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Cracks in juniper tabletop

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Forum topic by TZH posted 10-23-2014 12:33 AM 1238 views 0 times favorited 17 replies Add to Favorites Watch
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TZH

526 posts in 2606 days


10-23-2014 12:33 AM

Topic tags/keywords: question cedar juniper cottonwood router carving tool carving finishing refurbishing joining sanding refinishing butterflies dowels rustic arts and crafts

Awhile back, I posted a project (http://lumberjocks.com/projects/100237) of a juniper table. One of the questions I was asked was how did I accommodate expansion and contraction. My answer was rather naive – that I didn’t account for either. The client I made the table for was ecstatic with it, and then the cracks started to form. He’s still ecstatic with the table, does NOT want me to make him a new tabletop, DOES want me to repair it somehow, and is being very patient with my ineptitude in this regard. And, that’s what brings me to this forum topic.

I NEED YOUR HELP!!!!!!!!

Here are some images of the cracking:

The cracks all seem to follow along the knots in the wood which actually makes sense because the expansion and contraction didn’t affect the jointery I did – the glue held up beautifully. The fourth photo is of some black streaks that also started showing up in the cottonwood. I believe this is spalting, but am not sure. Has anyone seen anything like this?

Anyway, in discussing what might be done, I threw out several possibilities including butterflies, routing the cracks out deeper and filling them with turquoise (or some other agreeable material) and epoxy, running long dowels (wood or metal) all the way through the table to reinforce it, reinforcing the seams from underneath, redoing the entire tabletop with an epoxy finish to fill the cracks and give the top more durability, or, as stated above, replace the entire tabletop. He seemed to lean toward the epoxy top and reinforcing from underneath. I simply don’t know what would be best, or if something else might come to someone’s mind here on LJs.

He loves the knotty grain of the juniper, so doesn’t want to go with a different wood.

Thanks for any ideas, suggestions, recommendations.

TZH

-- Where The Spirit In Wood Lives On


17 replies so far

View Greg In Maryland's profile

Greg In Maryland

550 posts in 2464 days


#1 posted 10-23-2014 01:09 AM

Do the cracks go all the way through the top? If so, I would add butterflies on the bottom to stop further cracking. How were those breadboard ends attached? They may be the source of your problems. Also, it may make sense to make sure any wood movement is complete before you attempt a repair. With winter coming up the wood shortly will be subject to it’s driest indoor conditions (presuming you do not live in the Sonoran desert, then it would be dry year round)

Regarding the repair, I think that epoxy mixed with India ink would be the best and easiest approach to filling the cracks.

Good luck.

Greg

View grizzman's profile

grizzman

7798 posts in 2769 days


#2 posted 10-23-2014 01:11 AM

you could get creative and get some dutchman in there to stop the cracks, or maybe you could drill a hole at the end of each crack and then plug the hole with the same wood, make some juniper plugs this would stop the current cracks, i just hope more do not appear, was this juniper dry when used or where was it moisture wise…

-- GRIZZMAN ...[''''']

View bondogaposis's profile

bondogaposis

4035 posts in 1817 days


#3 posted 10-23-2014 01:40 AM

There are two places that are potentially causing the problem. One is the bread board ends. If you didn’t allow for movement there you need to reconstruct them to allow the width of the table move w/ changes in humidity. The other potential trouble spot is how the table is attached to the legs, you also have to allow for movement there as well. That table will continue to pull itself apart until you give it room to move. After you do that then you can repair the cracks.

-- Bondo Gaposis

View TZH's profile

TZH

526 posts in 2606 days


#4 posted 10-23-2014 02:17 AM

Thanks, Greg. The ends were doweled and glued. They’ve also elongated a bit and come to think of it may indeed be the problem. The wood had dried super fast in a forest fire, and I milled it last year – total time elapsed was about 4 years. That’s why I thought it was safe to work with. A couple cracks do go all the way through. We live in Colorado, so the dry weather is pretty normal around here. My client is more than willing to wait and see if any more cracks show up. Thanks for your input.

Thanks, grizzman. Not sure what you mean by “dutchman”. I thought the wood was dry. Guess it may not have been.

Thanks, Bondo. The more I think about it, the more the bread board ends being the problem makes sense. How would you recommend I reconstruct them? If you look at my blog, http://zhawke.blogspot.com/2014/04/thought-i-saw-finish-linefor-second.html , I go into quite a bit of detail on how it’s fastened. If you see anything, anything at all, you would recommend changing, please share.

Again, thanks, all. This really helps a LOT!

-- Where The Spirit In Wood Lives On

View jerryminer's profile

jerryminer

528 posts in 907 days


#5 posted 10-23-2014 03:28 AM


I thought the wood was dry.

Doesn’t matter. Wood moves with humidity changes. Just because it was dry once doesn’t mean it won’t move as the seasons change. Woodworking 101

Research breadboard ends. They need to be made in a way that allows for wood movement. Gluing and doweling them practically guarantees the top will crack. I would re-do them. Patching the cracks is only a temporary solution. Those BB ends are the real problem

View OldWrangler's profile

OldWrangler

731 posts in 1060 days


#6 posted 10-23-2014 03:54 AM

I think butterflys are the most reliable to pull the wood back together at the cracks. I doubt if you can make them look inconspiculate so you may have to go for contrasting. color and grain in another kind of wood. Grizz suggests the use of Dutchmen and I am curious how he would go about using them. They are patches that are inlaid to usually cover up a hole, flaw or knot. You have a problem here. I don’t suppose you can pull the cracks together with side to side clamps but if you could maybe there are other answers. I once repaired a table top with the same problem by drilling in one edge through to the other. The a piece of threaded rod can be used to such the wood together, The start of the hole on both side need to be drilled out enough to get a nut with a socket to turn it. Screw it together as tight as possible and the fill the holes in the side with a plug cut of similar material with the grain matching as close as possible. One of these about every ft. would eliminate this problem in the future. Lot of work with a lot of precision will be needed but on a 2” thickness, it should not be terribly difficult. You can put glue in the cracks before you pull them closed. That will help some too. That’s my 2 cents worth and that may be an overcharge for this advice. I think we all would be interested in what you wind up doing and pictures of the results. Let us know.

