brazing

I had an 'Ahaaa' moment. For the longest time I was working the flame wrong. too close and too hot. The blue flame too close. So I stepped back and relaxed and washed the flame feathers over the lugs. Much better! Everything comes up to heat nice and smooth. The silver flows like butta! The shore lines are crisp and the joint fully flowed. Nice!

Okay.. where are we??

Its been fun but a little weird. Couplers are something else. Somehow I managed to produce a little runout off axis. No big deal. apparently the weirdness lies on bth sides so I rotated the short end in 90 degree increments so that the wobble evened out. I say wobble.. the two halves were joined and the assembly rolled along the floor. The alignment issues were apparent. Little of this and little of that and they were strait-ish.. enought to build with. Really I should not have these things but I do and respect the install. I found some Verus tubes from Henry James that have insane butt lengths. Something like 152mm. still though it was a pinch to nest the couplers into the butts. I laid the entire frame out in Autocad so I could easily see where they were. Then I changed the design a bit. Weary of needing to work around brake caliper clearances.. long or short.. I decided to use canti brakes so I could raise the crown for longer blades. Now I can fit 35's for off road situations. What all this means is that the DT was rotated up to 59 degrees rather than the standard 60. This is a 58ish cm frame so the HT looks a little squat. Its all good though.. FREEDOM!!!

couplers.. As can be seen, I trued and clamped the tubes and couplers to plumb in two planes. All good right? not so much. the tubes ended up being about a wall thickness out. so it goes... I had and have concerns brazing an assembled coupler. However the more I think about it, these are made for retro fit so therefore assembled. Did not have the nerve to try. Now I know.

second frame begins

For all interested, I plan to document and comment to a greater depth the build of the second build. There is nothing wrong with the first and is being finished by its recipient. Maybe it will finished soon so I can post it here. Anyway...

The plan has always been to build a pack/travel bike for myself. This means using couplers. Why I did not use the couplers for the first frame was that I was very unsure about brazing. The couplers, being the first parts brazed into the frame, proved daunting to a newbie. So I waited and learned from the first effort. So that said here we go!

First order of buisiness was to map out the location of the couplers in the butted sections of the tubes. The tubes I used for this application were thus..
Double butted Verus 28.6mm TT ( 102-51-309-51-152 ) x .8/.5/.8 wall
31.8mm DT ( 102-51-324-51-152 ) x .8/.5/.8 wall

I am 6' even so the frame dimentions lended themselves well enough to land the couplers in the thicker butt ends although the coupler points do over lap into the taper transition. If there is any concern about not landing the couplers over the butt sections of a chosen tube, move up to .9/.6/.9 walled tubes. Little heavier frame but the couplers are not exactly light either. Better safe than sorry right? S&S machine suggest installing in the thicker butt lengths although sometimes doing this is difficult based on frame geometry cut lengths.

Cutting the tubes. This is all done old school with two types of tools. Hacksaw and files.. although I did order a pair of tube cutters from Andy Newlands of http://www.strawberrybicycle.com/. Nice tools that will help with dead on copes. Having filed tubes of my first practice front triangle and then the second full build, I would like to try these. They were a bit of a pinch to afford but will last a good long while. I would however suggest that everybody who would build a frame hand miter the tubes for the first few frames. Doing this will teach much. Anouther reason for getting tube cutters is that I want to do fillet brazing later on. However for both lugged and fillet frames, the copes must be spot on for optimal fit and strength. I do however all of the other fitted joins by hand. I just want to see what cutters can do so I have a given that I can tweek otherwise. I will use a mill to cut the tubes at the proper angles.

Strait cuts.. I use blue tape as a cylinrical line and a 1/32" kerf 32TPI blade. I like to work around the tube creating a score all the way around, rocking the blade along the line around the tube. Try to stay close to the tape but not cut it. I mean right against but not on. Takes practice and a steady hand but marking the line this way is MUCH easier to see and follow than a scribed line is. Also the tape, because it is thin and wide, it will naturally want to lay a strait edge. If the winding angle is off a bit, the two ends of the tape at the 360 degree overlap will not line up. Unwind, correct the start angle and re-wind. This process creates a squarely aligned groove for the blade to follow. Working around the circumfrence the wall is cut thinner and thinner until it cuts through the I.D. . At this point, even a 32 TPI blade will grab the super thin remnants of the cut line. However because a path of least resistance for the blade was created all the way around the tube, the blade will follow that path through. square cut.

