Large fiberglass mold questions
Large fiberglass mold questions
(OP)
Hello,
I am involved in building a mold for a small single person wet submarine for an international contest my college engineering club has decided to enter for the 2nd year in a row.
Last year another college built out hull and it didnt make it to this year... I have decided to undertake the construction process of mold making and casting the hull out of fiberglass.
I have a few kinks to work out and I will start with the basic plan of attack in order to get feedback.
After designing the general dimensions of the hull, we plan on making foam washers of the desired diameter and skewering them onto a pipe to make the basic outline of the body. --- it will look like a function that has been estimated by a riemann sum. The surface will be sanded smooth by rotating on a rotisserie. The pipe will be removed and a layer of bondo will be applied. When sanded smooth again, it will be molded.
This is where it gets a litte grey.
What I was thinking of doing was taking two 1/4 inch sheets of plywood and cutting the shape of the plug into the center of each in oder to bisect the plug. After prepping the plug with mold release, laying layers of glass to one side, letting it dry and repeating for other side. Then splitting the two pieces of plywood in order to remove the plug. Now I sould have my two sides of the mold to cast the final product into.
This sounds like the best way of doing this to me but I have not any experience in mold making of this size.
Not to mention, Im not sure of what type of foam to use...
Any suggestions would be appreciated.
I am involved in building a mold for a small single person wet submarine for an international contest my college engineering club has decided to enter for the 2nd year in a row.
Last year another college built out hull and it didnt make it to this year... I have decided to undertake the construction process of mold making and casting the hull out of fiberglass.
I have a few kinks to work out and I will start with the basic plan of attack in order to get feedback.
After designing the general dimensions of the hull, we plan on making foam washers of the desired diameter and skewering them onto a pipe to make the basic outline of the body. --- it will look like a function that has been estimated by a riemann sum. The surface will be sanded smooth by rotating on a rotisserie. The pipe will be removed and a layer of bondo will be applied. When sanded smooth again, it will be molded.
This is where it gets a litte grey.
What I was thinking of doing was taking two 1/4 inch sheets of plywood and cutting the shape of the plug into the center of each in oder to bisect the plug. After prepping the plug with mold release, laying layers of glass to one side, letting it dry and repeating for other side. Then splitting the two pieces of plywood in order to remove the plug. Now I sould have my two sides of the mold to cast the final product into.
This sounds like the best way of doing this to me but I have not any experience in mold making of this size.
Not to mention, Im not sure of what type of foam to use...
Any suggestions would be appreciated.






RE: Large fiberglass mold questions
RE: Large fiberglass mold questions
Underwater, smooth taperd surfaces are key to speed (forgot to mention it is a speed contest (human powered)). Not to mention that having a company constructing the hull eg. filament winding is against the rules.
Its gotta be split so we can install and secure our equipment because its gonna be a tight fit for one person as it is.
RE: Large fiberglass mold questions
How are you going to get the person inside the shell? Split the case of through an access hole? Emergency removal of a person from a split case system I believe would be time consuming and more dangerous.
Could you post a link to the rules of this competition?
RE: Large fiberglass mold questions
I dug further today and found a reliable source that gave some instruction to work out the kinks I had. I currently have a firm plan of action and plan on executing it by this weekend.
RE: Large fiberglass mold questions