This topic is where you'll find news of what molds have failed and what has to be done to replace them. The reason this is important is sometimes how a part is configured will be changed to make it easier to produce. So--
The mold for this part failed, part of which you can see on the edge where the bevel is. The mold for this part is typical of molds that get 'rethunk' later. Part of the problem in casting this part are the details on the rear deck. They just want to trap air!
Here, I've taken the master and sprayed a heavy coat of red primer on the rear deck. Once the primer has cured, those detail parts will be popped off and two new molds will be made-- one for the part itself and one for the detail parts.
The details will now be supplied as separate parts. This makes painting them easier and if it becomes necessary to sand any part of the rear deck, the details are not in the way. What you can't see here is the 'footprint' for each of the details. That is what the heavy coat of primer was for. Unfortunately, the coat of primer wasn't heavy enough. But, placing these parts accurately, without the footprints, is pretty easy.
The original mold for this part was made in the simplest way possible. It made good parts, but sometimes air was trapped somewhere and we did encounter parts we could not put into a kit. Removing the rear deck details and molding them separately was the best solution, since that's where the air was trapped most of the time. This enabled me to build the new mold that would be the most reliable for the overall part. But doing so included a chance air could be trapped in another spot.
To insure no bubbles would be created, a small 'fin' vent was added to the part, which is indicated by the red arrow. Builders must remove this fin before assembly or they'll find things won't sit quite right! I also had to encroach into a surface I did not want to-- the broad, curved front. This is the only place I could put the gate and vents. This face is actually the easiest to repair, because of all the edges, it is the broadest.
Scott
The mold for this part failed, part of which you can see on the edge where the bevel is. The mold for this part is typical of molds that get 'rethunk' later. Part of the problem in casting this part are the details on the rear deck. They just want to trap air!
Here, I've taken the master and sprayed a heavy coat of red primer on the rear deck. Once the primer has cured, those detail parts will be popped off and two new molds will be made-- one for the part itself and one for the detail parts.
The details will now be supplied as separate parts. This makes painting them easier and if it becomes necessary to sand any part of the rear deck, the details are not in the way. What you can't see here is the 'footprint' for each of the details. That is what the heavy coat of primer was for. Unfortunately, the coat of primer wasn't heavy enough. But, placing these parts accurately, without the footprints, is pretty easy.
The original mold for this part was made in the simplest way possible. It made good parts, but sometimes air was trapped somewhere and we did encounter parts we could not put into a kit. Removing the rear deck details and molding them separately was the best solution, since that's where the air was trapped most of the time. This enabled me to build the new mold that would be the most reliable for the overall part. But doing so included a chance air could be trapped in another spot.
To insure no bubbles would be created, a small 'fin' vent was added to the part, which is indicated by the red arrow. Builders must remove this fin before assembly or they'll find things won't sit quite right! I also had to encroach into a surface I did not want to-- the broad, curved front. This is the only place I could put the gate and vents. This face is actually the easiest to repair, because of all the edges, it is the broadest.
Scott
