18ft molds

[Nick F]

Hey guys

A question for all the mold builders out there. I am about to embark on a project to make some molds for a 18ft run about.
In the past I have built and used molds that are made of solid polyester resin and chop strand matt. I have been looking in using A profile resin or tooling resin which has very minimal shrinkage but it is twice the price of standard polyester resin.
My main question is weather the mechanical advantages (Accuracy) of tooling resin is worth the extra cost.
What is seen as the best laminate for a mold these days? (Solid glass or with a core i.e. Core mat?)
A monolithic mold construction seems a waste of material or am I missing something here?

Any input greatly appreciated

Regards Nick

[jim lee]

No one else is saying anything..

Some like the new non-shrink resins. Some are not so happy. If I was in your place, with a system that worked in the past, I'd look really hard at what I was trying to fix by using a new resin.

-jim lee

[Nick F]

Jim
Thanks for reply: I guess im just woundering what is working for people and weather its worth me doing some testing with the tooling resins. The main advatage i can see is being able to make very accurate molds. for a 18ft runabout/tender i dont think the accuracy is needed.
Maybe with no one answering, that might be that answer to my question. ha
Regard Nick

[Herman]

I do like the low profile tooling resins. I did see some difference between them, however.

Difference is not only in the accuracy of the mould (which is less important for an 18ft boat, but I must say as well that it is very annoying if you need a ton of clamps just for glueing the hull and deck together, just because they do not really fit onto each other).
Main thing is the surface quality. A high quality boat has a high quality surface, which can only be reached by using high quality moulds, from high quality plugs.

One of my clients just made 2 sets of moulds, in 2 different places, by doing the following:

-cover all windows with brown packing paper. Install extra lights. (you really do not want the sun to attack your mould. This is a common cause for problems, and covering the windows is a much forgotten step.
-fairing the plug to high quality standard. Lot of elbow grease. Then paint with a 2K pu paint. (applied with a roller, he is a master in rolling pu paint)
-let cure for a week
-buff to high sheen, apply mould release
-apply tooling gelcoat (really, these are much tougher then normal gelcoat)
-apply rapid tooling system (in this case RM3000 from Nord Composites in France). This VE based system gives even better results than the RM2000 system, which needs a couple of skin coats, to keep the surface OK.

I hope this info helps...