Finishing the Tail molds

Once the resin was all set on the lower right side tail mold, it was time to remove the polyethylene walls and the foam blocks, and start preparing to make the lower left mold next.

I now realize I used too much hot glue between the foam and the plug… I figured the glue wouldn’t adhere well to the plug after 4 applications of release wax. I was wrong, so it took a lot more effort to remove all the glue. Had to use a combination of acetone, which wasn’t really working on the glue, and using Goo Gone, which did a better job.

I also tried a heat gun on the glue first, but that just seemed to make more of a mess. Best approach was to sharpen a popsicle stick into a nice sharp scraper, and slowly work my way under the glue using a slicing type of motion. In this photo the polyethylene has been removed, that comes away very easily.

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I had actually been stalled at this point for a few weeks; initially it was because I ran out of resin, so I had to wait for an order to arrive. When the order finally arrived it included some 2 ounce fiberglass cloth to use as that initial layer after the gel coat.

That worked out much better, still problems with small air bubbles around the access panel. I worked on them, stipling them in with a bristle brush, until the resin was finally curing up enough to hold the cloth where I wanted…. mostly. After that it was the same process: 2 layers 3K CF, a cross of UD, and then a finish of CF veil.

Someone commented recently to a post, reminding me about a better process for areas like this: make a paste with some microfiber beads or chopped CF and press into those areas first, to create a smooth radius for the CF cloth to work with better. Yep, good reminder to me, I’ll do that next time. Although these molds around the access panels are the most detailed areas on the plug, other areas are smooth curves or bumps.

Here’s the finished lower left side. I’ve installed a bunch of these Clekoloc clips in place along the tail and underside, to insure these 2 molds stay together. Combined with the curvature on the upper edges of these molds, the molds won’t go anywhere until I’m ready to remove them. The clips are a nice simple system; a special pair of pliers to install or remove the clips, insert into 1/8″ holes, quick and easy.

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When removing the green foam blocks to prepare for the next mold, a small area of gray gel coat stayed with the glue, so it made a small hole in the plug. The more inexperienced Me would have stopped work on the molds to fill that hole with body filler, and apply more gel coat to fix the damage; and most likely it would have taken a couple attempts to get it done well. (Also at the top of the photo you can see a rippled area; that happened because of varying temperatures while the orange gel-coat was curing. My fault for trying to ventilate the workshop too early. Fortunately it’s only on the flange and not the mold surface itself).

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Now I recognize on small damages like this, a simpler approach: fill this with molding clay, match as best as possible, and make the mold. Filling with clay will invariably leave a slightly lower area relative to the gel coat surrounding the hole. But when you make the mold, it will be a positive area that can be sanded out easily enough.

Here you can see I used a lot of molding clay on the back side of the poly, to help form and keep the contour that I want. The top mold is finished in this photo, just getting ready to remove the three molds. I was just starting to install mold clips on this new mating flange.

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I put together a time lapse video while I was making this third mold for the tail cone.

I used an oscillating saw with a carbide cutting blade to cut off excess areas on the flanges. Worked nice and quick, but I wouldn’t use it on something that needs to be more precise. Now it looks like a SteamPunk velomobile!

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When it came time to remove the molds, they came off the plug pretty easily, which is always a relief!

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