icelemmings

I want to build up my own frame, I was wondering where I could read up on lug making? I realize there are a good variety of pre-cut lugs that can be further customized. I have done some reading about that, how to hand-cut your lugs from pre-ordered lugs once the angles are set.

I was curious about making my own lugs, completely from scratch. Is this possible, or does this process require machinery the average man does not have access to? I am only wondering because I would like to make a bicycle with non-traditional angles, thus, pre-made lugs would not work.

Danke

Scooper

It's certainly possible, but not very practical.

There are two primary lug making techniques used today. One is the traditional stamped lug that is stamped from sheet metal, folded, and then welded. The other, developed in the late seventies/early eighties, is the "investment cast" lug that represents the overwhelming majority of lugs on today's lugged bikes.

Retired framebuilder Dave Moulton has a brief description of both lug making methods HERE.

NoReg

Hey I asked a similar question last week, so if you check out here and FF you will get some other answers. I pounded the internet pretty hard, and it found reference to a few classic builders in Italy and some here who make their own lugs for every bicycle, etc... They all seem to tig tubing together. This would be a pretty good master's class in bike building since you would get ample training in both methods.

One thing I would caution is that unless you are doing something way off the margins, you probably can find a lugset that will work. Like if you are mixing all kinds of crazy tubing for a mixed or tandem, OK, you need some home made lugs, maybe. But a standard bike with slightly off the wall angles, there may be more choices than you imagine. I would scope out Henry James first.

Scooper

Very good points.

Here's a lugged Waterford with a 5.2° sloping top tube. The lugs are standard investment cast lugs that have been tweaked.



...and here's a lugged frame with sloping top tube from Craig Forest Ryan using Mini-6 lugs by Darrell McCulloch (Llewellyn Bikes).

squirtdad

couldn't filet brazing be used if the angles are very "non traditional" ?

Nessism

Go to bikelugs.com and get some of those Pancenti lugs - they have long sockets that have lots of extra meat on them for carving. No need to go full custom unless you are using some unusual geometry.

NoReg

"No need to go full custom unless you are using some unusual geometry."

Unless one doesn't want to sell out to those crappy investment castings. What's with that?

icelemmings

HMBAtrail

You absolutely can do what you are asking. As mentioned previously, you can get lugs with most traditional angles (typically ranging from 72* to 75*). You can also get the lugs from Kirk Pacenti that have a sloping 6* top tube and you can get them in either 72* or 73* head angle. If you want anything other than that you can either cold set one of these lugs, typically you can get about a degree or so in either direction, or you can make your own lugs.



Making your own lugs is not hard, it just takes a long time. Go to www.aircraftspruce.com (or similar supplier of 4130 steel). You need to purchase 4130 tubing with an I.D. that is the same as the O.D. of your tubing (so, if your top tube is 28.6 then you would get 1 1/4" tube with .058 wall). Do the same thing for head tube, seat tube, and down tube. Then you simply cut and fillet braze the 4130 and any angle your little heart desires. You have, in essence, built a fillet brazed joint with the 4130 tubing. Then cut the tubes a couple of inches from the fillet joint and you have a raw lug in the angle you want. Cut and shape the shoreline of that lug, file and smooth the fillet braze, thin the hell out of the lug because .058 is some thick stuff, ream the inside of the lug to remove any heat distortion, and you are good to go. Insert your tubes into your lug and get to building.



Basically you are building the bike twice. Once as a fillet brazed frame and then again as a lugged frame. Honestly, you would only do this for aesthetics. If you like the look of lugs, have plenty of free time, and aren't concerned about the excess weight then go crazy. Remember, each joint has both a fillet braze (on the lug) and a silver solder braze (inside the lug) so the frame will be a little on the portly side.



I did this exact process when I built up suspension corrected 29er (for which no lugs really work) and I was pleased with the results. I never built up the frame, I just have it hanging in my shop as a reminder that just because you "can" doesn't necessarily mean you "should".

yellowjeep

Where are the pictures?

unterhausen

If I were to do this, I'd start with sheet metal and beat it into shape. I don't think it would be all that difficult, my understanding is that this is how it was done. I've had to beat lugs into shape for angle changes -- the bottom head tube lug is usually a little off.