Not Such A Catastrophic Newby Learning Experience (TM), News at 11

[veryredbike]

The weekend started off well enough:

table.jpg

Brazed another joint and minimal tweaking got my partial front triangle and printout matched up. I feel like my brazing is coming along nicely.

Then I got the paper out of the way and started in with the height gauge... and discovered 3/4 mm of twist over the length of the head tube. I figured that, by the time that reached the ground, it'd give me a few mm off from the handlebars, and got to twisting.

scrunch.jpg

The results were... less than satisfactory. Thinking I should have waited until I had a top tube to put that kind of torque on it, and should have listened to my gut when it said to ease off a bit. The twang it made was painful, but I learned, and I'm going to start over as soon as Henry James can ship me some stuff. Speaking of which, I'm going to go make a call...

[e-RICHIE]

...and discovered 3/4 mm of twist over the length of the head tube.

Three quarters of a mm OR three to four of them?
What method was used to measure this ^ atmo?

[NBC]

3 or 4mm of ht twist is huge over just it's length, i wouldn't have even started trying to twist it back !

are you using silver solder ? if so have a look at the set named oops atmo on e-richie's flickr account, and remove the down tube and use the frame as practice / for personal use only

only way to learn is by making mistakes, it's unfortunate that framebuilding gets expensive quick !

good luck

NBC

[veryredbike]

Richie: Somewhere between .75 and .85mm... measured by using a height gauge on each end of the head tube. Frame was clamped to the table on the drive side, seat tube was only about .1 off.

NBC: .75mm, silver... but honestly I think I'll start over on this frame. I know there's stuff I can do better, and I can always keep the joints around to try a repair later when I'm bored. Ain't that the truth!

[e-RICHIE]

Richie: Somewhere between .75 and .85mm... measured by using a height gauge on each end of the head tube. Frame was clamped to the table on the drive side, seat tube was only about .1 off.

You've made a big mistake 1) trying to fix it and, 2) caring about it. PS Measuring the O.D. makes no sense at all because the true center line is created when the reamer cuts the interior. And if you (or others) think the outer is mirrored by the inner, I have a bridge in Brooklyn to sell you. Get some precision cones and a rod that's at least twice-three times as long as the head tube, and use the center line as a guide.

[afwalker]

There really is some good brazing lessons to be learned from pulling a downtube or toptube from a lug. It will NOT be anywhere near as easy as you think. You will have to learn another level of patience waiting for the it all to come to temp. Consider just trying to pull one tube for practice, unless you already have done some. I bet it surprises you how darn good that joint was, just trying to get it apart.
cheers
andy walker

[veryredbike]

Richard: Roger, that all makes sense.

Get some precision cones and a rod that's at least twice-three times as long as the head tube, and use the center line as a guide.

Anyone have a good source on an assembly like this? No lathe in my toolkit yet.

Andy: I was mostly hesitant because I'm too frustrated for the re-assembly at the moment... destructive education on the other hand... yeah, I'll give that a go.

[echelon_john]

Joe Bringheli sells a head tube bar with cones that's very good for the $. Not as long (or probably as precise) as a much more expensive unit, but plenty for your needs from the sounds of it. BRINGHELI

It's not listed out separately but he does sell them á la carte.

Richard: Roger, that all makes sense.

Anyone have a good source on an assembly like this? No lathe in my toolkit yet.

Andy: I was mostly hesitant because I'm too frustrated for the re-assembly at the moment... destructive education on the other hand... yeah, I'll give that a go.

[sam]

joe bringheli sells one, and andy at strawberry might sell one as well
eschelonjon beet me to it

[druptight]

There really is some good brazing lessons to be learned from pulling a downtube or toptube from a lug. It will NOT be anywhere near as easy as you think. You will have to learn another level of patience waiting for the it all to come to temp. Consider just trying to pull one tube for practice, unless you already have done some. I bet it surprises you how darn good that joint was, just trying to get it apart.
cheers
andy walker

I've never done this with a DT or TT, but I had to remove CS once and I was SHOCKED how hard they are to fully warm up uniformly and fall out (positioned DO to the ground and hung something heavy from the DO while heating it up). Gave me a whole new respect for frame tube replacement/repair.

[Rody]

Veryred...

Dude, for your first frame don't sweat the mm's of alignment, focus on the process. In reality, that .75mm you were trying to correct will be unnoticed when rolling down the road with a smile on your face. Tire irregularities, pressure, physical disproportion, hell even a stiff breeze will add up to more than the sum of your small imperfections as you begin your learning process. Let the guys who get paid to do this worry about perfect alignment, focus on immersing yourself in learning the process and refining it than what some piece of equipment says about your effort.

