Permit Kits now in production.

[Parallax]

I would be very interested in seeing a video on the entire process. I am not familiar with vacuum bagging, is it similar to thermoforming? I really need to become more familiar with a lot of these techniques as I would very much like to make my own kits one day, to fill in gaps for subs and ships that are not currently available. ( Maybe ww1 era U-boats like UB-iii's, or the British Trafalgar class) And Matt please don't forget about me when the Sturgeons become available

[thor]

Thanks, Mike. Will do. I am very close on the Sturgeon and the Oscar II.

[thor]

All Precision Pattern kit propellers will now be cast with a brass shaft sleeve. The purpose of this is to make certain that the bore of the propeller is 100% round and dead center.

You will find that other kits will have the propellers bored after de-molding and are solid white metal. White metal can be very soft and is easily bored off center which allows the propeller to wobble and run unbalanced.

The other downside of a while metal bore is that bore wears very quickly when placed on a stainless shaft which will, once again, lead to a propeller that wobbles, out of balance, or both. It can, also, lead to the loss of a propeller while on patrol....

[thor]

Here are some photos of a Permit kit being vacuum bagged for a customer last night.









If you look closely at this last photo, under the green bagging membrane you will notice light and dark spots in the bleeder cloth. These are areas where excessive resin resides which increases the weight and volume of the part, while greatly reducing strength!

If anyone ever tells you that thicker is better in fiberglass construction they have absolutely no idea what they are talking about, especially in this hobby where ballast tank size is greatly influenced by mass & volume of the waterline up structure. Mass is not required for strength, only a properly designed laminate with the correct cloth schedule and resin saturation.



This is after approximately 90 minutes of being under vacuum.

[thor]

Four hours after initial layup under vacuum. The bag and bleeder cloth have been stripped off the nearly cured fiberglass part. Now, into the autoclave for some baking at temperature! This assures consistent material properties with zero uncured areas which is very common in lesser laminates. The white material you see residing on the inside of the laminate is called Peel Ply. It removes the amine blush that greatly reduces the ability of other glues to adhere to the fiberglass part, plus it leaves a beautiful surface that is 100% ready for bonding WTC saddles or whatever you may wish to attach. Otherwise it is required to get out the grinding wheel and grind away to remove the amine blush and make the part suitable for adhesion.



The peel ply will be removed after 6 hours of baking in the autoclave revealing the lightest and strongest part available. There is significant use of carbon fiber cloth in all of these parts.

[sam reichart]

cool stuff, Matt. I only had a foggy idea in my head how vacuum bagging and the build process went nowadays on hull kits. awesome!

[thor]

These photos show the laminate after the peel ply has been stripped and spending 6 hours in the autoclave, revealing a very nice, clean, and extremely strong part.



Notice the flat surface left behind by the peel ply. No amine blush dulling the surface nor shiny surface left behind by the use of excessive resin. No sanding or grinding required. You may proceed directly to construction without getting all dusty and itchy.



Close up of newly revealed surface.

[sam reichart]

how do you get the edges of those hull halves so smoothly cut?

[thor]

Sam-Another trade secret, but I'll share. I pull the bag & bleeder cloth when the resin enters the 'B' stage of cure. It is rigid, but not completely cured. It is still somewhat pliable, so I use industrial razor blades to trim the laminate off even with the parting flange on the mold. This will not work well with standard 'resin only' molds that do not utilize a very robust tooling surfacing resin. After the part is trimmed and checked, the mold containing the part goes into the autoclave (pressure oven) for 6 hours or more, depending on the resins system, size of the part, and laminate schedule.

[sam reichart]

Sam-Another trade secret, but I'll share. I pull the bag & bleeder cloth when the resin enters the 'B' stage of cure. It is rigid, but not completely cured. It is still somewhat pliable, so I use industrial razor blades to trim the laminate off even with the parting flange on the mold. This will not work well with standard 'resin only' molds that do not utilize a very robust tooling surfacing resin. After the part is trimmed and checked, the mold containing the part goes into the autoclave (pressure oven) for 6 hours or more, depending on the resins system, size of the part, and laminate schedule.

gotcha. neat trick; the hull half edges are so smooth that I assumed you had a way to trim them that wouldn't screw up your molds...

[thor]

Here is a small example of the huge advantage that a vacuum bagged hull kit with carbon fiber parts can provide.

The first photo below is of the standard urethane resin sail provided with the 1/96th Permit kit. Notice that it weighs in at 30 grams. Not too bad!



The next photo below shows the all new Carbon Fiber Vacuum bagged sail for the 1/96th Permit kit. It is every bit as strong and rigid as the urethane resin sail, however it only weighs 5 grams!

That is an 83% reduction in weight and an even larger reduction in the volume displaced by the sail! This means a significantly smaller ballast tank will do the trick which opens up more room for other things.

The other advantage of glass & carbon fiber over urethane resin is the overall strength and robust nature of the material. Urethane resin can be very fragile and quite heavy.

[eckloss]

83% difference. That's extremely impressive!

[thor]

A few quick shots of Permit upper hull halves after being trimmed and demolded.

[sam reichart]

They look awesome Matt. The weight reduction in parts is impressive. How much smaller are we talking about in ballast tank volume with that kind of weight reduction (for the Permit, for example).

[thor]

Sam,

I'm looking forward to testing the new kit to be 100% certain, but it should be quite significant. I'm estimating an overall reduction approaching 30%.