FAQ | Quality Control Questions
Are special gages required to check Spiralock threaded holes?
Yes. A three-part Spiralock gaging system is used for most hole sizes. A two-part Spiralock gaging system is used for holes with very fine threads. Back to top ↑ How do we use the gages?
The GO Pitch Diameter/Ramp gage is designed to check that the minimum material limits of the threaded hole have been met. The GO gage should enter the threaded hole for the full length of the engagement. The NO-GO Hi-Limit Ramp Plug gage and the NO-GO Pitch Diameter Plug gage check that the threaded hole is within maximum material limits. Threads are acceptable if the No-GO Hi-Limit Pitch Diameter Plug Gage does not enter the threaded hole. Threads may also be acceptable if this gage enters the threaded hole, not to exceed three (3) full revolutions before definite drag is felt. Back to top ↑ Can worn out Spiralock gages be repaired?
Generally the best thing to do with worn out gages is to replace them. The gage repair process is in most instances more expensive than gage replacement. Back to top ↑ Do you re-calibrate Spiralock gages?
Yes. We can re-calibrate Spiralock gages and supply a long-form certification for a nominal fee. Back to top ↑ How do we inspect the mating male thread that's used in the Spiralock internal thread?
Inspect to UN Class 2A or 3A fractional/6g or 6h metric Standards for the size of bolt. If it meets these standards, it will fit a Spiralock hole. Back to top ↑ Is gage certification supplied with Spiralock gages? And, if so, is it the long- or short-form certification?
All Spiralock gage members are certified using the long-form certification. Back to top ↑ Can we gage our parts after heat treatment and/or after coatings have been applied?
It depends upon the particular process. Due to the precise tolerance relationship between Spiralock taps and gages, the plating thickness and/or shrinkage during heat treating may not allow the GO gage to enter the hole. Back to top ↑ Why are there three gage members?
Unlike the typical 60º thread form, the Spiralock thread form has a wedge ramp that should be checked to ensure that the crest of the mating male 2A or 3A fractional/6g or 6h metric thread will contact the ramp properly. That's the purpose of the Hi-Limit Ramp Gage. The other two gage members, the GO and the Hi-Limit Pitch Diameter, are very similar to a commonly used GO and NO-GO gage system. Back to top ↑ Are all three gage members necessary?
Yes. In order to check all attributes of your Spiralock threaded hole, we recommend using all three gages Back to top ↑ Will Spiralock gages check a standard 60° threaded hole?
No. Spiralock gages will not enter a 60° threaded hole unless the thread is substantially oversize. Back to top ↑ How do we call out Spiralock on our drawings?
Simply add the word Spiralock after the thread size specification for the tapped hole. We would also recommend that the hole diameter be added to the call-out. For example: |
