Thread lead is one of the most important thread elements and directly affects a part’s functional size.
Lead error is most commonly generated by manual and CNC lathes not cutting properly. Therefore, it’s important to take measurements at the locations where the most lead error typically occurs. These readings help detect machine tool error and worn lead screws on your lathe.
Lead gages inspect both internal and external lead on a variety of thread forms.
The ULG-6002 uses a two-point system to inspect thread lead for Acme, Stub Acme, Stub Acme Modified I and II, Metric M & J, UN, UNJ, UNR, 7º X 45º Buttress, and general purpose pipe threads. The two points allow for a sweeping action to obtain the measurement.
Before inspecting parts, the lead gage must be preset to a nominal predetermined dimension using a lead gage setting
standard. See chart below for the proper standard based on pitch.
Union Thread Lead Inspection-Lead Gages
| Model | Description | Minimum Bore | Range |
| ULG-6002 | 2-point Lead Gage | 1.200 | 1/2″ – 4″ Thread Length |
Fyou Gauge’s precision lead gage setting standards are manufactured in accordance with ASME B1.5 and ASME B 1.8 Specifications.
Lead gage standards are used to set the gage prior to the inspection.
| Model | Connection Type/Description | Threads Per Inch (TPI) |
| LS_Fig0602 | Straight Threads, Hammer Union Fig602, 4” length | 3&4&6 TPI |
| LS_Fig1002 | Straight Threads, Hammer Union Fig 1002, 4” length | 3&4&6 TPI |
| LS_Fig1502 | Straight Threads,Hammer Union Fig 1502, 4” length | 3.5&3 TPI |
| LS_Fig2002 | Straight Threads,Hammer Union Fig 2002, 4” length | 4 TPI |
| LS_Fig2202 | Straight Threads, Hammer Union Fig 2202, 4” length | 5 TPI |
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