tool to stall, slow down or lag, which causes the thread pitch to be shorter than programmed on the first and second threads.  This in turn results in lead error…standoff error… and eventually a failed connection.

The lead gage inspects thread lead using contact points that seat in the threads of a part. Thread lead is the distance between threads, measured on a plane parallel to the centerline of the threaded part. The pitch of the thread determines the diameter of the contact points required for taking measurements.

Thread Lead Gages inspect both internal and external thread lead for a variety of thread forms and provide dimensional verification of product print data on the integrity of your threads. Gagemaker has both two-point and three-point system lead gages that are designed to accurately inspect lead for ACME, Stub ACME, UN, and API threads.

Inspecting lead is a highly recommended practice industry wide for both straight and tapered thread manufacturers and it is a required inspection by the American Petroleum Institute for line pipe, rotary shouldered connections and casing and tubing.

The LG-6001 and the LG-6002 use a two-point system to inspect thread lead for straight and tapered threads. The LG-6002 inspects both external and internal threads, while the LG-6001 inspects external threads. The two point system allows for a sweeping action to obtain the measurement. Both gages are available with higher resolution indicators.

The LG-5003 uses the three-point system to inspect internal and external thread lead. Two fixed contact points at the rear of the gage and one moveable contact point at the front of the gage provide complete stability when taking thread lead measurements. This unique design does not require sweeping to obtain measurements.

Contact points can be easily changed to allow the gage to be used on a variety of thread forms. Each gage comes with a default set of contact points, but customer may specify another set.

Before inspecting parts, the lead gage must be preset to a nominal predetermined dimension using a lead gage setting standard. Lead standards are available for both straight and tapered threads. Our setting standards are manufactured according to ANSI and API specifications, respectively.

Features

  • Uses a three-point system for greater stability when inspecting parts (LG-5003).
  • Uses interchangeable contact points to allow inspection on a variety of thread forms.
  • Requires presetting using Gagemaker’s lead gage setting standards
  • Supplied with one set of contact points. Customer may specify points.
Number of
Contact Points
Thread Length
Range
External/InternalMinimum
Bore
Indicator
Travel
Indicator
Resolution
Contact Point
Spacing
DescriptionModel
2½” – 2” (12.7 mm – 50.8 mm)External2.750”.100".0005”.200”2-point external lead gageLG-6001
2½” – 2”(12.7 mm – 50.8 mm)External2.750”.025”.0001”.200”2-point external lead gage, ½” travel, .0001” resolutionLG-6001-1
2½” – 4” (0 mm – 101.6 mm)Internal1.450”.100".0005”.200”2-point internal lead gageLG-6002
2½” – 4” (0 mm – 101.6 mm)Internal1.450”.025”.0001”.200”2-point internal lead gage, ½” travel, .0001” resolutionLG-6002-1
2½” – 4” (0 mm – 101.6 mm)Internal1.450”5 mm.01 mm.200”2-point internal lead gage with metric indicatorLG-6002-M
3½” – 4” (0 mm – 101.6 mm)External/Internal1.340”.100".0005”.500”3-point external/internal lead gageLG-5003
3½” – 4” (0 mm – 101.6 mm)External/Internal1.340”.025”.0001”.500”3-point external/internal lead gage, ½” travel, .0001” resolutionLG-5003-1
3½” – 4” (0 mm – 101.6 mm)External/Internal1.340”.100".0005”.193”3-point external/internal lead gageLG-5003-J
3½” – 4” (0 mm – 101.6 mm)External/Internal1.340”.025”.0001”.193”3-point external/internal lead gage, ½” travel, .0001” resolutionLG-5003-1J
3½” – 4” (0 mm – 101.6 mm)External/Internal34 mm5 mm.01 mm12.7 mm3-point external/internal lead gage with metric indicatorLG-5003-M
3½” – 4” (0 mm – 101.6 mm)External/Internal1.500”.100".0005”.167”Load to load 3-point external/internal lead gageLG-5003-L
3½” – 4” (0 mm – 101.6 mm)External/Internal1.500”.100".0005”.167”Stab to stab 3-point external/internal lead gageLG-5003-S

Gagemaker’s precision lead gage setting standards are manufactured in accordance with ANSI Specifications, API Specification 5B, and API Specification 7-2. Lead gage standards are used to set the gage prior to inspection.

