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Edge glue-up for a table top and straightness of edges

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Forum topic by Dan Wolfgang posted 04-09-2016 01:08 AM 690 views 0 times favorited 7 replies Add to Favorites Watch
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Dan Wolfgang

39 posts in 272 days


04-09-2016 01:08 AM

Topic tags/keywords: laminating question

For my first-ever attempt at fine woodworking I’m building a little table. I’m working on the top and am going to laminate five pieces together to create it. I’ve set the pieces together to check fit of the edges. None of them perfectly mate. I didn’t really expect them to be perfectly matched because (at this point) I have simply dimensioned the wood. I’m doing this all by hand, by the way.

So, when doing this sort of thing, how close to a perfect match do all of the edges need to be? I was trying to match two pieces this evening and they’re down to less than about 1/16” wobble. I can push it together with my hands to make it tight, so I’m sure that clamps would have plenty of force to get it tight. (I’m using soft maple and white oak, by the way.) Should I focus on getting the edge perfect, or can I rely on the clamps and glue to pull the wood and close the gap?


7 replies so far

View MadMark's profile

MadMark

978 posts in 917 days


#1 posted 04-09-2016 01:12 AM

Things like this should be made a little large and then trimmed for final fit.

It is sooo much easier to trim a ragged edge than to try and get everything perfect while gluing.

M

-- Madmark - Madmark2150@yahoo.com Wiretreefarm.com

View rick1955's profile

rick1955

258 posts in 895 days


#2 posted 04-09-2016 01:31 AM

Technically you are edge gluing, not laminating Look up the definition.

-- Working smarter with less tools is a true crafts person...

View AlaskaGuy's profile

AlaskaGuy

2406 posts in 1773 days


#3 posted 04-09-2016 01:48 AM

The joint between the pieces should be very straight and fit together well. Don’t rely on clamps to pull gaps together.

Watch this video. They use a jointer but you can do the same with hand plane.

https://youtu.be/ukfBnyDXO1o

-- Alaskan's for Global warming!

View pintodeluxe's profile

pintodeluxe

4856 posts in 2278 days


#4 posted 04-09-2016 03:04 AM

Ultimately you can do a dry fitting with clamps to see how well you did. I wouldn’t worry too much about a 1/16” or less gap, as long as the clamps can easily close it.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View jonmakesthings's profile

jonmakesthings

68 posts in 282 days


#5 posted 04-09-2016 04:06 AM

Glue would probably hold them together with no gap, but its extra stress on the joint that you can avoid. You’d probably be best off planing the mating edges a little till they’re perfectly flat, then glue them.

-- How can you have any pudding if you don't eat your meat?

View JBrow's profile

JBrow

818 posts in 384 days


#6 posted 04-10-2016 01:52 AM

danwolfgang,

It sounds like you are speaking of gluing the edges of five narrower boards to create one wide panel. My method for hand jointing edges is what I will call the double board jointing method (which I do not do by the way, I use a similar single board technique at the jointer). It starts by laying out the boards that will form the panel with the show faces up and in the order to be glued. Each joint is marked with a number from 1 to 4. Both boards that will form the given joint line will have the same joint number. Then clamp the unmarked faces of two boards together so that the matching joint numbers are out and up. Both edges to be jointed should be more or less flush and positioned ready to be planed together. Mark all along the edges of the two boards with chalk or a pencil. Then plane these two edges at the same time from one end to the other until the pencil or chalk marks are gone. This process is continued until all the numbered joining edges are similarly planed together. Before gluing, straightening the outside edge (unglued edge) of one of the outside boards so the glued-up panel has a straight edge to run against the table saw fence would make squaring up the panel easier.

The resulting glue lines should be all perfectly matched assuming the entire length is planed with each pass. Also the placement of the boards in the glue-up is critical. The edges that are jointed together must be the same edges that are glued to one another. This is easily accomplished by ensuring the joint numbers match during glue-up.

I do not believe completely closing the gap that may exist between two pre-glued boards is necessary, so long as when the joint is brought together, the edges are in full contact. For example (and I have never used this technique) there is method for edge jointing that actually introduces a progressively wider gap between the two boards at their joint line. The idea is that this “spring joint”, where the ends of the joint touch but the center of the joint does not, requires a single center clamp to pull the joint tight all along the jointed edges. I am not sure of the size of the gap created in the center, but I would expect it to be no more and maybe less than 1/16”. Also I would think if the unclamped joint line does not mate perfectly and a gap only disappears with clamping pressure, as in the “spring joint”, the glue-up would require clamping pressure until the glue is fully cured since stress exists in the panel’s joints.

I am a little concerned by your use of the term “wobble”. If the faces of the boards are not flat and this is the source of the “wobble”, then the edge glue-up could result in a panel that is not flat. Getting the boards as flat as possible before edge gluing would probably be a good thing. If the “wobble” is a rocking along what will be the glued edges, using the double board jointing method outlined above should remove the “wobble”.

If you are speaking of face jointing, gluing the faces of boards together to create a thicker board, I would think the mating surfaces would have to be close to perfectly flat to get a good glue bond, probably very difficult to do by hand.

View Dan Wolfgang's profile

Dan Wolfgang

39 posts in 272 days


#7 posted 04-10-2016 10:46 AM

Thanks for all the feedback, all. JBrow, I’ve read about the double-board match method a while ago, and somehow complete forgot about it That should certainly make short work of the small variances I see. Yes, the wobble is on the edge, not face.

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