Monday, July 17, 2006

Lower Head Tube

Blogger isn't wysiwyg, so it's not clear the order in which you'll see these images. The first should show the jig, after removing the combined head-tube/down-tube. My vice can swivel, which is great. In this position, it's easy to put tacks on both sides of the joint.

The next two shots show the tacked joint. Sorry, should've taken the pic before beginning to smear more flux on. In any case, there is a tack on each side, and one at the top.

After cooling, The angle and fit of the joint were double checked. All looked good, so it was on to more flux. The joint is held upside down because it seems to be easier to control the flow of filler, plus the flux inside the joint tends to stay at the joint instead of sliding away from it.

The last pic is post-braze. I'm using Fred Parr's Fillet pro. It's a little lumpier than I'd like - but I find it sands down easily to a smooth filet.

Because the down-tube is about 0.8mm thick at the joint, and the head tube is closer to 1mm, the direction of the torch is critical. Instead of pointing straight into the line of the joint, I point the flame a little towards the head-tube to balance the heat between the two tubes. Experience has show that failing to to this causes scorching of the flux on the down-tube.

That's all for tonight.

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