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Tantrumcycles #1
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Is there anyone who knows the reason for this two short lines of weld just behind where TT and DT meets on the Rocky Mountain Instinct Alu frames?

Is it holding some kind of reinforcement on the inside? Or could it be welds closing some slots made prior to welding to evening out stress due to deformation in the material after welding to avoid cracks to form?

I imagine this is the spot where the TT and DT will bend the most if bottoming out on a flat landing..


 

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Is there anyone who knows the reason for this two short lines of weld just behind where TT and DT meets on the Rocky Mountain Instinct Alu frames?
This is a great question, so i'm replying to bump it up.

I propose that there are vent holes there, and the last weld is to seal them. This is based on absolutely nothing.
 

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The machine used to cut the long odd shaped mitre on that top tube leaves a square(ish) corner on the underside of the top tube, instead of re-setting the tube within the machine to make a second cut and round off the mitre, after all it will never be seen, a bead of weld is laid down at approx 45º degree to that 90º corner to releave, reliefe (why can't i spell that word today?) stress. This is then mainly welded over when the top/down tube is joined. At least this is how a similar joint was described to me in a factory that was welding landing gear structure for a light aircraft. So basically it is to stop a crack forming and propogating away from the high stress corner.
 
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