I need help with wood movement and temp
Good morning everyone. I have a problem that I have never encountered and I am not sure what to do. I am located in Florida and we have been having some unusually cold weather here the past few weeks and the past two days have been the coldest. Yesterday, I was sanding some door panels and I heard a loud Pop! I got to looking around at the piece I have been working on for the past few months and I noticed the back glued up panel had separated at a glue joint. I know there has been an extreme drop in humidity but I have never seen that happen before the board moved 1/32 of inch. I was blown away, luckily it was on the back panel my first instinct was to dowel the ends of each board in the panel to keep the rest from splitting so I did that but left the board where it split alone. I was wondering if that board will swell back up when the humidity returns? Also I wanted to move the piece into a heated area but I am afraid that the extreme temperature change will cause me more problems. Its been in the high 20’s and it is supposed to warm back up in the next few days which means the humidity will return but I have a deadline of Jan, 31 and need to start finishing but I cant do that with the temp’s where they are. What do I do? The piece has been in 50 to 30 degree temps and will be going to 76 degrees if I move into a heated area I know it will needs to acclimate but what will happen if i move it? The wood species that did all the moving was soft maple, other woods used are Sapele, Birdseye maple, and ebony. I have figured out a way to cover the split and make it look good but I didn’t want to go through all that if it would swell back up I am willing to wait if I can be assured that it will move back in a few days, if it wont the I will make it disappear. This piece is very important I am entering it into a competition and it has to look its best. Also it is completely glued up so replacing it is out of the question.
Replies
Is the panel floating in a frame (good), or glued on the edges (bad)? I'm not sure I follow the description of your dowling procedure -- firmly fixing the panel in place is the last thing you would want to do. You will never be able to stop the wood from moving -- you can only design to allow for it.
The wood will swell back up. The glue will not repair itself, however, so the crack is not likely to disappear. Also, the temp is not as big a deal as you seem to think -- it's the humidity that's important. If it wuz me, I'd move it to an interior environment for a few days to acclimate and settle down (I assume the show will be indoors in a heated space). Then make what repairs are necessary and finish it, also in the heated space. Ideally, furniture should be built and finished in an environment as close as possible to that where the piece will be used.
Mike Hennessy
Pittsburgh, PA
Temperature per se should not affect the expansion much but in my experience when raising the temperature some thirty degrees could easily lower the relative humidity fifty percent from its original reading.
Edited 1/24/2009 1:28 am ET by Tinkerer3
Mike is correct. I will reiterate that it's not the temp as much as the very low humidity. Evidently your panel had become captured somehow so it was not able to move when it dried out. So it split. Look for why it couldn't move.
Earl
You have several things to consider.
Here is my 2 cents worth of free advice. Some of it may apply and some may not. **That's why I offer a free money-back guarantee on the free advice!
Your panel split
**Does not apply in Florida and can be revoked at any time
"Humidity changes, not temp, will cause wood to expand and contract... "
You are fishing and groping somewhere in the right area, but what you say is not quite true Tbagn.
Changes in wood moisture content affect or influence its size.
Temperature does have an effect in conjunction with relative humidity on the moisture content of wood. The following are some examples of the sort of equilibrium moisture content wood will achieve if the following listed conditions are maintained for long enough.
10ºC coupled with 40%RH = ~10% EMC
20ºC coupled with 40%RH = ~9% EMC
50ºC coupled with 40%RH = ~6% EMC
The last temperature and humidity condition is of course not one you will see very often in normal workshop or house situations, but such temperatures and RH conditions are purposely set up by kiln operators to condition or dry wood for sale to woodworkers Slainte.
