I did a few bolt deals in the Government. The Air Force and Army complained about bolts being out of spec and under strength, so the mental giants in charge set up a sampling system, in the receiving warehouse to inspect bolts and big screws. Now think about how many ways this could be screwed up. Sorry, you were not even close. So I was in the warehouse pulling samples of my stuff for test when I saw the new facility.

 

An air conditioned room built along one wall inside a WWII building 1/2 mile long and 150 yards wide. There were 12 ladies in there with screw thread machines in front of them. They were checking the class of fit of the bolt threads. I asked if we were farming out the metallurgy and tensile testing?

 

What does that mean? the supervisor wants to know. They had a guy outside in the heat de milling the bolts with a 4" grinder. They had de milled a number of cargotainers A 4 foot by 4 foot by 4 foot steel box full of really good looking bolts.  De milled by grinding on the threads. The bolts come in a nice cardboard tube with metal end caps. They have a pedigree. A copy of the pedigree is in the can with the bolt, along with a silica gell bag. The bolts for nuclear service are serialized. The manufacturer can trace that bolt to its destination.

 

These bolts were not made in China as is the case of so many bolts.  They were made by California Fastener and SPS (Standard Pressed Steel corp) They were not the crap from China we should have been looking for. They were the very best bolts on earth. I had the demill guy take a break. I called my supervisor, who sent engineers. The base commander had got his butt kicked real good over shipping crap to people.

(Count and condition contracts is all we do) No testing of anything. So he had the warehouse guy set up some kind of testing. So, he did, some kind of testing. Of course they wanted legal to go after the bolt people over all of the bad bolts they had found. That didn't happen. Having never heard of oversized bolts, they found a lot of them. An those metric bolts don't fit the dies at all, do they? At the sale the 1700 pound lots of the undemilled bolts avaraged $400.00 each. There were 17 cargotainers sold. The next week the room was still there. The equipment was gone and the ladies were gone. Your government in action. 

 

The Chinese build bolts of all qualities, to any contract you want. Send them a bolt of any shape with no specs at all and you get back bolts that look like the sample. But that's all. It looks like the sample. If the bolt was American made it could accidentally be better than anything from China. But we make some awfull crap as well. You have to know who built it, or you don't know anything. If you have lot numbers from SPS and the supplier will furnish contracts to support the source then you are on the right track. Not perfect but better. We have to trust our suppliers, like the aircraft supply catalogs and such. 

 

Lynn E. Hanover

 

 

 

Lynn,

Personally, I wouldn't feel comfortable using the grade of hardware typically found at the home stores.  Should be fine for plugging up a hole here and there, but not for holding the airplane together.  The bolts I bought at the NAPA store were very high grade, same as those from American Bolt.  Not so from Home Depot. 

 

Mark S.