[veryredbike]

Rody: I'm a couple in at this point... And I managed to get the first couple straighter... I think that's why I let myself obsess about it. "Well LAST time...". Which is silly, especially since I don't get to work on this stuff too often. Inevitably not every aspect of every frame will be better than the last.

Thanks for the good advice!

[Rody]

Striving for efficiency and to make each effort better than the last is commendable. That's what keeps me motivated :)

rody

[Craig Ryan]

Try to adopt a policy for your personal work to never coldset a front triangle. Follow someone's known sequence until you can establish your own. During the time from tacking and pinning to the brazing the last corner, the frame will move of it's own free will. Once it's finished and the head tube is faced you can determine just how good it is. I've painted frames that had 6mm. of twist and the owners thought they were magnificent. Once you establish a method you can move your tolerances closer and be confident of what's to be expected.

[Michael Gordon]

Red,

What material is your flat surface? Your height gauge will be no more accurate than the surface it is sitting on.

I'm a bit OCD, but as a hobbyist a granite surface plate or Blanchard ground steel plate is not justified at this time. I scrounged up a dining room table from my aunt, but when I put a good straight edge against it I realized I had a nice table, but not the flattest surface. I upgraded with a piece of granite countertop, but still with my straight edge I can see that it too is not perfect. I have come to realize however, especially after reading the many threads about alignment and surface plates, that my table, for my needs is flat enough. As long as I have a feel for the imperfections of my table I can "use the force" to gauge how straight my frame is as I use my height gauge to check it. It will be good enough or Wabi-sabi. Wabi-sabi represents a comprehensive Japanese world view or aesthetic centered on the acceptance of transience and imperfection. The aesthetic is sometimes described as one of beauty that is "imperfect, impermanent, and incomplete".

Judging from what I can see in your picture where you have your frame held down with a clamp and your board resting on a folding table, I get the feeling you are in the same boat most of us hobbyists are in.

Do the best you can, and go with it.

[veryredbike]

It's flatter than it looks ;-) It's self leveling epoxy. Poured right, it should be flat to around .07mm. Not sure if I made it quite that flat, but it seems to be pretty solid, might give it another pour at some point for giggles. As far as the clamp goes, that's just for rough checks against the paper, the bolt on the other side is anchored in the aluminum extrusion below the pour.

Honestly, I enjoyed playing with the epoxy mostly as an end in itself. Always fun to learn something new.

THAT SAID, I agree with your post. If I don't let things be what they are to some extent, it'll both get in the way of learning and frustrate the hell out of me to no real end.

Geez, the responses to this post have been great! I was expecting a few "yeah, don't do that"'s and "I did that once"'s, but everyone has been really insightful and helpful.

[bencooper]

Having the back wheel directly in line with the front wheel is a nice thing to achieve, but it doesn't have all that much effect on the handling. I've ridden bike which (deliberately) have an offset back wheel - some versions of the Ratcatcher recumbent were 3" out of line.

What does feel a bit odd is when the line from saddle to stem isn't pointing directly forwards when riding.

[PaulE3]

Red,

It will be good enough or Wabi-sabi. Wabi-sabi represents a comprehensive Japanese world view or aesthetic centered on the acceptance of transience and imperfection. The aesthetic is sometimes described as one of beauty that is "imperfect, impermanent, and incomplete".

Do the best you can, and go with it.

Wabi-sabi... I've heard this before from my father and grandfather and thought they were just mumbling without cursing. Now I know this is actually sound and wise advice!

[MrkiMedo]

It's flatter than it looks ;-) It's self leveling epoxy. Poured right, it should be flat to around .07mm. Not sure if I made it quite that flat, but it seems to be pretty solid, might give it another pour at some point for giggles. As far as the clamp goes, that's just for rough checks against the paper, the bolt on the other side is anchored in the aluminum extrusion below the pour.

Honestly, I enjoyed playing with the epoxy mostly as an end in itself. Always fun to learn something new.

Which epoxy have you used? How much you have used for the table?

[steve garro]

Joe Bringheli sells a head tube bar with cones that's very good for the $. Not as long (or probably as precise) as a much more expensive unit, but plenty for your needs from the sounds of it. BRINGHELI

.

I have one gathering dust - I'd sell it for a fair price if I knew what that was.
- Garro.