Experience with thermal/moisture expansion on Repeat (or other) builds?

Has anyone run into trouble with plywood/MDF of their printers (MP3DPs, Repeats, or others) having issues with expansion/contraction of the wood/MDF components as humidity/temperature changes?

I’m curious specifically about the Repeat builds with their linear rails which can be more prone to binding if they get pushed out of alignment by expanding/contracting substrate.

I have not experienced that yet, as I built the printer last fall/winter with already low humidity, granted that the printer leaves in my basement which is temperature and humidity controlled.
But if you are planning on building out of plywood or MDF, I would recommend a good coat of sealer and paint to minimize the problem.

I’ve considered paint/sealer but if I want to print PETG/ABS/ASA I was concerned about those coatings degrading due to the 100C+ temperatures.

Well, I painted mine with exterior paint, assuming that if the paint can stand hot summer days, rain and cold winter, it would not be a problem when I do print CF polycarbonate for 16+ hours straight


They make high heat paints that go well beyond the temperatures you’ll be printing at (well beyond the temperature where the wood would combust first, for that matter). No idea how well they seal the wood, but here’s an example:


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