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  #1666  
Old 01-16-2021, 09:05 AM
mhespenheide mhespenheide is offline
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Those remind me of Bruce Gordon's work, and I mean that as a high compliment.
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  #1667  
Old Yesterday, 06:16 PM
d_douglas d_douglas is offline
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Quote:
Originally Posted by David Kirk View Post
"Idle hands make fretful minds" - Shelley Shepard Gray

I've run into a bit of a material supply issue related to Covid and I don't sit around very well...so the set of lugs and BB I had sitting in a drawer waiting to be completely reshaped to match the image in my head came out and I had some fun putting the imagined shape into metal.

Photographing raw lugs is always problematic - they need context and tubes in them to make the most sense. But these will give a rough idea of the shape I've had bouncing around for a while now.

So many lug shapes of old look like the doilies my grandmother knit. Nice in their own way but not my thing. I like long simple lines with a bit of asymmetry to make the eye and mind wander around the part.

Now I just need a bike to build these into! If these blow up your skirt let me know and we'll use them as the basis for your new ride.

dave

Wow, that is beautiful Dave. While symmetry is platonically pleasant to the eye (like most bikes), a dash of asymmetry is what makes it interesting. I recall seeing some Black Cat bilaminate lugs that were kinda weird and absolutely beautiful in an art deco way.

Are there any structural implications to asymmetry in lugs? Will one side be stressed more than the other is a lug is cut on a bias?

This blows wind up my skirt for sure! I can see these tubes and lugs painted glossy white with gold lining and decals and some 700x48mm tires - all deeply soaked in mud .
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  #1668  
Old Yesterday, 06:40 PM
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David Kirk David Kirk is offline
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Quote:
Originally Posted by d_douglas View Post
Wow, that is beautiful Dave. While symmetry is platonically pleasant to the eye (like most bikes), a dash of asymmetry is what makes it interesting. I recall seeing some Black Cat bilaminate lugs that were kinda weird and absolutely beautiful in an art deco way.

[B]Are there any structural implications to asymmetry in lugs? Will one side be stressed more than the other is a lug is cut on a bias? [/B]

This blows wind up my skirt for sure! I can see these tubes and lugs painted glossy white with gold lining and decals and some 700x48mm tires - all deeply soaked in mud .
Good question. The short answer is 'no'....and long answer is 'maybe'.

The very small relief I made is so structurally insignificant as to not be there. So the answer in this case is no. On the other hand one could cut the lugs so much that there could be issues. So it's not to say that the lug shape doesn't matter but it really only matters when you take it to extremes.....and these lugs are far from extreme.

It's important to remember that the real core strength with a lugged joint comes from the two tubes meeting each other inside and having the filler flow between the them. This is what holds the tubes together. The lug adds surface area for the filler to attach to and a safety margin and its not the primary structure.

Make sense?

dave
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  #1669  
Old Yesterday, 07:48 PM
d_douglas d_douglas is offline
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Thanks for that explanation. Yes, I am no framebuilder (understatement of my life) but I imagined that the lug design is not where the strength is derived from. When seeing this impossibly delicate pointed lugs, one must assume that theyre there mostly for their beauty and elegance, while the fitting of the tube into the lug socket is where the strength comes from.

Those are just right for being ornate. Those ones that Ive seen of old timey Bayliss frames seem more like artwork than rideable bikes, cool as they are.

So, do you just pack those lugs away and one day some lug-lover will ask for something unusual and you coyly say ' why yes, I have something that might interest you' as you reach into your desk drawer??? That would be fun fo both you and the client when the stars align.


Quote:
Originally Posted by David Kirk View Post
Good question. The short answer is 'no'....and long answer is 'maybe'.

The very small relief I made is so structurally insignificant as to not be there. So the answer in this case is no. On the other hand one could cut the lugs so much that there could be issues. So it's not to say that the lug shape doesn't matter but it really only matters when you take it to extremes.....and these lugs are far from extreme.

It's important to remember that the real core strength with a lugged joint comes from the two tubes meeting each other inside and having the filler flow between the them. This is what holds the tubes together. The lug adds surface area for the filler to attach to and a safety margin and its not the primary structure.

Make sense?

dave
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