June 2016 Gage Report

Strengthen Your Quality System

A solid straight thread inspection system (ACME, UN, Metric Threads, etc.) should measure all of the vital thread attributes – Functional Thread Size, Pitch Diameter, Lead, Height, and Form. By properly inspecting threads, you will minimize process error, verify exact mating and interchangeability and ultimately guarantee your quality.

Gagemaker offers the complete kit for your gaging needs, the JSS™ Straight Thread Inspection Solution. Each JSS kit includes every gage you need to measure all the necessary elements that contribute to making the perfect part. The kits come in a few different size ranges and all accessories (rolls, points, & standards) will be selected to fit your individual needs.

Over the next couple of gage reports, we are going to be examining the critical elements of ACME, UN, Metric, and other general machining threads as well as the best way to inspect them.  We’re kicking off our series with probably the most important and that is Functional Size.

Functional gaging should be the first inspection performed as it takes into account the cumulative effects of Diameter, Lead, Taper, Flank Angle and Form Error. A bad functional size can be the first indication that a part or machine has issues. If your functional size is incorrect, you will need to inspect further to determine the cause of non-conformance.

Gagemaker Functional Gages use a variety of thread rolls to provide the same functionality of ring and plugs, with the added benefit of accurately inspecting a range of sizes while providing quantitative data.

After setting your external functional size gage (RG-7000 series), place the fixed lower thread roll onto the external thread. Use lower roll as a pivot and seat the upper roll into flanks of the threads. Sweep gage back and forth and then align side to side noting the measurement.

Measure internal parts with an internal functional roll gage (PG-6000 Series) by retracting the lever far enough to place the fixed, lower roll into the flanks of the thread and then carefully release to seat and align the upper roll. Hold the lower arm steady with one hand using it as a pivot, then sweep and align gage accordingly to get the largest reading.

Make sure to check back next month to learn about the rest of the JSS Straight Thread Inspection System covering Pitch Diameter, Lead, Height, and Form.