Fillet brazed and Bi-laminate bikes = Sexy

[Lewis Moon]

Originally Posted by David Kirk

I don't say this to try to change your mind nor to say you are wrong. If you don't get turned on by fillets I more than respect that.

I suppose the reason I write is to comment on the word "spackled"........it may come as no surprise that I would not chose that term for top shelf fillets. The laying of a tight fillet is every bit as neat and fastidious as laying tig beads and is quite the opposite of what some might think......that a lot of brass is schmeared on with little care and then filed down to look good. A skilled fillet guy will lay the brass in such a way that shaping and polishing the joints takes nothing more than emery cloth and a short period of time.

Fillets are heavier than tig beads but the amount heavier is often a surprise. Typically the brass used to make the fillets contributes about 2 oz of weight to the frame compared to tig welded construction. Most people find that surprising and expect it to be much more.

As a 'form follows function' guy I think you might appreciate the fact that more often than not a well built fillet frame will have better fatigue resistance than a tigged bike and the ultimate strength can also be higher depending on the tubes used. The thing is that laying of fillets only bring the tubes up to about 1800° F which is much lower than the typical 3500° F used in tig construction. The key difference here is that the heat needed for fillets is low enough that the molecular structure of the tubes isn't altered so the tubes don't lose vital strength during the process. On the other hand tig welding gets the material much hotter and this very often compromises the strength of the tubes and lowers its fatigue resistance. This is why we so seldom see a fillet joint, or the adjacent tube, fail and why it's much more common to see a solid tig joint hold up very well only to have the tube next to it (in the heat affected zone) fail.

Combine this with the fact that the typically larger size of a fillet joint is better at distributing the loads compared to a tig joint and I personally see fillets as being the ultimate 'form follows function' way to hook together steel tubes.

The real downside of fillets is that they are time consuming to make. Tig welding is much faster and then the joint is done, it's done. With fillets it takes longer to lay the fillet, and then the flux needs to be removed, and then typically they are polished to get that classic fillet look. This all take time and in that way tig welding has a real advantage over fillets - and this is of course why the industry moved from fillets (and lugs) toward tig welding. Welding saves time and time is money and that is important.

In the end all three of the popular ways to join steel tubes can make a very nice bike and of course if the tubes are the same the bikes will ride just the same. That said the properties aren't always as they seem and there are hidden advantages/disadvantages for each way of hooking tubes together. Like everything there is compromise and the buyer gets to choose which compromise is best for them.

Thanks for reading - as usual I got wordy and I apologize for that. Have a great weekend.

dave

Thanks Dave. I learned to fillet braze way back in the early '80s when I built my first frame in a hovel in Ft. Collins. It was mainly lugged but I fillet brazed the BB and HT/DT junctions so as to get custom dimensions I couldn't find a lug/BB for. The fillets were nice but they WERE time consuming. The only welded bikes around then were sewer pipe BMX bikes.
When I say form follows function, I consider price as a part of function. One of my promises to myself was to never own a bike I couldn't afford to crash and I've never paid more than $400 for a frame. It's not that I want a mass produced frame, it's just what I can reconcile with my budget.
Bikes can be a means to an end or an end in-and-of themselves. I prefer the former.

[David Kirk]

Originally Posted by Lewis Moon

Thanks Dave. I learned to fillet braze way back in the early '80s when I built my first frame in a hovel in Ft. Collins. It was mainly lugged but I fillet brazed the BB and HT/DT junctions so as to get custom dimensions I couldn't find a lug/BB for. The fillets were nice but they WERE time consuming. The only welded bikes around then were sewer pipe BMX bikes.
When I say form follows function, I consider price as a part of function. One of my promises to myself was to never own a bike I couldn't afford to crash and I've never paid more than $400 for a frame. It's not that I want a mass produced frame, it's just what I can reconcile with my budget.
Bikes can be a means to an end or an end in-and-of themselves. I prefer the former.

I hear you - and think I understand.

