Sunday, April 29, 2012

Framing and Skinning the Walls

The above layout is for the frame of the walls. Both walls are framed exactly the same. I am using 2 4X8 sheets of 1/8 inch masonite to sandwich the frame on each side. The lower right section of this frame will be skinned with a full sheet. Imagine the top left of the door frame being the top left corner of a 4X8 sheet. The second sheet is split lengthwise into two pieces 2 feet by 8 feet. One of these will be placed in a vertical orientation to cover the very left (front) section of the frame. The other piece will be laid in a horizontal orientation to cover the top right portion of the frame. You kinda have to use your imagination because I did not get a good picture of this. The frame is made of 1X4 pine. Which is actually 3/4 inch by 3.5 inches. Note that the very rear section of the frame which has quite a tight curve was cut from 3/4 inch plywood. I have one sheet which I will be using for the counter top of the galley. I am using part of it for this part of the frame and to frame the galley hatch which you will see later.

Oh, in the previous blog entry I mentioned the set back. I eventually settled on 1/8 inch masonite for the inner and outer skin. I would have preferred to use the luan for the wood grain but the luan plywood I got my hands on was junk as mentioned in the previous blog. The masonite will need to be painted instead of stained and finished but it should have good quality and structural integrity. The exterior is going to be covered with fiberglass and painted anyway so I did not care about the wood grain on the exterior but I will miss it on the interior.

I joined all of the pieces of the frame together with wood glue and pocket screws. I had never used them before. Here is the jig you have to buy to drill the pockets. It comes with a special drill bit, driver bit and pocket screws not shown. It works really slick.

Here is a picture of the frame fastened together and laying on the masonite in my basement. Sorry about the weird orientation of the photo.

And here is a picture of the frame after I have skinned one side and cut the foam insulation for all of the spaces. 

Its laying on top of the trailer. A few things to note here. I placed 2 inch pieces of 1X4 in all of the spaces so that I can have a solid glued link between the sandwich of skins. The frame and these blocks are all glued on both sides with a generous amount of gorilla glue. I like the gorilla glue for this application because is is strong and it foams up to fill in gaps so there is a continuous bond even in places where I don't have the gap completely closed. While the glue is still wet the masonite is tacked in place with #6 screws 5/8 inch long. I placed them about 6 inches apart around all of the edges and along each frame member to hold the sheet down while the glue set. I also placed weights on the entire frame after gluing to try to get a good seal everywhere and keep things from separating. I glued the foam insulation on both sides into the sandwich using liquid nails construction adhesive. The adhesives are costing about the same as the lumber for this project. Note also a set of wires running through a block of wood above the door opening. This will be for the "porchlight" which will be switched from inside the compartment so that you can see outside if you need to go out in the dark. 

Well, I feel pretty good about the progress so far and these frames seem very strong when the sandwich is built up. The are considerably lighter than using 3/4 inch plywood and the insulation should help a good deal in hot or cold conditions. 

In a week or so I hope to have some nice pics of the walls mounted to the trailer. That will be a real milestone because you will have a taste of the 3D shape of the project.

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