Honest discussion

[Brendon_t]

Bob,  thanks for the link.  I actually saw that last night but given that it doesn't seem to have been updated in two years,  and there may be a "wood movement pt2 subtitled damn was I wrong" that I didn't know of, was slow to bring it into the discussion. 

That's a trip about the hold fasts.  That would tick me off something fierce. 

[Andy Wright]

I have read articles that recommended speeding up the drying lumber by tenting over it with a tarp and using a dehumdifier. If you google it you will find more info

[Eric.]

Keep in mind that Schwarz was working with enormous slabs that had been resting for thirteen years, not milled 8/4 that was cut less than a year ago and nuked in the Los Angeles desert.  Two different ballgames if you ask me.

Your instinct may be, "Screw it...I have to flatten the top at the end anyway, so what's the difference."  The thing that would scare me most is any movement in the slab can throw off the alignment of the nut block rails, which is fairly critical for smooth operation.  If your slab twists and throws those rails out of coplanar, you may as well expect to build a whole new top.

[bgreenb]

"  The thing that would scare me most is any movement in the slab can throw off the alignment of the nut block rails, which is fairly critical for smooth operation.  If your slab twists and throws those rails out of coplanar, you may as well expect to build a whole new top.

Yup.  Watch the guild video about tail vise installation, and Marc demonstrates that even tiny movements of those rails can cause dragging or binding in the mechanism.  

[Guest]

Keep in mind that Schwarz was working with enormous slabs that had been resting for thirteen years, not milled 8/4 that was cut less than a year ago and nuked in the Los Angeles desert.  Two different ballgames if you ask me.

Your instinct may be, "Screw it...I have to flatten the top at the end anyway, so what's the difference."  The thing that would scare me most is any movement in the slab can throw off the alignment of the nut block rails, which is fairly critical for smooth operation.  If your slab twists and throws those rails out of coplanar, you may as well expect to build a whole new top.

Where is Schwarz?  Louisville?  Western Europe is wet, they dry wood to 15% there.  Louisville is wet. California is dry.

Those french oak trees probably grew very slowly without the aid of fertilizer and irrigation.  So they are more stable and will move less going from wet to dry.  Ash trees planted 50 years ago, in California, likely saw year-round water and heavy doses of nitrogen/potassium/phosphate. They grew faster and might be less stable.  Schwarz alludes to this when he says the oak has moved less than pine and fir benches he has built.  Softwoods get a bad rap by woodworkers but they generally shrink less than hardwoods.  

 

[Brendon_t]

Keep in mind that Schwarz was working with enormous slabs that had been resting for thirteen years, not milled 8/4 that was cut less than a year ago and nuked in the Los Angeles desert.  Two different ballgames if you ask me.

Your instinct may be, "Screw it...I have to flatten the top at the end anyway, so what's the difference."  The thing that would scare me most is any movement in the slab can throw off the alignment of the nut block rails, which is fairly critical for smooth operation.  If your slab twists and throws those rails out of coplanar, you may as well expect to build a whole new top.

which was another of the schwartz-isms.

I know he had used some monolithic slabs for some tops that weren't dry,  not sure if that was the one in his reference. In that case its apples to vw bugs. His address is Indiana which I think has humidity,  unlike here. 

Nut block binding sounds like something from a fetishist film. . Not what you want on a bench. 

[Tom Cancelleri]

Dragging tail vise hardware will drive you nuts! My vise sticks a bit for some odd reason, my nut block moves freely with no binding when all is well, if I tighten the dog a bit too hard, then when I back off it it sticks until I spin the handle and huge acme screw about 10 revolutions. I've cleaned and wax the guides and the screw, it's smooth, until I overtighten again. I'm thinking it's backlash or something on the threads.

I will say this, being the most recent active builder of a Roubo. It's a hell of a process and a lot of work, those slabs dry are no joke, and you wanna move them around wet? I'd worry about them cracking and your slabs splitting as they dry. My advice to mill closer is to remove excess material thats just gonna be milled away anyway to help with the drying process. 

[Cliff]

it's a truth as universal as the apple and Newton's head.

If I may -

http://msgboard.snopes.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=104;t=000291;p=0

I think there is often brilliance in going where others swear you shouldn't. But there is just as often disappointment, failure and stupidity. As long as you are prepared and expecting the disappointment - a success will be all the sweeter.

