Don Young's 0-4-0 dockyard tank 'Tug' (7.25"gauge)

The builder of my loco chose to use 4BA steel hexagonal socket cap head screws to attach the steam dome to its bush, similarly, the regulator assembly uses the same fixings.

I am removing these screws as there is a weep from the regulator assembly. Removal is proving difficult enough where there is space aplenty, i.e. the steam dome but the dome is now off and I shall probably use alum to eat away at the remnants of the screws. I have yet to tackle the six screws holding the regulator assembly in place.

What is the current thinking for replacement screws. I have it in mind to use M4 x 20mm marine grade stainless steel hexagonal socket cap head screws or even M5 if space permits.

Is my thinking flawed?

Bronze?

Sorry to hear the builder used steel.

After alum the 4BA threads should be ok, and ok for new 4BA fitted bolts made of non magnetic stainless. I make up all my own bolts out of stainless for boiler fittings, a job I hate but short cuts only lead to problems later on.

I have used hard drawn phos bronze bolts in the past but it isnt as tough as stainless.

Commercial bolts are often undersize plus are threaded up to the bolt head whereas a plain unthreaded portion through the removable dome is desirable.

Cheers,

Julian

Edited By julian atkins on 09/09/2017 21:57:42

For all my boiler fittings and fixtures bolts/set screws/studs and nuts i have used either phosphor bronze PB102 or stainless steel. PB102 has a tensile strength greater than mild steel. Regards, Howard

Thank you Julian and Howard, much appreciated. If you are ever in Hampshire, drop in: **LINK**

The builder of my Tug deviated from Don Young's plans in many ways. Pencilled in on the drawing of the regulator are the words, 'Use Bullock regulator valve'. I haven't been able to find any information about this variant. Can anyone help?