ANOTHER PROBLEM SOLVED.

 I woke up this morning just as the new day started, fired up the machine for coffee and started the computer. It's been annoying me that I couldn't pop holes in a cylinder or a semi-cylinder quickly and easily. In theory the way to do it is to create the cylinder create a solid the size and shape you fancy for one hole, place it so it cuts the cylinder wall then do a polar array followed by an orthogonal array to pop the polar array up the cylinder. Using the old Part workbench in FreeCAD it was like taking candy from a baby. The Part Workbench is a Primitive based modelling system, it's major drawback being that it isn't parametric. This means you can't alter anything without starting again. The Part Design Workbench is sketch based so one can change anything you have drawn and it will update the finished model.

Anyway here is a very smart looking cylinder with some fancy holes in.

Perfect, the reflections on the inner surface are just that, I light these images in Blender using HDRIs and should have paid some heed to it's relative location.

Here it is plonked on the exhaust pipe.

It's not the correct size but I can do it which is what matters. I have one more part that I'm having bother with but I'm not far off modelling the complete engine. 

I'm beginning to feel a bit like Stephan. He's a Polish welder and a great bloke. Last year he was welding a large funnel and I said don't forget to put plenty of tacks in or it'll be all over the place. He says.

"Don't worry, you don't need to instruct, I know what I'm doing in fact I know fuck all. I tell girlfriend just the other day I know fuck all."

Curry for tea tonight, a vegetable curry with chicken in. It should last three days unless I get greedy. Tomorrow is a horse morning so that's something to look forward to.

Have a great weekend.