Question on lugged construction

[jmoore]

I just picked up a Mondonico Diamond (thank donevwil!) and was doing the obligatory OCD inspection. Inside the headtube there are no holes where the top and down tubes join. The headtube is one solid piece. Is this common construction for a lugged frame?

I think the bottom bracket has the holes. Not sure about the seattube/seatstay juncture.

Not that it makes any difference. The frame is lovely. Just curious as to "normal" construction methods.

[David Kirk]

There is no structural 'need' for the holes......they are usually put in place for a few reasons of convenience.

The holes are put in for two reasons usually -

1) to let the hot air and gases inside the tube expand with creating any pressure that will put the molten filler out of the joint of the joint apart.

2) after the frame is brazed it it most often placed in a hot water bath that takes the flux off the frame, both inside and out, and once this is done it's much easier to get the water out of the frame if there are two holes (one at each end).

i would not be at all concerned that there are no holes in the head tube..........I would however think it odd if there wasn't a hole from the top tube into the seat tube.

dave

[jmoore]

I was not really concerned with the construction, mostly curious as to why it is the way it is. I just assumed there would be holes. I figured there was some reason.

I think there are holes in the seattube/top tube juncture. I'll check the whole frame tonight.

Thanks for the reply Dave. As always, much appreciated.

There is no structural 'need' for the holes......they are usually put in place for a few reasons of convenience.

The holes are put in for two reasons usually -

1) to let the hot air and gases inside the tube expand with creating any pressure that will put the molten filler out of the joint of the joint apart.

2) after the frame is brazed it it most often placed in a hot water bath that takes the flux off the frame, both inside and out, and once this is done it's much easier to get the water out of the frame if there are two holes (one at each end).

i would not be at all concerned that there are no holes in the head tube..........I would however think it odd if there wasn't a hole from the top tube into the seat tube.

dave

[ultraman6970]

Never understood a good reason for the holes either... but besides weight and maybe some breathing of the tubing looks like aren't really necessary if the builder handles the torch like the gods.

[Dead Man]

I have a welded metal frame with no holes... and there's a little piece of debris rattling around inside the top tube.

So there's another solid reason to have holes!

[e-RICHIE]

Never understood a good reason for the holes either... but besides weight and maybe some breathing of the tubing looks like aren't really necessary if the builder handles the torch like the gods.

No amount of god-like torch handling can equalize the natural reaction
that occurs when air wants to escape from an enclosed area atmo.

ps

arrange disorder

;);):p
;);):rolleyes:
:):):cool:

[Doug Fattic]

I think what you are describing is a one piece head tube with sockets for the top and down tube. The Nikko company in Japan used to make these by bulge forming so the outside had the appearance of a head tube with 2 separately attached lugs but in actually it is all just one piece. It makes frame assembly faster and easier without the need for perfect mitering or tube orientation. They are perfect for production frame work. I used them to have some frames made in Ukraine because of their convenience. Of course to work properly your design has to match this head tube combination. The seat lug and bottom bracket shell on a frame using a one-piece head lug will be the normal kind you are familiar with. I don’t think they represent quality workmanship but in reality probably doesn’t make that much difference.

[jmoore]

Interesting! Thanks Doug. They don't feel like it's bulge formed. The inside of the headtube is solid the whole way down. Like the lugs were slipped over the headtube. I think I also felt some pins down near the bb shell too.

And the frame in question - Columbus SPX tubing as per the sticker. As little as I paid for this frame and what I have in mind for it's usage, construction is not really germane. I'm sure it will ride great.


I think what you are describing is a one piece head tube with sockets for the top and down tube. The Nikko company in Japan used to make these by bulge forming so the outside had the appearance of a head tube with 2 separately attached lugs but in actually it is all just one piece. It makes frame assembly faster and easier without the need for perfect mitering or tube orientation. They are perfect for production frame work. I used them to have some frames made in Ukraine because of their convenience. Of course to work properly your design has to match this head tube combination. The seat lug and bottom bracket shell on a frame using a one-piece head lug will be the normal kind you are familiar with. I don’t think they represent quality workmanship but in reality probably doesn’t make that much difference.

[zmudshark]

Jason,

Mondonico pinned his frames, one of the few builders who did that. That frame is a beauty. You are lucky that no one I know in PHX can ride that size. Are you planning on building it before you ship?

[Doug Fattic]

Ah, now that you had to rephrase your question, I see I misunderstood the situation. A Nikko one piece head tube/lug has giant holes where the top and down tube are inserted into the head tube/lug. It is easy to tell the different between giant vent holes in a head tube and the rounded corners of the sockets of a bulge formed lug. The top and down tube can't bump up against the head tube like normally would happen when using separate lugs. Never mind!

[jmoore]

Jason,

Mondonico pinned his frames, one of the few builders who did that. That frame is a beauty. You are lucky that no one I know in PHX can ride that size. Are you planning on building it before you ship?

Yes I will build it and get it dialed in. Prob ride it this winter and ship in the spring to its new home in PHX.

The seat tube / top tube doesn't have a hole either. The entire top tube is capped in both ends. Not even tiny vent holes I can see or feel. And its definitely pinned in a few.spots on the bb.

Sent from my XT1058 using Tapatalk

[e-RICHIE]

The seat tube / top tube doesn't have a home either. The entire top tube is capped in both ends. Not even tiny vent holes I can see or feel.

Some effbuilders drill a small hole in the top tube and fill it after the brazing
is complete atmo. You wouldn't see it unless the paint was completely off.

ps

arrange disorder

:):):rolleyes:
:):p:p
:cool::cool:;)

[wallymann]

Mondonico pinned his frames, one of the few builders who did that.

indeed a gorgeous frame.

but the point about pinning...i never had the impression that it was such a rare practice. not everyday lunch-meat technique, but not necessarily rare either.

[pbarry]

It's all good. ;) Nothing wrong with the construction; maybe not commonplace these days. Have ridden the h*ll out of my Diamond frame. Best steel ride I have, even beats the Cinelli SC.

Lots of production parts in manufacturing are made without vent holes. A good brazer can join two or three parts together no matter what. Sausage making and all that.

:beer: