MADAS IX MAXIMA
I bought this machine from the proprietress of a photo shop. Her great-uncle, also a photographer, had somehow acquired the machine (either for his own use or as payment from a customer ?) and it had spent the last 20 or so years in an attic. Of course, it being a MADAS, it needed only a light cleaning before it would purr away as good as new ... The machine has, in the mean time, been sold.
Obviously, it would not do to sell the machine with a missing clearing knob, as can be seen from the pictures above - I decided to make a new one myself, starting from 10mm brass bar stock. Here's how-
Turning the profile (by hand ...being proficient with an Etch-a-sketch helps!), followed by hand-filing the flats, leads to this:
Then we center-drill, and drill to tapping size for M4 (3.3mm). The total length of the knob is 16mm, so I drilled it to a depth of 14mm. The last 4mm are relieved with a 4mm drill, otherwise the thread would have to be tapped too deep, with the risk of breaking the tap.
The resulting hole is tapped with an 4mm x 0.75mm (M4) bottoming tap.
The knob is cut off at a length of 16mm, and screwed onto a bolt in the chuck.
The remaining bit of metal is filed flat, and the whole thing is polished with sandpaper followed by fine steel wool, ready for nickel-plating.
These are the knobs back from the plater (who did a fantastic job as always)
...and this is the machine ready for packaging to go on its way to the new owner.