Thursday, 27 September 2012


Here is a lesson in quality control.

Some months ago I purchased some tapered 4130 tubing from which to make my handlebars. The tubing was exactly the right gauge and tapered from 0.75" to 0.6" over exactly the same distance as the original handlebars I am copying. In short they were perfect. There was however a drawback, the pair of tubes were in the States and there were only two of them left. Ever.

Tapered 4130 tubes.

I bought them and imported them at a reasonably high cost and this week I started to think about bending them to shape. Now, I have bent 4130 tapered tube before and it is not easy. The last time I did it I used a special alloy that melts in hot water and filled the tubes before bending them, It was still not easy. The alloy is known as Woods metal in the UK and as Cerrobend in the States. It is also horrible stuff, containing cadmium amongst other things. I have a small amount and I dislike using it. So I decided to outsource the bending to a professional tube bending shop. I made an accurate drawing of the bend I required and took the tubes around for a discussion. I spent considerable time explaining what I wanted and why I thought it would be a difficult bend, the tapered aspect making it an order of magnitude harder. The professional airily dismissed my concerns and said he would ring me when they were ready.

I later received a timid phone call, suggesting that I might like to call in.

A professionally bent tube, yesterday.

So the lesson here is that when you outsource something you instantly loose all control over quality.

I'm not sure how to proceed here, I can get thinner gauge tapered tube of a similar taper but I don't think it will be strong enough as a handlebar, I need to have a think about this. When I'm a little calmer.

Whatever I decide to do, I'll be doing it myself.

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