Hey Bob, let me know how you would us Dutchmen on this repair….I’ve got plenty to learn.

-- I am going to go stand outside so if anyone asks about me, tell them I'M OUTSTANDING!

View bondogaposis's profile

bondogaposis

4035 posts in 1817 days


#7 posted 10-23-2014 05:01 AM

Thanks, Bondo. The more I think about it, the more the bread board ends being the problem makes sense. How would you recommend I reconstruct them?

This video explains pretty well.

-- Bondo Gaposis

View jdh122's profile

jdh122

879 posts in 2283 days


#8 posted 10-23-2014 10:30 AM

Like Jerry said, whatever you do to fill the cracks will be for nothing unless you deal with the breadboard ends, since it will crack again with seasonal expansion and contraction. I would think that you need to saw them off and re-install them using the method presented in the video that Bondo linked to. It will not be easy to rout a tongue/tenon in the table top now that it’s installed. Or you could do floating tenons into matching mortises in both the top and the breadboards, three of them (one in the middle that is glued and one on each end that are pinned in elongated holes/slots).

-- Jeremy, in the Acadian forests

View TZH's profile

TZH

526 posts in 2606 days


#9 posted 10-23-2014 02:44 PM



Thanks, Bondo. The more I think about it, the more the bread board ends being the problem makes sense. How would you recommend I reconstruct them?

This video explains pretty well.

- bondogaposis

I went to the video and it only showed the very end of the process where the end wouldn’t come off (only a few seconds in total length of video). I’ll try some of the links provided in the sidebar, too. The video you provided looks like a really good one if I could just get the entire process.

Thanks.

TZH

-- Where The Spirit In Wood Lives On

View Dallas's profile

Dallas

3599 posts in 1953 days


#10 posted 10-23-2014 07:11 PM

It looks to me like your lumber came from close to the pith of the tree. Tree pith or close by will cause a lot of cracking and splitting as it acclimates.

In the olden days, (1980’s), we never cut closer to the center of the tree than 4”, and if there was any chance of a crack forming we would go out even farther.

You’ll also notice that none of the sapwood has cracked, only the heartwood. The trees this piece was made from was a small tree, whether it was Juniper, Cedar, Oak or anything else it is going to have problems.

A Dutchman, (Butterfly), might help, but there is going to be a huge amount of stress on the table as it swells and contracts. It probably won’t help as you don’t know when the wood is at it’s widest or narrowest.

-- Improvise.... Adapt...... Overcome!

View a1Jim's profile

a1Jim

115202 posts in 3043 days


#11 posted 10-23-2014 07:40 PM

Wood movement is a subject I try and caution folks about all the time, particularly dealing with table tops. I see many tables on Ljs that have cross grain problems (such as bread board ends glued on and cleats on the bottom of the table top glued or screw on) that won’t allow for wood movement.
I’m not very enthusiastic about trying repair this with a dutchmen. I think corecting the wood movement problem and replacing the center board is the best option long term even though it will take a considerable amount of work, I would also check the replacement board’s moisture content before installing it.

Here’s a famous woodworker’s article about table tops and wood movement. It’s one of the best articles I’ve seen.

https://www.finewoodworking.com/media/TabletopsFlat.pdf

-- http://artisticwoodstudio.com Custom furniture

View SCOTSMAN's profile

SCOTSMAN

5839 posts in 3051 days


#12 posted 10-23-2014 07:44 PM

See what Norn Abram did with cracks on a table top he filled them with black epoxy.Epoxy added to old toner from a printer seemingly works great, but try it on scrap first it finished beautifully when he did it looks just like a part of the wood as God intended.. Or you can buy the black past additive it aint expensive added to clear epoxy. Alistair

-- excuse my typing as I have a form of parkinsons disease

View runswithscissors's profile

runswithscissors

2192 posts in 1491 days


#13 posted 10-24-2014 01:49 AM

A soft filler, such as bees wax, or the colored crayons used for matching different wood species, should allow wood movement and take care of your present problem. I’m wondering if bees wax could even be colored with some sort of dye or stain to match the various colors in your juniper. (I love working with that stuff because of the smell!)

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened

View runswithscissors's profile

runswithscissors

2192 posts in 1491 days


#14 posted 10-24-2014 01:50 AM

Sorry, duplicate post. I wish these could be erased.

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened

View redryder's profile

redryder

2394 posts in 2568 days


#15 posted 10-24-2014 05:41 AM

This rustic work is probably my favorite kind to build.

The following is just my 2cents worth:

I read your whole blog on the table build (nicely written). I suspect you have a lot of time in this table especially the base. I think this table is toast. Unless you really can ever get over those cracks. This will be a great learning experience. The older I get, the more research I do before I dive into a project that I am not that familiar with. I hate to mess up. (see the above comments and suggestions on wood movement and reason for failure). The above video link is quick but to the point. There are others that show more detail leading up to the pinning of the ends. Your blog suggests a lack of experience with the router and practice should be used before your next table to get the ends to line up. There is also a lot of good info on doing glue-ups and the best way to attach the base to the top for stability and easy removal when you want to move the whole thing.

The table in your original project is definitely a looker. I can see why your customer was satisfied. He seems easy to please. Remember: R & D (heavy on the research)
Good luck. You don’t sound like a guy who quits….....................

-- mike...............

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