Trevithick Dredger Engine. Finishing the flat end plate.

by John

Today I brazed the inspection hatch to the flat end plate.  I did have some qualms about using the shape which I hade made, because it is quite round, whereas the example in The London Science Museum is more elliptical with one edge shaved off, and bolts which are irregularly placed around the perimeter.  But it is done now.  I admit that I was influenced by reactions from club members who were complimentary about the hatch which I had made, picking it out for special mention when I took it to yesterdays meeting.  And if I do not like it later on, I can remove the surface and make another one, more wonky like the original.


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The inspection hatch is ready to be brazed into position, and I have made a ring to attach the firebox door and surround.  The blowdown valve is very close and I had to grind a recess.

Before brazing I made a firebox door and surround, and bolted it to the end plate.



The surround bolts to the end plate, through the ring.  Here setting them up for drilling and tapping the M2 bolts.  That is an adjustable parallel, making sure that the door surround is horizontal.  Being glued to hold the position for drilling and tapping.



Hand tapping the 2mm bolt holes.  I drilled them after glueing the surround to the end plate with SuperGlue in the previous picture.   Then heated it to release the glue.  Did not break the tap, but I was careful to avoid touching the copper, and used tapping lubricant.



The door is cut out, but yet to make the hinge, catch and latch.


And just to remind you what I initially made, according to the Cain/deWaal plans…



These parts are now in the “failures” drawer.  Or should it be the “I changed my mind” drawer.