by charliehm » Sat Oct 08, 2005 10:07 pm
On Using Cheap Plywood (vs. Better Quality)
Zack,
You raise a question that I’m trying to answer for myself as well, as I plan my construction of a tiny trailer.
It seems to me that the initial cost of the plywood alone is only one factor to consider, and it may not be the most important one.
Q: Are you intending to build a prototype that will be replaced in the near future, or do you want a long-lived and low-maintenance trailer?
Luan is cheaper than birch, and if varnished, it is serviceable and attractive. (And both are dirt-cheap compared to top-quality, marine-grade plywood.) But the 4’x8’ sheets of luan and the 5’x5’ sheets of Baltic birch sold at Home Depot/Lowe’s/etc. (in thickness ranging roughly 3mm to 19mm) aren’t intended for exterior use, and either will delaminate if not carefully sealed. Sealing requires careful work and some expensive materials.
Now comes the confession: I’ve successfully built knock-about rowboats with Luan without doing more than glassing the seams and varnishing everything, and I would use the material again if the project --a boat or a trailer chassis-- were a throw-away project, i.e., a project that might provide years of service but is really intended to be an initial-low-cost exploration rather than a true-costs-over-its-useful-life project.
One of the huge advantages that comes from using better quality materials initially is product uniformity and ease of workability. You aren’t dealing with trash that has to be tweaked and fussed with, babied and patched in order to create a serviceable product. In other words, “low-cost” often isn’t low-cost if you consider labor and frustration. And with plywoods, you are generally receiving a better quality product for the additional money. (Someone posted his informal hammer tests done on laun vs. birch, and I was shocked to see the differences in impact resistance.)
Part of the reason birch costs more than luan (and hardwood marine-grade plywoods cost multiples of them) is the number of plies used, the soundness of those individual layers, and the type of glue. If those properties are important to the project’s fabrication or use, and plywoods made with luan/doug fir/etc. don’t provide them, then they aren’t truly cheap in dollars or in grief.
Yet another confession: I’m probably going to use luan for my first shell–-rather than dig into my stock of marine-grade plywood-- because I’m assuming that my first shell will be a throw-away experiment (rather than any sort of final statement, much less a piece of furniture on wheels). Using luan means I can build fast and simply fix my mistakes as they occur. (It’s one thing to ruin a $8 sheet of plywood and quite another to mess up one costing $60.)
Lastly, the bulk of the financial costs of fabricating a tiny trailer –-teardrop or non-traditional-- don’t seem to be in the shell itself (unless one is using high-end metals, woods, or construction techniques), but in the amenities added to the shell.
So, your question –-and mine, too-- might be better paraphrased as “What is the appropriate skin for this project? (and let costs follow use).
Charlie
Last edited by
charliehm on Sun Oct 09, 2005 12:50 pm, edited 1 time in total.
There are 3 ways of doing work, but you can only have 2 of them at the same time:
FAST and GOOD isn't CHEAP. CHEAP and FAST isn't GOOD. CHEAP and GOOD isn't FAST.
