Old Yeller

After looking through the dropout list thread, I was wondering how the frame builders dome shape the seat and chain stay ends. Anyone know how it's done? Also,is there any structural benefits for the different end shapes used by different builders?

Captain Blight

I think the domes are formed with a repetitive, iterative process of sawing, bending, brazing and filing. Structurally, the more metal-to-metal contact, the better.

Velognome 

Some Lug sets include include decorative or domed ends. The tube is butted and brazed. Some track frames do not have domed, pointed, wrapped or feathered ends at the seat lug, the tube is left open since the bile will not be exposed to weather.



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Old Yeller

Yes, I agree with the tops of the stays but it's the dropout treatments that have me curious. For example, Colnagos appear to have the tube crimped or flattened to the dropout where others are done differently.

Wulf

I think the bullet ends come like that on Reynolds and maybe Japanese tubes. I think Columbus tubes come with a chisel shaped end. The scalloped ends are made by grinding a shape on the end of the tube either straight cutoff, slanted or curved. Each will produce a different effect when filled with brass.

zigmin

This is the stay end treatment that was on a Mondonico built Torelli I had about two years ago, I always thought they were unusual, and quite handsome.

Captain Blight

From approximately 1957 on, the Viking Severn Valley used a very handsome fluted arrangement on their seatstay clusters. I'm very much in the market for a 63cm example of one of these.

Wulf

I am at least partially mistaken. A columbus SLX set of tubes pictured on EBay shows straight cutoff tubes.

ftwelder

In the old days if you buy production tubes, the bottom (small end) end work could be formed to your specification. Some builders turn little plugs on the lathe, braze them in then slot and chisel point the stay. That produces the cleanest area around the cogs as the tube can be machined away. Some builders just braze up the hole in the end, solid. Others use a thin sheet cap.

On the "eyes" (big end) you can buy those cast plugs or make some sort of cap.

Velognome 

I didn't intend to limit the observation to the "eyes". Some lug sets or rather dropout sets have finished ends also, like these distributed by Long Shen


I did read somewhere, a builder was explaining his scalloped end as lending strenght to the connection by distributing the load...or something to that effect.

repechage

The Italians in general did this the most where the stay was "blacksmithed" into submission on the inside, then brazed up, sometimes extra filler added to the outside of the tube to show a nice flat surface once the file was taken to it to control the form.
That is why in the 60's and 70's it was always easier to get an Italian frame to work with a 6th cog and a bit easier to drop the rear wheel or replace without marring the paint.
Quite a bit of framebuilding effort.

Same goes for the Italians who often brazed a tube into the seat lug ears, filled the surrounding area with brass then cut and filed it back to create a solid looking structure. Rare was the time an Italian frame had stretched out seat lug ears.

None of the above much applies after the investment cast era started.