Lee Valley & Veritas
Woodworking Newsletter
 
  Volume 11, Issue 2 - November 2016    
 
Table Top Glue-up Techniques

Start with boards that are a bit thicker, wider and longer than necessary. To reduce warping, your boards should be given time to acclimate to the temperature and humidity levels in your shop. Store the boards flat with stickers between them for at least a week.

If you are using rough-sawn material, flatten one face and square the edge on the jointer before running it through the thickness planer. Next rip the rough edge on the table saw. I have found that the Freud® Glue Line Ripping Blade does a good job of creating a clean edge. If you don't have the Freud blade, you'll need to plane the edge after ripping it. If your material is already planed to size, just joint and square the edges.

 
Flat and straight boards
The flat and straight boards ready for use.
 

After the boards are flat and straight, lay them out. To create a good-looking top, you need to consider the grain direction. I always try to lay out the boards with the heartwood side up, if possible. This side of the board is the one that faces toward the center of the tree. Boards tend to cup away from the heartwood side as they dry. This can affect the flatness of the panel when making a top of many boards.

 
The marked boards
After deciding on the best lay out for the boards, mark them with a pencil or chalk.
 

If you alternate the heartwood sides some up, some down the panel will stay relatively flat across the entire width. However, it can result in a washboard effect. Once you have decided on the best layout for the boards, mark them with either a soft pencil or chalk. I have found that drawing a large triangle works well in the center of the top, and edge to edge.

I use a DeWALT® biscuit joiner to lock the boards in alignment during glue-up. The biscuits are normally spaced about 8" to 10" apart. Be sure to center them in the boards and keep them well away from the ends so they will not be exposed by trimming.

 
The flat and arranged boards
After the boards are flat and arranged, it's time to start thinking about the glue-up procedure.
 

With all the boards flat and arranged on your work surface, you are ready to start thinking about the glue-up procedure. Make sure the surface you are working on is flat. An uneven or twisted one will result in clamps that are not in the same plane and this could cause a twisted top. I use my table-saw table and extension table for small glue-up jobs, my workbench for medium-sized tops and a fabricated 4' x 8' table for large glue-up jobs.

You are now ready for a practice run. Depending on the size of the glue up, it may require two people. Yellow glue (aliphatic resin glue) sets in about five minutes at 70°F (21°C) or colder. All of your clamps should be laid out. I have found that Jorgensen® 3/4" pipe clamps, which are very stable, work well for larger glue-up jobs. On large glue-up projects, your clamps should be spaced not more than 16" apart.

Keep in mind that you need to alternate the clamps top and bottom. Clamp together and review the glue lines. If you see a gap, rather than putting more pressure on the clamps, remove the offending board and run it through the jointer again.

 
Glued-up and clamped table top
The glued-up and clamped table top needs to set overnight.
 

When all the boards are aligned, it's time to start gluing. Re-arrange your clamps and align the boards, biscuits, if needed, and an old plastic credit card. These make the best glue spreaders. Apply glue to the entire edge and use the card to spread it. Slide the boards together with the biscuits in place.

Check the underside of the top to ensure that it is sitting flat on the clamps. If not, hit it with a hammer and a block of wood to fit. Starting at the middle of the top and working towards the end, apply additional pressure to the clamps. If any of the boards are misaligned, mount C-clamps at the ends of the top across the joint that will not align. Apply additional pressure to the end bar clamps.

The pressure from the clamps will always cause the glue to spread from the joints. After the glue hardens, it is a chore to remove the squeeze-out. To make it easier, allow enough time, usually about 15 minutes, for the glue to turn rubbery. Using a scraper or a flexible putty knife, scrape off the glue.

Allow your project to set overnight to ensure a strong bond; then remove the clamps. Check the top with a straight edge and mark any high spots with a soft pencil or chalk. Use a jack or jointer plane to level the high spots. After you have removed the marks, check the top again and mark as needed.

If your project is small, the ends and sides can be squared on the table saw. If it is too big for the saw table, the ends can be trimmed with a router. Use a straightedge and a jigsaw or circular saw to trim the ends square to the sides. Then use the router to achieve the final edge. Be sure to use a scrap piece of material to support the end of the router run, as you will tear out the end grain if you do not.

When everything is square, it is time for some power sanding with a belt sander followed by an orbital sander, using progressively finer grits to create a smooth final surface. When installing the top to your frame, I recommend that you use tabletop mounting clips. They require a saw kerf 3/8" down from the top and 3/8" deep. This will ensure that your top will never crack due to expansion and contraction.

 
Tabletop mounting clips   Kerf location
Tabletop mounting clips installed   Kerf location
 

Text and photos by Brian Murphy

In the furniture design field since 1981, Brian Murphy is recognized as a leader in the Arts and Crafts design discipline. His furniture is in galleries in Muncy, Pennsylvania, and throughout the United States. He has received numerous awards and recognition for his work and continues to design in a bold new style.

In 2008, he was awarded first honorable mention in the Custom Woodworking Business Magazine, a national contest for residential furniture. In 2012 and also 2015, he was among the top three in the same national contest. He has been recognized in numerous magazines and has been featured on the cover of a new book by Taunton Press.

He is the past Chair for the Escondido Chamber of Commerce, Vice Chair of the Escondido Arts Partnership, Chair of the Escondido Public Art Commission and past Chair of the North County Cemetery District. Brian resides in Escondido, California, with his wife Nancy. They have two children and three grandchildren.

 

 
 
 
 
     
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