Sawmill School - Air Drying Your Lumber

[Music] hi i'm dave boyt and welcome back to the potter shop hollow tree farm and portable sawmill well the number one question that i get on the videos that i've done for norwood have been about drawing the lumber now i made a video on cutting blocking and stickers for the sawmill and another one on stacking it for drawing but what about the drying process itself so we're going to be looking at air drying lumber and some of the ways that you can help your customers or yourself for that matter air dry the lumber and know what to expect and when to expect it we're also going to be looking at some of the myths around air drying wood the first myth is that lumber from a log that has been cut for a while can be air dry right off the mill so let's mill up a freshly cut log from and an old oak dot and see how they compare this red maple log came from a local tree service just a couple of days ago so so been there a while i'm also going to take the other part of the nail out of the slab that i cut just to make sure that that doesn't get run through a planer so this is a pin type meter and it has two very sharp pins that penetrate into the wood it measures the electrical resistance and from that it gives you a good idea of what the moisture content is well let's see what we've got here and of course it's reading upside down but uh you turn that around it looks like we're at uh 44 moisture content this log obviously has been around the mill yard for a while it's looking at about though three years on this that it's been down it looks dry it feels dry but we're gonna cut into it get to the middle of the log so we'll determine whether or not the wood actually dries while it's in the log well we're getting down towards the middle of our log here i'll turn off the water piece of the blade right so we don't add any moisture in the mill itself and we'll see where it comes out so let's check out the moisture content here that is tough wood all right so that's reading 44 so i would say there's not a whole lot of drying that took place even though this has been down for at least three years and the maple log was fresh cut a week ago so that's myth number one blown out of the water the wood does not dry in the log okay what you'll likely find though is when we get to the end of the log or the end of the board you can see how cracked that is from stress get down to the end here 20 23 moisture content on the end so roughly half the moisture content at the end of the board as there is in the middle so since it's drier here the wood has tried to shrink back further it it's got more moisture to it that wood as it shrinks it's got to do something and it's going to crack to relieve the stress which is what we see here and that's why encoding your valuable logs with something like anchor seal is real important seal yes it costs a little bit of money but it might save us a foot aboard foot of of lumber just on this one piece well that could be five bucks so but the only rule of thumb is one year of drying time per inch of thickness but even that brings up questions because different species of wood dry at different rates wood in phoenix arizona where it's dry is going to dry much more quickly than it does typically in seattle washington so how do we how do you know you don't know unless you have a moisture meter one of the things that you're going to run into is that after a period of time when the wood weathers and turns gray you can't tell one species from another and it's real easy to think okay i'll just remember i put the sweetgum in this pile i put the poplar over here and maybe even draw out a rough map of what's where uh i've got piles i'm going to have to take boards and run them through the planer so i can try to figure out what the heck they are i don't remember that what i do and i've been doing this for some time now is take a tin can lid and i've got a punch set it's got numbers and letters and i just punch an identifier on a lid and staple it to the end of one of the boards and it'll uh tell me what i've got here and also when i cut it this stack of soft maple was cut over four years ago and it's been covered i just took the tin off of it so we could get some good shots of the moisture content reading so let's check out this myth about wood air drying to kiln dry moisture content and to be kiln dried we got to get it down to seven percent well you don't need to be a rocket scientist but wood does have its own theory of relativity now not that one but close to it and that is the equilibrium moisture content of wood is proportional to the relative humidity what that means is that for any given relative humidity in the air the wood will reach an equilibrium of moisture content that is proportional to that to get an idea of how wood will air dry in your neck of the woods find the average humidity for your area then look at the chart that gives you the equilibrium moisture content of wood for any given relative humidity and temperature has a little bit to play in there as well so the chart shows that too that'll get you close and she's reading 11 so that myth busted i don't care how long you air dry it with the with the average relative humidity that we have here in southwest missouri it isn't going to happen this trailer is a really good example of what can happen to wood as it dries i cut this decking about eight months ago to replace it and i use post oak it's in the white oak family very tough durable wood but it does tend to warp and split and not a real pretty wood for fine wood working perfect though for hauling tractors and lumber and bales of hay so it does its job well but i wanted to use this as a good example of why it's important to know the moisture content of the wood it's not just a matter of having wetter wood it's a matter that as the wood dries loses moisture it shrinks changing dimension in a fine china hutch for example could be disastrous you want everything to be at the final moisture content in the final dimensions where it's going to stay when it's inside the house so this has never been inside the house but it was put on the trailer fresh off the mill these boards were perfectly straight and they were tight up against each other you couldn't get a piece of dental floss between them now look at them so this board here in particular it's bowed on us we've got uh close to a three inch gap here and they're touching in the middle and then another three inch gap at the far end so that's why you let it dry first before you use it so let's get an idea of just how much these boards have moved on us wood changes almost none in length as it dries and that's a really good thing especially for this where you get most of your change is in the width and the thickness so when i milled them they were 10 inches wide two inches thick and 16 feet long and we started out with them touching each other and take a measurement now for width we're looking at nine and a quarter inches and for the gap between them we're looking at three quarters of an inch so the idea is to have the wood as stable as possible the final moisture content and have as few defects as you can and that's how you get the most value out of it and that's what keeps your customers coming back for more that kitty cats go catch a mouse so thanks for stopping by i hope i didn't confuse you too much you'll figure it out with experience and come with your and come up with your own strategies for dealing with air drying the wood from your mill and what to tell your customers and pretty soon you'll be the expert on the subject when you are don't forget to pass that on down to others help them out and if you have suggestions things that you've come up with uh either questions or strategies either saw milling drawing wood anything to do with the with the process or the business for that matter leave a comment let me know and we'll share it with others and get the word out that's what that's what we're here for so till then uh be careful out there and keep on making sawdust [Music] so [Music]

Channel: Norwood Portable Sawmills

Views: 404,053

Keywords: air drying, drying, lumber, boards, planks, wood, Sawmill, saw mill, portable, mobile, portable sawmill, mobile sawmill, portable saw mill, mobile saw mill, bandmill, band mill, band sawmill, bandsaw, mobile band sawmill, portable band sawmill, Norwood, Norwood sawmill, Norwood saw mill, sawing, sawmilling, forestry, forestry equipment, forest management, WoodMizer, Wood-Mizer, Woodland, Woodland Mills, HD36, LM29, MN26, Logosol, Timberking, chainsaw sawmill, chainsaw, M8, HM130, HM127, Frontier, yt:cc=on

Id: 56oQQLmOUOA

Length: 12min 48sec (768 seconds)

Published: Tue Nov 24 2020