Tube damage - what happened?

[mayan42]

I recently finished off 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 looked as shocked as I did, and denied all knowledge of it. I know categorically that it wasnt there when I left it with him, and he spent a good long time looking it over when I dropped it off, so I'm pretty sure he would have to admit it wasnt there when I left it with him.
He's been great, and has said he will replace the down tube at no charge, which I guess is the best possible outcome from this situation, and I'm not writing this looking to blame him or for "ammo" to go after him.
However, he did suggest that it had happened due to in-built tension in the down tube due to my brazing skills (and I'll be the first to admit, my skills are pretty poor) I find this hard to understand and want to make sure if this was my mistake, that I dont do do it again.
I finished the frame probably 2 weeks before handing it over to him. In that time I was handling it a lot, filing it, cleaning it etc. The dent is about 1/3 of the way down the down tube, on the underneath, about an inch long, running straight across the tube, with a very sharp, very straight line in the middle, my guess would be that it was 3-4mm deep at its deepest and approx 1.5cm across at its widest. I dont have a photo, as I left the frame with him for him to fix it.

Like I said, he's been great and without admitting any liability, has taken on the repair free of charge.
Is it possible that I screwed up badly enough to buckle the tube like that?
Is it possible to tell what caused it without any photos?

thanks,

[mjbabcock]

Sounds like the clamp on his stand. Might have been torquing the frame when prepping it and had it a little too tight. What was the tubing in diameter and thickness?

I recently finished off 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 looked as shocked as I did, and denied all knowledge of it. I know categorically that it wasnt there when I left it with him, and he spent a good long time looking it over when I dropped it off, so I'm pretty sure he would have to admit it wasnt there when I left it with him.
He's been great, and has said he will replace the down tube at no charge, which I guess is the best possible outcome from this situation, and I'm not writing this looking to blame him or for "ammo" to go after him.
However, he did suggest that it had happened due to in-built tension in the down tube due to my brazing skills (and I'll be the first to admit, my skills are pretty poor) I find this hard to understand and want to make sure if this was my mistake, that I dont do do it again.
I finished the frame probably 2 weeks before handing it over to him. In that time I was handling it a lot, filing it, cleaning it etc. The dent is about 1/3 of the way down the down tube, on the underneath, about an inch long, running straight across the tube, with a very sharp, very straight line in the middle, my guess would be that it was 3-4mm deep at its deepest and approx 1.5cm across at its widest. I dont have a photo, as I left the frame with him for him to fix it.

Like I said, he's been great and without admitting any liability, has taken on the repair free of charge.
Is it possible that I screwed up badly enough to buckle the tube like that?
Is it possible to tell what caused it without any photos?

thanks,

[mayan42]

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.

[bencooper]

due to in-built tension in the down tube due to my brazing skills

Ha, that's a new one!

Sounds a lot like he clamped it too tight in the stand and then it was damaged from the force of turning the BB taps or similar. Easy to do, especially on 0.6mm wall tubing.

[Andrew R Stewart]

Tube defects often are located at the butt transition points, although not always. Your description of the dent's location doesn't seem to line up with the DT's butts. I have never seen a dent happen from brazing reasons. I have seen bulges happen, but not indents. Usually the stresses that are built up from poor building or aligning don't cause dents, buckling in the extreme, maybe, but not a dent. It would be interesting to see what happens when the guy cuts the DT. If the ends of the cut stay pretty lined up with each other then there's not too much stress. If the cut ends spring out of line...

I agree that the described dent seems more likely to be caused by handling. Perhaps you should document frame #2 before it gets worked on by another guy. Andy.

[mayan42]

Thanks for the replies. I'll see what he says when I pick it up. I have to admit that my immediate thought was that it looked like it had been clamped too tight and then twisted against the holding force of the clamp.

Perhaps you should document frame #2 before it gets worked on by another guy. Andy.

I think the real lesson for me with this is that I should buy my own tools. I could have accepted and learnt from my own screw up, but I'll now never really know how good / bad my first frame was.
Number 2 will be better......

