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Setting an ITC – Internal Thread Comparator

An internal Thread Comparator is an ideal way to inspect the functional diameter of internal threads and collect actual measurement values as opposed to fix limit Go and No Go gaging. The ITC reads the actual size of the  pitch diameter showing its position in relation to the high and low allowable limits.. The ITC reduces gaging time compared to Go and No Go gaging.

The ITC method of inspection can assist in meeting the requirements of product acceptability in accordance with SYSTEM 21, SYSTEM 22 and SYSTEM 23.

When setting the ITC - DO NOT ROTATE THE MASTER RING GAGE OR THE PART ON THE SEGMENTS AS THIS COULD CAUSE DAMAGE AND WEAR TO THE GAGE AND OR SEGMENTSErroneous readings may result from rotating the gage or the part due to the helical pull of the thread path.


ITC - Internal Thread Comparator

ITC - Internal Thread Comparator


Section 6.6.2 of the ASME B1.13 standard only applies to the values in table 12 per ISO 965-1

B1.13 is the same as ISO 965-1
I emailed the sectary of ISO and asked about this issue and he replied,
In the ISO/CD 965-1:2012 (ISO/TC1 N 621-1) the clause number is 10.4.2. The new one is in this annex.
In the first paragraph of the chapter 1 (Scope), it said that all the tolerances for the series of threads specified by ISO 261 are given.
For some special series of threads their tolerances are not given in the table 5. In these cases the designer shall give the tolerances by his self. Usually he decides the tolerances by the tolerance formulae.
----- Original Message -----
From: Bruce Osborn
To: 'Frank J Cox Sales'
Sent: Wednesday, May 23, 2012 12:09 PM
Subject: RE: Metric Revision
After conferring with several Industry colleagues it appears section 6.6.2 of the ASME B1.13 standard only applies to the values in table 12 per ISO 965-1. When calculating values not in the table you do not use this calculation.
We made the same assumption when we developed our software. Please let me know if you have further questions.
Thank You,
Bruce Osborn
Osborn Products Inc.
1127 W Melinda Lane
Phoenix, AZ 85027-2812
PH: 623-587-0335
FAX: 623-582-1387
ISO 9001:2008, AS9100B Certified
Hi Bruce -
You sent a revision to Dominic Scully changing your metric program. Previously your program calculated P.D. Tolerance and if the calculated tolerance was greater than .25p, you used .25p as the P.D. Tolerance. We believe that this is the proper application of the standard but when I applied your new version, you use the calculated P.D. Tolerance. As an example, try M50.0x0.5 6H. The previous version gives NoGo pd as 49.800mm and the revised version gives 49.808mm. Please check your basis for the change and advise.
Many thanks as always,
Jim Brehl
Frank J. Cox Sales Ltd
40 West Drive
Brampton, On
L6T 3T6
Tel: 905-457-9190
Fax: 905-457-3120

Thread Profile Templates

Thread Check Inc. offers a wide range of standard and special Gagemaker thread profile templates. Inspecting the thread form is a critical part of thread inspection. Gagemaker precision thread profile templates quickly and easily check thread form for alignment errors. If a threading insert is aligned with the part incorrectly, the profile template will pick it up quickly. The profile template will also detect chipped or worn inserts by displaying light in the area of non-conformity. Thread profile templates are important tools that are both economical and easy to use.

Contact Thread Check Inc for information on standard and custom profile templates

Thread Profile


Using a Go Thread Ring Gauge

It is always advisable to clean threaded parts before applying the thread ring to gauge part. If the radial slots in the ring gage accumulate chips and dirt, it is likely the parts have not been cleaned and /or the ring gage is being applied too harshly and removing material. Remember that a ring gage is a precision gage and not a die. The ring gage should not be used to re size over sized and defective product. The ring gage should turn over the part with very little force or drag. Many books state that the customary amount of pressure is 2 pounds of force but there is no specification or standard that dictates this.

On the whole it is suggested to turn the part onto the ring but this should be determined by the configuration and size of the parts. If the workpiece is large and heavy then of course the ring should be turned onto the part.


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