Bolts have a variety of compositions, structures, and properties. Some can be machined, some welded, some both, many neither. If you are ignorant of the parts condition, you should not alter them.
Regards,
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
Yes, they're typically hardened and good bolts have rolled threads. Rolled threads are basically forged, rather than cut into the bolt, making them stronger. Why would you want to make a bolt?
I seen this design, and before comming up with an alternative i wanted to confirm you can/can't machine a bolt. They have put a step, and hole to trap the part, allowing it to be jacked in either direction.
I've drilled and tapped many a bolt in the search for a good place to mount an accelerometer. Of course the originals went back before driving on the road!
I've seen bolts modified many times. It is generally frowned upon in a production environment because of the high scrap rate. In an application like yours the bolt is often larger than absolutely needed to get a larger head or because it can live with more corrosion and still function.
Many years ago we armored a limousine for an overseas client. After they received it they tore it down in order to bench mark it. They found welded extensions to the seat bolts, very embarrassing. All the techs had to do was ask for longer bolts, and we could have procured them.
Welding to bolts is generally a no-no for two reasons. The plating on the bolt interferes with the welding process, and welding usually does no good to the heat-treat of the bolt.
Those are the generalities, there are always exceptions.
As part of R&D it's a rare day that I don't machine a bolt in some manner.
