Tube damage - what happened?

[Chauncey Matthews]

Won't you rather chase & face after all the welding around the b.b. area is done? Just asking

He said chase/face before the seatstays, so by that point all the bb torch work has been done.

[steve garro]

First of all, one does not need to tighten the frame that much on the stand. Has to be solid, but not to the point of damaging the tube.
And for this very reason, I do avoid stand with a "snap" clamp, in favor of a standard threaded one (you can't beat Kestrel Repair stands); and most important: if a dummy seapost cannot be used, clamp the frame by the upper part of the seat tube.
I only clamp by the top or the down tube some heavy-gauge build frames, like Dutch bikes or so

I use a tube block on the appropriate tube to grab it soundly as the stand rocking while chasing/facing is kind of dicey........the block clamped in the vise is much more solid, gives you better threads, and avoids chatter and less then optimal finish.

One good way to dent a tube (I have done it all, hopefully) is to have it in a block and bump the frame, leaving more of a crease then a dent.
How do you dent a frame through shoddy brazing?
That's a new one on me.
- Garro.

[Gattonero]

I've worked on frames with the b.b. threads so tight that both pins of the Park chasing tool broke. But never felt the frame being on such stress to get a dent or a crease.
Mainly, it could sway and hit the workstand, and that's the last thing you want on a frame that's already painted

[shiggy]

How do you dent a frame through shoddy brazing?
That's a new one on me.
- Garro.

Whack it with the torch!

Or drop it because you grab it before it has cooled.

[steve garro]

Whack it with the torch!

Or drop it because you grab it before it has cooled.

Well I guess you got me there..........

Best way to keep shit from getting dented I have found is to keep people out of your shop!

- Garro.

[mayan42]

An update, if anyone's interested..........
Had an email from the guy, in it he says the beginning of the dent is from his jig, however it collapsed under stress, due to the frames alignment. He also stated it was so badly made, in his opinion, it should never be built into a bicycle. My feeling this last bit was added as a disclaimer "its not my fault if you die" kind of thing, as previously he seemed to think it was OK.
So, after stating he would replace the tube in the next week, he mailed yesterday (2 weeks later) to say he had the new tube and would get round to replacing it sometime in mid Jan.
I collected the un-repaired frame from him today, together with a replacement tube, the middle of the down tube was cut out, so I couldnt see how much the frame "sprang apart" under stress, nor do I have the dented section.

So I'm going to do the repair myself, and wont be asking him to do any more work for me.

My plan is to use gravity and the flame to try and pull all the brass out of the down tube / head tube lug then gently pull out the section of down tube and repeat for the BB / down tube, and fit the new tube into the bb / head tube lug.
* Will flux make the brass flow out of the lugs and away from the joint better?
* Would I be better off leaving the lug attached to the head tube, and then flexing the frame to get the new tube into place, or removing the lug from the head tube and doing the entire joint over?
* Anything else I need to consider?

thanks!

[bencooper]

You should still be able to measure the BB to bottom of HT distance and compare it to your plans.

Sounds a lot like he's fibbing to me, though.

Neither gravity or flux will do much - what you want to do is get some mole grips tightly clamped onto the tube stub, then heat the entire lug carefully all over and pull hard. If you're lucky and skilful, the tube will pop out. However, this is quite a bit harder than brazing the joint in the first place.

[Andrew R Stewart]

I've only removed tubes from joints with heat when they were silvered in place. It takes a fair amount more heat then you'd think and the hardest part was getting the entire joint up to the remelt point at the same time. A second torch and third hand helps. With brass I'd consider the slow but cold method and grind out the tube after cutting it off real close the the sockets. Andy.

[bencooper]

The other way - and this is how I do it with most brazed-in tubes really - is to cut the tube off about 1cm from the lug, and cut a small notch in it. Then with careful torch control heat from the inside and tear - with care the tube will tear at the notch, the brass will melt, and the tube will peel off the lug. Needs care and sometimes needs to come out in several sections.

[EricKeller]

I've tried to take tubes out all at once, and it's way too hard for me, even with silver. I think cutting the tube and peeling is the way to go. I think you can even do this with brass, because the area you need to heat is smaller and it has almost no strength in the peeling direction when hot. Only done it with silver though.

[Gattonero]

I'm a mechanic, not a framebuilder.
So I'm wondering where the problem is, I guess due to the stub left? With a full length tube one gets better purchase, or not?

[Andrew R Stewart]

I'm a mechanic, not a framebuilder.
So I'm wondering where the problem is, I guess due to the stub left? With a full length tube one gets better purchase, or not?

Not sure if you're asking if leaving the original tube in place, in the socket, and butting a section of new tube between the two ends. But if so this is not considered the best way to replace a tube that has a defect/dent. The aligning between the old and the new would be hard to get good enough to avoid the tell tale signs, a line of reflected light would have a kink at the butted points. While a simple sleeve internal at the butted joints would serve the task structurally tying the tubes together this method has not been suggested as a "proper" repair in all my years of playing with framebuilding and reading the interweb. Andy.

