semicolo wrote:If you've got an M3 tap you must use M3 screws (or I misunderstood what you said).
Instead of a nail maybe one of these punch tools, don't know how it's called in english, a pointy metal thingy used to make a small bump where you want to drill, but I think you'd be better off with nuts or some wider tapped material on the back of your metal sheet.
The nail was to simulate the press thing... didn't even get close to working, unfortunately. I thought a hammer could apply the same pressure as a press, but the mechanics are different... easy to see when you do it, but hard to explain. it lacks the support to form the metal.
The tap worked pretty well on 2 to 3mm sheets i tested. the screw go in stay firm until abused for a while, then it gain some play.
sadly on the 1.2mm sheet i will be using, they get some 20° of play right away... in fact, the tap already have play because it's only riding on one, maybe 1 1/2, threads.
well, this is the last pic here, i will be moving to documenting this joke of work i'm doing on the project thread viewtopic.php?f=3&t=3034
This is the tapped hole on the 2mm steel. even though you can see 3 threads there, two of them are almost on the rim, so they are not 'usable' by the screw as the metal on that rim is firm as butter.
here is something i didn't imagine would happen with the tap being inserted slowly... it deforms a lot the metal on the exit point. The two holes in front are my taps. the back one is the original, reinforced one. in this case, it's not only just pressed to have more steel area, but it seems there an extra sheet soldered there for more thickness. (this is a reinforcement plate that was holding the heavy transformer for the original receiver)
And here is just me being dumb. tried to insert the screw directly into the 2mm of steel after having drilled a hole with the diameter of the inner threading... it did worked like a tap for a while, but while trying to remove the screw it went ...no idea the word to use... in Portuguese we say the screw went "blind" or "spanned". you can see the portion that i managed to move out as it's 'polished'... that screw has no play though
*edit: on the last pic, on the left side, you can see more pics of the simple pressed rim we were talking about doing with the screw.