Have a great weekend.


dave

[Black Dog]

Originally Posted by Lewis Moon

Thanks Dave. I learned to fillet braze way back in the early '80s when I built my first frame in a hovel in Ft. Collins. It was mainly lugged but I fillet brazed the BB and HT/DT junctions so as to get custom dimensions I couldn't find a lug/BB for. The fillets were nice but they WERE time consuming. The only welded bikes around then were sewer pipe BMX bikes.
When I say form follows function, I consider price as a part of function. One of my promises to myself was to never own a bike I couldn't afford to crash and I've never paid more than $400 for a frame. It's not that I want a mass produced frame, it's just what I can reconcile with my budget.
Bikes can be a means to an end or an end in-and-of themselves. I prefer the former.

I will have both whenever I can, these need not be mutually exclusive goals. I think Dave's work proves this.

[Vonruden]

Heading out early to enjoy me some fillet



Gone but not forgotten

[Black Dog]

Here is a strange question.

Can titanium be fillet brazed? Or for that matter could Ti be built with lugs and silver or brass brazing?

I am imagining Dave producing a naked Ti bike with some nice fillet brazed joints...

[El Chaba]

The Taylor brothers started doing fillet brazed frames out of necessity during WWII as there was a shortage of lugs and other framebuilding parts. Norman (the framebuilder) could do a fillet joint like few others......

[William]

[William]

[William]

[Mzilliox]

Because this!!!
[IMG]Fillet braze by Matt.zilliox, on Flickr[/IMG]
[IMG]Berthoud on an old fence by Matt.zilliox, on Flickr[/IMG]
the lines can be so fluid on a fillet brazed bicycle. I love them too.

[Mzilliox]

Originally Posted by David Kirk

I really do enjoy the process of making fillets and then just staring at them. It's never gotten old.

dave

Awesome work!!!

[William]

Mmmm....

[William]

Sweet Eisentraut fillet from this thread in the Gallery!!!





William

[fiamme red]

https://www.flickr.com/photos/263834...7660291726939/

[velotrack]

Originally Posted by David Kirk

I don't say this to try to change your mind nor to say you are wrong. If you don't get turned on by fillets I more than respect that.

I suppose the reason I write is to comment on the word "spackled"........it may come as no surprise that I would not chose that term for top shelf fillets. The laying of a tight fillet is every bit as neat and fastidious as laying tig beads and is quite the opposite of what some might think......that a lot of brass is schmeared on with little care and then filed down to look good. A skilled fillet guy will lay the brass in such a way that shaping and polishing the joints takes nothing more than emery cloth and a short period of time.

Fillets are heavier than tig beads but the amount heavier is often a surprise. Typically the brass used to make the fillets contributes about 2 oz of weight to the frame compared to tig welded construction. Most people find that surprising and expect it to be much more.

As a 'form follows function' guy I think you might appreciate the fact that more often than not a well built fillet frame will have better fatigue resistance than a tigged bike and the ultimate strength can also be higher depending on the tubes used. The thing is that laying of fillets only bring the tubes up to about 1800ï½° F which is much lower than the typical 3500ï½° F used in tig construction. The key difference here is that the heat needed for fillets is low enough that the molecular structure of the tubes isn't altered so the tubes don't lose vital strength during the process. On the other hand tig welding gets the material much hotter and this very often compromises the strength of the tubes and lowers its fatigue resistance. This is why we so seldom see a fillet joint, or the adjacent tube, fail and why it's much more common to see a solid tig joint hold up very well only to have the tube next to it (in the heat affected zone) fail.

Combine this with the fact that the typically larger size of a fillet joint is better at distributing the loads compared to a tig joint and I personally see fillets as being the ultimate 'form follows function' way to hook together steel tubes.

The real downside of fillets is that they are time consuming to make. Tig welding is much faster and then the joint is done, it's done. With fillets it takes longer to lay the fillet, and then the flux needs to be removed, and then typically they are polished to get that classic fillet look. This all take time and in that way tig welding has a real advantage over fillets - and this is of course why the industry moved from fillets (and lugs) toward tig welding. Welding saves time and time is money and that is important.

In the end all three of the popular ways to join steel tubes can make a very nice bike and of course if the tubes are the same the bikes will ride just the same. That said the properties aren't always as they seem and there are hidden advantages/disadvantages for each way of hooking tubes together. Like everything there is compromise and the buyer gets to choose which compromise is best for them.

Thanks for reading - as usual I got wordy and I apologize for that. Have a great weekend.

dave

Dave, fantastic post as usual. I learn something new every day.