PROCRASTINATION.

 I was awake long before the Lark this morning and after an espresso was raring to go at the crack of four. I couldn't face learning the Assembly Workbench in FreeCAD so decided to model another version of the cylinder head. I got there after a couple of hiccups but the model is no good. I had a big topology problem which is something that happens far too often in FreeCAD. I know the answer is not to put sketches on model faces, one should instead attach a Datum plane and sketch on that. The model needs doing again so I'll be more considerate of my workflow next time.

This looks okay but will cause problems if converted to a line drawing/blueprint. It would be impossible to convert to machine code.

This measures 32mm x 15mm, the groove is for a silicon "O" ring to seal the glass cylinder, it doesn't need to be a groove so in the next version I'll make the minor radius of the hemispherical combustion chamber larger.

I then lost two hours of my life. I found the formula for calculating the volume of the hemispherical section and then very vaguely remembered having to generate this during calculus at school. That's all I could remember so I foolishly searched for the derivation on YouTube. As is always the case I had a couple of false starts then found this chap who explained the matter perfectly.

This was fun and he got the correct result which is more than I did all those years ago. Clever bugger he is. Looking at his white board a scruffy clever bugger.

If I manage to complete this project, I'll either be very happy or totally insane. I'll leave you with this.

Have fun.