Elm split!

OK - I had a pile of Elm that was sitting in the barn for a few years (8 or 9 years). It came from a tree on a friends property that we had milled, and then just stickered it in the barn - unheated/conditioned environment. Having had a yearning for a solid workbench for some time, I decided to use it to build the bench from (think cheap... this wood cost me about $0.10 per board foot, and a workbench takes a pretty fair amount of wood).

So I planed and sanded and joined the legs/cross members by laminating 3 or 4 boards together using Titebond III. Note that during planing, it was obvious that this Elm moves a fair bit due to residual stress (twisting, curving, etc... its a bit of what I would call 'onery' to work with).

THEN, after cutting the joinery and having it sit in my garage for a few weeks while I chase other projects, I come in to learn that the cross braces had cupped on the outside board and actually split the vertical legs!!

The failure was 'mostly' along the glue line, but it was actual wood fiber failure so I cant competely blame a poor glue joint. The culprit seems to be one outside board on the cross member in particular, that cupped and just forced the legs apart.

Some pics here. Since then, I have resawn them and resurfaced reglued them. So far it seems to have taken this time.

Dont know if it is going to split again as the weather changes again. I was surprised, since it seemed that it should have air dried long enough and the joinery that failed had both pieces with the grain going with each other. I guess one of the pieces still had a lot of moisture in it (I have heard Elm is hard to dry).

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Now that's impressive. When we say wood moves, I don't think we are talking to that degree. Wow.

Elm is one of those woods that is best quarter sawn. I made a china cabinet out of it and the back of the carcass moves like it is alive. I told loml that it's part of the charm of a handmade piece.

Have you a moisture meter? The Delmhorst J-lite does the job and won't break the bank. Would probably save you money in the end.

You got elm to split? didn't you could split elm! :D are you sure there isn't any of the pith in those boards or some cracks in the wood?

In the bottom photo, the end of the leg shows the pith of the tree centered in one board. That one is definately a culprit! The wood movement along the glue lines shows that the wood dried faster on the outside surfaces, cupping toward the outside and ripping the glued joints apart. I will put elm on my list of woods to use when kiln-dried only!

Elm firewood is definately hard to split with a maul! Maybe I should try gluing my firewood together! LOL!!

There's differing opinions on the subject but IMHO, the wood should have been acclimated to the garage/shop environment prior to milling. The wood sought it's EMC in the barn which was obviously diffeent from the heat/humidity level in the shop.

However, I've only worked with Elm on the lathe so I really shouldn't even be speculating as to it's properties. Turned bowls do move a lot, however I've not had too many of them split.

I also used lumber from the barn to build my bench, only it is burr oak. And one of my legs cracked too. Used the french style from Schwartz's book, and it is very stout. No way I'm going to try to take it apart and redo the leg. I glued the mortise and tenons. And the pegs. If I happened to move, would have to use a forklift to load it.

Quote:

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Originally Posted by Cody Colston

There's differing opinions on the subject but IMHO, the wood should have been acclimated to the garage/shop environment prior to milling. The wood sought it's EMC in the barn which was obviously diffeent from the heat/humidity level in the shop.

However, I've only worked with Elm on the lathe so I really shouldn't even be speculating as to it's properties. Turned bowls do move a lot, however I've not had too many of them split.

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The red elm I've used was very prone to movement until it acclimates well. I let it acclimate, dimension it close to size and let it acclimate again, then dimension to final size.

All good observations here. Indeed, one of the boards laminated between others in the vertical leg had some bad spots. My thinking? Its laminated between other pieces, is grossly oversized structurally anyway, and takes mostly vertical stresses. Besides, although a pretty good stack of wood on hand its going to take all of it to get the project done and there isnt much to spare. So into the works it went.

Also. I dont think the glue joints were really strong. Just by the fact it seemed to come apart along the glue joints.

I do think its a moisture related issue. The outside board cupped (a lot... maybe 1/8 inch cup across a 5 in board. This leads me to believe it was drying from the outside surface (concave, so the outer surface shrank wrt the side that was against the other pieces). Also, I wonder if the particular board in question may have been near the bottom of the stack (raised off a concrete floor by about 3.5 in resting on 2x4 on edge). So maybe some higher moisture because it was on the bottom of this stack.

And the only real reason it split (that I can tell) was the forces due to the cupping. If it hadnt cupped, it wouldnt have split the leg. Meaning, some pretty impressive forces created just due to the shrinkage. (definitely need a moisture meter.... on the list).

When I tried regluing I tried just working glue into the crack area and clamping. A dozen heavy duty clamps later... no chance of this working, and in fact it was looking like the outside surface of the wood itself was just going to be pulled apart this way. So a aresaw/surface/glue, with acclimation this time.

I just didnt expect it to fail this catastrophically. Figured all the pieces would move together. Live and learn. It was just what wood I had and it will still come out decent, just a little setback/redo. I am glad I hadnt yet glued it up (sometimes distractions are a good thing??). Remember, you cant have too many projects 15% complete!! ;)

All repaired now, and the glued up top (~2ft wide by 4.5 in high... some 50 pieces) is holding flat and true, so I am hopeful its still going to make a decent bench. Ask me again in 3 years of temp cycles..... maybe it will just pop apart piece by piece.

A couple detours here and there (other duties call), but I did finish this project off so posting some pics of the finished bench. I will add a face vice later in the year.

The front board on the top is 8/4 hard maple, and I made the dog holes from a piece of cherry and laminated between walnut (for no particular reason)

In the end it came together nicely, and a worthy end product from a stack of some pretty rough wood to start with. We will see how this Elm behaves in time.

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The Elm certainly made an attractive bench...almost too pretty to work on...naah. :D

Seriously, you did a great job on the bench. Thanks for showing.

Very nice bench, interesting read!