[Daniel Merenyi]

The facing, reaming tools aren't so expensive stuff. I suggest to all beginners to have at least the basic tools before they start to make the nr. 1 frame. You learn a lot about the material you use seeing how oval could be a once round BB shell after applying heat. You'll see it, when you re-cut the threads. And this is just one example.

[afwalker]

I've only pulled a few bent dropouts, but the reheating sure was harder than the just brazing the dropouts.
I've hard a hard time not cooking the metal to the point of being brittle at the ends of the stays. I would think it will be hard to bring up all the tubes to temp, especially in the bb area.
Might use a rosebud, or 2 torches like Andy S. suggests.
If you really want to save the frame, being your #1, cut the tubes and grind them out to start over.
However, this is a great learning opportunity to see what it's like to master heat control over a large area, so get a full bottle of acetylene and go at it!
Look at some photo sets by Richard on some of his repairs, he can make it look easy!
cheers
andy walker

[bencooper]

With dropouts, the trick is to do the chainstay first - clamp a mole grip onto the dropout, heat the CS joint while pulling hard, and it'll spring right out. Then do the same with the seatstay joint. Its easier to do it that way around because the seatstay is springier.

I do a lot of dropout swaps and repairs, I made a jig out of a Park alignment tool to fit the new dropouts quickly and easily without the hassle of setting up the big jig.

[Peter Polack]

Similar to bencooper's suggestion, Peter Weigle replaced a damaged chainstay with a similar method, and posted photos on his Flickr page. Perhaps these will help the OP through the repair process.

[EricKeller]

I've only pulled a few bent dropouts, but the reheating sure was harder than the just brazing the dropouts.

when removing something, you can just concentrate the heat on the part that's not going back on. With rear dropouts, cut them in half and go to town on the pieces. Easy to pull them and the stay doesn't have to get hot at all before the filler goes into a liquid state. Same with the pieces of tubing when removing them. Just concentrate the heat on the tubing that you are removing. If you want to get good at it, I suggest removing tubes from a frame you don't care about, it's a lot more obvious once you do it yourself. The hard part is cutting just the tube without cutting into a lug. Removing the tube is easy

[afwalker]

Wow! some really good lessons there. Thanks for those. Mayan42 will you choose Peter Weigle method, I noticed he used flux, or try to heat the whole tube and worry about ovalizing the remaining tubes? I think this may be a more advanced brazing skill, will these good pointers maybe easier as I get more experience. I'm guessing a mole grip in Scotland is probably a vice grip to the US. I like mole grip better.
cheers
andy walker

[Nate Zukas]

Just put up some pics of a TT replacement in my Smoked Out thread. Not to many in depth details in the photos but a general idea on basic lugged frame tube replacement. The frame was silvered together which made it easy to heat the entire lug with a small rosebud tip. This is the 3rd repair I have completed and used flux for the removal. I cut the tubes about 2 inches from the lug and grabbed it with a pair of pliers. When the entire lug was heated, the flux indicated this, I begin twisting and then gently pulling out the tube not to distort the lugs socket. I have done this with a brass together frame as well. Again the flux was my guide to let me know I was close to the point of removal. Hope this kinda helps!
NATE

[G-reg]

An opinion/full up manifesto from a Newby Hack:

.......frame number 1 and found someone local to finish it off, ie ream the seat tube, face / chase the bb and face / ream the headtube. I went to pick it up last night and discovered a dent in the underside of the downtube.......he did suggest that it had happened due to in-built tension..... The dent is about 1/3 of the way down the down tube........
thanks,

#1. It's frame #1. Blame the Internets/HGTV/Painting fishing lures/etc. for setting the bar this high for DIY hobbies. Fact: melting thin tubes of metal together in your garage with fire to a fraction of a mm accuracy requires more skill than Scrapbooking or Homebrewing.

#2, #1 WILL SUCK, if you're lucky you can get some miles in before it kills you. If #1 hasn't killed you....and it's undoubtedly plotting to kill you at this very moment. Cut your losses and apply what you've learned towards the next frame.

#3 Frame #1 always sucks. YOUR first ride on a selfbuilt frame will be rainbows and horny unicorn levels of euphoric, but that doesn't always happen on attempt #1.

#4 If you are so mechanically new to bicycles that you are unable to build up a frame, you've got some homework to do before building a frame.

#4 #2 Will also SUCK. But ride the hell out of it anyway, and learn why it sucks. Hopefully before it fully realizes its master plan to kill you.

#5 Your LBSs will be stingy with those tools because they are expensive, some Rando off the street isn't going to crack the wooden Campagnolo case and go to town on whatever pile of steel they tried to set on fire. That said, if they don't want to help a dude out who walks in with a homebuilt frame and some good beer/bottle/burrito's, than maybe find another shop. A huge cost for the hack hobby builder, and an established commercial shop, is the cutters themselves. Invest in the cutters and show up to a shop at an opportune time with an appropriate aforementioned amount of beer/burrito/bottle and they will likely happily show you how to use those cutters on their tools on your hackass frame.

