Not sure it was needed but I 'normalised' the steel blanks
I knew I shouldn't have gone out to the workshop, feeling a little under the weather after being brutalised by my younger brother Stephen (he maliciously tripped me up when I was already wobbling - my life is spent being 'wobbly' all the time). However he also suffered some damage to his ribs, from laughing so much!!!
I have to make excuses for a very poor couple of hours at the milling machine somehow. Those who have been following the build of a pair of Westbury Seals here (or on my main website) will know I made a fixture for making the con rods and that the methodology for machining was in development. Well the radius turning for the ends worked well, and I shall keep that, but profiling the rest of the con rod didn't achieve either consistent, or satisfactory results, so it is going to be left until after the crankshafts now.
Another reason to stop is the revelation (to me after 4 years or so) that always using my scrap box (I call it recycling to be politically correct) for all my parts is not really the way to go for critical parts. Hugh, my nearest model engineering neighbour, supplied me with a link to his metals supplier. So I am going to order some aluminium flat, with known properties for the con-rods. That allows me to put them to one side, waiting for the metal to arrive (smart excuse eh!). I am simplifying my procedures as well. Milling to shape using 'normal' techniques is the best way to go only using my fixture to radius the small end and mill the indentation in the centre of the con rod body.
I tried to be to clever really, and use the rotary table in the same way I made the 4 chess knights. So when the correct stock arrives, at a known grade, and closer size, I am sure it won't take long to get them done.
Now over the the crankshafts. I got myself tied up in a knot over the requirement of HT steel for the crankshafts as described in Westbury's article and plans. This brought no end of trouble in cutting a bar of HT steel in half (again being to clever for my own good bought a bar of sufficient diameter to get two cranks from). In the end I went back to Hemingway's site (supply plans and a kit of castings as well as bar stock) and ordered two crankshaft blanks from them.
They arrived quickly enough and I put them to one side to concentrate on the con rods, however as you know from above this has now changed. A couple of years ago now I machined a piece of flat steel bar and was amazed when releasing it from its clamps, to see it bend like a banana! HMEM (the forum I use) members explained how cold rolled steel (that was what I was using at the time) had so many stresses when rolled that before use the metal should be 'normalised'. This is achieved by heating it to a cherry red colour, then letting it cool naturally, so releasing all the stress. Whether the steel as bought was normalised or not, ( knowing my recent luck, or rubbish working....) being bent like a banana, is not good for an engine.
Since I had never carried out the simple procedure before, it seemed sensible to heat it up so that's what I did. Whether my cherry was dark enough I don't know, but its been done. So when I next go out to my home from heaven I will face off the ends of both bars so they are square, then drill 3 holes for the lathe centres to run in. One for the two central end shafts and the others for each throw.
I never seem to learn that the body is a better teller of my potential workmanship than my head!
