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Why did it all go wrong?

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Blog entry by KnickKnack posted 08-15-2011 06:23 PM 995 reads 1 time favorited 17 comments Add to Favorites Watch

I thought it might be fun, or at least interesting, not to say a challenge, to make a box-like thing using joints like this…

I took a fair amount of care.
I measured three or four times.
I did “sneaking up”.
I fitted each leg/stem individually.
I sanded for final fit.

Finally I had the required pieces (pine and jatoba)...

I’d fitted, very carefully, each of the 8 joints.
I’d “trial fitted” the complete piece several times – the legs started out square and only got rounded towards the end.
I trial fitted again.
I slept.
The next day I sanded everything – the pine to 240, the jatoba to 400.
I trial fitted again.

These joints were just perfect.
Not “burn him, he’s a witch” perfect, but pretty jolly good.
Firm pressure required, but not too firm.
No mallet required.
Almost no glue required, and I did toy with that idea.

And then I put the glue on.
I was pretty quick, but I didn’t rush.
And now the thing doesn’t fit anymore!
By the time I realised it wasn’t going together, it was all too tight to pull apart.
No way could I get any clamping together because of the angles. I had nothing prepared since I wasn’t going to need clamps.
No-where to mallet.

I ended up with this…

which doesn’t look too bad, until you look not very closely and you see how bad it is…

I’ve filled the grand canyon sized gaps with sawdust.
In fact, the pictures don’t do justice to exactly how terrible it is.

I’m depressed
These were, by quite a long way, the best set of joints I’ve ever made.
And this was what happened.

THE LESSON
I’ve spent a few hours thinking about this, and I’ve come up with the following reason it all went wrong.
If anyone has alternative/additional/better ideas, or even confirmation, I’d be grateful.

First up, I applied the glue to all the (what are basically) M&T joints.
All 16 of them.
And then I started putting it together.
I think that the jatoba started expanding as soon as I started to put the glue on. I know that beech expands a lot when moist and I’m assuming Jatoba is somewhat similar?
I put the joints together in reverse order of glue application. Just stupid, I know. That gave the first glue joints even more time expand and mess with my world.

NEXT TIME
  1. Always assemble in the order of glue application
  2. Do not attempt so many joints at one time – I should have glued 4 panels to 4 legs, then 2 panels together, then the 2 pieces into the finished piece.
  3. Wood expands when it gets wet – some more so than others – take care with jatoba.
  4. Even if you don’t think you’re going to need to clamp, think of a clamping strategy should it be required.

Am I downhearted?
Sure I am.

Have I learnt anything?
Maybe.

Will I bounce back?
Bet on it!

-- "Do not speak – unless it improves on silence." --- "Following the rules and protecting the regulations is binding oneself without rope."



17 comments so far

View AaronK's profile

AaronK

1398 posts in 2149 days


#1 posted 08-15-2011 06:31 PM

ugh, what a downer! the idea is very cool and it sucks to be so close to making it all come out wonderfully. anyway, lesson learned. glueups are stressful!

btw, it still looks super cool.

View patron's profile

patron

13092 posts in 2026 days


#2 posted 08-15-2011 06:36 PM

great concept and execution
of the joints

to bad about the glue-up

i never run glue
till everything is ready now

for the same reasons
you ran into

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

View Gary's profile

Gary

7355 posts in 2118 days


#3 posted 08-15-2011 06:40 PM

Ask Edison about mistakes…. Box is really interesting. Looking forward to the next one

-- Gary, DeKalb Texas only 4 miles from the mill

View xwingace's profile

xwingace

204 posts in 1273 days


#4 posted 08-15-2011 06:40 PM

Fall down 7 times, get up 8. Try again, that looks to be a beautiful design!

-- I'm not as good as I once was, but I'm as good once as I ever was.

View Builder_Bob's profile

Builder_Bob

160 posts in 1744 days


#5 posted 08-15-2011 06:44 PM

Really, the joints look pretty good.

One thing for sure.

That box is never gonna fall apart!

-- "The unexpected, when it happens, generally happens when you least expect it."

