Plywood production requires a good log, called a peeler, which is generally straighter and larger in diameter than one required for processing into dimensioned lumber by a sawmill. The log is laid horizontally and rotated about its long axis while a long blade is pressed into it, causing a thin layer of wood to peel off (much as a continuous sheet of paper from a roll). An adjustable nosebar, which may be solid or a roller, is pressed against the log during rotation, to create a "gap" for veneer to pass through between the knife and the nosebar. The nosebar partly compresses the wood as it is peeled; it controls vibration of the peeling knife; and assists in keeping the veneer being peeled to an accurate thickness. In this way the log is peeled into sheets of veneer, which are then cut to the desired oversize dimensions, to allow it to shrink (depending on wood species) when dried. The sheets are then patched, graded, glued together and then baked in a press at a temperature of at least 140 °C (284 °F), and at a pressure of up to 1.9 MPa (280 psi) (but more commonly 200 psi) to form the plywood panel. The panel can then be patched, have minor surface defects such as splits or small knot holes filled, re-sized, sanded or otherwise refinished, depending on the market for which it is intended.
Plywood for indoor use generally uses the less expensive urea-formaldehyde glue, which has limited water resistance, while outdoor and marine-grade plywood are designed to withstand moisture, and use a water-resistant phenol-formaldehyde glue to prevent delamination and to retain strength in high humidity.
VIDEO HERE (8:42 minutes)
Very cool-looks like a loud job
ReplyDeleteGreen Chain Puller.
ReplyDeleteWonderful job ---- once you learn how.
I pulled chain at the planer of a sawmill before I got 'promoted' to piling green chain at the same sawmill. Pulling chain was fun. Piling at the mill wasn't. That's why it paid more.
DeleteLifting 5/4 sinker Sugar Pine moulding boards that were 28" wide and throwing them on top of a unit that was shoulder high to little old me wasn't fun. But I hung with it until the mill shut down. Just another reason my back is shot.
It was darn good money for a 'Green' 22 year old kid.
Dry chain puller or Dead table puller coming out of a 400 degree dryer, AKA Splinter picker. Don't ask me how I know this. 5 years plus summers and weekends helped put me through college. A couple of years stacking green lumber all night long prior.
DeleteHa! Looks like you let some spam through ;) Happens to everyone, in a hurry and click accept, on to the next.
ReplyDeleteI sure did, didn't I? Thanks for pointing that out to me so I could send it to spam hell.
DeleteI got to tour a plywood mill up in Oregon in the 80's. Worth the time of the tour if you get the chance. Hard to believe that wood could be peeled off at that thickness.
ReplyDeleteI've used birch plywood in model aircraft that is three ply and less than 1/16" thick. Amazing stuff.
DeleteI grew up in southern Oregon, and I've watched mills close all my life. Those that reopen two or three years later have automated equipment with several times the production, and one tenth the employees they used to run. And where they used to just burn the waste wood in wigwam burners, it's all chipped and used in everything from waferboard and particleboard to paper/cardboard. Some of the chip trucks from our local mill haul to powerplants in California to burn into electricity (but at least it's not that evil oil or coal, so it's "green" energy. Yeah, right).
Coos Bay has two huge chip export terminals, the stuff goes to Asia to make paper and cardboard products. Mountains of chips, they load a ship every couple of weeks.
DeleteDon in Oregon
Many years ago, I got to watch them making veneer at a factory in Aurora KY. It was a fascinating process. They had a big machine in another building all by itself that was dedicated to nothing but sharpening the blades of the shaving machine.
ReplyDeleteI use plywood (baltic birch) to vacuum press high quality veneer to.
ReplyDeleteSome of the worlds most beautiful woods are not available in marketable quantities or are prohibitively expensive.
Check this guy out. It is where I buy supplies and veneers from.
https://www.veneersupplies.com/
Please understand if you get bit by the pretty wood bug, you will never have any spare money again.
This is his educational page. If you enjoy beautiful wood, there is a lot of knowledge and wisdom here.
https://www.joewoodworker.com/
Steve in Ky
We used to have several Co-op plywood mills up in the PNW, good living, but hard work. Summer jobs for their kids at good $$. Took a tour of the one in Linton OR where my friend's dad had a share. Sadly, once the market started going south, their shares were about worthless.
ReplyDeleteThey also had a tank car for fuel which they also sold to the employees and since it never actually went out on the interchange tracks, it was dirt cheap, even back in the late 70s, early 80s.
Back in the '70s there was a breakthrough in Japan where they developed equipment for making ultra thin sheets-like 4 mils thick-that would go into high quality laminated veneer that would wind up in corporate board rooms. Japan, Inc. would buy all the American Walnut logs they could get their hands on, and that led to lumber poaching, especially in remote backwoods areas that had plenty of hardwood and hardly anyone living nearby. I had a buddy whose grandfather homesteaded in such an area right after the end of the Civil War. In the '60s his father sold off an 80 acre bottomland parcel that had running water and plenty of hardwoods. The buyer-a union boss from the big city-immediately had all the hardwood harvested; his father was beyond livid and when describing what happened he'd always say he never would have sold the land if he knew what the buyer was going to do.
ReplyDelete