Porobronze

[dxc0chappie]

Hi all,
I have this forum interesting and informative so I hope there is someone who can help with my query.

I have started constructing Don Young's 3 1/2" guage "Mountaineer" which I inherited from my late father.

In the notes for the boiler construction it states a high melting point spelter such as porobronze should be used for certain bushes.

Any one know what porobronze is? Is there a modern equivalent.

Thanks in advance.

Dermot

[baggo]

Hi Dermot,

Can't find any details about Porobronze but the idea is to use a higher melting point alloy than the B6 or C4 recommended for soldering the tubeplate into the boiler. The modern equivalent of C6 is Silverflo 16 and the equivalent of B4 is Silverflo 24. If you want to follow the same practise as recommended by Don for the bushes you will have to go up to Silverflo 5 or similar which will take a lot of heat. The only reason for using the higher melting point alloy for the bushes is to prevent the joints melting when you solder the tubeplate into the boiler. There's actually no reason why you can't solder the bushes at the same time as you solder in the tubeplate.

Personally I'd use Silverflo 24 to solder the bushes and then Silverflo 40 to fix the tubeplate into the boiler which requires a lot less heat than Silverflo 16 or 24. You've got a lot of copper to heat up when soldering anything on the boiler barrel!

John

[Shawki Shlemon]

Hi Dermont
At the end of the day you most probably end up running your locomotive in a club ,why not visiting a club near you and have a chat with their boiler inspector and get the best advice for free . After all,you will be better off having your boiler certified .

[steammadman]

Dxcochappie,
I don't think "porobronze" is on the market any longer, my old friend Don Young
described this loco in Model engineer in the late 60's , bronzes and brass spelters
were the norm inthose days ,but have now been outdated by more modern silver
solders which do the job technically better these days.
I remember my days at DONCASTER, we young uns used to go around the welders
and brazeing shops scrounging any spelters that we could get our hands on,
oh happy days ! ! ! ! .

[dxc0chappie]

Thanks for the responses guys. I'll probably do as John suggests and use Silverflo 24 for the high temperature joints. I'll also use Silverflo 55 in place of Easyflow No. 2. Both of these seem to be readily available from Reeves/Chronos etc.

Dermot.