View SSMDad's profile

SSMDad

395 posts in 1282 days


#6 posted 08-15-2011 06:58 PM

Bummer. Still looks like a nice box though! Love the idea.

-- Chris ~~Who controls the past controls the future. Who controls the present controls the past."

View Murdock's profile

Murdock

107 posts in 1169 days


#7 posted 08-15-2011 07:27 PM

I have never worked with Jatoba before but I am betting you are correct about the wood expansion from the glue.

I have heard that epoxy will not cause the wood to expand as much and is actually kind of slippery and can help assemble things since they seem to slide together more easily. I would think you would want the slower curing stuff rather than the 5 minute.

With that said, I have never personally used it, so your mileage may vary, I use the titebond glues for most of my glue need and have had to battle a few swollen joints.

-- "Anyone who has never made a mistake has never tried anything new." - Albert Einstein

View Elizabeth's profile

Elizabeth

810 posts in 1828 days


#8 posted 08-15-2011 07:30 PM

It does look beautiful, regardless. What about lining or flocking the inside, would that help?

View PurpLev's profile

PurpLev

8476 posts in 2333 days


#9 posted 08-15-2011 07:39 PM

yup, sounds like glue expanding the wood and I think the lesson you learnt is a viable one.

I have similar experience with box joints (not to the same extent, but same concept of wood expanding and joint becoming tighter) I use clamps to pull the joint together, and then take the clamps off as they are not really required (just used to pull it in).

first time around is always a lesson, make a 1000 and you’ll do them blindly and tighter than anything anyone has ever seen before ;)

looks really sweet joint.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View GregD's profile

GregD

622 posts in 1821 days


#10 posted 08-15-2011 10:31 PM

I had to stare at it a bit to see how you even got it together for a dry fit.
Seems to me you want to make 2 assemblies, each with 2 panels into 1 corner.
Then glue these 2 assemblies together adding the 2 corners where they meet.

Clamping would take some preparation, especially if you want to apply significant pressure to close the joint. Tommy Mac’s flag case project simply glued triangular scrap near the end of the boards to provide parallel faces perpendicular to the direction that the joint closed up. He used a hand plane to clean up the sides. That would be tricky for this joint because the corner blocks protrude from the outside surface of the sides. Instead the triangular scraps could be glued to a thin panel that is clamped to the side panels. Even better if panels actually hook the far end of the panel.

-- Greg D.

View SPalm's profile

SPalm

4844 posts in 2567 days


#11 posted 08-16-2011 12:22 AM

Pretty neat box joint. It is worth pursuing again.

Maybe just glue one corner at a time with the others in place but no glue. Then drive out the next leg after a wait, apply glue, and re-insert it. (?)

I think it looks pretty nice,
Steve

-- -- I'm no rocket surgeon

View Chris Camp's profile

Chris Camp

14 posts in 1560 days


#12 posted 08-16-2011 12:45 AM

A set of ratchet straps can be used in odd shaped glue ups in place of tradtional clamps. They grip in weird angles and don’t leave marks on the piece.

-- I'm always thinking one step ahead, like a carpenter building stairs...

View therookie's profile

therookie

887 posts in 1512 days


#13 posted 08-16-2011 12:55 AM

I really like the joint.

-- http://aewoodworks.webs.com

View Howie's profile

Howie

2656 posts in 1608 days


#14 posted 08-16-2011 01:19 AM

I think you forgot the beer.

-- Life is good.

View vipond33's profile

vipond33

1405 posts in 1182 days


#15 posted 08-16-2011 04:33 AM

Try this.
Dampen the joints and let them dry. Will they still go together? No? Then sand a touch with custom blocks (PSA paper is useful here). Yes? Then dampen slightly again just before gluing.
This will effectively stop the wood from sucking moisture from the glue, which makes it thick and unresponsive to hand pressure, for this is a no clamps possible no clamps necessary joint that you have created. Squeeze it for a minute while humming the theme from Jaws and then get out of the water.

-- gene@toronto.ontario.canada : dovetail free since '53, critiques always welcome.

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