Couplers laid in loose and aligned with a strait edge. be sure to mark the long taper end so there is no confusion as to where the long taper end is.
Un mitered tubes test fit into the couplers. The next step is to braze the couplers onto the tubes. Because mitering occurs after the coupler fitting, orientation of the tubes does not matter. Just braze 'em in square otherwise a nasty twist will be built into the frame from the start. Not good. This is why I waited until a later frame to attempt couplers. After the lay out and installation is done, treat the tubes like normal with coping and buildin. Extra care to align the points of the couplers and lugs should be taken.
I like building flat. Although the setup takes a bit longer, this system offers much flexibility from sub assembly to final fit. Not the only way to do things but an approached based on what I had available. The saddle blocks were made to be of consistant height and center. The saddle cuts are truly hemishperical so that the center line of the tube lies at the top plane of the block. I can then use these to support a strait edge to create two lines 180 degree opposed. These lines are for indicating the tube center for mitering so that when the lugs go on, the points will line up.

set

fork is done! WOW !!! much different than the frame. Lots of meat to get warm and no real visual cues to indicate full flow. The bending jig worked well as did the fixture. The blades moved around some but no too bad. Maybe .05" was the worst and that was side to side. I am working on brazing sequence to minimize distorion but really a good first attempt. Flowing silver is tough especially when I am chasing a heat and gravity around the crown. Going through the process is really the only way to see what happens. I dumped too much in but it is stout. Lot of cleanup but stout none the less. What you see on the bending jig is a '170 lb.' rake. No lever just me balancing on top of the blade on top of the table. The blades do get stiff in a hurry! The rake actually came out to be right on. still though I need a lever. something to compound with a roller and a hoop to pry under. Pinned the drops, solid! drilled vent/ drain holes. Doing all of this I wonder about fillet brazing forks. That is alot of work and to keep everything aligned?? I will stick with lugs for now. crown and steerer went together then drop outs and blades. then glued the two together.

Time for a fork

Yippy!!! to finish the frameset. Being the chronic knucklehead that I am, I forgot to order a steerer tube. This one was made the hard way... It started life as a 1" solid bar of 4140. lots o' chips! anyway.. the big ass post in the back of the fork jig is to hold in the vice. eventually I will modify it to fit a duty made, multi purpose floor mounted post. It can rotate 180 deg. to make the best of gravity. I might make anouther after using this one. The plate is good, I just dont know if I have enough travel in the drop bracket to do all needed rakes. The bending jig has two radii.. 13" and 15". that is easy to change ( make a different base ).. I just created a curve based on the plans for this one frame. Stops will go into the "V" groove for consistency.

Its been a while

Good front triangle this time and good rear triangle too! Now for the fork... I have not yet decided what I think about the wishbone setup. I like the looks. Either a person does or they do not. The traditional method of attaching the stays to the ST lug is a level less of fit work. It is way easy to cut the transition from the bone casting to the ST lug too short. Which is what happened here. I would have liked the stay to reach the lug. I am working on designing a wishbone lug that does the same thing but spreads the load out more. This will be fine for this frame as the ST is a Verus and thick. The seatpost will carry the load. although the constant hammering will make a set that will bind over time. I think... First frame being sent into the wilderness. It is built for my wingman Hagen so it will be close so I can observe.

post

Here is a photo overview of work. Being a single person in the shop, its difficult to capture every detail of process and usually after the fact. All of the fixturing is obviously to build flat. I have yet to decide if this is a prefered method as there are some pros and cons. Pros.. My arms dont get tired holding the torch up and whatever tools needed to do the job at hand. cons.. access. but reall not much is needed. I think a new steel surface plate is in order. then again a pro fixture would ease set up of the tubes. Lengths are what I am having a difficult time with. the drawing from the first post.. crap. Too much info but a good exercize none the less. Drawing something out gets a person in the groove of building. sort of like meditation. It is easy however to generate incorrect angles and lengths. I dont propose that a computer drafting program is needed. Rather known lengths and trigonometry and a subscale drawing. Unless one has access to a machine shop, miters will be cut by hand. Lug lines will get you close then move to a nice quality protractor and a half round file to dial in. I do have access to a shop but it is far away. if something is not cut properly I have to do fitting the old fashioned way. Filing is a good good skill to have. Nothing wrong with it. What else are you going to do? Watch T.V.?