It's a 31.7mm "oversized" downtube, 0.9 / 0.6 / 0.9mm thickness. I'd guess the dent is half way between the bottle bosses and the headtube, so in the 0.6mm region. Sold as a "butted cromoly" tube.

#6 It may be one of those things you have to learn for yourself.... But that's some thin tubing that shouldn't even be on your radar for #1. Drilling out/brazing H2O bosses only F's that tube even more. It's not a BoronFibreUhberbike, you save single grams with thin tubes. Get cheap tubes for #2, worry about fine tuning ride quality and weight to that extreme with frame#200.

Well, you gotta hold it by something? especially if you are working on the BB. Most shops though don't have a good set of wood or aluminum blocks that make this easy and foolproof. I too have dented tubes with a park stand, it is easy to do. Sounds like the OP needs some tube blocks.

Bohemian Bicycles

Dave Bohm gives good wood!

P.S. Preferably take a good aluminum block from Paragon but wood would work too and clamp the tube in the block around the dent. Use some lube and roll the tube back and forth quite liberally, it helps to pop the dent out mostly. Then it may be very easy for your painter to fill what is left.

Confirmed that Dave ships some awesome wood. I'd recommend his wood over other tube holding equipment. Innuendo aside, his wood is totally worth the $$

Sounds like perhaps it was clamped in a vise that had a square beam and the frame rotated down while the bb threads were being chased and the down tube came into contact with the vise beam...... been there...done that..Doh! :-)

Dave

BTW...your guy sounds like a standup dude.

I've seen this happen with nearly everynoob frame I've built. At least once in the process for each frame. Things slip, even with(gucci) tubing blocks, the DT endos into vise threads/beam. I'll sleep better this evening knowing it's not just my dumb ass. But it's also the instant when that particular buffoonery occurs I stop everything and ensure I don't need to scrap everything.

= Why I do all the facing & chasing before I even put the seatstays on.........
- Garro.

Even if you're not Garro, this stage is really the last chance to fix things anyway. My opinion (gained from minimal experience and the internets) at this point is fix with heat things that are barely F'd up, and if really F'd up think about starting over.

Cold setting a frame here is putting the cart waaaay before the horse, especially for a newby builder. None of the badass framebuilders here "cold set" anything. They properly mitre, tack in a jig, and then check alignment. They're badass enough to correct to the n'th of an mm via how they apply heat during the finish welding of a frame to bring things to within the aforementioned alluded to N'th degree. Not that they would admit it if they did, but no pro builders posting here cold set anything because they are bad ass. And that's not to say Noobs/Hacks shouldn't strive for that accuracy, but you're doing more harm than good getting there via cold setting vs. solid miters/welding skill. Accept that unless you are excessively awesome at least anything below frame #20 will be crap.

I've worked on frames with the b.b. threads so tight that both pins of the Park chasing tool broke. But never felt the frame being on such stress to get a dent or a crease.
Mainly, it could sway and hit the workstand, and that's the last thing you want on a frame that's already painted

In all my LBS guy time, I've put quite a bit more effort into my own homebuilts when facing/chasing compared to a commercial frame. But not too much more effort, certainly not enough to crimp (even thin) tubes. I'm not bragging (because holy crap the "market std" sets the bar pretty low) when I say my frames suck, but in the context of facing/chasing things they are not too far off of some big name mass produced brands.

An update, if anyone's interested..........
Had an email from the guy, in it he says the beginning of the dent is from his jig, however it collapsed under stress, due to the frames alignment. He also stated it was so badly made, in his opinion, it should never be built into a bicycle. My feeling this last bit was added as a disclaimer "its not my fault if you die" kind of thing, as previously he seemed to think it was OK.
So, after stating he would replace the tube in the next week, he mailed yesterday (2 weeks later) to say he had the new tube and would get round to replacing it sometime in mid Jan.
I collected the un-repaired frame from him today, together with a replacement tube, the middle of the down tube was cut out, so I couldnt see how much the frame "sprang apart" under stress, nor do I have the dented section.

So I'm going to do the repair myself, and wont be asking him to do any more work for me.

My plan is to use gravity and the flame to try and pull all the brass out of the down tube / head tube lug then gently pull out the section of down tube and repeat for the BB / down tube, and fit the new tube into the bb / head tube lug.
* Will flux make the brass flow out of the lugs and away from the joint better?
* Would I be better off leaving the lug attached to the head tube, and then flexing the frame to get the new tube into place, or removing the lug from the head tube and doing the entire joint over?
* Anything else I need to consider?

thanks!

IMO
"The Guy" doesn't know much more about this than you do.

It's time to cut your losses. Find a wall that needs decoration and apply #1 to it. On a steel bike frame a full up tube replacement by a pro is only worth it if you are extremely emotionally attached to the frame or it has serious historical value. Frame #1 does/should not have anything close to either.