The idea of building a bench for experimental purposes intrigues me. Not because I don't think it will move, but because I want to see how much it will move. I still won't do it because, for me, it adds nothing to my life to know the answer to that question right now.

Edited October 27, 2015 by Cliff

[Eric.]

If I may -

http://msgboard.snopes.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=104;t=000291;p=0

 

Ignore the apple part then if you please.  The fact still remains...just because some guy decides he's gonna be the first in history to leap off the earth with only the propulsion of his own hairy legs - and assures us he will not be pulled back down - let's see how well that works out for him.  Comic characters do not count, Cliff.  We're talking actual humans and physics here.

[xxdabroxx]

I built my benchtop from KD lumber from the box store.  It has stayed fairly flat, although it has a slight bow across the depth of it but nothing that can't be fixed with a little time on a hand plane. 

I don't think I would trust green lumber though, that stuff moves like crazy. 

[Brendon_t]

Did you by chance  take any moisture measurements? Before the build, what it is now, how long has it been, and what would you estimate the bow at?  

[Cliff]

Ignore the apple part then if you please.  The fact still remains...just because some guy decides he's gonna be the first in history to leap off the earth with only the propulsion of his own hairy legs - and assures us he will not be pulled back down - let's see how well that works out for him.  Comic characters do not count, Cliff.  We're talking actual humans and physics here.

Heh. You can't invalidate me just because I like comics. Come to the awesome side, Eric. Batman rules. Meanwhile.. physics - requires the the scientific method. The gentleman wishes to test his theory, and I say he should go for it as long as he doesn't mind losing out on the wood.

I tend to be pretty open minded on "facts." Like others have said they have done similar and not ran into issues. Doesn't mean you should do it, but that means it's not cut & dry 100% going to fail.

This is all the further I can speak without bringing quantum mechanics into it.

*edit - Also remember you poo'd my new crosscut sled technology - which I'm totally going to try. And maybe I'll fail, but maybe you'll bow before me and proclaim your love for almighty Batman too. Err, I mean, my technique.

Edited October 27, 2015 by Cliff

[Eric.]

The loss of the wood would be the easy part...the hours of labor would be the disaster.

I gave Brendon this analogy in a PM...building with unseasoned lumber is the same as wrapping a solid wood panel with a mitered frame.  You don't have to do it personally to know what's gonna happen.  If you understand wood, you understand why this poses a problem.  These are fundamental woodworking 101 rules.  Rules that were established many many moons ago and established for reasons.

Tails first is not a fundamental rule.  Rounding tenons or squaring mortises are not rules.  Alternating smileys and frowns in a panel is not a rule...these are traditions that can be picked and chosen or left behind altogether.

But "wood moves as it dries" is a rule.  And a more basic one I cannot fathom.  Perhaps "only square is square" is more obvious.  But that's about it.

[Cliff]

Yeah. I mean, I don't know why I'm arguing when I agree with you. I've seen first hand what happens, and it was wood that was *supposed* to be kiln-dried. I think I just retain my "right to make a mistake" with all things.

[RenaissanceWW]

I've re-read your original question and I still don't know where our lumber sits right now as far as MC.  You mention 15%, if your softwood material at 15% or are you posing a hypothetical? 

As has been established here many time, wood move...all the time.  Even one "dry" it continues to move as the climate changes around it.  However you can lesson that movement by kiln drying lumber.  Kiln drying, at least in North America, means dropping the wood down to 6-8% and holding it there as the kiln moisture and temperature levels return to ambient.  This process actually bakes the wood to some degree as if forces out an unnatural amount of water and hardens the cell walls of the fibers.

This process makes the wood quite stable since an ultra dry material won't absorb moisture readily.  Think of a dry creek bed that sluices off water in a flash flood before it absorb it into the dirt. 

So if you wood is indeed at 15% and if the source if a big box store then it is highly possible that it was never actually kiln dried but rather went through a truncated kiln schedule.  This will mean that your lumber is closer to air dried than kiln dried.  It will be easier to work certainly but it will also react quicker to climate changes since the spongy nature of the cell walls remains. 

However as stated above softwoods in general tend to be more stable than hardwoods due to a different pore structure and lower density that allows for more internal movement without distortion.  The TR ratio of most of the Pinus genus is close to 1.5 where 1 would be a perfectly isotropic material.  So its pretty stable already.

