The correct way to tighten a nut is to measure the length of the bolt and stretch it the correct about. This is how we did large bolts ( above 2” ) Engineering would give the amount the stretch would be"
I fully agree. I worked in a company which built Pielstick motor for ships up to 10 000 BHP. The nuts of the cylinder heads were bolted via an hydraulic device which pulled the stud, extending it. The nut was only approach to contact by hand and after the pressure was released. This is the most perfect way, and the only way when you work with large parts.
SKF produces this kind of tool:
http://www.skf.com/binary/83-124616/PUB_MT-P2_10255_EN.pdfA second way,if you apply an angle, as said before, by exemple of 90° with a 2mm screw pitch, in fact you extend the stud or screw of 0.5mm (2*360/90)... if the parts to assemble are stiff. This method is relatively simple to apply and more precise than a dynamometer wrench, if you know the angle to apply, and could be used on our wire wheels. These 2 methods avoids the friction problem.
At the moment I use the hammer, but try to improve the blacksmith uses, and a prescribe angle could be an help to answer at the question of the post.
Some searchs on the net indicate that a 1kg (2 lb) hammer can provide a force around 4000 kg (9000 lb).
