Post by Starflyte68 on Aug 13, 2022 21:27:33 GMT -8
So we all know that staples were the primary method for connecting wood studs and beams within the walls. I've often heard this was simply because it was buth adequate and cheap. The popular method with restoration is to use pocket screws, which add to the ridgidity, but is less efficient (we supposedly have time on our hands -I might also add our lack of the industrial staple gun). As I've been working on my trailer, I've been contemplating the engineering, both original, and with my pocket screw job.
These trailers need to flex a little for bumping down the road. Sure the dream of the mid-20th century was to pave everything, but they still needed to anticipate some pot holes. The brilliance of their trailer engineering was to make them strong yet flexible without rigidity. Cabinetry gave shear strength to the overall form of the trailer. The strength of the walls themselves came not from fastening studs and beams together, but by sandwiching them between well-attached paneling inside, and aluminum skins outside. It is also probably not coincidental that sheets of aluminum exterior on the sides go lengthwise while paneling runs vertical. The studs connected loosely by staples add strength when sandwiched WITHOUT causing ridgidity.
My pocket hole work looks cool but adds a lot of rigidity. I'm wondering how well these really hold up over time? I know pocket hole screws have been in use by restoration experts long enough that there should be some indications. I might expect 10 years or so bumping through potholes would strip a lot of the pocket screws out, but maybe they still help keep wood in the right places even after they are stripped?
Who has experience lifting skins after years of bumpy roads with the pocket hole connector methods? What do these look like? I've occasionally thought that if I fully rebuild someday, I might use dowel joints, but that might be even more rigid and thus short lived?
I use "toe screws" similar to pocket screws without the jig. It's lasted well but have never had to take one of mine apart to check? Honestly, I feel staples flex too much, not to mention the ones I have had have been very rusty.
A lot Of my older trailers were not stapled and were much more ridgid. They lasted well with no problems. The cracked boards discovered over the years have been at knots or from impacts.
Post by wisconsinjoe on Aug 17, 2022 15:52:05 GMT -8
I make the argument that they were flexible because they built them as fast and cheap as possible (with a great waterproofing system that lasted 20 years at best). Were the automobiles of that same era built to be flexible as they traveled over the same crappy roads? I know my modern truck and car are not "flexible."
I scratch built my trailer to be as stiff as possible, with pocket hole screws and glued interior skins, and considerable interior cabinetry with strong front and back bulkheads. On our maiden voyage, I lost a wheel at 55 mph. Messed up the wheel, studs, and almost ripped the axle off. There was not a single other piece of damage anywhere on the trailer.
We need to be aware of the scientific adage: "correlation is not causation."
And just because someone you might trust says something, doesn't necessarily mean it is true.
Staples were used because they were fast and cheap. You didn't even need a clean mitre cut with staples. If the cut was off a tad, throw it in the jig and let the staple bridge it. Once the paneling was on, it became a rigid shear assembly. I don't believe the factory was thinking about flexing while on the road. They were doing what the bean counters dictated and that was keep the bottom line low. I wouldn't want anything flexing. Flexing stresses fasteners and materials. I vote for as rigid as possible on the frame and let the suspension deal with the road abuse. On the topic of flexing, think of a fiberglass boat. They are built solid and can take the pounding of waves. Any flexing in the water will loosen fasteners and stress the fiberglass.