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Two Cylinder Engine

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Roger B:
I decided to make an updated version of my vertical engine using the same design concept but increasing the capacity and making it as a twin. I did think about a 4 cylinder version but it would be too large for my machines. The original was 16mm bore and stroke, this will be 20mm bore and 19mm stroke. The crankcase will be the same 40mm square aluminium with the crank running in two ball bearings. The cylinder liner will be more conventionally fitted but I am still wavering between cast iron or brass.
I started with the crankshaft. This is a piece of 30mm diameter moderate carbon steel (ST50). The ends were faced and centre drilled using the fixed steady and then one end was rough turned to 16mm. This reduced end was held in the Keats and the two centres for the crank throws were drilled on the mill. The Keats was then mounted on the faceplate and the bar was centred. The V block part of the Keats was then moved across the required 9.5mm (towards the centre for better balance) and the centre was put in the appropriate centre hole.
I started cutting with a 1.5mm blade type parting tool at 500rpm and 0.1mm depth of cut. As expected there was significant chatter but not a problem as the finishing cuts will be made with conventional tools. A short way in I realised that it would be better to cut the throw furthest from the chuck first  ::) The shaft was loosened and turned 180°, the alignment being checked with a square on the side of the Keats and a square across the centre holes.

crueby:
Great start, will be following along...

Roger B:
Thank you Chris  :ThumbsUp:

I gradually turned the journal to round but there were various clearance problems which resulted in an ever greater overhang. The crankwebs were finished with LH and RH 8mm shank tools. I them moved on to finishing the journal with 6mm tools but there was too much overhang with the Hobbymat toolpost. The QCTP gave more support to the tool. The ridge in the middle was removed with an 8mm straight tool. Back to the other journal.

Art K:
Roger,
Count me in, I'll be following along.
Art

stevehuckss396:
Nice start. Looking forward to your updates.

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