Okay...I give...when WILL my pine table top quit moving??


New to building furniture (not new to finishing work), and my first project is a utility table for the woodshop. I'm overbuilding the hell out of this thing because I want a "practice" project that I can actually use.
Rather than use plywood for the tabletop, I glued-up some 4/4 pine so I could practice glue-ups.
Now, mind you, this is a *first* project, so I used the cheapest wood I could get...construction pine. Knotty as hell to be sure. But I have a planer and jointer, so I dressed and four-squared the lumber quite well. Or so I tought.
I had the lumber acclimatizing in my shop for about three weeks. I first rough-dimensioned it, then let that sit for another 3 - 4 days in case it moved again. Finally, I four-squared it to its final dimensions and glued it up.
Only to find that, after gluing-it up to near perfection (straight, flat, I was damn proud!), ONE of the four boards has cupped AGAIN and warped the tabletop.
Granted, I'm using crappy plainsawn knotty pine, but is that my only mistake here?
Thanks for any help!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
construction pine is not even close to being dry - as in 7-8% moisture content. Depending on the temp/humidity in your shop, it could take weeks to dry out enough to be called "stable".

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wood snipped-for-privacy@yahoo.com wrote:

probably the wood, like Mike said.
another cause would be applying finish to only the top. be sure to apply finish to the underside next time. better yet, use nice wood like oak, maple, etc.
Dave
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Good. You learned something: If you are going to put hours into a project, materials cost can start to look small.
Find a hardwoods supplier in your area and find out what is available afordably in your area. It's a regional thing. In my neck of the woods, I can get "brown maple" which is just maple with some dark heartwood streaks, for 1.90/bf.
It's still probabably twice the price of 2-by's, but I think it's a good value as a utility wood.
I'm sure that everybody would like to chime in and tell us how the get fill-in-the-blank species for less, but everybody's market is a little different. The point is that are other ways besides knotty pine to do woodworking on a budget.
-Steve

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
*snip*

Some stores have lumber scraps that you can get. We got some nice red oak for $0.51 a board at a Home Depot. Sometimes the 1x4x4 ft is just what you need. :-)
Puckdropper
--
www.uncreativelabs.net

Old computers are getting to be a lost art. Here at Uncreative Labs, we
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I work a lot with Pine and it can be a real roller coaster. I think even the moisture that the glue introduces can add to some movement. If you are talking about a 4/4 thick top, that sucker will move for ever. It's just the way it is with pine. I often just pull the sucker flat with a few extra attachments to the apron and add a shim or two if needed.
One help is to select boards that are closer to a rift or quarter sawn cut. Look at the end of the boards and you want to see the rings running as nearly straight across the thickness of the board as possible. If you see the center of the log or rings that intersect the same face twice, ie like a smile, fhugetaboutit. That sucker will curl up like a potato chip.
You can alwas re-rip the panel and reglue it to help flatten it but depending on the severity of the cup you might just have to rip out the piece entirely and glue in a new one.
Finally, use quartersawn White Oak next time and you'll get a flat panel that stays that way.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

cut. Look at the end of the boards and you want to see the rings running as nearly straight across the thickness of the board as possible. <<
Couldn't agree more. Also, you didn't say, but did you use some kind of mechanical alignment device such as dowels or biscuits? I have found these to be most valuable in pine, less valuable in harder, denser woods.
I also cheat with pine on table tops and put a couple of slats of 1X2 on the bottom and glue and screw through the 1X2 with a screw that stops 1/8 from coming through the top.
While I am thinking of the bottom, don't forget to seal it when you seal your top. A wood that is movement prone like pine will move even more dramatically if the moisture is allowed to leave on only one side.
One last thing, if the ends of the boards are moving, your only hope is a breadboard type trim. You rarely see any type of pine furniture (never soft pine) without an edge treatment.
I like pine, and have made some antique reproductions out of it and they turned out quite nice. I have used it at client request for pine cabinets, etc. It is good stuff if you like the look and you want to (or are getting paid to) work with it.
Robert
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
You have to drive a vampire through its heart.
wood snipped-for-privacy@yahoo.com wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wood snipped-for-privacy@yahoo.com wrote:

It will stop moving about six months after you put it into an chamber with constant temperature and humidity.
You can minimize movement by sealing it all around with shellac.
If one board is giving you a bigger problem than the others, and it is not exposed more (or less) to the ambient atmosphere or spilled moisture or some such than the others it is probably what is technically referred to as a 'bad board'. Seriously that particular board may be reaction wood cut from a leaning trunk or maybe it has asymetrical grain or something.
If you replace that board and seal the whoel tabletop (sides top and bottom) with shellac you may be happy with the result.
If you can find used bowling alley, a cheap solid core door, or a small butload of used hardwood flooring you'll probably be happier with those in the long run.
A number of people have had success with using Doug Fir for their benchtops. The availabliity of Doug Fir dimensional muber varies wildly. It is very rare and expensive in Suburban Washinton DC, but 8' 2x4s in DOug fir used to cost $3.50 each at Hechingers, when there still were Hechingers here.
--

FF

to be not


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

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.