Building a Cracker

[Marinus]

Day 10:

Wheels:

The wheels are made from a piece of mild steel bar. The piece was turned down to 26 mm and the rough shape was turned. The wheel profile was then machined and the boss at the back was cut using a parting tool, taking light cuts. After the recess at front was cut with a radius HHS cutter it was drilled 4 mm and parted off, this was repeated 4 times as there are only 4 wheels. The bosses at the back was drilled and tapped M3. The recess at the front was then sprayed the same black as all the other parts.

Pictures

[Marinus]

Day eleven:

Crank assembly:

The crank assembly was made up from stainless steel and brass. The crank was cut from brass bar turned to 13 mm and drilled 2.5 mm. The piece then got the crank pin hole drilled in the milling machine. The crank disc then got parted off and the two sides were milled away with an angle.

The crank shaft was salvaged from a broken CD player's slider shaft. The shaft is very hard so I used it as a reamer as well. The shaft got press fitted into the crank disc and a suitable 2 mm piece of steel was press fitted for the crank pin.

The cylinder block was reamed with the crankshaft as well as the back support bushing while it was assembled on the frame.

Steam delivery tube:

The steam delivery tube is made up from brass and copper. Two small rings had to be made from brass. The copper tube and brass rings were silver soldered together and after it was cleaned up with some files and sanding paper it was bent to shape.


All the brass and bronze parts were cleaned up and polished. Some of the parts received a layer of clear coat.

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Video of engine's first steam run:

<a href="https://www.youtube.com/watch?v=N3RGR41u1oU" target="_blank">http://www.youtube.com/watch?v=N3RGR41u1oU</a>