John Di Gregorio
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| 08 Feb 2010 04:11 PM |
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I have recently just fabricated a bunch of 1 1/4" thick solid walnut table tops. The planks I used were 5" to 6" wide and were glued together (using Titebond 2). We cut the blanks to size and then ran them through the surface sander. We took them to the finish shop and put a coat of stain on them. After we let the stain dry over the weekend, we came in today and noticed that many of them have separated at the joints. The separation travels in about 2 to 3 inches and is as wide as an 1/8" in some spots. Any thoughts as to what would cause this? Is my finish shop to dry? Why did it only travel in a a couple inches? What can I do in the future to prevent this? What can be done with to save the tables that were close to done?
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Kelsey Crisp
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| 08 Feb 2010 06:41 PM |
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jjdjr1 First of all, the 5-6" wide is a little wide for walnut, to be gluing up. My first question is, is it kiln dried lumber and if so, was it taken down to 6-1/2% moisture content? But if it was moisture.. you would be asking about warpage. If is was KD, you should be fine with that. Next... when you dry fitted the wood before glue up, were the joints so good, it looked like a solid board. If you had to tighten clamps, even just a little, to pull the joint together, this is your problem. Walnut is actually a pretty stable wood. My guess is this based on my 30+ years of woodworking. You did not have straight tight joints from the start. Glueup was made with the comment.. "yeah that will pull up". Did you run each edge through the jointer before glue-up? Did you alternate the grain, up/down? Let me know about the dry fit...and the size of your panels, and I can get you to the next easy step...  KC |
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Wags
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| 09 Feb 2010 05:47 PM |
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I agree with Kelsey, the width was my first red flag. As he said alternating the grain (up and down) is critical. We handle Craft Art Wood tops, theirs are almost always in the range of 3" wide. When you ran then through the sander, did you make sure to remove all sanding dust, to allow the adhesive to grab?
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Tom M
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| 09 Feb 2010 06:13 PM |
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KC, isn't walnut a particularly oily wood? Would that make a difference? |
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David Gerard
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| 09 Feb 2010 11:53 PM |
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water borne stain? |
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Kelsey Crisp
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| 10 Feb 2010 04:01 AM |
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David, yep... and Tom no... walnut works great.
Reading what wags wrote, I noticed I mis-read the post. Blanks were run through the sander. I have never been able to run anyhting through my wide-belt to where I would get a glue-edge flatness.
Pictures would be great. I have glued up 10's of thousands of panels, and I never had a joint fail that I was aware of. It should be the strongest point after glue-up. |
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Andy Graves
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| 10 Feb 2010 11:29 AM |
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I do not work with wood much, but would biscuits help ? |
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andy@thefabricatornetwork.com
Countertop Company - www.OliveMill.com |
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Steve Mehan
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| 10 Feb 2010 05:09 PM |
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jjdrj, Is your finish shop & your shop in the same building or different location?
What part of the country are you in?
How was the stain applied and what type of stain was used?
Stain Walnut????
To much clamp pressure?
We have fabricated many BB tops and are working on both a Walnut & Cherry tops currently. What I have found is in my part of the country the Northeast during the winter months the humidity is very low and people are also heating there homes, this has a tendancy to dry the wood more and can cause the joints to split if the wood has not been finished and is unstable. We dont let any unfinished layup sit for more then a day in these very dry conditions.
Titebond II is a very strong glue and I have also used it for the same applications you have and what I have found is that sometimes the boards may split before the joints do. Has this happened to every table or just to one? Also is the spliting occuring on every joint? |
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Steve Mehan
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Dani Homrich
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| 23 Feb 2010 09:52 AM |
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Made the same mistake some 33 years ago on a 8' top. 5" wide Walnut is OK if it is fabricated correctly. My first flag was doing the edges on a surface sander and not a Jointer. Second The boards MUST fit perfect with out any clamp presser, if you have to clamp the strips to pull them together they will separate. The mistake I made years ago was thinking that an 1/8" space in some of the joints that could be pulled together with clamps would be ok not the case. The fix was to cut the tops apart at the joints run them through a Jointer and redo. With light clamping presser you should not be able to slip a sheet of paper in any of the joints. |
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| Changing the way you finish your tops. |
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Andy Graves
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| 23 Feb 2010 10:06 AM |
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Nice looking tops Steve. Is the cove wood countertops taking off for you? |
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Steve Mehan
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| 23 Feb 2010 05:27 PM |
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Andy,
Most of the wood BB tops we do people like the idea of the cove for all the same reasons that SS customers do.I like doing them and the cove is a nice upsell. It,s strange they kinda go in spurts. We've had a few jobs recently for butcher block but also alot of interest in laminates. |
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Eli Polite
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| 05 Mar 2010 09:48 PM |
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i agree with all the only thing i would add is sometimes letting the wood acclimate to the environment it is going to be in helps as well |
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Paul Bingham
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| 11 May 2010 04:21 AM |
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We have glued up thousands of panels for dining room tables, buffet/hutches and doors for many years in walnut, oak, birch, maple, ash, cherry, etc.. Jointing on a good jointer is essential to good joints.
The most important thing to achieving long term success with solid wood glueups is finishing both sides equally with the same finish material. Without the same finish on both sides (usually the bottom gets none or little) the wood will warp across the panel as one side or other is always taking on or releasing moisture at a different rate than the other. Drying wood to a particular moisture content is the correct way to start, but the wood will always be changing moisture content from winter to summer in most climate areas. In the winter most houses are bone dry and in the summer get very humid in the summer.