ConnectionPitchTPITPFThread FormDescriptionModel
8 Round & 10 Round-8 & 10¾”EUE, NUE, LTC, STCLead standard for all 8 Round casing, tubing & drill pipe; 10 Round tubingLS-1001
Straight6-186-18-StraightLead standard for straight threads, 6-18 pitch, 4” length, .375” widthLS-1002
11½ Pitch "V" Threads-11½¾”Line Pipe & NPTLead standard for 11½ Pitch "V" ThreadsLS-1003
Straight & NPS11½11½-Straight & NPSLead standard for straight threads, NPS threadsLS-1004
4½” - 13⅜” Buttress-5¾”ButtressLead standard for ¾” ButtressLS-1005
16” & Larger Buttress-51”ButtressLead standard for 1” ButtressLS-1006
Hughes External Flush 2⅜” - 2⅞” -62”V-0.032Lead standard for 6 TPI, 2” TPF, V-0.032LS-1007
API Full Hole 4”, 5½” & 6⅝” ; API Numbered Connections #23 - #50; API Regular 6⅝” ; Double Streamline 3½” - 5½”; Hughes Slim Hole 2⅜” - 4½”; Hughes Xtra Hole 2⅞” - 5”; Hughes External Flush 3½” - 4½”; Internal Flush 2⅜” - 6⅝” ; Wide Open 2⅜” - 4½” -42”V-0.038R & V-0.050Lead standard for 4 TPI, 2” TPF, V-0.038R, & V-0.050 thread formsLS-1007
API Numbered Connections #56 - #84 & API Regular 5½”, 7⅝”, & 8⅝” -43”V-0.038R & V-0.050Lead standard for 4 TPI, 3” TPF, V-0.038R, & V-0.050 thread formsLS-1008
API Full Hole 2⅞”, 3½”, & 4½” & API Regular 2⅜” - 4½”-53”V-0.040Lead standard for 5 TPI, 3” TPF, V-0.040 thread formsLS-1009
API Numbered Connections #10, #12, #13, #16 & API Regular (Macaroni Tubing) 1” - 1.5”-61.5”V-0.055Lead standard for 4 TPI, 2” TPF, V-0.038R, & V-0.050 thread formsLS-1010
American Open Hole 2⅜” - 4½” & P.A.C. Connections 2⅜” - 3½”-41.5”V-0.076Lead standard for 4 TPI, 1.5” TPF, V-0.076 thread formsLS-1010
Hughes H-90 2⅜” - 6⅝”-3.52”90-V-0.050Lead standard for 3.5 TPI, 2” TPF, 90-V-0.050 thread formLS-1011
Hughes H-90 7” - 8⅝”-3.53”90-V-0.050Lead standard for 3.5 TPI, 3” TPF, 90-V-0.050 thread formLS-1012
Hughes Slimline H-90 2⅜” - 3½” -31”90-V-0.084Lead standard for 3.5 TPI, 1” TPF, 90-V-0.084 thread formLS-1013
USS Improved Buttress-8¾”USS Improved ButtressLead standard for USS ButtressLS-1021
Straight1-51-5-StraightLead standard for straight threads, 4.5” length, .750” widthLS-5001
Straight6-186-18-StraightLead standard for straight threads, 4.5” length, .750” widthLS-5002
Metric Straight1.25, 1.75, and 3.5 mm1.25, 1.75, and 3.5 mm-Metric StraightLead standard for metric threads, 1.25, 1.75, and 3.5 mm pitchesLS-5003M
Metric Straight1, 1.5, 2, 3, & 4 mm1, 1.5, 2, 3, & 4 mm-Metric StraightLead standard for metric threads, 1, 1.5, 2, 3, & 4 mm pitchesLS-5004M
Metric Straight6 mm6 mm-Metric StraightLead standard for metric threads, 6 mm pitchLS-6MM

*TPF = Taper Per Foot, TPI = Threads Per Inch