We tested some Eyebolts to see where they would fail with a single nut and where they would fail with a double nut. The test was a vertical tension test which shows how a product will perform under load.
Starting with a 5115 - M6 Eyebolt, we secured it in place with one standard M6 nut. At approximately 540kg the Eyebolt failed from the thread being shorn off by the nut.
We then conducted another test, this time with two M6 nuts holding the 5115 – M6 Eyebolt. This time the threads held strong and at approximately 1100kg the product failed from the eye breaking.
Our second test was on the 5116 – M8 Eyebolt with one nut. This, like the 5115 – M6 Eyebolt, failed from the threads shearing off at approximately 1200kg.
We tried the next test with 2 nuts attached. Interestingly the thread failed before the eye did, this time snapping at approximately 1970kgs.
Conclusion
Is a double nut better than a single nut?
Yes it is. This testing shows that using an extra nut makes a big difference in the load that a thread can handle. If you want the most strength, or extra safety factor, using two nuts are better than one.
These tests show only the failure points of these individual products under the above conditions on 24th September 2020 and are in no way indicative of current or future performance. We recommend having the product on hand prior to manufacturing and carrying out your own testing should load ratings need to be certified.
