And here's the top of our plug in cure state. And the real treat is that you get to see one of the top secrets of the trade as practiced by me, hacker that I am...clothes pins!
Here's the deal:
Woven fabrics don't like to go around corners, especially sharp-ish ones. When they are asked to do so, they often do their best to straighten out into their natural position - flat. Sometimes, this is a good thing - like when straightening out forces them more firmly into the mold.
But with the part we're making here, the straightening out actually pulls the 'glass off the mold at the edges of the tank, which is the worst possible thing we can have happen.
To combat this, we actually have a few options:
1. We could paint in the initial layer of epoxy and let it cure until it's just barely tacky to the touch. Then fast as humanly possible, lay the first layer into the mold. and press it into the nearly cured layer. The tack holds the first layer right where we want it and after things are fully cured, we come back and lay up the rest of the part. But this is a plug that's going to be reshaped anyway so I don't care about a few flaws.
Plus, this method means I have to keep close watch on the part and I have a limited amount of time to get that first layer in. In all, it's too much effort for this plug and not necessary at this point in the process. I'm after investing as little time as I can in these non quality-critical parts.
2. We could vacuum bag the part. We'll be bagging the final carbon parts but again, for my money, overkill for this plug.
3. We do what I did here. I used the Partall on some large mixing sticks that I normally use to stir the hardner into the epoxy. Then I clip them to the mold to hold the composite in place during cure. Benefits? I don't have to play the waiting game in method #1 and I avoid the bagging process (more supplies used = more money) of method #2. Plus, it always tickles me to see this sort of thing used in this world of composites. So full of mystery and black art...and now, clothes pins and popsicle sticks, too!
Here's the deal:
Woven fabrics don't like to go around corners, especially sharp-ish ones. When they are asked to do so, they often do their best to straighten out into their natural position - flat. Sometimes, this is a good thing - like when straightening out forces them more firmly into the mold.
But with the part we're making here, the straightening out actually pulls the 'glass off the mold at the edges of the tank, which is the worst possible thing we can have happen.
To combat this, we actually have a few options:
1. We could paint in the initial layer of epoxy and let it cure until it's just barely tacky to the touch. Then fast as humanly possible, lay the first layer into the mold. and press it into the nearly cured layer. The tack holds the first layer right where we want it and after things are fully cured, we come back and lay up the rest of the part. But this is a plug that's going to be reshaped anyway so I don't care about a few flaws.
Plus, this method means I have to keep close watch on the part and I have a limited amount of time to get that first layer in. In all, it's too much effort for this plug and not necessary at this point in the process. I'm after investing as little time as I can in these non quality-critical parts.
2. We could vacuum bag the part. We'll be bagging the final carbon parts but again, for my money, overkill for this plug.
3. We do what I did here. I used the Partall on some large mixing sticks that I normally use to stir the hardner into the epoxy. Then I clip them to the mold to hold the composite in place during cure. Benefits? I don't have to play the waiting game in method #1 and I avoid the bagging process (more supplies used = more money) of method #2. Plus, it always tickles me to see this sort of thing used in this world of composites. So full of mystery and black art...and now, clothes pins and popsicle sticks, too!
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