Whats the rule on re-using bolts and screws?

danielhv · #1 05-09-2009, 12:57 PM

So, say for instance the fuel tank... once I screw it in, and run a few bolts... if I ever have to remove it, should I be replacing all the screws and bolts as well? Just curious as it was installed, then removed, and ready to be installed again so far in the build.

lucaperazzolli · #2 05-09-2009, 01:19 PM

rule of thumb : max three times for a nut lock, I use this for all

danielhv · #3 05-09-2009, 01:20 PM

Quote:

Originally Posted by lucaperazzolli

rule of thumb : max three times for a nut lock, I use this for all

noted... how about for screws and bolts that are going into platenuts?

Danny7 · #4 05-09-2009, 01:22 PM

screws and bolts going into platenuts- use them until you don't like how they look. they are not going to wear out, unless you are buggering the phillips head part

Ron Lee · #5 05-09-2009, 01:56 PM

On the phillip head part, be very quick to throw out ones that are becoming "gouged." Once you have to use a tool to remove one that is bad, you will realize that it is cheaper and quicker just to replace them.

Frank Smidler · #6 05-09-2009, 09:40 PM

After problems removing a few phillips head screws with stripped heads a friend told me how to get them out. He told me to get a tube of valve lapping compond and put a dab on the end of the screw driver. It worked great, even on the #4 screws I used to attach the wing tips (cleavland kit). I remember seeing a product sold at OSH for this very purpose. The local availability of the valve lapping compond is why I used it.

woxofswa · #7 05-10-2009, 12:18 AM

In the absence of valve grind compound, pumice hand soap or even toothpaste will help in a pinch.

grahamcalder · #8 05-11-2009, 01:12 PM

Myron,

Ouch!! What does your toothpaste do to your teeth??:

Graham (Dentist when not RVing)

DanH · #9 05-11-2009, 02:20 PM

Daniel,
Assuming no damaged threads, shanks or heads, the physical part goes like this.

If the application was subject to high cyclical loading, and bolt was not preloaded to a stress higher than the cyclical load, the bolt has accumlated stress cycles and should be replaced just to be prudent. Actually a lot of general prudence is in order, because the above would be the result of poor design, poor installation, or outright overstress.

If the application was subject to high cyclical loading, but the bolt was preloaded to a stress higher than the expected cyclical load, the bolt can be re-used....but nobody does. Connecting rod bolts are a good example.

If the application pretty much applied a steady stress to the bolt, and that stress did not exceed its yield strength (check the root thread for stretch), it can be re-used. Most of the screws and bolts we use are in this group.