desk build, surprising wood movement/crack.. or something else?
#21
  Re: desk build, surprising wood movement/crack.. or something else? by mound (My 11yr old Son and ...)
Very nice desk. By the way, that looks more like African Mahogany to me. Sapele is often called "Sapele Mahogany" as they woods are pretty similar. In some projects, they can be used almost interchangeably. I don't think I've seen any Sapele that has curved grain like that, though it is possible. Most of my quartersawn Sapele is of the ribbon variety.

I will say that bookmatching a single board like that introduces a lot of natural stress. If your board was not perfectly jointed flat on that side, bookmatching will compound that. I don't think it's this or has anything to do with the glue - the grain itself shows that's how the board wants to move because that's what the tree did. The cellulose is programmed to do that.

Have you tried clamping it shut? You might be able to squeeze a bit of glue in there and clamp it closed. If not, and assuming the top is removable, you can simply rip out the middle and re-glue. If you're not OK losing 1/8" of width, you can always add a filler strip.
Reply
#22
  Re: desk build, surprising wood movement/crack.. or something else? by mound (My 11yr old Son and ...)
Let it sit a while without a hot laptop and see if it closes.
Gary

Please don’t quote the trolls.
Liberty, Freedom and Individual Responsibility
Say what you'll do and do what you say.

Reply
#23
  Re: RE: desk build, surprising wood movement/crack.. or something else? by Gary G™ (Let it sit a while w...)
(10-08-2020, 05:32 PM)Gary G™ Wrote: Let it sit a while without a hot laptop and see if it closes.

I suspect folks are correct about the laptop heat. Years ago I built a desk from a sold live edge board, with a recess cut out for computer components, and a glass cover. After a few weeks the warmth of the computer dried the whole top so it shrunk slightly, and ~12" wide strip of glass was now 1/8" too wide for the dadoes it sat it.  Had to take it apart and slightly enlarge them.

So I can believe the heat of a laptop could be enough to further dry that top, and unevenly, enough to pop the join apart.
Reply
#24
  Re: desk build, surprising wood movement/crack.. or something else? by mound (My 11yr old Son and ...)
Beautiful desk.
Did you get an even glue squeeze out when clamped up? Maybe lack of glue?
Steve

Missouri






 
The Revos apparently are designed to clamp railroad ties and pull together horrifically prepared joints
WaterlooMark 02/9/2020








Reply
#25
  Re: RE: desk build, surprising wood movement/crack.. or something else? by Gary G™ (Let it sit a while w...)
(10-08-2020, 05:32 PM)Gary G™ Wrote: Let it sit a while without a hot laptop and see if it closes.

That was my first thought as well.  If it does close, then perhaps putting the laptop on a stand will prevent it from happening again.  Would be worth a try, before taking it apart and reworking it.

Very nice desk, BTW.   Yes
If you are going down a river at 2 mph and your canoe loses a wheel, how much pancake mix would you need to shingle your roof?

http://blazinbladesscrollers.webs.com/
Reply
#26
  Re: RE: desk build, surprising wood movement/crack.. or something else? by Bill Wilson ([quote='Gary G™' pid...)
Thanks everybody.

Yah, standard glue-up procedure, even squeeze out.. We even used Dominos.. (I'm pretty sure I put glue on them too but now that I type this I can't remember if I did or not.. sometimes I just use them for alignment..) 

Interesting comment about the curved grain and how it wants to move that way.. Never thought about that with book-matching.

My son was fascinated by heat being able to undue glue, started reading about it online..  He even then said "maybe we should fix it with epoxy."  smart kid! Nice little science class came out of this I guess.. We had talked about wood movement due to humidity during the build.

Not going to fix it immediately, we'll see if it closes up at all without the laptop heat (though I think it still needs to be "fixed" as that will never close tightly and invisibly.)  We'll just re-rip it and glue it back together with epoxy.  Probably have to sand & refinish the whole top then too I suppose (currently it's several coats of poly plus paste wax).  Could be worse!

To the species, that top definitely doesn't look like the standard ribbon grain quartersawn sapele.. Doesn't show up much in these pix, but the panels and drawer fronts are all very straight, obviously QS sapele.  It all came together in one bulk order I got years ago which was all labeled "African Mahogany"  (closeup of a drawer front during construction wet down with MS below)


Attached Files Image(s)
   
Reply
#27
  Re: desk build, surprising wood movement/crack.. or something else? by mound (My 11yr old Son and ...)
Yep the heat for sure.  BTW - a very beautiful desk.  That's on my list of things to build. 

Only thing I can think of - after you fix it - is to put some sort of pad under the LT.
John

Always use the right tool for the job.

We need to clean house.
Reply
#28
  Re: RE: desk build, surprising wood movement/crack.. or something else? by FS7 (Very nice desk. By t...)
(10-08-2020, 02:53 PM)FS7 Wrote: I will say that bookmatching a single board like that introduces a lot of natural stress. If your board was not perfectly jointed flat on that side, bookmatching will compound that. I don't think it's this or has anything to do with the glue - the grain itself shows that's how the board wants to move because that's what the tree did. The cellulose is programmed to do that.

^^^ This.

The heat likely softened the glue a bit so that it was the glue that opened and not the wood splitting.

The relatively localized heat from the laptop also lowered the moisture in the wood under it.

I would suggest not trying to repair the joint. Treat it as a feature. With that grain structure, a glue joint is unlikely to last from season to season or as your son moves around the country. Simply treat it as a dynamic part of the piece.

Putting a sheet of plexiglass or glass on it could be used and/or you could use a good temperature support for the laptop.

Also, everyone is right that is a beautiful job with gorgeous wood. Very nicely done.
"the most important safety feature on any tool is the one between your ears." - Ken Vick

A wish for you all:  May you keep buying green bananas.
Reply
#29
  Re: desk build, surprising wood movement/crack.. or something else? by mound (My 11yr old Son and ...)
I'm thinking you can rip the two halves and glue back together ... but, I would also rout and insert four or five evenly spaces "butterflies" into the top to act as a permanent mechanical clamp across the joint.
Reply
#30
  Re: desk build, surprising wood movement/crack.. or something else? by mound (My 11yr old Son and ...)
The heat might have accelerated the failure, but the underlying problem seems to have been that the wood held too much moisture, which the heat removed.

Nevertheless the bond was insufficient and might have been improved by the use of better glue, such as WEST epoxy. Also I use many biscuits (WEST epoxy glued) in a joint like that.
Wood is good. 
Reply


Forum Jump:


Users browsing this thread: 1 Guest(s)

Product Recommendations

Here are some supplies and tools we find essential in our everyday work around the shop. We may receive a commission from sales referred by our links; however, we have carefully selected these products for their usefulness and quality.