Here is part of the news you've all been waiting for-- the mold for the lower hull has been started. Finally. At LAST. I won't go into the process, but figuring out how to make this mold has been one of the worst brain-teasers I've experienced. Everytime I tried to plan this thing, I'd run into a dead end. I knew I had to add venting fins to the top and bottom of the part, so I put those on, and I was ready to continue with a plan that would have worked, but would have been very complicated. The new solution hit me like a ton of bricks while I was eating a Taco Suave for lunch the other day...
So, here we go--
I'm not going to explain all the circles, other than to say they are planning aids. The inner circle represents the inner wall of the interior core mold. The straight lines are used to locate the holes in that wall where registration rods will be inserted. The next circle out represents the part, the lower hull. The straight lines also indicate where the rods will penetrate the fin on the bottom of the lower hull.
Here, you can see one of the plugs inserted into the opening for the landing gear. This plug will be removed before the exterior part of the mold is poured. On the plug in this photo, you can see the shapes I added for registration. In case you're wondering-- yes, they are wiggle eyes!
In this shot you can see the interior wall of the mold and all of the registration rods. I changed the pattern of the rods while I was installing them, so they don't follow the lines I drew. This new pattern makes better use of the 6 rods.
This shows how the ends of the rods penetrate the fin and you can also get a better look at the plug. The plug was made by first pouring some resin on a waxed surface and letting it set up. I made a pattern out of paper and then cut the plug out of the sheet of resin. The plug started out flat, but I was able to reshape it by heating it until it was soft and pressing it over a form that has the same diameter as the hull. When the resin cooled off, it was a simple matter of trimming and fitting it into the opening. Believe it or not, this was simpler than trying to fit a flat sheet of plastic into the same opening!
The fin was originally going to be for venting, but its purpose changed with the new solution. This fin and the plugs will be removed before the exterior mold is poured so the exterior mold and interior core will register with each other through contact at the landing gear openings.
Clay is used to prevent the rubber from leaking through the holes for the rods.
So, this is the first part of the pour that will form the inner core. The core has to hold its own shape and yet be removable by collapsing it and pulling it out of the part. The core also has to be registered at both the top and bottom. The registration at the bottom orients the two parts of the mold correctly and the registration at the top keeps the two parts oriented so the venting fin can do its job. You can see the venting fin in this last photo, in the bottom corners. This fin is added to the part so air has somewhere to go and any bubbles that form will be in this fin instead of the part. When the casting is finished, the fin is cut off.
The next step is to do exactly what was done in these photos, but at the top of the part. I'll be doing that tomorrow and the photos will follow.
Scott
So, here we go--
I'm not going to explain all the circles, other than to say they are planning aids. The inner circle represents the inner wall of the interior core mold. The straight lines are used to locate the holes in that wall where registration rods will be inserted. The next circle out represents the part, the lower hull. The straight lines also indicate where the rods will penetrate the fin on the bottom of the lower hull.
Here, you can see one of the plugs inserted into the opening for the landing gear. This plug will be removed before the exterior part of the mold is poured. On the plug in this photo, you can see the shapes I added for registration. In case you're wondering-- yes, they are wiggle eyes!
In this shot you can see the interior wall of the mold and all of the registration rods. I changed the pattern of the rods while I was installing them, so they don't follow the lines I drew. This new pattern makes better use of the 6 rods.
This shows how the ends of the rods penetrate the fin and you can also get a better look at the plug. The plug was made by first pouring some resin on a waxed surface and letting it set up. I made a pattern out of paper and then cut the plug out of the sheet of resin. The plug started out flat, but I was able to reshape it by heating it until it was soft and pressing it over a form that has the same diameter as the hull. When the resin cooled off, it was a simple matter of trimming and fitting it into the opening. Believe it or not, this was simpler than trying to fit a flat sheet of plastic into the same opening!
The fin was originally going to be for venting, but its purpose changed with the new solution. This fin and the plugs will be removed before the exterior mold is poured so the exterior mold and interior core will register with each other through contact at the landing gear openings.
Clay is used to prevent the rubber from leaking through the holes for the rods.
So, this is the first part of the pour that will form the inner core. The core has to hold its own shape and yet be removable by collapsing it and pulling it out of the part. The core also has to be registered at both the top and bottom. The registration at the bottom orients the two parts of the mold correctly and the registration at the top keeps the two parts oriented so the venting fin can do its job. You can see the venting fin in this last photo, in the bottom corners. This fin is added to the part so air has somewhere to go and any bubbles that form will be in this fin instead of the part. When the casting is finished, the fin is cut off.
The next step is to do exactly what was done in these photos, but at the top of the part. I'll be doing that tomorrow and the photos will follow.
Scott
