misc. updates: horrible epoxy rash, rudder, volvo ocean race, sewing machines

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volvo ocean race updates twice a day on their youtube channel, & the short legs are pretty engaging, well, probably mostly team SCA is in the lead right now so I’m more interested than usually :)

~~RUDDER~~
re: rudder construction, have not had a chance to sit down & upload/document/write-up everything,

but in brief —

Solid bronze inside. We did CNC foam on a shopboat, laid down fiberglass, the rudder post & pre-stressed the trailing rods[1] , closed the mold and poured 2-part foam-it! 15lb urethane foam, de-molded, three more glass layers to connect the two halves, then gelcoat, install, and antifoul coat.

We also have a nice 3d model of outside of our rudder now (and a renewed complaint list against solidworks):
https://github.com/nouyang/scienceboat/blob/master/boatrudder.STL
& the mold:

https://github.com/nouyang/scienceboat/blob/master/rudder-mold-bottom.STL

[1]  (glassed some GPO3 blocks down, after tack/cure time we tightened some bronze nuts against the gpo3 blocks, checked that the rods were stressed by
i added two pictures to the end of the “rudder skeleton” album
https://picasaweb.google.com/113942194695013581888/SailBoatMay2015?authuser=0&feat=directlink

~~INSTALL~~

the details i left out are: we put so much “gelcoat” (just epoxy layers since our rudder is unlikely to be flexing a lot) on that it we lost clearance on the back edge (oops), so after installing we found it didn’t turn well put rather “popped” to rotate fully since it was catching where it rotated against the keel.

we sawed & scraped until we had clearance and now the rudder turns like a dream now (we can do a sweet 180 turn now) — it’s a little “less waterproof” on that backedge since we had to take off most of the gelcoat layers, but worst case seawater finds its way to the foam, which can sit in water for up to 2 yrs before deteriorating — realistically it has so much glass still that it should be fine.

~~EPOXY~~
also, my face/arms rash is still itchy 1 week from last exposure (which did not even involve mixing epoxy –I was just cleaning up). Do not f*** with mixed / uncured epoxy, folks, and also do NOT use acetone to wash epoxy off your skin.
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i’m using dipenhydramine (over-athe-counter skin numbing agent) & seeing a dr. on wed, but for the record:

5: Do not under any circumstances use acetone to clean up. This is the very quickest way to become sensitised. The acetone will immediately remove any natural protective oils in your skin and take anything it has dissolved, that is ANYTHING it has dissolved straight into your body. If you are going to use acetone to clean up your skin, you may as well just grab yourself a syringe and wack the crap up your arm and be done with it because it is much the same deal.

Inline image 1

~~singer sewing machine, 7442 disassembly / troubleshooting (bobbin did not wind, all lights blink & beeps) ~~

btw if you’re curious this is what the singer 7442 looks like inside when it’s operating, pretty interesting set of cams and mechanisms
https://youtu.be/RASgDLSg3Xw?t=24s

(pt 3 shows the “lights blinking” error https://www.youtube.com/watch?v=P4Cqt1lBxLY)

(pt 1 points out the things we fixed https://www.youtube.com/watch?v=T47fLW1PscE)

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2 thoughts on “misc. updates: horrible epoxy rash, rudder, volvo ocean race, sewing machines”

  1. On a side note, acetone is a great way to dehydrateing something without actually hydrating it – assuming we’re talking about glassware.

  2. How do you remove the case on the Singer 7442? I have every screw out and all seem separate except the last tab near the bobbin plate. Is there a hidden screw that needs to be removed?

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