Port timing for piston valve, help needed

[bogstandard]

Hi Sandy,
Talk about trying to confuse me, my eyeballs swapped over when I was trying to envisage what you had said.
I don't know if there is a standard for rotation in steam engines, but in all the years I was building model boats, the standard was to have the motor (or engine) turning anticlockwise when viewed from the front (the end that connects to the shaft), so that the propeller was always trying to screw itself onto the shaft rather than off.
With reference to threads, in the early days of my career concerned with aircraft I used to work on helicopters that were designed by Sikorsky and built under licence by Westlands Helicopters in the UK. The thread problems were horrendous. Almost every thread invented were used on them, avionics used B.A. , but almost all threads in general use on the aircraft if it was smaller than 1/4" (approx 6.4mm)it would be B.A., but it could under special circumstances be BSF or BSW, above this size it all depended what it was screwing into, into steel it was generally BSF, into aluminium or magnesium BSW, until you came to gearboxes, which were most probably sourced from the US were all unified. There were high tensile, low tensile, shouldered, predrilled, this list went on and on,  All bolts carried their coding on the top of the head eg, three rings for unified, can't remember the rest, old age I suppose. The stores system to cater for all this (no computers in those days, we were still using abacus) was enormous, there would be a 6"x6" (150mmx150mm) drawer containing just one or two small screws, almost every screwed hole on the aircraft had its own type of bolt to go into it, and every bolt had to have its own draw, god knows what propulsion and armaments people had to contend with. Thank god for standardization.

[derekwarner_decoy]

Oh dear PD's... the threadform list on STEAM propelled vessels is endless :ohno ...during my 1504 days at HMAS Garden Island Naval Dockyard in Sydney....in  above Water Weapons we had

5"/54 calliber FMC gun mounts that used UN gauge SHCS in hydraulic systems
GMLS Mk 13 missile launchers with UN gauge SHCS [that failed when we launched a missle.... the SHCS suffered through hydrogen embrittlement during the plating process]
Vickers 4"/5's twin gun mounts....combination of BSF & BNF... which was British Naval Thread form - not used apart from military applications  :idea:
Australian/British 40/60 Bofors which were reassembled with araldite & Loctite  

The Australian Government sold their IKIRA anti submarine  missile system to the Argentian Navy & they started repaying the costs with their versions of SHCS      ...this was known a IKI bird as they did not fly all that well :nah & even though the launcher was above deck......IKI bird was BWWS [below water weapons systems as that was where their ACTION was]

It was good fun   as I was a Grade II foreman  :hmmm  :hmph in AWWS  


Oh BTW & on rotations of things ...if you were misfortunate enought to be in the lower compartment of a live missile launcher magazine & saw the missile rotor turning clockwize when you were looking upwards ......its time to get out  :boom  :rant  ... yes John - look at the propeller, rotor or blade & in a single engine application, by convention it will always be clockwise rotation when looking FWD toward the prop nut....