Must of this is ephemera which doesn't address your question but I would much rather spread a greater understanding of how wood dries and what happens to the material so that the woodworker understands WHY wood moves and WHY letting it properly season is a good idea.  I work with professional builders and contractors all day long that don't understand this and just want someone to give them answer rather than understanding the process and extrapolating for their own situation.  Trust me knowing WHY will always make you a better woodworker because wood movement is much less rolling the dice and more expected results based upon your knowledge of wood structure and grain patterns.

Sorry I went off the rails on that (but you did give me permission in your original post)

[Brendon_t]

I've re-read your original question and I still don't know where our lumber sits right now as far as MC.  You mention 15%, if your softwood material at 15% or are you posing a hypothetical? 

As has been established here many time, wood move...all the time.  Even one "dry" it continues to move as the climate changes around it.  However you can lesson that movement by kiln drying lumber.  Kiln drying, at least in North America, means dropping the wood down to 6-8% and holding it there as the kiln moisture and temperature levels return to ambient.  This process actually bakes the wood to some degree as if forces out an unnatural amount of water and hardens the cell walls of the fibers.

This process makes the wood quite stable since an ultra dry material won't absorb moisture readily.  Think of a dry creek bed that sluices off water in a flash flood before it absorb it into the dirt. 

So if you wood is indeed at 15% and if the source if a big box store then it is highly possible that it was never actually kiln dried but rather went through a truncated kiln schedule.  This will mean that your lumber is closer to air dried than kiln dried.  It will be easier to work certainly but it will also react quicker to climate changes since the spongy nature of the cell walls remains. 

However as stated above softwoods in general tend to be more stable than hardwoods due to a different pore structure and lower density that allows for more internal movement without distortion.  The TR ratio of most of the Pinus genus is close to 1.5 where 1 would be a perfectly isotropic material.  So its pretty stable already.

Must of this is ephemera which doesn't address your question but I would much rather spread a greater understanding of how wood dries and what happens to the material so that the woodworker understands WHY wood moves and WHY letting it properly season is a good idea.  I work with professional builders and contractors all day long that don't understand this and just want someone to give them answer rather than understanding the process and extrapolating for their own situation.  Trust me knowing WHY will always make you a better woodworker because wood movement is much less rolling the dice and more expected results based upon your knowledge of wood structure and grain patterns.

Sorry I went off the rails on that (but you did give me permission in your original post)

yes I did and when someone wants to drop a knowledge bomb,  I'll allow it.

To answer the unknowns, this wood is ash cut about mid-late July sitting in 100*(nuclear fallout) of California. Mc is mid teens depending on what board. Tree was dead standing 2 years before coming down. 

If kiln drying was an option, I'd happily pay someone to do it,  I have exhausted every Avenue I know if and cannot Find a single one in southern California. 

[RenaissanceWW]

Do you know what your equilibrium moisture content is in your shop?  I would imagine LA is pretty low as compare to my 10-12% EMC out here on the east coast.  Ash is quite stable but also much more resistant to warping because of the highly ordered ring porous structure.  What size are your boards?  Can you do any milling like cutting to length and ripping to approx width?  This will only speed up the drying process by exposing fresh wood and decreasing the material around soft, nougaty center of a board.

And FWIW, I'm not suggesting you get it kiln dried.  That's a tough call because kiln operators won't dry someone else's wood unless they can fill the kiln with it.  Kiln operators want to eliminate as many variables as they can when drying and one of those is removing dead air from the kiln and shooting for a single species as well as similar thickness to all the boards.  That way the kiln schedule can be more consistent.  So showing up with less than a couple thousand board feet will result in your getting turned away (or less than 15K bf at my yard...our kilns are BIG)

In the unique climate of Southern CA your lumber will get quite dry on its own.  The fibers may not be hardened like a board that lives in a kiln at 180 degrees for a few weeks but it will still get dry.  What you have to do is balance your shop EMC with the MC of the actual boards and know that it will continue to drop X% til it reaches EMC.  Knowing this you can predict how it will move based on the grain of an individual board and also begin to place your boards as part within the bench oriented in such a way that the potential movement won't have an effect.

In other words, yes, I think you could begin building but careful thought needs to go into how much you mill and how you orient the parts.   Or just wait til it reaches EMC and build with reckless abandon

[Brendon_t]

Measuring the oldest wood in my shop that has been in there the longest,  I get anywhere from 3%-5%. I assume that would be about emc.

