Mercedes 1909 aero engine 17

1909 MERCEDES

AERO ENGINE BUILD

Part 17 by Steve Gosling

The exhaust pipes and the inlet manifold are 8mm tube bent to quite tight radii which I can't do with my normal bender so I made up a mandrel pipe bender to see if that would work.

That was a nice job to do and quite satisfying, being made from bits lying around. This one shows it with the first trial bend in place.

It came out quite promising but there was a definite flat on the outer face.

Looking at the bullet on the end of the mandrel, you can see that I had it just a little bit too far back. The full diameter needs to be just a whisker to the right of the centre line of the roller. I adjusted it over and had another go.

That worked well so I started getting cocky and put another bend in at 90°

To put my pipe bender to work I started with the exhaust pipes which are brass, bent at 30°. The brass was much harder to bend than the copper, even when annealed, and the securing plate marked each one. Actually, you can see in this photo that the hole centres too far apart and the plate does not sit straight allowing the edge to cut in.

After cutting to length, I turned up some threaded ferrules which I silver soldered into place.

A couple of hours in the pickle and a quick polish and they look OK although each does have a mark from the bender. I may be able to polish it out but we shall see.

On to the inlet manifold which isn't drawn at all so I had to make it up as I went along. This item proved tricky, even with the bender, There are two bends very close to each other in each part and I hadn't quite sorted out how to achieve that. To that end, I started by making a new securing plate with the correct hole centres. That helped. I also filed the larger hole at an angle to allow it to move further along the tube.