Crankcase Catastrophe

crankcase wired ready for brazing

In recent weeks I’d gone back to the poppet valve engine and thought that the new found aluminium brazing rod would solve my bracket issues.

The small aluminium engine mounting brackets were starting to look rather good.

You can see that I’d been trying to follow as many of the basic design principles for brackets as I could,

It was time to use the Durafix to solder the mounts to each side of the crankcase.

I used some wire to fix the mounts in place and carefully aligned them so that they were centred and horizontal. Some small machining was expected to get the bottom of the mounts perfect once they were fixed in place.

So I heated the crankcase and mounts using a blowtorch. I thought I was well below the melting point of the 6082 aluminium and soon the durafix started to melt.

The problem is the durafix rather rapidly pooled on the side of the crankcase, I assumed this was just durafix rod, but it appears that I was also melting the crankcase and the mounting brackets.

The durafix didn’t capillary between the mounting bracket and the crankcase. It appears to have just run around the joint.

The result was no strength in the joint, but worse still I had melted the main aluminium case.

The crankcase is not recoverable, definitely a case of going back to the drawing board.

Plus, lots more practice using the Durafix before I use it in anger again.

About Nigel 324 Articles
I've been making models since I was around 7 years old and using a lathe from the age of 11, a self taught engineer with a passion for making model engines.

1 Comment

  1. Send the case and all the parts to me. Randythewelder.I’m a tool &die welder. I’ll fix you up and you will be happy. I’ll heli arc extra stock for you to machine . strong joints.myself I would of welded those brackets solid with all build up alum. is this alum 6063 or cast? You can hit me back with an e mail. Its I’m glad to help out.

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