CAUTION BIKE PORN; naked pics inside...

[rody]

Sure Weps, no problem

Once the downtube is cut to rough length, I place two long sloping wedges of tool steel (fat on one end, skinny on the other, about 6" high) into the mill vice and insert the tube between them.

The end of the tube to be ovalized is nestled between the thick ends of the wedges. The vice is slowly drawn together, squeezing the tube end, past the point of ovalization by about 10% and then the pressure is reduced, allowing the tubing to open back up a bit. During this process, the skinny ends of the wedge travel in against the tube and the tapering shape keeps the tube from crimping.

To ovalaize the other end, simply swap ends, rotate 90 degrees on the axis, center with dial indicator and repeat.

Make sense? No real magic wand, just good ol' american ingenuity

rody

 

[weps]

thanks!!! i'll pat myself on the back and smack me upside the head.

your explanation makes prefect sense and is roughly what i came up with as a 'solution' if i were to do it myself. (though i missed the wedges to avoid crimping) but instead, i convinced myselt that couldn't possibly be right, or that simple, and instead figured some expensive high-tech drawing machine with custom dies was involved or other convoluted process i couldn't imagine.

when you mentioined you only made a handful of frames a year, i had to rethink the need for expensive and sizable machinery though.

lol..you have no idea how much that question and simple answer has frustrated me. :roll:

 

[rody]

right on, I had the same feeling (DOOH!) the first time I saw it done.

That's what's fun about bikes...can be so techy and so simple all at once.

cheers,

rody

 

[rody]

more nakid pics, courtesy of Bob (MTBR)

Nice blog from a painter on some naked frames, including a Ritchey, Pinnarello, and a Falcon...

check it out...

http://bobbrowncycles.blogspot.com/

rody

 

[Eric]

Fillet brazed fineness.

.

 

[rody]

Thanks for posting Eric, always enjoy seeing the fluid appearance of a nice fillet. Looks like the frame has been ridden hard but still is yearning for more

Can't wait to see it with some new paint.

cheers,

rody