Another first time builder...

[rpecot]

Between Jazz Fest and the school fair, I managed to do all the inside fillets this weekend. Still need to sand them smooth.

I had an interesting occurrence when I made up a "big" batch of epoxy... after mixing the epoxy and hardener, I started mixing in the silica filler. Took me a while to get it to peanut butter thickness. Too much time, I guess. The stuff is deceiving. Anyway, I had laid down half of the fillets I was planning to do and then the reaction started to really kick off in my plastic cup. Started getting damn hot, real quick. Like so hot, I could barely hold the cup. When it got to the point that I couldn't hold it anymore, the damn stuff was smoking. And about 3/4 of what was left had formed into a solid mass. Wild. :shock:

I guess the learning here is if you're gonna make a big batch, use it quick!
(re: "learning" - sorry, corporate America is responsible for that one)

 

[oldsparkey]

Theirs another way of doing it and it works really well for me , nothing wasted.

Add the prescribed amount of the resin to the cup , now add what ever you are using , wood flour , glass bubbles , silica , what ever. Mix it and don't worry it will not set up ....YET.
When that is a shade thicker then normal and really mixed ... add the hardener , mix that into the mix you have and use the batch. After a while you will know when the mix is just right before the hardener is added.
This way only half of the mixing time is used when the hardener is added , not all of the time from the start which caused your problem.

Chuck.

 

[seedtick]

you already figured it out, you're mixing too big of a batch

the epoxy reaction is exothermic - it gives off heat as it cures and the only way it loses heat is through the surfaces of the batch

as you inrease the batch size the surface to volume ratio decreases so it's trying to give off more heat through a relatively smaller surface area. It can't do it so the batch heats up. The higher the tempeature of the batch, the faster the reaction progresses and the more heat it gives off. Kind of like a snowball rolling downhill.

You can slow the reaction down by mixing in a shallower container so it's spread out more, or chill the resin and hardner before mixing, or keep the unused part of the mixed batch in a refrig or freezer until you need it - even if it's only a few minutes, it helps.

obviously a slower hardner and working faster helps also

 

[gbinga]

I always try to be careful about where I put the leftover epoxy, paper towels, etc when I quit working. Had a batch cook off just exactly like you described one time, and it made me think. Need to be careful with epoxy leftovers just like you do with oily rags (linseed and similar oils give off heat as they cure)

With epoxy I usually put everything in a big steel washtub and set it outside in a place where it can't cause trouble.

With oily rags I usually put them in a chimney starter (charcoal starter for grilling out) and burn 'em.

Another exothermic reaction story - - At a door factory where I worked we used polyurethane foam - a two part industrial version of "Great Stuff" - to insulate steel doors. As part of the QA process we would do "bag shots", which were a couple of cubic feet of foam shot into a trash bag so as to analyze volume, density and shrinkage. Put one of those in a dumpster before it cures, buried under a bunch of trash, and you have yourself a fire.

George

 

[rpecot]

More baby steps :wink:

I've got my inside fillets done. Today I flipped the boat and trimmed off the excess on the bottom panel. First I used a flush trim bit on the router, but there was still a little bit left. I tried the round over bit, but because of the angle of the sides, I still couldn't get it all the way flush. So out with the random orbital sander. Getting ready for glass. Guess I need to get that ordered.





The bottom isn't perfectly symmetric, and there is a little bit of a twist to 'er, but hell with it. It'll be good enough for me. I'm liking the way it's coming out

 

[seedtick]

bottoms don't need to be perfectly symmetric

99% of the folks won't notice it anyway and to those that do, make up some BS story about friction losses vs. hull shape.

BTW looking good

 

[bearridge]

Good goin' Russell,

I kinda like the grain 'n that EKG cross the bottom. I know ya'll tole us, but how come ya'll put a flat bottom on them pirogues, instead of a roundish bottom.

regards
bearridge

Owners of capital will stimulate the working class to buy more and more expensive goods, houses and technology, pushing them to take more and more expensive credits, until their debt becomes unbearable. The unpaid debt will lead to bankruptcy of banks, which will have to be nationalised, and the State will have to take the road which will eventually lead to communism. Karl Marx (Das Capital)

 

[oldsparkey]

Love that grain in the wood , it will be really nice when epoxied and glassed , you have a winner.

