desk build, surprising wood movement/crack.. or something else?
#11
  
My 11yr old Son and I built this desk for him together and finished it in March, using "African Mahogany" (Sapele? mostly?) that I had sitting in my shop for close to 15yrs (it's all solid wood.)

Posting a couple pix of the desk just 'cause I never did when we finished it.  Cool    (special thanks @DaveR for Sketchup and design help!)

The top is two pieces with a single glue-line, bookmatched from a thick board I re-sawed. 

Anyway, he's had a laptop on it for the past several weeks due to Covid19 at home learning.  I just noticed when I moved the laptop, the seam is split wide open!! Check out the last pic. (you can see inside the crack the Dominos I used).. This was not like this even 3-4 weeks ago.

Very surprised to see this.. And it seems like it happened directly below the laptop (heat? fans?) 

The top is attached loosely using figure 8 fasteners, I wouldn't have expected this.

Certainly repairable (re-cut/glue/finish it) but was very surprised this happened.


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#12
  Re: desk build, surprising wood movement/crack.. or something else? by mound (My 11yr old Son and ...)
I share your thoughts, but also want to congratulate your son and you for a beautiful desk...that is really nice wood!
I started with absolutely nothing. Now, thanks to years of hard work, careful planning, and perseverance, I find I still have most of it left.
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#13
  Re: RE: desk build, surprising wood movement/crack.. or something else? by fredhargis (I share your thought...)
(10-08-2020, 09:22 AM)fredhargis Wrote: I share your thoughts, but also want to congratulate your son and you for a beautiful desk...that is really nice wood!

thank you sir!
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#14
  Re: desk build, surprising wood movement/crack.. or something else? by mound (My 11yr old Son and ...)
That's a really nice looking desk and well constructed.  It's really surprising the seam in the top opened up, especially since you used Dominos in it. So I'm guessing the root of the problem was the glue you used.  TB III perhaps?  TB III has really poor creep resistance and strength at high temperature.  With a laptop sitting on it running for hours/days at a time it might have added enough heat to cause both the wood to contract and the glue to creep resulting in the seam splitting.  

When you rip and reglue it I would use Gorilla Glue, epoxy, PRG, or even TB Original.  All are far better than TBIII.  

John
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#15
  Re: RE: desk build, surprising wood movement/crack.. or something else? by jteneyck (That's a really nice...)
(10-08-2020, 09:33 AM)jteneyck Wrote: That's a really nice looking desk and well constructed.  It's really surprising the seam in the top opened up, especially since you used Dominos in it. So I'm guessing the root of the problem was the glue you used.  TB III perhaps?  TB III has really poor creep resistance and strength at high temperature.  With a laptop sitting on it running for hours/days at a time it might have added enough heat to cause both the wood to contract and the glue to creep resulting in the seam splitting.  

When you rip and reglue it I would use Gorilla Glue, epoxy, PRG, or even TB Original.  All are far better than TBIII.  

John

Thanks John.  I used TBII actually.

I suspect the heat is at play. Maybe I should make him put a cooling pad under the laptop.  Agreed, I'll use epoxy for the fix..
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#16
  Re: desk build, surprising wood movement/crack.. or something else? by mound (My 11yr old Son and ...)
Definitely heat. My laptop runs to 80-90 degrees at times, which I was okay with until I realized it was Celsius! That's internal temp, but it has to go somewhere - and the top of the case gets hot enough to be uncomfortable. 

If your son is playing games or anything else intensive, I can easily see this generating a ton of heat. Have you thought about a laptop stand and an external keyboard/mouse? Anything to get some air space under the computer.
Computer geek and amateur woodworker.
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#17
  Re: desk build, surprising wood movement/crack.. or something else? by mound (My 11yr old Son and ...)
That is a shame, but at least it is wood and you and your son can make the repair. A pain for you and a learning expeirence for him ... I hope.

It is a beautiful desk I'm sure you are both very proud of. Yes

--
See ya later,
Bill
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#18
  Re: RE: desk build, surprising wood movement/crack.. or something else? by Bill_de (That is a shame, but...)
(10-08-2020, 10:27 AM)Bill_de Wrote: That is a shame, but at least it is wood and you and your son can make the repair. A pain for you and a learning expeirence for him ... I hope.

It is a beautiful desk I'm sure you are both very proud of. Yes

--

very proud! He was involved in every step of the way from initial sketches, to some computer SketchUp work, to hand-planing and milling etc!

This crack from heat is a learning experience for me too!
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#19
  Re: desk build, surprising wood movement/crack.. or something else? by mound (My 11yr old Son and ...)
Thanks for this informative post. I think we all learned something here.

Did your son help with the DTs also?

I'm sure he wasn't gaming on this, it's remote learning!  Big Grin

Jim
Jim
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#20
  Re: RE: desk build, surprising wood movement/crack.. or something else? by Halfathumb (Thanks for this info...)
(10-08-2020, 10:56 AM)Halfathumb Wrote: Thanks for this informative post. I think we all learned something here.

Did your son help with the DTs also?

I'm sure he wasn't gaming on this, it's remote learning!  Big Grin

Jim


He made some of the cuts for the tails, with my guidance but had trouble and got frustrated and didn't want them to look bad so I took over.. They're all cut by hand and I did most of it for all intents, but he did some chopping and sawing.  He also cut the tenons on the breadboard ends on the typewriter tray.

Oh he's definitely doing some gaming on it, no doubt! (Minecraft)
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