LumberJocks

Wood expansion--why I doubt.

  • Advertise with us

« back to Wood & Lumber forum

Forum topic by FreeRangeWoodworker posted 02-23-2017 01:28 AM 2462 views 1 time favorited 46 replies Add to Favorites Watch
View FreeRangeWoodworker's profile

FreeRangeWoodworker

21 posts in 292 days


02-23-2017 01:28 AM

One of my favorite YouTube woodworkers made a comment in one of his great build videos that expansion is something to worry about with wood flooring, but not really with furniture. This certainly runs contrary to conventional wisdom, so it got my attention. I Googled examples of damage from wood expansion and the only images that came up were of wooden floors. There are endless articles and videos about how we have to account for expansion in tables and other projects that are much smaller than a floor, but I haven’t seen any photos of such damage.

I’m not looking for explanations of why we have to account for expansion and contraction—I get the concept. I’m interested if anyone has pictures of your own work (not from the Internet) or even stories of your own experiences (without pictures) where you know the piece failed because of expansion and contraction and not some other factor.

Thanks!

-- Life is what you make of it.


46 replies so far

View RubberDuc's profile

RubberDuc

45 posts in 360 days


#1 posted 02-23-2017 01:34 AM

As someone who has never fully understood expansion issues, I’m very interested to follow this thread.

View Aj2's profile

Aj2

1171 posts in 1631 days


#2 posted 02-23-2017 01:39 AM

The best way to discover the power of wood is to do some experiments.
Try this one make a frame and panel out of solid wood.Make the corners of the panel real strong.Mortice and tenon or bridle joints. Fit the panel real tight with no room to expand.And glue it real good on all sides.
Wait and see what happens.

Aj

-- Aj

View firefighterontheside's profile (online now)

firefighterontheside

16905 posts in 1690 days


#3 posted 02-23-2017 01:46 AM

Early on in my woodworking, I built a table where I did so many things wrong. I didn’t use breadboard ends, but instead I mitered the corners. This table is pin oak that I had milled, but didn’t allow to dry long enough. I did not have a moisture meter at the time either. Well, one night there was a Big Bang in the dining room. Several things fell off and got knocked over on the table. In one big movement the interior glueup of my table broke at a glue joint.

-- Bill M. "People change, walnut doesn't" by Gene.

View Snipes's profile

Snipes

150 posts in 2078 days


#4 posted 02-23-2017 01:56 AM

I think u should find a new favorite on that there youtube..

-- if it is to be it is up to me

View sawdustdad's profile

sawdustdad

334 posts in 719 days


#5 posted 02-23-2017 02:24 AM

Museums and antique shops are littered with examples of failed joints and cracked panels due to cross grain construction methods. In the 18th and 19th centuries, homes did not dry out in the winter like they do now. So not as much care was taken to prevent shrinkage from causing damage.

Bring those pieces into the modern home and the joints open up and panels start to crack. I have an 1850 walnut chest of drawers that has sides made from single 20 inch wide boards. Both sides have cracks about 1/4 to 3/8 wide down the middle of the panel due to shrinkage. The drawer runners are nailed and glued, but have come loose in many places. The chest has moldings around the top and bottom that have prevented the panel from moving as a whole. I recently restored this chest, but there is nothing that could be done about the cracks in the side panels without rebuilding the chest from scratch. That particular chest is shown here.

Here is a modern example. this shaker walnut chest has a top surrounded by a molding. It’s glued across the front but is mounted via a sliding dovetail on both sides and is glued only at the front. That is to allow the panel to expand and contract. During the winter, the 22 inch wide panel shrinks about 3/16 and the side moldings stick out at the back edge. This is how cross grain construction should be done to allow for wood movement. In the second front view, you can just make out the small molding protrusion at the back corners.

-- Murphy's Carpentry Corollary #3: Half of all boards cut to a specific length will be too short.

View TungOil's profile (online now)

TungOil

741 posts in 329 days


#6 posted 02-23-2017 02:45 AM

https://www.extension.purdue.edu/extmedia/fnr/fnr-163.pdf

Everything you ever wanted to know about wood expansion and contraction

-- The optimist says "the glass is half full". The pessimist says "the glass is half empty". The engineer says "the glass is twice as big as it needs to be"

View WhoMe's profile

WhoMe

1564 posts in 3077 days


#7 posted 02-23-2017 03:24 AM

I agree, you need to find new favorite. We made some laminate tops for some ship stands. These were 8/4 thick and about 1”+ wide. The tables are roughly 20” – 22” wide so there are about 20 strips glued up. This wood had been in the shop for a long time and was well seasoned. We did bread board style ends but just butted the pieces up to the end. We glued and screwed the center and screwed the ends of the bread board with elongated holes for movement. The tables have polyurethane on all surfaces and the they still shrunk almost 1/8” per side over time. Almost 3/16 – 1/4” total.
If these would have been a fully glued and screwed end caps, im sure we would have joint failures on all the tables.
Wood movement needs to be taken into account when designing furniture.

-- I'm not clumsy.. It's just the floor hates me, the tables and chairs are bullies, the wall gets in the way AAANNNDDD table saws BITE my fingers!!!.. - Mike -

View Rick_M's profile

Rick_M

10606 posts in 2214 days


#8 posted 02-23-2017 08:47 AM

I’ve built a number of tables, the only one to ever have a problem was the first one which was finished on the top side only. Years later it was placed near a floor register, the bottom dried out, shrank, and cupped badly snapping the wood buttons. I was able to fix that table but other tables I’ve built that were finished top and bottom equally have been in that same spot and none cupped.

My FIL built a solid wood post and panel headboard but glued the panel, within months it tore itself apart. I tried not to tell him but he asked where it went. He gave up woodworking after that.

