Messerschmitt: Bf109 Part
Scans of the drawings for the Bf109 have long been part of my archive, but I was always reluctant to spend anytime on this aircraft as many others have already done a great deal of work producing CAD data from these designs.
However and occasionally I come across an item that presents a challenge and this part is one of those.
8-10910-2501: Lower Frame mount.
This is a cast aluminium part with a 3 degree draft on all faces (refer second image showing cross section) except the lower edge and the top edge on centre.
The challenging aspect of this part has to do with the top face, where it was important to achieve tangency with the draft faces at each of the mounting holes and maintain this through to the centre portion where the face locally is perpendicular.
The material thickness also increases marginally at the extent of the 2 inward holes.
The front edge of this face has a center portion of a fixed radius; so to achieve the desired results based on the above criteria for the back edge I used a tangential spline. I could have just used a radius arc instead of a spline as the difference was only 0.2mm, but I am keen to get this stuff as accurate as possible.
It worked out rather well.