Just to prove it doesn't always go to plan I had a failure today.
A chap brouht me a Cube Attain, 28mm Marathons, disc brakes. Could I fit mudguards? Sure. No problem. What could possibly go wrong . . . ?
First off there are no mudguard eyes. There are M5 threaded holes in the frame but they face backwards from the dropouts, front & rear. I sourced some Trek Domane(?) fittings and, apart from a total lack of a bridge - nowhere to fix one to - the back was a doddle.
Come to the front and there's no hole in the crown but there's an M5 boss in the bottom of the steerer. Fit the bosses at the dropout and see how the guard lines up at the crown. I needed to drill the rivets out of the crown fastening. First one went ok but the second, well, the drillbit picked up and despite the bracket being trapped in the vice, suddenly the guard is in two pieces. Cue bad swears.
Customer says it's OK, he only wanted a rear one anyway.
No prizes for 2nd best...