[steve garro]

I bet it fits one of your frame blocks perfectly..........
- Garro.

[EricKeller]

I managed to put a huge dent in the seat tube of my first frame. I must have over-tightened a Park stand on it. I noticed it much later, had no idea at the time of damage

[Clockwork]

I used a tube block a little too close to the oval section of a MAX tube and put a tiny dent in it. My painter was able to save my butt. Your painter can probably do the same. If you're powder coating, clean the dent and fill it with JB Weld. Let it set up for 24 hr. and sand it smooth.

-Joel

[mayan42]

I bet it fits one of your frame blocks perfectly..........
- Garro.

Not sure I understand you....do you mean I dented it and didn't notice ? or that I weakened it which caused the subsequent failure?
If the former, then it definitely categorically wasn't there, believe me the first thing I did when I got home was to check the photos...and absolutely no sign.


And I think it's too big to be filled / painted, plus he has said he will replace the tube.
I just want to understand if I did something fundamentally wrong with the build / brazing process, I guess I'll find out when he cuts it open.

[Dave Anderson]

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.

[e-RICHIE]

I just want to understand if I did something fundamentally wrong with the build / brazing process, I guess I'll find out when he cuts it open.

Have I misread here?
You made the frame but he's doing the repair atmo?

[mayan42]

Have I misread here?
You made the frame but he's doing the repair atmo?

In a nutshell -
I built the frame, gave it to him to do the finishing (face / ream / chase) as I dont have the tools.
When I gave it to him, there was no dent
When I picked it up (after paying for the work) I noticed the dent. He hadnt noticed it, suggested it could be due to my lack of experience.
He offered to replace the tube FOC.

As I've said, he's been great, not looking to go after him, just trying to understand what happened,
Did the tube fail cos I built it badly or cos he had a mishap or a combination of him clamping an already weakened / stressed tube a bit too tight ?

[e-RICHIE]

In a nutshell -
I built the frame, gave it to him to do the finishing (face / ream / chase) as I dont have the tools.
When I gave it to him, there was no dent
When I picked it up (after paying for the work) I noticed the dent. He hadnt noticed it, suggested it could be due to my lack of experience.
He offered to replace the tube FOC.

As I've said, he's been great, not looking to go after him, just trying to understand what happened,
Did the tube fail cos I built it badly or cos he had a mishap or a combination of him clamping an already weakened / stressed tube a bit too tight ?

Ya I got all that. What I didn't get is why you don't fix it. Even on the off-chance that it happened at his place, why would you entrust him to fix your frame?

[crumpton]

IMO dents are more easily spotted after paint.

[mayan42]

ah right, sorry, completely mis-interpretated you there.

errmmm, dunno to be honest, I was pretty shocked and dissapointed at the time to be honest, then when he mentioned it was probably due to my in-experience I guess I didnt feel confident enough.
Looking back, maybe I should have asked for a new tube and just walked out with the frame and the tube.

[steve garro]

Not sure I understand you....do you mean I dented it and didn't notice ?

Yep.
I did just that when I was a FNG.

Fundimentally if you let the frame out of your possesion to be worked on by a second party then it IS your fault it's dented............Never let a frame out of your hands until ALL metalwork is complete, facing, chasing, waterbottle bolts installed, all that.

It's really, really easy to overlook a dent.
A light shoeshine with a worn piece of 80 grit goes a long way.

I hate even sending it to paint........but I'm not going to learn to paint in a chair, either.

Got a picture?
- Garro.

[Will Outlaw]

Why not replace the tube yourself?

It's amazing how much you learn when you have to tear into a frame and replace bits. (I wound up doing this on #1 and, frankly, learned more from the repair process than I did building the thing in the first place.)

[mayan42]

Yep, couple of big lessons for me. I thought the lessons on #1 would be more like "measure twice cut once" or "remember not to blow a hole in that 0.6mm tube next time"

Be self sufficient, and fix your own screw ups.

[mayan42]

I'll get it right for #2 !!