Richard Jones Furniture
Edited 1/22/2009 6:07 pm by SgianDubh
er, yea... that's what I said :0)
Richard , I have a question on that note. If I buy a board that is nice and straight and bring it home how should I treat it other than let it acclimate. Also should I finish it as soon as it is furniture or what ever or let it acclimate for a little after it is milled sanded and joined I am worried about warping after I get the wood
Apart from allowing air to circulate freely and letting the boad acclimatise as you describe there isn't much else you can do there. You'll find some discussion relevant to the second part of your question here beginning at paragraph nine. Slainte.Richard Jones Furniture
Wow, thank you. That was very informative and I am reading all your other articles as well. Good writing! Is there any comprehensive book on wood movement and moisture or am I just going to need to learn it as I go. Thanx again, for your time
I'd say that until I complete my manuscript on timber technology for woodworkers, which I'd like to think will be very accessible for the average wood hack or lay person, ie, one who is not a specialist timber technologists, that R Bruce Hoadley's Understanding Wood is the most digestible book out there. Slainte. Richard Jones Furniture
Not that I am rushing you but hurry up I like the way you write. Lol. Till then I will pick up Hoadleys and start learing. Thanx again
You won't hurry me. I've been working on it for over three years so far: 100,000 words, 200+ photographs, over 100 figures I think, and counting in all cases. A publisher read some extracts and offered me a contract about six weeks ago. I turned it down as I'm working at a pace I'm happy with, not one determined by anyone else, which is the situation I'd be in if I sign a contract. Slainte.Richard Jones Furniture
Richard,
I second Wolfonce's "wow." Very good article.
Thanks, GeorgeYou don't stop laughing because you grow old. You grow old because you stop laughing. - Michael Pritchard<!----><!----><!---->
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Richard, On the article of joints you did not say anything about how you mill a board to get the spring. Thank you for posting those articles they are very informative
I didn't describe how to create a sprung joint. In the context of the discussion describing the mechanics of creating a sprung joint wasn't relevant. But if you find it useful, here is the way I normally create on.
I square an edge to the face on a surface planer of every plank in the panel, rip the boards to width from the prepared edge, then run them through the thicknesser to get the desired thickness and width. At some point in the proceedings I arrange the boards in an order or pattern and mark a big cabinetmaker's triangle on the show face of the arrangement. Next I use either a jack plane, but usually a try plane, and take a few stop shavings from each of the mating edges and test the joints. When all is as I want it I slap a bit of glue on and cramp up the job.
The big cabinetmaker's triangle I mentioned has a base line running along the length of the first board in the arrangement. The top point of the triangle is located on the face of the last plank in the arrangement. As long as you reassemble the triangle correctly you never lose track of the board order. Slainte.Richard Jones Furniture
Thank you very much sir. That is very helpful.
Hi Richard,
Re: your book. As the fellow said as he was holding up the heavy plank while his buddy was nailing it, "Hurry up, every chance you get!"
Re: the cabinetmaker's triangle. The first shop I worked in, the boss showed me how to draw an exaggerated "S" scroll across the faces of the boards to be glued-up, to accomplish the same end as your triangle. In addition he suggested (well, it wasn't a suggestion, he was the boss) that each board's edges be marked "B" and "F", at the glue line to denote that that edge be passed with the board's "B"ack or "F"ront held against the jointer's fence, so as to cancel out any variation of the fence from square.
Funny how after thirty-some years, the "right" way to do some things hasn't changed.
Ray
I hurry when I can Ray. Spare time to concentrate and write is a rare commodity.
I liked that interesting variation on the cabinetmaker's triangle. Like the triangle, once the S is in place there's little chance of losing the plank order. Slainte.Richard Jones Furniture
good morning Thanks for your help, I was thinking the same thing(that failure at a glue joint was pretty strange) So i talked to a few people and appearently Titebond III skins over very fast most think i have had glue failure because the fact that the glue joint gave and not the wood.
did you glue it up at a low temp? I use TBIII all the time. I think they suggest a minimum of 45 degrees. Perhaps that caused the failure?
No when i did the glue ups for the panels the temps where much warmer. I am a one man operation and the panels where pretty large so i think i took to much time to glue it up. when the say the gule has a 12 min open assembly time does that mean you have twelve min to apply final clamping pressure to the first joint you applied glue to?
"does that mean you have twelve min to apply final clamping pressure to the first joint you applied glue to?"
Yes. Less time is better still. Ireckon on a ten minute maximum at 20ºC (~68ºF)
I can't be sure from your original description if your panel is/was held in a groove inside a framework, eg, like a frame and panel door. If it is that configuration it is possible that the corners of the panel got glued in due to glue squeeze out during final assembly of the frame around the panel. This fault can be enough to cause a shrinking panel to split, sometimes right on the glue line, especially if the glue bond is not good due to a range of factors, eg, careless edge preparation, insufficient cramping pressure, too much time taken at glue-up, bad glue, etc. Slainte.Richard Jones Furniture
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