Frameless construction

[dwgriff1]

Thanks Andrew.

That pretty well explains the system I used.

dave

[reiltear]

I was at HD yesterday and found that one can order a 4' by 8' hollow-core door for $82.00(Long Beach price).

Any thoughts on this?

Thanks, Ilya.

[Miriam C.]

It would be less expensive to make one from foam and 1/8 or 1/4 ply.

[Arne]

Andrew, I don't have any cad drawings, but have briefly thought about having the tear come to a point in the front, where the top profile meets the bottom profile.. not an actual point, but a very tight radius, probably formed by using strip kayak pieces, which are cove and bead, 1/4 x 3/4... and maybe a 6" radius....

I'm pretty sure that tight a radius would be tough even with 1/8 plywood...

but, is it worth the aerodynamic effort to do that instead of a larger radius with 1/8?

And also, without going to bendy ply, what is the tightest radius anyone has gottent with 1/8, and how did you do it.... wet it, steam it, alcohol, etc.?

[Cary Winch]

We bend 1/8" plywood paneling in a couple of spots. The roof paneling bends in fine without anything special at about a 20" radius. The front storage box skins are about a 11" radius and we have to soak them for a few hours in a form to get it in the general shape before installing. If we just try to bend it on dry it will rupture about 25% of the time. On a unit with a furnace we bend a panel with about a 9 - 9 1/2" radius. We do this wet and prebent too. But, we have a high rupture rate on these, on the ones that survive we then glue on reinforcements strips to hold it in shape before it dries. Because then it will possibily rupture after it dries with that tight a radius.

So, with 1/8" paneling I woul say you can do around 18" safely dry maybe down to 12" with a risk of rupture. Wet it will do 10-12" pretty well. Smaller than that is then would require probably a aircraft grade plywood (we are just using cheap Luan paneling) and a steaming setup.

Cary

[Arne]

Cary, thanks for the real world feed back.. the very tight radius gives a 'strange' look to the front, but am going for light and aero on this one.

[brian_bp]

I have seen "hollow-core" doors in which the cardboard core is very open, providing little local strength - these are the ones which get holes accidentally punched in them. I would want to check out the internal construction detail carefully before using one.

I quickly found an example of a hollow core door; those are pretty big honeycomb spaces. Some doors (like this one from General Veneer) are not honeycomb, but wood strips. I also stumbled across some design overview information from CraftMaster (who I know nothing about, but they seem to make a variety of doors...). They mention that not all cardboard-cored doors use a honeycomb.

[Arne]

re hollow core stuff... my plan is to use 3/8 on top of floor, 1/8 on bottom. Inside will be strips and rigid foam... the strips will form girders with the ply, the foam will provide 'anti-sag' in between.... am still thinking about strip spacing, but am looking at 8 inch spacing right now.. strips will be 3/8 ply. The foam and strips will be 1" thick/high. There will be no steel x-members except at the back where the battery, microwave and pet cool will sit... there, the floor will be double 3/8 on top.

Outer perimeter of floor will be a mix of 2x3 and 2x4 (needed to bolt suspension to).

Walls will be 1/8 inside and out, built the same way, with 'nailers' where I need them.... design will be .... critical.. using lots of graph paper.

[asianflava]

I have seen "hollow-core" doors in which the cardboard core is very open, providing little local strength - these are the ones which get holes accidentally punched in them. I would want to check out the internal construction detail carefully before using one.

Accidentally huh?