I have a problem. - while here in Australia I can get metric bolts by the tonne (that is a metric ton) (lol) (giggles hysterically as I type this), the actual lengths in the parts list at my local Bunnings and/or Masters(closing down) are not always present. the have lengths that might be 5mm under, or 5 to 10mm over what is listed in the parts list.
So my question to the community, is that bolts from the list have to be “exactly that long” due to things like clearance between parts, and what bolts can be a bit longer (i.e. clearance is not an issue).
Secondly, it is also not clear what bolts need what type of head i.e. HEX, philips, flat, or spanner and what type of form i.e. Flat, countersunk, round or button(yes they are 2 different things), since I think in some parts of the assembly (and ongoing support and maintenance) having the correct head for the bolt (you cant really have a different form factor for the nut) will impact who easily it gets put together and/or on-going support.
I understand that weight is always a consideration, but sourcing the metric bolts in exact lengths and quantities is a problem, and trying to find a single online shop that has them them all is like ----ing in the wind.
Hope you can help (I got motors/electronics/tubes[25mm]/bearings/print parts as I type).