On to thread types, drilling, tapping, fixing screw types, dynabolts etc.
Bolt and thread type videos:
1) MACHINE SHOP TIPS #8 Types of Threads part A tubalcain
2) MACHINE SHOP TIPS #9 Types of Threads part B tubalcain (YouTube) local copy available also in flv DB7
What we did when the black vinyl cladded metal was all we had:
Beware about parallel circuit when using spot welder.