Wood Movement: Is this a typo?

Page 1 of 3  
Stolen without permission from:
http://www.woodworkerssource.com/shop/wmov.html
"A 36" wide top, made with flat sawn lumber, can move more than an inch with a 10% change in moisture content."
That comment was included in the following paragraph:
"Allow tops to move freely. Attach tops with Figure 8 Connectors, Z clips, shop made blocks or elongated screw holes. All of these methods will securely attach the top but all (sic) it to move across its width. A 36? ?? wide top, made with flat sawn lumber, can move more than an inch with a 10% change in moisture content."
I'm pretty sure that a Figure 8 connector is not going to handle movement of "more than an inch" unless it's a *really* big one. ;-)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 08/15/2016 10:21 AM, DerbyDad03 wrote:

Well, it's not a mistake in terms of what's possible, but it assumes the 10% is an absolute MC, not relative to dry. Absorbing 10% absolute moisture would require soaking it and maybe not even then...
The amount of shrinkage calculated is: 1.1057 inches or: 1 3/32 inches (rounded to nearest 1/32 inch)
The information you entered was: Width: 36 inches Initial Moisture Content: 0.1 (decimal percentage value) Final Moisture Content: 0.2 (decimal percentage value) The type of lumber you chose was: Flat Sawn
The Shrinkage Percentage Value used for the species you chose (Oak, Northern Red) was: 8.6%
<http://www.woodweb.com/cgi-bin/calculators/calc.pl?calculator=shrinkage If you assume 20% of stable, so 10% to 12%, you get the more reasonable answer of something like 1/4"...
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

An inch sounds like a lot ver just 36". But depending on the wood and amount of moisture content it can happen.
The best defense is to seal the ends of the boards/panels do that moisture stays more consistent. Sealing all exposed surfaces is even better.
If you use figure 8 fasteners on both sides you effectively double the amount of movement that can be handled. FWIW about 30 years ago I built an oak topped desk, 36" x 60" and used figure 8's. No issues so far.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Monday, August 15, 2016 at 12:02:54 PM UTC-4, Leon wrote:

OK, I guess I'll wait a few more years before I continue with my project. Please keep me updated on the status of the desk top. ;-)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

LOL
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 8/15/2016 12:02 PM, Leon wrote:

would be a huge change, more like 2-3% ...would be normal, I would think.
So if 10% change, yea maybe 1".. but that's not a practical moisture change.
--
Jeff

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 8/15/2016 3:21 PM, woodchucker wrote:

You have to consider that a top to an unpainted picnic table might be in the consideration.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Probably not as a single 36-inch-wide plank.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 8/15/2016 7:23 PM, Doug Miller wrote:

Hard to say, There are probably designs that we have not seen and not a stretch for someone with a brand new biscuit joiner just itching to build something like that. ;~)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Monday, August 15, 2016 at 11:42:02 PM UTC-4, Leon wrote:

This design would take a lot of biscuits. ;-)
http://i.imgur.com/2Jmu2RF.jpg
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 8/16/2016 7:43 AM, DerbyDad03 wrote:

Pretty cool!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

It didn't work out so well. Too much slop in the joint. The biscuit was pretty much useless. The jointer has now been used *once* and it'll likely stay that way until my heirs sell it on ebay.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Has anyone ever tried those hinges that are mortised out with a bisquick joiner? Just wondering if that might be a handy use for it, rather than a dust collector.
Puckdropper
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Puckdropper <puckdropper(at)yahoo(dot)com> wrote in

Is a bisquick joiner something you use in the kitchen? ;-)
I used mine, right after I got it, for a couple of panel glue-ups, and concluded that it provided no advantage over edge-gluing and clamping -- in fact, it took longer, was more work, and produced sloppier results.
And then it sat gathering dust.
Until it was time to remodel the kitchen, and I had a whole bunch of face frames to make. Then, it got used a *lot*.
I've also found that the #20 setting is ideally suited to cutting slots in the apron of a table, for inserting z-clips to attach the top.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wednesday, August 17, 2016 at 8:02:13 AM UTC-4, Doug Miller wrote:

Sloppier in what respect?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload


in the thickness of individual biscuits, to allow for noticeable misalignment in an edge-to-edge glue-up, enough to leave a ridge that's too big to remove with just a few passes with a card scraper. I found that I can get better alignment, faster, without the biscuits.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 8/18/2016 7:08 AM, Doug Miller wrote:

I understand how that can happen but I've not really had problems with it. I've been using Porter Cable biscuits and keep them in a pretty stable environment so they don't swell.
I did once use a bag of generic biscuit and found more variation though.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I used PC biscuits and PC cutter and found and had the same problem. It's back in the box with just a little dust on it.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Same here: PC tool and PC biscuits.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 19 Aug 2016 02:49:04 -0000 (UTC), Doug Miller

If I couldn't trust it to align flat panels to each other (with the help of clamps and cauls), I figured there was no point in even trying anything more complicated. There are too many other joinery techniques to bother with it anymore.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.