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Oak log just fine in the workshop for weeks, once debarked, split like crazy

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Forum topic by RobinDobbie posted 06-15-2015 10:48 PM 1201 views 1 time favorited 15 replies Add to Favorites Watch
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RobinDobbie

133 posts in 1201 days


06-15-2015 10:48 PM

I had an oak log in the workshop for probably over a month with no problems. A very small amount of endgrain splitting, but not a huge deal. Cut about 3 inches off each end and then put it on my cylinder jig about 5 days ago and debarked it. I knew I wanted to take more off, but I just didn’t have time that day. I just took a look at it, and it looks as bad as logs that have been outside for YEARS. Would this have been completely prevented if I’d sealed the ends up, first?

http://i.imgur.com/BV5PYl7.jpg


15 replies so far

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Tim

3119 posts in 1428 days


#1 posted 06-15-2015 11:27 PM

No, sealing the ends doesn’t completely prevent checking. Sealing reduces splitting by something like 70% for sawn lumber, but less for a log. Looks like what happened is you cut off the ends and that let the moisture out again and that leads to differential drying between parts and when that’s in a log you get serious checking. Basically the outer rings shrink faster than the center and have nowhere to relieve that stress so it cracks.

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mahdee

3554 posts in 1234 days


#2 posted 06-16-2015 02:26 AM

Tim is right. Also, if the piece got hot as you debarked it, it contributes to the cracking. Some folks put the piece in a damp saw dust in a bag/bucket to prevent checking after it is turned. One month is no where near enough time.

-- earthartandfoods.com

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RobinDobbie

133 posts in 1201 days


#3 posted 06-16-2015 05:31 AM

So is my dream of using logs for furniture legs a pipe dream?

I dont’ think it got hot, it was spinning around at 150+rpm while the table saw blade cut around it. Just imagine it in a lathe, but instead of using a gouge, the table saw blade was removing the material. No burn marks anywhere, the blade just doesn’t stay in one place long enough.

I realize drying time could be years, but how do I get it there without trapping all the moisture inside, or accelerating the cracking?

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mahdee

3554 posts in 1234 days


#4 posted 06-16-2015 11:22 AM

I am not really sure. I have had branches of oak, hickory, mulberry and so on sit on my wood pile for 2 years and they did the same thing. One thing you can do is to used the cracks as character by filling the cracks with darker/lighter sawdust or stones mixed with glue/super glue.

-- earthartandfoods.com

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Underdog

907 posts in 1502 days


#5 posted 06-16-2015 06:40 PM

You want to CONTROL the drying process, which means slowing down moisture loss, and taking precautions to prevent cracking.
Since it loses most of the moisture out the end grain, you absolutely must seal the end grain with something flexible like a wax emulsion, or latex paint. The other thing is to store it in a cool dry place while it dries.
To prevent splits, one really needs to cut the log in half, at least, so the outer perimeter has a place to shrink. The interior doesn’t really dry faster than the exterior, it dries at the same rate. There’s just more area drying, and shrinking, so it has to go somewhere. That’s what creates the cracks.

If you removed all the bark, and cut off the ends, and left it to dry in these kinds of temperatures (it’s 96 degrees here right now) then it’s no wonder it split…

If you want to use the whole branch, or log, or whatever, then you’ll need to dry it slowly and carefully before opening it up.

When I rough turn (green wood) a bowl, I turn it to 10% thickness of diameter (so 10 diameter would be 1” thick). Then I usually wrap well it in newspapers and let it dry for 6 months to a year, and then true up the tenon, and finish turning it.

-- "woodworker with an asterisk"

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RobinDobbie

133 posts in 1201 days


#6 posted 06-16-2015 07:20 PM

The first reply suggested sealing the end grain would only have reduced cracking by less than 70%. I’d say 30% of current cracking is still 100% more than I’d want, and 95% of what I’d be OK with.

“If you want to use the whole branch, or log, or whatever, then you’ll need to dry it slowly and carefully before opening it up.”

Yes, I want to take advantage of the whole log. If I split it in the middle, then I’d have to have logs that are more than twice the size to get the same size cylinder.

I just don’t see most log furniture having giant cracks in it. Maybe it does, but just not what I see. My local grocery store started carrying log furniture, and none of it has massive amounts of cracks. Also, google image searches show that while some log furniture does have lots of cracks, most does not. I don’t want my furniture to have “character cracks”. I want solid wood.

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Wildwood

1887 posts in 1601 days


#7 posted 06-16-2015 08:10 PM

Next time get a log as shown in the picture rough cut to length (longer & wider than will actually need) End seal, you can buy wax emulsions like Anchor Seal, or Green Wood sealer both wax emulsions already mentioned. I also used latex paint, oil base paint, & clear poly finish to end seal large bowl blanks.

For my spindle blanks less than 5” in diameter use canning wax called Gulf Wax bought at grocery store or in my case commissary. Very expensive on line, checked Walmart and they now want $20 for one pound box. Found it in Walmart store for $3.00 couple years ago. So check local grocery or craft stores for better prices.
I melt wax on a hot plate in an old pot and dip ends.

