16. Broken screws, a common problem

The name of this blog is “The rust killing blog”. Most of the content happens about repair techniques of rusty panels and sometimes about repair of panels damaged in accidents plus presentation of interesting tools and machines. But this time I`m concentrating on a very common problem and tell how to solve it correct.

First some words about the equipment used in the panelbeaters shop. Today, unlike the situation when I started many years ago, you can buy all necessary equipment. The market is flooded by products with low prices. But, some of the machines or tools can be made by yourself in your workshop, often in better versions than bought machines. Later when all different tools for the shrinking/stretching machine and they are a lot, have been discussed we are going further with machines or tools developed and made by myself.

Almost every day in the workshop I see screws or nuts or both impossible to unscrew in a normal way, or worse, broken screws left in a nut welded to a panel. The nut can also be fitted into a basket for a limited adjusting possibility during the fitment of a panel.

Even if it´s impossible to grip the remnants of the screw there are methods or solutions, almost all broken screws are able to remove. For more detailed information, see the book, Don´t give up.

Many of my friends try, with very limited success, to loosen such screws with different chemical products. Everything from Coke to more specialized sprays, Image 1, with promised magic qualities is used. Very seldom the promised magic result is obvious; maybe they are hidden for me by a chemical industry conspiracy.

Image 1 Rust loosening spray.

If the situation is studied in detail the reason for the problem is unveiled. The space between the screw and the nut and their threads are very limited from a macro perspective but immense from atom and molecule levels.

Despite that the screw and the nut are joined together by the rust which fills the space between nut and screw. The rust can be of several types but all consists of iron, oxygen and hydrogen. An iron atom which has become loose from the solid metal is joined tight with the others, Image 2, and now we talk about a molecule, in this case a rust molecule.

Image 2 Rust molecule. 1. Iron (Fe) atom 2. Oxygen (O) atom 3. Hydrogen (H) atom

The molecule need more space than the iron atom alone and with time the space between screw and the nut is tightly packed with rust. The narrow relation between screw, nut and the rust molecules in the thread is often strong enough to make it impossible to remove the screw by rotation.

But, if the attraction forces between the atoms in the rust molecule can be broken and the oxygen and hydrogen atoms can leave, space is created and the screw can be removed. The solution is adding energy in such amount that the strong attraction forces between the atoms are broken. Chemical products, so called rust release penetrate spray, Image 1, can´t add the energy needed. But the acetylene welding torch can, see the book.

The advice is to carefully, taking care of heat sensitive parts near to the screw, heat the parts, Image 3. If possible to a light red colour and as soon as possible carefully unscrew the screw. Screws of importance for critical details, for example in the suspension, must not be used again.

Image 3 Screw heated with the welding torch.

When a new screw is fitted or the old one is used again, smear the threads with grease or better, with copper paste. And avoid the use of too long screws, two or three threads protruding at the back is enough. Important when using self locking nuts, three complete threads must protrude through the locking ring eliminating the risk of self loosening, Image 4

Image 4 Three threads must protrude at the nut.

Finally, a few words about more specialized shrinking and stretching tools for the Eckold machine, this time exclusively for the Handformer. Note that these tools have no equivalents amongst other makers.

In Image 5 a beak shaped tool is visible. Next Images, number 6 and 7, shows tools for aluminium or stainless steel. Eckold supply both shrinking and stretching variants of these tools.

Image 5 Beak shaped shrinking/stretching tool for a U-shaped panel.
Image 6 Tool for shrinking/stretching of aluminium and stainless steel.
Image 7 Beak shaped shrinking/stretching tool for aluminium and stainless steel.

Note the adjustable stop.

To be continued……

Panel Beating Doctor Bengt Blad

At this point in my life when I was about three quarters through the medical schooI I discovered the English wheel and the Eckold machine, and, one thing leading to another - no more time for med school.

More about the book

This book, with around 1,500 pages of reader-friendly text and about as many illustrations, is a summary of 40 years of working with vintage, collectors' and racing cars.

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