HC14 Build - First Ever

[peter-curacao]

Okay just making sure you saw those pages, trust me the glue will hold

[JCordray]

Thanks for the tips!

My wife and I did the spot welds and you are all right! They do hold!

While this does not seem a miracle to someone who has done this before it was a little more miraculous for me. All of the effort that went into bending the ply and making it shape up seemed to make those little fillets seem weak. But they cured overnight and I took a few cable ties out and the wood holds without moving so all is well.

I don't have any pictures just now but will post some later. I will start on running the fillets out for the whole seams now.

An odd thing happened though and I wondered if it has happened to anyone else. The epoxy I am using is from a company called Resin Research and contains no formaldehyde and seems to be a bit friendlier around children as well. Up until I mixed it with the wood flour it has never shown any tendency to heat up. Maybe it has gotten a little warm but not enough to really notice. Then I mixed it up with the wood flour and put it into a plastic bag. A few minutes later the bag was smoking and melting and the epoxy had gone off and hardened. What causes this?

1) The wood flour? Seems unlikely...
2) The plastic bag reacts with some of the epoxy chemicals? Perhaps...
3) The bag was closed and thus the lack of air caused a problem? Dunno chemically how this might happen...
4) Extra stirring due to mixing wood flour caused some extra heat?
5) Maybe mixture proportions were off somehow? I did mix the epoxy and hardener and then add the wood flour so I am pretty sure the mix was right but maybe not...

Any thoughts?

[peter-curacao]

I think we all had that at least once, it's because of the mass in other words al the epoxy packed together in the bag, if this batch of epoxy was spreaded over a larger surface this most likely wouldn't have happened, next time try make a smaller batch until you are comfortable and fast enough handling bigger batches. Hope this explains it

[JCordray]

That does help! I had been making up fairly large batches - 150 ml at a time. I thought this was too large so I have gone today and purchased some plastic 1oz shot glasses to measure the stuff out in. They are 50 for £1 so I can just use them and throw them away. Some plastic cups to contain and mix with and I am good to go - I think.

[dbcrx]

Don't worry. As already mentioned, you're not the only one. Even after 4 years of using epoxy, I still get caught out ocassionally and have to throw a smoking pot of filler over the side of the boat!

Basically, it's a bit of everything you mentioned. Epoxy always gives off heat when it's curing, and the hotter it is the quicker it will "kick off". So the extra mixing will add a bit of heat then the bag will contain the heat making it even warmer. The more quantity you mix the quicker all this will happen.

As for the mix ratio, it depends on the brand. With the resin I use (C systems) you can play with the 2:1 ratio a bit to make it cure faster or slower. However with something like the West systems which is a 5:1 mix, if you don't get it right it just won't cure at all.

[sds]

You guys might find this epoxy measuring method useful:

http://www.boatdesign.net/forums/fiberg ... 12809.html

[dbcrx]

That sounds like far too much effort. Much easier to just use these:


And cured epoxy just pulls out so you can still use them over and over again. Although it is a good idea if you can only get plain cups.

[sds]

Yep. Lots of options. Whatever floats your boat.

[JCordray]

So I have finished one of the two bottom seams now. The fillets seemed small to me but others have said new builders tend to make their fillets too big. Here are a couple of pics:

http://gallery.bateau2.com/displayimage.php?pos=-40390

http://gallery.bateau2.com/displayimage.php?pos=-40389

These two are slightly different widths. I stuck my finger in there to give you some idea of the size. The fillets seem smaller where the gap between the two panels is widest. This is because more of the flour/epoxy putty went between the panels in the gap. Do these look alright?

At any rate, I managed to get one seam done while everything was wet and it is setting up nicely. I'll post some pics of it later I think - my phone battery died last night!

[jacquesmm]

Mixing epoxy:
It's all here, on our HowTo site
http://www.bateau2.com/howto/epoxy_mixing.php
and a movie here:
http://www.bateau2.com/howto/mix_epoxy.php