Fire door

The fire door is a typical small round door, found on many branch line locomotives of that time. With a stainless steel plate the complete fire door assembly will be screwed to the back head of the boiler. The door opening is 45 mm.

The door is made of plain carbon steel and was turned on the lathe with several  radiused tools to get it in this shape. The door on the original locomotive was casted from cast iron. The four small holes in the door are for secondary air over the fire.

The stainless steel base plate was turned in the 4 jaw chuck and a small recess on the back of it, was made so it can be snug fit to the boiler fire hole.

In the milled reces on the door, a small hinge was inserted and fixed with the three M2 hexagon bolts

The other part of the hinge was made from rectangular bar. This was set up in a four jaw chuck to get a small cup at the top side of the hinge. With the aid of a dial indicator the block was centred.

  This cup on top will have a small groove that will act as a catch for the door handle.

The surplus of material was milled away.

The recess for the hinge was milled with a 6mm endmill

The almost finished part of the hinge; only fixing holes to be drilled and a groove in the cup for the door handle

 The set up for the door. A small screw can be seen at the back of the door hinge; this will lock the hinge pin.

The door handle is filled from 2 mm steel plate. On top of the hinge pin a bush is taking up the handle. A small 2 mm reces in the cup will keep the door  locked  in position.

The door temporary fixed on the boiler

A 1 mm stainless steel fire door back plate was spun in the lathe.

For the spinning of the plate a tool was made. This is nothing more than an old ball bearing pressed on a bar, which is hold in the tool holder.

Two former blocks hold the plate in place while spinning. This spinning is done at approx. 250 rpm

The spon plate.

Fixed on the door. The secondary air will first hit the hot plate, before entering the firebox.

The finished door is burned in old motor oil. This will leave a black coating on the door which is fire resistant.

 Only the door handle grip is polished. The wide fire hole makes the grate visible; even when looking from above. Checking on the fire while driving the loco should be a bit easier this way.

Fire grate

The grate and ashpan in the Solidworks drawing. The grate is hinged and can swing away when the drop pin is pulled out. The ashpan is completely open at the bottom. So there is plenty of air to keep the small coal fire burning and there will be no build-up of ashes; good for a full day of driving. If needed a separate plate can be mounted on the underside of the ashpan. I've closed the bottom of my 5" 14xx class locomotive; but this wasn't a success due to the build up of ashes which deprived the fire of oxygen in the end. 

The fire grate of the T3 is only 150 x 100 mm and is a relatively simple affair. The bars are cut from stainless steel 3mm plate (316L). This takes an afternoon to saw these from a plate by hand.

On the shaping machine the strips of steel were shaped to bars of 12mm height.

In the milling machine all the holes were spotted with a centre drill.

 With the aid of a simple jig, which was made on the shaping machine, the bars were V-shaped milled. Only at the position of the bushes the bar was left parallel.

A test setup with the spacer bushes in place, they are 4 mm wide.

 The complete grate, viewed from the under side. The lugs in front is for the hinge pin, with which the grate is held in the boiler. The lugs on the left are for support of the so called dumping pin. If this pin is removed, the grate will swing down and the fire will be consequently dropped

 The ashpan is build up from 1 mm stainless steel plate, which was left over from the kitchen renovation. 

With a few M2 screws the parts are firmly bolted together.

The complete ashpan and fire grate read for assembly to the boiler. In the front there is a double plate; I saw this on real locomotives, so the radiation heat is kept away from the axle.

The grate 'in working order'  at DBC-H Schackendorf  30 June 2018.