Re: making the bulkhead thicker.
Er, no thanks. Not worth the trouble of changing everything I've already modeled in the galley, and don't want to lose any of the extra "tucking" space for the mattress on the cabin side. Besides, the 3/4 foam with wooden frame and skins will be plenty strong enough for the bulkhead because the loads are primarily in compression at the edges, or in shear at the skin panel glue bonds, not bending along the panel axis (so thickness here doesn't really add as much as you might think). There will be 3/4 foam in the dividing panels under the galley counter, too, so it's no big deal to buy a sheet or two. Still haven't ruled out using two layers of 3/4 foam for the roof...make it easier to form the curve, perhaps w/o the need for all of those messy kerfs. (We need a smilie for pink and blue foam dust!)
In another thread someone mentioned using a jig saw w/ the saw teeth ground back into a knife blade. That has my interest. I have always heard that an electric carving knife would work, but thought that would be more for the spongy types of foam and for free form carving, not so much slicing/parting/slab work on rigid. The family home (that I took over in my teens when Mom moved out, then passed to my sister when she moved back form Callie and I got married/moved out) has a bunch of stuff my mom left behind, including a seldom used elec. carving knife. Mom said I was welcome to it, so now it is just a matter of getting my sister to find it and pass it on to me to give it a try.
I do have a little bit of hot knife experience. Started to build an elec. powered foamie RC glider of my own design. Built a simple knife using inconel wire and a battery charger to cut the wings, guided by aluminum flashing rib templates pinned into the wing roots and tips. It didn't have any method to hold tension as the wire heated up, and there was no control over the current (except 6 or 12v), so on the second wing I had some dragging and a pretty good sized low spot...but a little light weight plaster spackle took care of that. Never finished or flew it, but had fun working on it as a hobby interest. Have a few balsa & tissue rubber powered free flight planes under my belt over the years. Every once in a great while I get the aero bug.
And now a build update,
I have started to build!!! Yippeee!
Well, so far all I have done is cut out the little steel end caps for the various trailer frame ends, but I wanted to have them for tomorrow when...
I start cutting steel and building the trailer. Yippeee!!!
soon. The piece of scrap steel I had for the little caps was easier to rip up on the large vertical bandsaw at work, than it would be to do at Karl's shop. He's got cut off saw, very large Marvel vertical band, plasma cutter, abrassive cut off wheels, etc., etc. His little cut off band saw can even be converted into a vertical saw with small table, but the 16 inch saw at work has a nice big cast table and a rip fence attachment, so that's what I did after work today. That and a little more detailing on the floor assembly drawings. Have to work out a few details in the "glue & screw" schedule to make sure that any fasteners holding the floor subframe together don't interfere with the later attachment of the walls. Had thought about using plate (biscuit) joinery for the floor frame, but that has some down sides to it, too. I think I can squeeze all of the screws in and have them be happy together, but it will take careful and accurate layout. Complicating matters slightly is the fact that the side rails of the floor subframe will be 1x on edge, so the fasteners on the insides holding the walls to the floor will have to be strategically located to land in the larger 2x floor xmbrs and the corner blocks where the floor anchors to the trailer frame. The screws on the outside of the wall will go through the base plate of the wall and into the 1x edging using a Kregg, so those can be located along the rails anywhere along their length. So for the narrow 1x on edge floor xmbrs I can screw straight through the centers from the outside, but on the 2x floor xmbrs I will place the screws holding the rim rails on towards the front half of these xmbrs, and the screws on the inside of the walls will be aimed down into the back halves of these larger targets. Seems like a lot of details, and potential error to save a little bit of weight, but everything is a compromise. I want the full perimeter steel frame that is tough enough to bottom out on a rock or three, but will try to win back that non-ultra light weight feature by being crafty in other areas. Planning and details I got covered!!
(light weight, probably not so much.)
On a side note, I have been doing a lot of stainless steel tube welding at work this week (I get to do the design work
and build the systems) and today I had some awsome beads...had to stop and take a pic of the lovley "row of nickels", thought I would use it as a teaser for you all for the fab work to come, I was so impressed with myself. For our sanitary systems (stainless steel food grade stuff) we butt the tubes and tube fittings, use a back purge, and do a full penetration fuse with no filler...comes out as nice on the inside as it does on the out..., but I forgot to put the somewhat blurry pic on my stick drive for to upload here this evening...so I guess it didn't really happen. (drat)