CONE TEMPLATES

To make the cone templates, I can use knowledge learnt from my study of maths to make a shape that effectively looks like a pizza slice with a bite out of it with corresponding radius' to the ones on my design.
I had to re-do one of the templates for the long exhaust length. It is 1058mm long and I didn't think to consider the limit on size imposed by the length of the sheet metal roller. By looking at a picture of Bruce Simpson's and his Pulsejet, I can see that his has a weld halfway up the exhaust where it has been made in two parts; I will overcome the problem with this same solution; by spitting the cone to be rolled in two halves. Although this will create more to weld.

I have thought about the way I can make the templates and I reckon I can just print the templates onto paper; this is much easier than drawing out full size templates through geometrical methods.  To do this I need to digitalise the designs I have worked out; the choice of software to do this is Google Sketchup and AutoCAD; being relatively familiar with both, I know it will be easier to print and work to a 1:1 scale from AutoCAD so that is what I will use. My printer prints in A3 so printing shouldn't be an issue.

I had originally done all the calculations by hand which has turned out to be a waste of time when I could've just done them on the computer to start with. I suppose they gave me something to double check the templates against so they are definitely right.

From reading Bruce Simpson's work on building a jet engine, I have found that he used a plasma cutter to cut out his metal pieces. I still believe my idea of using an angle grinder will be fine for the larger radius', but I may have problems with the tighter radius'; I may look into the possibility of using a smaller cutting disk; if these do not exist I may need to look at sourcing a plasma cutter.