thomson

Looks quite nice Steve. Something that may escape us is this isn't just a bending/brazing project. You end up with a finely tuned frame/fork that you actually have confidence to take up to a pretty high speed. I know if I were ever able to build a frame, I wouldn't want anyone riding it.

big john

Do you heat the fork tubes when you bend them? How do you decide how much to bend them and pick the rake, etc.?

Cassave

No heat. Heat is evil, the less the better.

The blades are bent cold and need to be overbent to set at the correct rake.
The blade actually bends down to the aluminum form on the bending tool so you
can see how much spring back there is.

The rake is determined by the desired trail dimension. The headtube angle on this
bike is 73 deg. and I want about 58mm of trail. So with a 700C wheel that works out to
44mm of rake.

rm -rf

The pictures are great. I like to see all the details, more than just the frame triangle being assembled.

You mentioned filing the lugs before brazing. Can you explain that some more?

Cassave

Filing the lugs just involves squareing up the edges, smoothing the surface a little (these are investment
castings so they have a fine matte texture) or actually changing the shape of the lug somewhat.
I've modified these just a little.

zzzwillzzz

steve, do they make different lug angles for the down tube/head tube junction and also for the bottom bracket shell? those lugs would have the most change in angle depending on the size and length of the top tube. or is there some play built into them?

roadfix

^^^ Good question Wil, I was wondering that myself.

Cassave

Some makers do. A "standard" angle from seat tube to downtube is 60 deg. You have some play in
the crankshell sockets (and you can cold set) to adjust that open or closed by a few degrees.

DT / HT angle is also basically 60 + / - 1 deg. Some lower head lugs can be gotten
in 59 and 61 degrees. Uppers are available as 73 and 74. Again, some room for adjustment
by bending the lug a bit.

These are investment cast lugs (most are now) and run very tight. The old stamped and formed
steel lugs could be twisted all over the place giving lots of adjustment.

thomson

So, Steve, what is the difference between a 53 and a 58 ? Is it just shorter tubes or would you need a different set of lugs too?

Cassave

All else being equal, just a lower toptube. It would just slide down the seat and head tubes
5cm from the 58cm position.

But it's likely that the toptube would need to be shorter for the 53. That would require
opening the ST/DT angle a bit to keep the lower headlug at the same elevation.

For really radical geometries you need to either cut and weld existing lugs, fillet braze
or weld the tubes.

Seamus

Very very cool. I love lugged steel frames (have two). Would love to try building one sometime. I'm thinking I need a vacation to the UBI framebuilding course one of these years...

Jim

thomson

I get it. Very nice.

pv0463

Bravo! this is how an artisan with an engineering mind would build a bike. Sort of how things were done prior to Business Majors taking over (no hate, just facts)...
A beautiful piece of work, would love to see the finished product.

Cassave

Well, thanks.

You will see updates all the way through to finished paint, at least.

Cassave

Next installment. I finished the fork and did a little more work on the main triangle.

The fork with tips brazed to the blades fitted up in the jig. Set for 42mm of rake.

Fluxed and ready to braze....

Brazed and cooling in the fixture....


Checking alignment with the Campy "bells". Came out of the fixture needing no coldsetting.

Nice....Finished except for polishing the crown and paint.

I also face milled the headtube. I'll ream the tube for the headset cups when all the brazing is done

...Nice and square...Now on to the rear triangle, chainstays first.

merider1

Awesome, Clint!!! Now that I know a little more about how to even maintain a bike, I'm in awe that you build your own. Great pics.

Indolent58

Extremely cool pics. Thanks. If I could fit anymore things in my garage I would be tempted to buy more tools and give it a try.

Cassave

A little more progress..

The stainless fork crown polished. Only the fork blades will be painted.

Started work on the rear triangle.The chainstays and stainless dropouts....

Fitted up in the jig with the proper length and bottom bracket drop. These are set at 425mm length with a 70mm drop.

The drops brazed in place. This guarantees the correct rotation of the blades... Ready for filing and polishing. After that it's brazing the chainstays into the crankshell.

Dunwood

Clint,
I know you are doing this from a hobby level (rather than a full time gig), but have you tried any lugs from Pacenti or Sachs?

I know its easier to "one stop shop" with Henry James. I don't think Kirk sells tubes and I know RS doesn't sell tubes (unless its an odd ball dimension laying around).

roadfix

Nice progress! I love the polished fork crown.
Did you create the chainring clearance dimple on the chain stay or did it come like that?

Cassave

I form the dimple in using a 4" diameter slug of steel bar. Only takes a second.

This coming week I'll have more time to work on the thing.

Cassave

I've had these stainless HJ lugs sitting around for years and thought I'd use them.
The tubes came from Nova along with the crankshell and crown.

I haven't used Pacenti lugs but a friend builds with RS lugs and they are VERY NICE.

buck65

Steve...just wanted to say that this thread is amazing! Keep up the great work; I'm just loving the progress that you've been sharing. Great, great pictures.

magicant

Beautiful pics, Steve.

The text however =

Cassave

Thanks. Glad you like it.
I'll document construction through to finished paint.