skinning over windows

[Raymond smith]

We want to skin over our windows ( after removing old windows ) I was told to heat the skins prior to fastening to avoid warpage. My question,how do i heat it? Thanks in advance Raymond

[belfert]

A lot of people use a propane or kerosene torpedo heater aimed at the metal to heat it up.  Aluminum will have more issues than steel with movement.

[Raymond smith]

I am using 26 guage galvanised painted black on one side - gray on the other side. Each skin is 34 feet long and 41 inches wide.Raymond

[buswarrior]

34 FEET long?

Hold the phone, you want some tension on that as well as heat, to keep it from oil canning once you are done.

Where's the experts in this bigger sheet install?

happy coaching!
buswarrior

[Seayfam]

Wow! 26GA seems awfully thin to me. I think no matter how tight you get it, in the heat of the day, it will be wavy. When I have done metal, I used a weed burner and started in the center and worked out.

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[TomC]

Just my opinion-but I would cover each window with a separate sheet of aluminum.  When painted, you will hardly be able to tell.  I wouldn't mix aluminum with steel sheet-just asking for galvanic corrosion-even with the sheet galvanized.  WITH it galvanized-it will be very hard to keep paint on it since galvanizing is made to sluff off.  You should rethink your method.  Good Luck, TomC

[Jeremy]

I'm sure I remember seeing photos on the website of (I think) a professional bus conversion company showing a large, flat-panel electric radiant heater mounted on a tall stand being used to heat a long skin as it was being attached to a bus. I can't find that photo now, but here's another of a couple of small gas space heaters being used:




These photos show a long aluminum skin being attached; no problem at all having a one-piece skin, but in the first photo below the aluminum looks to me to be very thick indeed - almost plate rather than sheet. Three different buses in these photos you'll notice.





Just to stress that I've no personal experience of doing this myself; personally I'd use glassfibre skins, and they'd be bonded-on without a pop-rivet in sight.


Jeremy

[robertglines1]

26 ga is lite duct work material is going to show every fastner and limb scrape. I use 16 ga cold roll. I tried 18ga and had warpage problems took it off. no alum vs steel argument! Just my preferance.  Heat isn't going to make much differance on material that liteweight except show how eeasy it will deform in sun.  In the end do it you way. and if you use heat on a area that large it is going to heat and cool fast on something that thin so you will have to work in heated area.Can't imagine the handling problem with a sheet that thin and long trying to keep it from kinking.     Do it your way.  Good luck .   Bob.

[Raymond smith]

I made a mistake, it is not 26 guage , it is 20 gauge material that i have. sorry folks.Raymond   PS thanks for all the replys

[Charles in SC]

I remember reading on this forum about skinning outside in the hot summer time. Turn the bus so you are working on the sunny side and the sun will heat it enough to make it tight. At least in the south. I would think you would want thicker metal.

[John316]

I made a mistake, it is not 26 guage , it is 20 gauge material that i have. sorry folks.Raymond   PS thanks for all the replys

I don't know even about the 20g. If it were me I would probably go with 18 minimum. However, some of the other guys might have a better thought.

FWIW

John

[buswarrior]

In heating the skin as you are installing it, I think the principle is to get the metal a bit hotter than the sun is likely to get it, then you get more stretch than it is likely to encounter, thus preventing it from doing the oil can bulge between fasteners.

Everything cooler than install temp will pull the skin tight.

As for metal thickness, you want a skin that will resist a tree branch being dragged across its surface. Too thin, and a branch will leave a crease, making you very sad.

Bus campers are prone to dragging through a lot of trees on the sides of roads/trails/campsites.

happy coaching!
buswarrior

[TomC]

On most commercial trailers and straight truck boxes, they use .030" thick Aluminum sheet.  I used .060" on my truck for branch resistance.  I don't know what that converts to in gauge. Good Luck, TomC

[belfert]

.030" aluminum is the same thickness used on most enclosed trailers.  That thickness is not resistant to much abuse and I know from experience that road salt will eat right through it even when coated with whatever they use to color it.  Some trailer manufacturers are even using .024" to save money.  They might as well use aluminum foil!

I certainly wouldn't use anything as thin as .030" aluminum if I wanted my bus to look good long term.

[Uglydog56]

My bus is skinned in .050 aluminum.  It hasn't creased yet, but I certaintly wouldn't go thinner.  Additionally, while I haven't used any for bus skinning, I have built panels out of 20 gauge for other non-bus projects and they are too easy to wrinkle and tear.