I want to build my first frame, and I think I’m almost ready. I was lucky enough to get a Jig for free and Ive verified its square with a stripped frame. Im working on my braising skills (I could however also use some advice about building up my own Oxy-Propaine setup) and I think I’m ready.
For my first frame I want to build up something lugged and rim brake. A randonneur style setup to be specific. Maybe I didn’t look hard enough but Framebuilder Supply, Metal Guru, Bicycle Fabrication Supply, Track Supermarket, etc all didn’t have a set of head tube lugs for a 28.6mm top tube, 36mm head tube, and a 71º or 72º head tube angle.
I don’t want to do fillet braising yet and a lot of the allure of building my own frame is defining my own geometry. Does anyone know where I can get a set of 71º or 72º lugs?
P.S. Ive gone so far to design my own set of lugs in Fusion 360 and have printed a few prototypes in PLA before realizing that 3D printed stainless steel custom lugs might be a bit too far for my very first frame. Nonetheless, if anyone’s interested in that side project I’m more than happy to share.
Llewellyn Cadenza lugs are close - 36mm HT, but 31.7mm TT and 73 deg HT with a level TT - you might be able to cold set them enough to get to 72, or slope the TT a bit. They also do a set with the same tubes but a 6 deg sloping TT. I think you’ll struggle to find many 36mm HT/28.6mm TT lugs.
Honestly I just prefer the look of horizontal top tubes. However, ill have to keep that in mind, I think it’s one of the only 36mm HT/28.6mm TT Lugs i’ve seen.
For a first frame, try not to get bogged down with details and trying to get it perfect. Lugs are always a compromise because they limit the builder to certain combinations (but they certainly are cool and a nice way to build). You’ll almost certainly mess something up enough to make you want to do another one, and you’ll learn so much just from putting something together.
You don’t read much about it here but it’s pretty common to have to do some blacksmithing with lugs. It’s rare that they always meet your geometry requirements. You probably won’t find many for a 71* HTA. As someone mentioned, Ceeway in UK (Framebuilding.com) is probably your best bet. Peter has stuff that isn’t listed.
You will need to find the lugs that are close and then manipulate them to suit your needs. The old pressed lugs were good for this as they were softer and easier to bend. Investment cast lugs are a little harder. You literally just use thick walled tubes of the appropriate size and bend them to your will. You can generally get 2* pretty easily. Make sure you get the socket to fit tight around the tube once bent. Especially at the shoreline so you don’t get gaps.
An alternative is to make your own lugs. Essentially you take .065" walled tubing that is .125" larger in diameter than your frametube and fillet braze the joints you need. You end up making the frame twice and you have a fair bit of fillet finishing and lug carving to do but what a great way to exercise ALL of the framebuilding skills!!
.058 will work well for brass but I find once I have the joint made and then clean up the ID, it’s a bit too loose for silver which I prefer to use. Using .065 works better for me. Reaming it (with a slightly larger diameter reamer/adjustable reamer) makes a nice inside bore after grinding the hole through; but simply using a die grinder with a drum sander works well too. I grind away all of the adjoining tube. For those of us who don’t do this all the time (I have done it a handful of times) it’s pretty labor intensive (which is why you see slack angled bikes being fillet brazed). I believe Kellogg (Spectrum) or Holland make all of their lugs. I doubt they do it much any longer as I would guess most of their bikes are Ti now but at one point they made them all this way.
Leave enough tube to be able to measure that they are at the correct angles and aligned after tacking and before you braze them all together. If you mess this joint up, the final joint will be messed up too.