Sunday, 13 May 2018

The new TR1 engine - welding up and skimming a test piece (part 19)

The more observant and knowledgeable amongst the fine readership of this blog will instantly notice: This is not a XV1000 cylinderhead - and you're absolutely right. But just as with walking, you first have to walk, before you're able to run, it was necessary to ruin an already broken XT500 cylinder to try out my hefty flycutter and more importantly to figure out the potential pitfalls, when it comes to welding up cylinder heads.

The biggest issue I found was heat. Even though I put the cylinderhead on a hot plate and got it to well over one hundred degrees, it would cool down within minutes and basically just soak the heat away from the weld.  Next time, I'll go with the hot plate and the real XV1000 heads only need to be built up in one spot, I'll heat that spot up with a propane torch.

 Second was cleaning action. Even though a I ground about 0.5mm deep into the material, there is still quite a bit of peppering in the welds. As skimming showed it was mostly only cosmetical, yet still, it kind of bothered me.

That's the head in a different light, when put on the mill's table and you can see some of the inclusions a lot better. 

Still after running the flycutter over the whole thing, it becomes obvious that the peppering was superficial and nothing to worry about. A lot more worrying is the gap on the right side of the combustion chamber, as the weld didn't fuse all the way round with the base metal. (Mind you, this was at 200 amps...)

As usual, any input of knowledgeable folk is greatly appreciated. I tried out 4047 (AlSi12) filler, which crystalized instantly, so the rest of the welding was done with 5336 (AlMg5), which wetted out nicely and if the metallurgical handbook is to be believed, will work harden after a few heat cylcles.

Things worth considering for the next attempt: Try grey ceriated tungsten electrodes (I used golden ones and they stood up to the task nicely, white and blue failed rather quickly), maybe get a bottle Helium-Argon mix to get more heat into the head and heat the work area with a propane torch. Additionally, I will look into getting a digital TIG in the future as there's no way of playing around with frequency-settings on mine, when in AC mode.

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