Pat, Jim, Based on Googling, numerous Chinese manufacturers offer 1220 mm x 2440 mm plywood for US market in various millimeter thickness.
There wasn't much info on length and width tolerances. A Google image of a construction reference indicated dimensional tolerance for plywood used for flooring, sheathing, etc is +0, -1/16". As joists and studs are laid on 16" centers here, it would be better for the 48" and 96" dimensions to be slightly short, to keep all the joints over a support; if slightly long, the error accumulates. The 48" dimension and tolerance converts to a range of 1217.6 mm - 1219.2 mm, so I'm thinking the 1220 mm is a nominal and they try to be a little short (but no data sheets defined that). (Actually, the 96" dimension would be more important vs support spacing). Sorry for all the inch dimensions, but I would expect the Chinese manufacturers to take into account their customer's preferences (which I am guessing at) Thickness tolerances are pretty tight: Sanded plywood: ±1/64" (0.4 mm) up to 3/4", then 3% Unsanded: ±1/32" (0.8 mm) up to 13/16", then 5% Federal construction, which is metric, supposedly uses 400 mm centers and 1200 mm x 2400 mm sheets, but I don't know if they really do, or have declared an exemption. The Chinese suppliers had a number of other standard sizes, including 1250 mm x 2500 mm (???), but most didn't offer 1200 mm x 2400 mm. ________________________________ From: Pat Naughtin <[email protected]> To: U.S. Metric Association <[email protected]> Cc: U.S. Metric Association <[email protected]> Sent: Mon, July 5, 2010 6:39:45 AM Subject: [USMA:48047] Re: Metric (partly) plywood On 2010/07/05, at 14:12 , James R. Frysinger wrote: I bought some sheets of plywood at Lowe's today. I was looking for some thin stuff to use as workshop cabinet backs, in lieu of the cardboard provided by the cabinet kits. > >What I got was labeled as "5.0 mm" thick plywood in 4 ft by 8 ft sheets. Yes, >that precision on the thickness is perhaps pushing things. The plywood is also >labeled as being made in China. > >Jim > Dear Jim, Could you please let us know the width and length dimensions in millimetres. I would be interested to know what the Chinese plywood makers did when they they had to convert 4 feet by 8 feet to metric so they could produce the sheet on their all-metric machinery. Cheers, Pat Naughtin Author of the ebook, Metrication Leaders Guide, see http://metricationmatters.com/MetricationLeadersGuideInfo.html Hear Pat speak at: http://www.youtube.com/watch?v=_lshRAPvPZY PO Box 305 Belmont 3216, Geelong, Australia Phone: 61 3 5241 2008 Metric system consultant, writer, and speaker, Pat Naughtin, has helped thousands of people and hundreds of companies upgrade to the modern metric system smoothly, quickly, and so economically that they now save thousands each year when buying, processing, or selling for their businesses. Pat provides services and resources for many different trades, crafts, and professions for commercial, industrial and government metrication leaders in Asia, Europe, and in the USA. Pat's clients include the Australian Government, Google, NASA, NIST, and the metric associations of Canada, the UK, and the USA. See http://www.metricationmatters.com/ to subscribe.
