The Frame Building Fail Thread

Frame number #0
Definitely had the bb in backwards, fixed that with some red lock tite and never looked back.
I also got super excited and sort of winged the seat stays. I had ordered a cx tube set from nova but had neglected to check tire clearance. I wound up having to dimple them in situ with a large pipe and some ratchet straps. It actually worked pretty well but needless to say it wasn’t the plan.
That frame is hanging in the shop as a reminder to take your time.
Measure 18 times, cut twice?

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On my second mtb frame I had things pretty close to dialed, but my seat stays were a bit too long. I trimmed the seat tube end rather than the dropout end and ended up with not enough tire clearance. I took it for a few rides before deciding to cut off the tops of the seat stays and sleeve them, attaching differently and increasing the clearance. It worked great and gave the rear end a unique look, so no real harm done - just learning!


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Over the decades at both Co-Motion and Moots I have made, seen and fixed a lot of mistakes. Twisted downtubes, bulging seattubes (filet brazed softened tube), backwards bb ( did that once) dropped and dented headtubes, broken frames in a variety of places etc. Learned what I could from these.

One thing that it came back to again and again was fixturing that was off (even from a very popular fixture maker, we had to abandon them). I have reworked several fixtures to make them straight over the years. Remember a very small amount of deviation at the dropouts can have a big effect at the front of the CS and top of the SS and even more at the headtube. Weld/brazing sequence can have a huge impact on alignment as well. I am a big believer in tacking a complete frame at one time in a well made rigid fixture. I know a lot of builders like to do subassemblies, align and reload. I have always felt that if the fixture is rigid and straight (I really like Jeff @ Sputnik’s frame fixture), the mitering process is accurate and precise and the facing is done properly the frame will be good. IMO final alignments are always necessary for the fine tuning.
Obviously a lot of folks are doing this as a hobby etc so a good flat plate can go a long way to figuring things out as well.

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Thanks for participating in the forum Butch! You have more institutional knowledge than the rest of us combined.

You have been building a long time and I’m sure have seen it all. I wonder if you could share what you’ve seen to be the most common builder or process errors that result in frame failures? Or the most memorable failures you’ve seen at Co-Motion and Moots? I realize it’s a public forum so you may not want to share but had to try :slight_smile:

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There are a few memorable failures. (1) Early on at Co-Motion we made a mountain bike frame with elevated chainstays for a local guy, remember the Nishiki Alien. We used Tange Prestige MTB tubing, nice and light, this must have been '89-'90. He loved the ride, nice and complient until the seat tube broke between the E-stays and the bb shell. Of course it had a 3 color candy fade paint job as well. So we made a 10" long sleeve that we brazed on, sent it back to the painter and got him going again. Yes it broke again so we ended up building him a traditional hardtail. We were broke at the time but our pride made us replace it, plus it was our fault for saying yes.
(2) Another lesson I learned the hard way was when Moots built the MX Divide full suspension bike. I was responsible for outsourcing the aluminum swingarm. We had done prototype with SAPA, previously Anodizing Inc, when I got the call that they were stopping all bike products. So I started working with Zen manufacturing. Things went well, we had good results from testing and were ready to go to production. Last minute I decided to move one of the welded on zip tie cable guides on the drive side chainstay 1 inch closer to the weld at the yoke. We had a batch made and started shipping frames. Didn’t take long for chainstays to crack. Ended up moving the weld on back, recalling all the swingarms and replacing them with the ones that did not break.
There are more. I learned a lot from testing over the years and from fixing frames made before I arrived at Moots

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My dislectic brain saw 418 for the Y plane to set my fixture. But it had to be 481.
I mitered the tubes, down tube and top tube didn’t work with the numbers from bike cad. So I made it work.
When I came home today I made the same frame in bike cad to see what’s going on.
And yes there it is 481.
Start again next week, 2 more tubes for the pile

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Here is another that falls into that category. When I arrived at Moots Kent did not drill water bottle boss holes until after the frame was built. At the time the YBB had taken off and we were doing pretty big batches, 15-30 of a size at a time. So we knew the locations (before we had CAD drawing) and could predrill downtubes and seattubes. I knew the holes were 2.5" center to center but the person mitering and drilling transposed numbers on the metric measurement on a batch of 18 downtubes in one size. I called my friend Ron Andrews and each frame came with one custom Ti King Cage gratis from Moots.

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That reminds me that when I made my travel frame, I put the seat tube water bottle bosses as low as I could. Not thinking about the couplers. I customized a king cage to raise it a centimeter.

That’s a classic story! Those should’ve been the Team bikes… :rofl:

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I have to admit that I have had occasion to call up King Cage to bail me out a few times as well.

-Walt

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Most recent failure, I had the inner air bladder fail during the cure, so the plies lost compaction. I cut it all apart to diagnose the problem and sort out solutions.

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That 42g weight savings made you way, way faster before it cracked though. Think of all the trophies and prize money you’d have missed out on!

-Walt

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The real moral of the story is verify every tube. I have found plenty of tubes with defects including butted sections much shorter than advertised. I check every tube as I pull them to build.

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Just had a nearly big time fail today. I noticed that my acetylene tank was nearly half empty despite having barely used it. Turns out there was a leak in the adapter to the regulator. Glad I caught it before something exploded!

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The beauty of a raw frame, the frame looks just as it was new!

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@liberationfab I’m about to set up an acetylene tank with an adapter for the regulator so I’m super interested in this. When you first set everything up did you do a leak test (pressure or bubble style)? Was the leak due to bad threads on the adapter or contaminated threads on the cylinder? Or was everything just not tight enough? Thanks for sharing!