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Couldn't think of a good title for this vid, but the link has been doing the rounds of various bike forums for a while, and it has most certainly given me tool envy!
I know it's totally non-cnc related, but I'm sure all the engineering types here will enjoy it.
http://www.vimeo.com/18969652
mmmmmmm.... work of art...
Just finished reading Robert Penn's 'Its all about the Bike' where he describes the process of being measured and then having built for him a hand-built frame from one of the last few craftsmen in the UK.. The way he described it there was a lot more done 'by hand and by eye', like shaping the matching halves of a joint on a belt sander little by little by trial and error, rather than machining it out as shown here... the welding jig looks remarkably similar to his description though...
i love the use of a standard micrometer to measure the thickness of a pipe....doh.
I used to build (as a hobby) bicycle and tricycle frames and I've done a fair bit of research into it. Sean's setup is very much at the "production" end of the craftsman scale. Some places don't even use jigs, preferring to use a lugged construction and pins to hold it all together while it's hearth brazed. I think most builders have some form of mitring jig for the main tubes though even if it's just an electric drill and hole saw held in a basic jig - the fit affects the strength of the joint so it's important to get it accurate.
I built my first frame in my bedroom (as a teenager) with just a vice and basic hand tools and brazed it together using two plumbers torches. It's a very slow method but it gives you a good feel for the materials and it produced a pretty good frame if I do say so myself :-) A local frame builder was kind enough to finish off the threads and bearing faces (which needs specialist tools) for a nominal charge. Later I flycut the tube ends in a lathe fixture which was much quicker and I built a jig which has unfortunately been lost over the years.
To introduce a CNC angle, I've recently been thinking what would be required to cut fancy lugs such as these (http://www.llewellynbikes.com/thegallery/lugcutting) - it's a very time consuming (and skilled) part of making a lugged frame and should be fairly easy to do with a 4th axis on a mill.
He'll be checking the butting to get the tube the right way around, rather than measuring the thickness.Quote:
Originally Posted by i2i
Now if he'd "measured" both ends that would be more obvious to the uninitiated. Wouldn't he would be able to feel the difference, after all he's skilled in this work right?.:smile:Quote:
Originally Posted by m_c
Possibly, but you've got to remember the vid is more an artists view of the craft, rather than an accurate engineering documentary!Quote:
Originally Posted by i2i
Also, depending on the tubeset, there may not be that much difference in the butting thicknesses.
fair enough, an artists view works for me. It is a good vid, you certainly get the feel of it.