A lot of YouTube woodworkers are beginners and you shouldn’t depend on them for advice. There are many known experienced woodworkers that have written books or articles from whom you can learn properly. The Tage Frid book trilogy is a college course in woodworking.

-- http://thewoodknack.blogspot.com/

View Tabletop's profile

Tabletop

127 posts in 581 days


#9 posted 02-23-2017 09:43 AM

One of my first builds, over 20 years ago, was a 6/4 red oak table top attached to a metal frame. Lumber came straight from local saw mill and he had told me to let air dry for at least 1 year, (what did he know lol.). I got anxious, in other words tired of my wife nagging me about it and built it after about 3 months drying. A beautiful top with 3 coats of poly, top and bottom. After a few months noticed a hazy finish, first sign wood was not dry, but still looked pretty good. Everything was fine for about a year and then we noticed one side was no longer attached to the frame. I had secured top to the metal frame with screws about every 16” in all directions. If I recall correctly almost 1/3 of them had snapped and top was now cupped. Just one af many examples of me learning the hard way. Lol!

View Tony_S's profile

Tony_S

765 posts in 2916 days


#10 posted 02-23-2017 11:24 AM



https://www.extension.purdue.edu/extmedia/fnr/fnr-163.pdf

Everything you ever wanted to know about wood expansion and contraction

- TungOil

This is a very well written, easy to understand paper. Aspiring wood geeks, and veterans as well should have it bookmarked.
It starts with an emphasis on equilibrium moisture content and it’s relation to region, and climate changes throughout the different regions(the most important factor).
It gives the reader a good understanding of the hows and why’s of design failure, and how to avoid it. Read it, understand it, and accept it.
Too many people here, and in the rest of the nether’s of the internet, make broad sweeping declarations, some veterans included, that are nothing more than complete horse shit.
What works(or what you can get away with) in one climate/region, may suffer anything from partial, to absolute failure in another.
Wood breaths and moves…period. To what degree depends on a variety of factors, including climate, stability of relative/ambient humidity, kiln dried vs. air dried lumber, type of wood, cut of wood, finishing techniques, etc.
I live in a shitty climate for solid hardwood construction….I’ve seen it, and I live it everyday.

-- It is the mark of an educated mind to be able to entertain a thought without accepting it. Aristotle

View EricTwice's profile

EricTwice

228 posts in 367 days


#11 posted 02-23-2017 11:34 AM

Look up where he lives.

I grew up in the western deserts. The humidity is usually less than 5% and wood movement is no issue.

However, I have lived in Florida which has a very high humidity and wood movement is a very real problem. I now live in the mountains of Virginia which is somewhere in between the two.

Western Colorado expansion gap for 18 inch panel is 1/16. (You also find that hide glue is a bad choice here. It will dry out and crumble to powder from lack of humidity)
Florida the same panel would get 1/4 inch gap and that may not be enough if the wood is very dry when it is built. I have seen many explode from a panel that expanded too much.
Virginia 1/8 is generally enough, but I would allow 3/16 just because.

Woodworkers have traditions for a reason. If they say you have to allow for the wood to expand and contract and someone tells you otherwise, ignore it and keep with tradition just to be safe.

-- nice recovery, They should pay extra for that mistake, Eric E.

View rwe2156's profile

rwe2156

2710 posts in 1314 days


#12 posted 02-23-2017 03:49 PM

Sawdust is 100% correct. It is true lots of antique furniture was built with little to no regard to movement because the environment in the shop was the same as a house. We can’t get away with that anymore.

I recently completed a double dresser. There was one particular drawer that drove me nuts trying to tune it. It was almost there but I decided to let it go.

Well, after only 3 weeks inside the house, guess what, that drawer is sliding like silk!

And, this, even tho I built the piece in a climate controlled shop – in winter – ah, but in FL :-).

-- Everything is a prototype thats why its one of a kind!!

View shipwright's profile

shipwright

7779 posts in 2631 days


#13 posted 02-23-2017 04:10 PM


This is a very well written, easy to understand paper. Aspiring wood geeks, and veterans as well should have it bookmarked.
It starts with an emphasis on equilibrium moisture content and it s relation to region, and climate changes throughout the different regions(the most important factor).
It gives the reader a good understanding of the hows and why s of design failure, and how to avoid it. Read it, understand it, and accept it.
Too many people here, and in the rest of the nether s of the internet, make broad sweeping declarations, some veterans included, that are nothing more than complete horse shit.
What works(or what you can get away with) in one climate/region, may suffer anything from partial, to absolute failure in another.
Wood breaths and moves…period. To what degree depends on a variety of factors, including climate, stability of relative/ambient humidity, kiln dried vs. air dried lumber, type of wood, cut of wood, finishing techniques, etc.
I live in a shitty climate for solid hardwood construction….I ve seen it, and I live it everyday.

- Tony_S

Hey Tony, I just love the delicate, diplomatic way you write your posts!
.... and it helps that you are always right…

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fibreglass trees. http://thecanadianschooloffrenchmarquetry.com/

View Manitario's profile

Manitario

2551 posts in 2716 days


#14 posted 02-23-2017 04:15 PM

Wood expansion is real and a problem for woodworkers. I’ve had two panels on frame and panel doors for cabinets crack because I didn’t leave enough room for expansion. Average humidity where I live ranges from 30% in the winter to 70-80% in the summer.

-- Sometimes the creative process requires foul language. -- Charles Neil

View jimintx's profile

jimintx

509 posts in 1418 days


#15 posted 02-23-2017 04:24 PM


I agree, you need to find new favorite. ...

- WhoMe

Who is the woodworker that is mentioned in the opening post here?
Thanks

-- Jim, Houston, TX

showing 1 through 15 of 46 replies

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com