Moisture escapes 12 times faster from ends of a log than across the grain; wood dry from the outside in. Store your sealed logs out of the weather in cool dry place like your work shop.

Have no idea where you live so no idea of relative humidity or temperature range for your area. Drying or seasoning wood all about water removal. This is accomplished by evaporation due to air circulation. When your logs stop gaining or losing moisture you are at EMC.

See figure 13-1 and table 13-2 on page 5 of the link.

http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr190/chapter_13.pdf

You can use a scale to weigh logs, when weight remains the same for week or two you are at EMC, or use and inexpensive moisture meter for ball park number.

I bought this meter when darling of woodwork message boards and only cost $10 & change but still recommend it.

http://www.lowes.com/ProductDisplay?partNumber=78059-56005-MMD4E&langId=-1&storeId=10151&productId=3136919&catalogId=10051&cmRelshp=rel&rel=nofollow&cId=PDIO1

-- Bill

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RobinDobbie

133 posts in 1201 days


#8 posted 06-16-2015 11:18 PM

As for sealing I bought 5 gallons of driveway tar, but you did give me a good idea. I was going to “paint” it on, but just dipping it in would make more sense.

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yvrdennis

27 posts in 543 days


#9 posted 06-17-2015 12:43 AM

Wood shrinks more tangentially to the rings than across them. For oak from wet to oven dry the shrinkage is about 8% in the tangential direction and about half that in the radial.

In other words, as the rings dry they want to get smaller in diameter, but they can’t because the centre of the branch is still there. So, any piece of wood that contains the pith is almost certain to crack as it dries. Sealing will slow this down, but not prevent it.

You can use whole branches as legs, in fact it’s common in twig furniture, but you have to accept the splits as features and not defects.

View Tim's profile

Tim

3119 posts in 1428 days


#10 posted 06-17-2015 01:06 AM


Yes, I want to take advantage of the whole log. If I split it in the middle, then I d have to have logs that are more than twice the size to get the same size cylinder.
- RobinDobbie

Seems like thats what’s done most of the time rather than an extremely careful drying process only to have it crack anyway. How large of furniture are you making that you can’t use a log split in half and make a spindle or whatnot out of the remaining thickness? A 12” diameter log still leaves 6” of thickness and even taking away the bark, pith, and sapwood if you remove that leaves a pretty good size for a cylinder.

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RobinDobbie

133 posts in 1201 days


#11 posted 06-17-2015 01:58 AM

I don’t think that’s what done on most of the log furniture I see. I say that because most of the log furniture I see still has knot protuberances all the way ‘round, unless they purposefully carved those back in(and I seriously doubt it!). Either way, I like the idea of having the tree’s growth rings available to integrate into the design, if possible. For example I want to make a table that uses logs for legs with the end grain visible from the top. And, I want that end grain to be round.

View splatman's profile

splatman

563 posts in 865 days


#12 posted 06-17-2015 03:52 AM

A bit late in Robin’s case, but here’s
An idea:
While still green, saw (bandsaw probably best) the log in half, dry it with whatever method you choose, run the halves thru a jointer to remove the saw marks, and flatten the now convex faces, then glue the 2 halves back together. A dry, split-free log.
Probably over-dry the log by a % or 2. When it regains moisture, tension will build (and any splitting will occur) in the center, not the outside.
Or cut a slight hallow on one or both faces, like the back of a molding, and near-eliminate the chances of splitting.
Or cut a saw kerf on each face (use a table saw) to basicly do the same, but perpendicular to the faces.
If this is all too much, just saw a kerf 1/2 the log’s diameter deep, on the side that will not show. This will function just like a control joint in a concrete floor.

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jdh122

879 posts in 2284 days


#13 posted 06-17-2015 09:09 AM

One thing – most log furniture is made from softwood, often pine. Generally softwoods are more dimensionally stable than hardwoods, which will reduce cracking some.
I use green wood quite a lot for chairs, and never have problems with cracking, but I always split and always remove the pith. It clearly is possible to dry whole logs without major cracking, but it can’t be easy.

-- Jeremy, in the Acadian forests

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Underdog

907 posts in 1502 days


#14 posted 06-19-2015 04:21 PM

If you figure out how to keep whole logs from splitting, be sure to let the lumber industry know…’
Or not.
Patent the process and get rich.

-- "woodworker with an asterisk"

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RobinDobbie

133 posts in 1201 days


#15 posted 06-19-2015 05:17 PM

splatman, I really like your ideas. I wonder if some of these techniques were in play on some of the log furniture I’ve seen, and I just didn’t know it?

jdh122, you’re absolutely right. I did a couple quick searches for log beds with different hard woods in quotes. I saw one, but most results turned out to be some of the softest woods: pine, some variety of cedar, or aspen. So having solid oak or(drool) black walnut log furniture is going to require some wizardry.

Underdog, I think I figured it out. They just heavily seal the furniture as quickly as they make it. The vast majority of this furniture looks shiny as heck. That, or, they just take picture minutes after it’s assembled, then have a disclaimer that cracking and checking is normal. Then they add the usual “it adds character” bullsh!.

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