As I was shaping and finishing the rear section of the velomobile plug, I ended up with 2 different and distinct designs left and right, mostly caused by my being over-zealous with the hot wire foam cutter on the left side. After thinking and musing about it I decided the right side was a more appropriate design.
So I had some significant areas on the left side that needed to be filled so I could make the symmetry match, left to right. Filling all that area with auto body filler would have taken a couple gallons of filler, and ABF is not meant to be a filler for such a thickness.
In my most recent order with FibreGlast I ordered what they call a mix and pour 2
part expanding foam kit. The kit has 2 metal cans, about quart sized but they are marked with their weight rather than volume. One of the resins is slightly denser than the other. Price wasn’t that bad, I think $35.
These two resins are mixed in a one to one ratio, rather than a weight/percentage ratio like all the resins I’ve been working with. So I also purchased some of these little mixing tubs, which were quite handy in pouring out the correct volumes. I ended up re-using them a few times so I got my money’s worth 🙂
This was a great time to figure out how this stuff works; I’ve never used it before.
I rotated the plug so that the left side was facing up. I built a quick little dam from coroplast sign material, taped it in place with flash tape and duct tape, and mixed up some resin. The resin is a bit runny when first mixed together. I was expecting a rather quick foaming, but it was more sedate.
After about 45 to 60 seconds of stirring the two resins together, the foaming would start to accelerate a bit. I used a throw away bristle brush to apply the resin as well as simply pouring larger amounts in areas.
But the resin would tend to run downhill when I gave it a chance. After 2 applications I found the best application method was to build any dam needed, and brush and pour the resin where needed. When the resin would try to make a little river downhill I would use the brush to bring the resin/foam back to the spot I wanted it.
After a minute or so the foam would become more solid and would stay where I brushed it, then I could leave it alone to expand and cure. The foam would be fully cure in an hour, and could be sanded.
This foam is very different than the polyisocyanurate foam I typically use for plug making. Stronger, I used the air orbital sander to shape this foam.
I’m looking forward to getting the left side completed. Once that side is complete I will rotate the plug back to upright, and finally be able to remove that center metal spindle. Then I can complete the nose and tail designs.
The tail cone will secure to the main body using 10 screws, very similar to the WAW’s 9 screws. I’m adding one more screw to my design, I’ll explain in another post.
It’s not difficult to remove the tail cone on the WAW or on the Zephyr, but since the rear wheel will (hopefully) be mostly covered by a fairing, putting air in the rear tire would be awkward. Also there is the air shock for the rear suspension, those things need regular checking.
So I decided to add two access panels into the design. This is the access panel for the air shock.
Once the sides and access panels were ready, I rotated the plug 180 degrees, so the underside was facing up.
My earlier work on the reinforcement ribs was sloppy, the left side rib was visibly larger than the left and not very straight, so I ripped the left rib up a bit and rebuilt it, along with completing the third and final revision to the rear wheel cowling.
Once I had it the underside ready I went ahead and sprayed the bottom with 2 coats of the gray molding gel coat, and sanded it down to a “mold ready” finish. I didn’t want to do all this sanding later on, while climbing under the plug! Here it is next to the WAW.
Once the underside was done the plug was flipped upright once again, and I finally could remove the metal spindle and my support columns. I used some rock climbing gear and some simple rope pulley set ups to levitate the plug up and onto a work table.
Once all the gray gel coat was on, and before starting all the necessary sanding, I had to move the plug outside for a photo shoot next to it’s two inspirations….
There were a few areas on the access panels that I couldn’t get to a satisfactorily smooth level before spraying the gel coat. You can see here in this photo, where there are still low spots, they appear darker because they haven’t been sanded. This was after two coats of gel coat. Now it will get a third coat which will help to really fill in those low areas.