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Smokebox Door Hinge

by JRinTawa   13th June 2012

As part of my customising a Regner Lumber Jack kit into my NZ bush fell loco I've named Manawanui I added some detailing around the smokebox including rivets and non functioning hinges on the smokebox door.

At the time I considered making the hinges functional but took the easy route and made them fixed.  However lighting Manawanui from the top of the funnel, as per Regner's instructions, is, shall we say, and art.  So out with the mini blow torch and unsolder the hinge and fabricate a working hinge.

1 - The parts.  Smokebox front, door, dart (locking bolt), and in fresh brass the new parts.

2 - Smokebox door.  The hinge straps on the door are from the first version and are some brass mini-strip with brass pins as rivets soldered to the kit's smokebox door.  The hinge pin is 1/16" brass rod with bits of K&S tube soldered on.  Before solder the rod and tube onto the hinge straps flats were filed on the tube so there was a bit more surface area to solder and to give a bit of clearance when the door swung.

3 - The yucky rear view.  Hmm should clean a bit of that solder work up.  A neat thing with flame soldering (using a mini gas "blow torch") is there usually not much cleaning up needed.

5 - Hinge barrels (correct name is?) for the smokebox is a short length of K&S tube soldered onto M2 countersunk brass screws.  The slot across the head was filled to give a dish for the tube to set in.  There of course are two of them!  The smokebox from was drilled to suit at 2mm plus countersinking to suit the screw heads so the hinge barrels sit at the right level, bolted as you've guess from behind.

6 - It fits together like this.

7 -  And bolted together.

8 - And door closed.  The dart (the central locking bolt) screws into an existing threaded hole in the smokebox front.  Might need asbestos fingers to unscrew at the end of a run, but as Manawanui usually only needs lighting at the start the locking screw should be cold when closing the door after lighting!

9 -  Painted and back in place back on Manawanui

10 - Light Up!
Not the best picture but suffice to say it is much easier to light, still inclined to flare with a full tank of gas, but pops back immediately onto the burner.  The door needs to be closed for the burner to settle properly, but way better than lighting down the funnel.  And even after 35 minutes from lighting to end of run the dart on the door wasn't as hot as I thought it would be, I was able to undo it with bare finger.  Warm but not burnie burnie!

22nd April 2013 Update
After some 10 months of successful operation of the soft soldered smoke box door hinge on Manawanui, while raising steam at a running day I must have had the burner running a bit hotter than normal, and yes you guessed it the hinge barrels and hinge pin unsoldered themselves!  At home the steaming area is on an elevated section of our railway and it's a lot easier to hear and see what the burner is doing than the ground level track I was raising steam on that day.  So to make sure it doesn't happen again I got some "high temperature solder", a mix of tin/lead/silver with a stated melting point of 296-301⁰C. I reckon if the smokebox gets to this temperature I'd have more than the hinge to worry about. The "high temperature solder sure needed more heat to flow than the normal soft solder used before.  If I can find a suitable adhesive I will also add some thermal blanket material I have (sold by Acme Engineering) to the inside of the smokebox door and smokebox front as a belt and braces solution.

I source my high temperature solder locally in NZ from RS Components  Mr Google shows something similar in the UK from Somerset Solders

Despite the above set back, the opening smokebox door has been a real plus in lighting Manawanui and I throughly recommend this simple modification to Regner Lumber Jacks or any of the other Regner locos with similar smokebox fronts and doors.