Working on our “tubes” project at some stage someone (I think it was Byron) mentioned the “Fail fast, fail often” mantra. Well, the last weekend ended up following this slogan to the last bit! Still, preparing for this post it came to me checking on what it actually means and ended up reading few articles on this.
“Fail fast, fail often,” as a mantra has seen some success. SpaceX comes to mind. But “fail fast, fail often” has been around for years. Thomas Edison, by example, “failed” 9,000 times before he was successful with his light bulb invention.Dan Pontefract (Forbes)
I picked the quote above as it resonated with me well – we failed too many times over the weekend! 😀
Plan B (Friday)
Based on our a new plan (see the end of our previous article) Serge and I tested 150C curing with single CF strip – two wraps, to check if we’ll be able to take it away when mold cools down.
We ended up preparing 20g of resin mixture (4g harderner + 16g resin).
All resin work started going much faster now when we know what to do. Demolding spray -> CF bath -> wrap -> white tape -> office tape. 15 minutes later all ready to heat up.
Keeping it for 20 minutes at 150C and wrapped seemed enough for our purpose so we let it cool down and unwrapped it.
Anyway, even cooling it down under water and using ice didn’t help and we needed to cut the tube to remove it from the mold again. There were not even signs that it would go off peacefully. Serge then used leftover resin to glue it in a tube again and we left it overnight to cure as is.
That did actually pretty well and we were able to see some mechanical stability being demonstrated for a first time.
Plan B+ (Saturday)
Before moving to a Plan C (splitting the tube) the idea came in that our demoulding spray might not be the best for our use case, so decided to re-run Plan B with our original TR mold release wax.
Eight layers later – tube mold looked like coming straight from Madame Tussauds museum. Serge needed to leave so Seb stepped in as the main assistant.
He seemed to actually have some good fun about it.
.. but it failed again. Even with X layers of mould-release wax – all still the same, it won’t release and we ended up cutting it again.
Plan C (Sunday)
Becoming reasonably desperate, I decided to go with the Plan C – cutting the tube. Not having Serge around to come with some better idea and being pretty upset after all those set-backs, it actually felt pretty relaxing to start manually splitting that two meter-long tube in half (Chris’s idea of split tubes modified by me to be doable in our environment).
It took one hour to chew through that pipe. It was far from being perfect, but also could look worse. Using caliper it was clear that there are probably 2-4 mm missing now on circumference, while those two halves flexed nicely.
I also prepare a jig to keep those halves split away to get additional gap which can be used afterwards to assist another demoulding attempt.
We used Kapton tape to bridge the gap on tube and Seb helped with another wrapping & heating round.
… and after all those failures, we finally had a nice tube. Short one, with imperfections, but it was a tube!
Plan C+ (Sunday night)
Finally seeing a way forward we instantly started preparing to demonstrate how to manufacture longer tube and took this opportunity to show how tube joining will work as well. Seeing how our mold flexes on longer distance, I decided to prepare new spacer which will fit between those halves.
We have that tube preparation already pretty much mastered and stopping in a middle and joining afterwards didn’t seem to be a big deal.
Seb then removed spacer-rods and after bit of wrestling – it worked out!
Final tube came out being roughly 65cm long and weighing 74 grams, which still fits into our plan.
I tried to demonstrate its stiffness on following video.
As you can see, that worked out very well! As always there are few things to improve, but there is a good potential that we’ll be really able to produce some decent tubes here!
Thanks for reading and don’t forget to leave us your comments & ideas as always!