We used to make dining tables of solid wood up to 108" long with two large end panels and three removable leaves. We had to be very carefull how we constructed them as the wood grain was across the table. We started with wood kilned to 6%, but by the time the wood travels thru several wharehouses and several months or more of sitting stacked in lifts and our shop the moisture usually was at around 8%. After a year or three in clients homes we measured the tables for total length on several occassions and found the tables would shrink up to 1" in the middle of winter and expand by the same amount in late summer. Of course we had to make table supports and skirts that could accomodate this movement or we would have had to spend a lot of time repairing tables. This is a movement of about 1% overall. This is typical for most woods.
It is possible to calculate wood movement by wood type, grain orientation and moisture content.
A kitchen top will be even more affected because of the environment. Proper sealing on both sides will be essential to the long term success of the tops.
Paul |
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Kowboy
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| 11 May 2010 11:23 AM |
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Posted By Paul Bingham on 11 May 2010 06:21 AM
The most important thing to achieving long term success with solid wood glueups is finishing both sides equally with the same finish material. Without the same finish on both sides (usually the bottom gets none or little) the wood will warp across the panel as one side or other is always taking on or releasing moisture at a different rate than the other.
Paul Paul: Bob Flexner, a wood finish writer and teacher for eighteen years, disagrees in "Finish Both Sides? Not Necessary". I'm not paying the $1.99 to make his point, but I got this much for free: "Finishing both sides isn't necessary. Leaving the underside of your tabletop bare doesn't cause warping." Joe |
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| ...One ought to choose likely impossibilities in preference to unconvincing possibilities.- Aristotle |
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Kelsey Crisp
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| 12 May 2010 04:26 AM |
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You said it Joe.... he is a writer and teacher. For those of us that has years in the field working with wood, we understand what works and doesn't.
Paul is right, however I can only assume your writer was probably talking about MDF.... |
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Paul Bingham
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| 12 May 2010 08:47 AM |
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Joe,
Being a writer and teacher does not make him right. Experience in making real products to use in real environments most likely goes much further to enhance a persons knowledge base. I have built hundreds of table tops over the years and you definitely have to finish both sides if you don't want to be hanged by your clients.
We would pass several tops thru the thickness sander late on a friday and set them aside for finishing the following week. They would be stacked one on top of the other, with only the top one exposed on one side. Two days later the top on the top of the pile would be warped badly from differential moisture uptake. As much as 1" or more bow. The top exposed surface expands with the extra moisture and the protected bottom does not. Voila, major bow.
An applied finish on wood slows moisture uptake on the applied side. The other side has no barrier, so it takes up moisture faster. BOW! The other misconception is that application of a heavy build finish stops moisture migration. Wrong!! It only slows it down. Both surfaces have to be trated equally if a top is to have a fair chance of staying flat.
Paul |
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Kowboy
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| 12 May 2010 06:58 PM |
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KC and Paul:
Please don't confuse the opinion I posted with that of mine. I didn't say I disagreed with Paul, I said the author did and gave his credentials. Readers have to weigh for themselves.
Joe |
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| ...One ought to choose likely impossibilities in preference to unconvincing possibilities.- Aristotle |
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Paul Bingham
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| 19 May 2010 03:29 PM |
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Hi Joe,
We got a job to engrave the logo of a Canadian brewing company ( a Stag Head, as in looks like a deer) into the tops of bar tables the other day. The tables are pine and have been in use in two bars for several years. The tops were coated with a heavy bar top plastic finish. The bottoms have no finish.
The tops arrived at the shop today and guess what? Up to a 1/2" warp across a 30" wide top. It's up on the edges and down in the middle as would be expected with differential moisture uptake on the bottoms. The bottom expands more than the top does creating the warp. We need to flatten the tables before CNC cutting begins. The top finish has been removed and we will mist water onto the tops over a few days to expand the top surfaces and flatten them before continuing. After cutting the tops will be finished equally on both sides.
Just a typical day to day example in the real world of woodworking versus the academic world of teaching.
Paul |
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Kowboy
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| 19 May 2010 10:06 PM |
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Posted By Paul Bingham on 19 May 2010 05:29 PM
Hi Joe,
We got a job to engrave the logo of a Canadian brewing company ( a Stag Head, as in looks like a deer) into the tops of bar tables the other day. The tables are pine and have been in use in two bars for several years. The tops were coated with a heavy bar top plastic finish. The bottoms have no finish.
The tops arrived at the shop today and guess what? Up to a 1/2" warp across a 30" wide top. It's up on the edges and down in the middle as would be expected with differential moisture uptake on the bottoms. The bottom expands more than the top does creating the warp. We need to flatten the tables before CNC cutting begins. The top finish has been removed and we will mist water onto the tops over a few days to expand the top surfaces and flatten them before continuing. After cutting the tops will be finished equally on both sides.
Just a typical day to day example in the real world of woodworking versus the academic world of teaching.
Paul Paul: Again, I must remind you that I have never made a claim either way. I read an article that disagreed with your position and posted it. Readers can pay the $1.98 and judge for themselves. Dissent is the beauty and value of this forum. Thanks, Joe P.S.: Speaking of academics vs. real world, I had a friend who was taking an art class. I told her if she sanded and flamed the edges of her Plexiglas project, they would turn clear. When she did and her classmates were amazed, her professor announced that flaming edges of Plexiglas "would never work".  |
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| ...One ought to choose likely impossibilities in preference to unconvincing possibilities.- Aristotle |
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