Coarse pitch is 0.5mm, fine pitch is 0.35mm, from past experience off the shelf will be coarse pitch. Mike
Oops, should read your post properly, am not aware of any coarser thread for 3mm, daft question but is the pump original? Could it be a BA thread?
That's what I would have thunk.......most electrical stuff was BA, but I'm not sure about Italian electrical.........although they did make a lot of washing machines and the electrical stuff on them was, I'm fairly positive was BA. AL
DeadWeight & Arquebus, thanks for the tip-off, it does sound promising. Just read a bit about the BA thread form and it seems to have been designed with metric in mind. The world of fastener threads: more twists and turns than an Agatha Christi whodunnit!
Wait until you get into 'Cycle threads'................ As far as I am concerned, TF for Metric threads...........sick to death with Whitworth, UNC, UNF, BA, AF and all the others that I have had to contend with in the past........I have so many taps and dies, it takes an eternity to find the right one.......or at least you think it is the right one, until you find it won't bl**dy well fit! AL
I have one of these pumps in the workshop and also a selection of oddball taps/dies etc and so, out of curiosity have been researching the matter. The bolt measures 3mm diameter but the thread is coarser than an M3, it's not BA - at least not a 4BA (too big) or 6BA (too small) and it 'fits' a 32 on a Whitworth thread pitch gauge. A 6/32 UNC tap will pass through the nut using only fingers to turn it, although it is a little tight - but this maybe because the nuts are a little corroded? A new 6/32 nut will screw onto the bolts no problem although the only one I have has a larger head than the Ducati nuts - HTH.
Guess what I went and ordered from a craft model site yesterday... Guess what I will be ordering from a craft model site this afternoon! Seriously though, many thanks for the details. When I started looking at getting the crate back on the road I never thought for a minute that I'd be jinxed by two tiny nuts!
It's probably American, and their "version" of Imperial sizes :-/ 6/32" is a common size used in various Yank bits of equipment I've worked on in the past. Very difficult to find over here, as you've discovered!