Chuck.

 

[Steve]

Russ. . . gotta go with the guys. . . you done good. . . that a fine feather in yer cap, my friend. . .

 

[rpecot]

Good goin' Russell,

I kinda like the grain 'n that EKG cross the bottom. I know ya'll tole us, but how come ya'll put a flat bottom on them pirogues, instead of a roundish bottom.

regards
bearridge

Re: the EKG panel...
That was the replacement piece I went and purchased after my first little mishap (shown somewhere earlier in this thread). The ply was a little spalted and looked interesting. More likely, it was the first decent sheet in the stack at Lowe's.

Re: flat vs. roundish bottom...
Depends what you can "roundish." It does have a moderate amount of rocker. At least, compared to my 17' aluminum barge... I mean... Grumman. Of course, it's flat side-to-side.

 

[bluegrasslover]

Looking good man!

 

[jdupre']

Good goin' Russell,

I kinda like the grain 'n that EKG cross the bottom. I know ya'll tole us, but how come ya'll put a flat bottom on them pirogues, instead of a roundish bottom.

regards
bearridge

A few reasons I can think of : easier to build- flat ribs are easier to shape than curved..... shallower draft- these boats were made to work in skinny water........ stability going over obstacles- vee and rounded bottoms are unstable going over logs and such. Pirogues were not really considered long distance paddling craft so the 1% loss of efficiency of a flat bottom was not a consideration. Think of a pirogue in it's natural enviornment as part wheelbarrow and part working platform on the water.

 

[Kayak Jack]

Part wheelbarrow? That explains a lot. You do a nice job of paddling your wheelbarrow, Joey. When you get that kayak put to work, you'll be using something more like a bicycle - faster than a wheelbarrow, carries less, meant as a stealth boat for hunting from a seated position.

 

[skiwright]

Great job! If mine had turned out that good I would not have had to paint it.

I had the same problem with the epoxy. I had finished the fillets with no issue. I was trying to rush the bottom fiberglassing and made up a big batch of epoxy. By the end of the batch it would not wet out the glass and I had to sand it all off and start over.

BTW, when I scarfed the sides I had too much beer and they ended up 1/2 inch off on either end. I reversed the sides and the difference was 1/4 in in the middle and 1/4 in at the ends. It caused a twist in the boat but I can't feel any ill effects when I paddle the boat. I would not worry about the bottom of your boat.

 

[rpecot]

Fiberglass cloth ordered. In the mean time, I started "testing" epoxy applicators for the saturation coat on the interior, which will be painted. First test, one of my wife's craft foam paint brushes. Result: FAIL. Left lots of little bubbles (or "dubbles" as the 3yo says) and bled a little bit of blue paint still in the foam. The little bubbles sanded and scraped off really easy though. One positive: Carbide scrapers RULE!

 

[bluegrasslover]

I agree with the carbide scraper! I found that the foam brushes got too mushy. I didn't like the foam roller either. Chip brushes worked the best for me.

 

[rpecot]

I was starting to get jittery. Glad the forum is back up. :roll:

Did my saturation coat on the exterior. Went pretty easy. I've settled on using the plastic spreaders from Home Depot.





And you might want to get your cardiologist to read this chart:


Fiberglass cloth was delivered today. I'm liking how it's coming along...
8)

 

[bluegrasslover]

Looking good.

 

[oldsparkey]

I was starting to get jittery. Glad the forum is back up. :roll:


And you might want to get your cardiologist to read this chart:

Heck that could of been anyone's EKG while the forum was down and folks were trying to get on it. :lol:

 

[rpecot]

Fiberglass cloth cut to size:


Now all I need is more resin. I've only got a few pumps left. I'd run out to West Marine, but seeing as my wife is slaving away in the yard right now, that might not be the wisest of choices. :x It'll have to wait.