The wood as it sits was milled on a woodmeizer and hasn't been touched more. Many of the boards are 9/4  10' long and everywhere from 5-14" wide. 

I suppose it shouldn't hurt to band saw rip a bunch for the top to oversized. At least opening up the center of the wide boards would give more area for moisture to leave. 

[wtnhighlander]

Anyone who knows anything will tell you not to work with lumber that has a moisture content higher than 10%, especially in the desert where you live...with the exception of actual green woodworkers who use moisture to their advantage.

 

Eric, how does one keep lumber below 10% when the average relative humidity stays pretty high?

Quoted from weatherspark.com for my area:

"The relative humidity typically ranges from 42% (comfortable) to 95% (very humid) over the course of the year, rarely dropping below 25% (dry) and reaching as high as 100% (very humid). "

I know St. Louis is no better. I also realize that % moisture content is not equal to % relative humidity, but can lumber in such an atmosphere really stay that dry after it leaves the kiln?

[Guest]

This chart is helpful.  All my furniture is indoors, which of course will have less extreme conditions.

In the winter, my house is 70 degrees and about 25% relative humidity.  EMC for wood at those levels is 5.4%. 

In the summer, my house is 70 degrees and about 50% RH.  EMC for wood at those levels is 9.2%.  

That is still a pretty big swing even though we heat and air condition year round.  I have had the hardest time getting the humidity up in the winter because we have very dry winters.  

 

http://www.woodworkerssource.com/moisture.php

 

[wtnhighlander]

Thanks for the chart, Mike. According to it, the EMC point for my part of the country never gets below 12%. Heck, it's even worse for Eric. I guess that answers my question.

[mkrusen]

I am just finishing up my Roubo. Just need to flatten the top and apply finish. It has been a looooooong journey. We all understand how badly you want to get started on it but I would definitely wait for your lumber to properly dry. Having now completed the work, I would be incredibly pissed off if I had to start over or had impaired tail-vise action due to excess wood movement. That being said, the wait and the work are well worth it. The Roubo has been an awesome project that will see decades of solid use. Good luck with your build

[Brendon_t]

Also as I understand it, you are comparing two different moisture content. Moisture content in wood I believe is a percentage by weight ie, 30% of this woods weight is water, or 10% of the wood weight is water.

[Al Capwn]

In other words, yes, I think you could begin building but careful thought needs to go into how much you mill and how you orient the parts.   Or just wait til it reaches EMC and build with reckless abandon

Not trying to hijack the thread, just curious as well as to better understand the milling process and how to tackle it properly without letting "perfect be the enemy of good". 

Explain to me like I am five: I understand that wood moves during changes in humidity. I am assuming wood moves when it gains moisture as well as when it loses it? For example, air conditioned spaces generally have less moisture in the air compared to a garage, or worse still, outside ambient air. Can wood be effectively worked with at EMC, knowing that ultimately it will reside in a location with different humidity?

Eric mentioned the internal moisture content should be 10% or less, but is that an absolute rule or that based upon region? Does this matter if you are in Florida vs Arizona, or is this based upon the general internal humidity of the average house?

At what point does the moisture percentage significantly affect the movement, or is there no real consensus due to the unpredictability (or rather, myriad of variables such as species, grain orientation, etc) of each piece? Presuming lumber is already kiln dried from a hardwood supplier, and less moisture = better, why should I let it acclimate it to my shop if the moisture is less? How does this affect moving project material from a garage shop into an air conditioned house?

[Tpt life]

Al, the slower the moisture moves, the more evenly it moves. If you let your wood dry before working, it has shrunk to its max expectation. You then square and put to use. If you leave raw, you can see some movement that will be catastrophic to any piece. If you hide all your end grain, you theoretically have glue on the end grain. This slows down the fastest moving moisture path helping the moisture to move more evenly. Oiling or finishing also slow the moisture movement. The problem with using green wood is that it has not shrunk to its max expectation. This means you have not milled the wildest moving parts off of the board. You go from a mild expectation to an uncertain expectation. That said, it is better to imitate your expected permanent location. Conditioned shops are the best way I know to accomplish this but the conditioning costs money. For us cold weather birds, we can build in dry AC or dry winter air. We can build in wet summer or humidify winter heated air. Avoiding extremes often goes a long way.