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Furniture #17: 1500mm Table under Bracing and shrinkage management

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Blog entry by robscastle posted 08-10-2016 04:04 AM 1374 reads 0 times favorited 5 comments Add to Favorites Watch
« Part 16: 1500 mm Table top working the top Part 17 of Furniture series Part 18: Base for the 1500mm x1500mm Table top »

I installed the underbracing for the table top today, I had the work on hold whilst the table underwent some stress changes over the last couple of weeks.

Some Shrinkage.

I had it stored away near where I was working and heard on numerous occasions a sharp crack from it.
I was sitting quietly near it when I heard it again and observed over the week a shrinkage crack appearing on one of the sets of edge jointed boards, at first it only barely visible but eventually grew to about 4mm wide.
I didnt do to much untill it settled and stopped the “cracking” noise and the gap widening.

I didnt even bother to take any pictures at the time as it was not entierly unexpected.

However once it settled down I brought it out to see what I could do.

There was no other effect on the Table so it was definately shrinkage, what surprised me was it was only in one section as well.

As it occured completely along the glue line it made it reasonably easy to repair.

First of all I cut the glue away with a trimming Knife and then cleaned the entire length out with a small rasp.
Then cut a “shrinkage strip to repair the gap. This strip consists of a length of timber cut and trimmed to size and then spot glued in place resting on the top of the biscuits, no attempt was made to close the underside.

If any more movement occurs its simply a matter of knocking the strip out from underneath and replace it.

The Under Bracing

Upon discussion with my Son and the metal fabricator the center frames will sit on 600mm centers
So a half lap jointed frame was constructed under the table in the center and extending from each side was a support frame and support blocks in each of the corners.

I used my box cutter blade to fabricate the half lap joints.

This is the bracing in progress

And now all complete.

The corner pads? they are here simply if required otherwise they can be removed later.

All the timber near the edges was chamfered to avoid any injury to hands / knees under the table.

Every lap joints on the bracing is free to move if the table experiences any more movement.

Weights: A couple of LJs comment on the Mass or weights I posted being a bit Hefferish , so a re-weigh was conducted.

The Results:

Each Board weighs approx 4.5 Kgs at 1500 mm and there are ten of them so we are looking at 45 Kgs for the boards plus the edging. I cannot physically check the completed top.

So my revised esimate is about 55 to 65 Kgs not 100Kgs as previously reported.

Here is a section of dressed board about 1M in length on the scales.

Now that should do it for the time being,... stand by for the completed Project possibly in the New Year as its due for delivery Dec 2016.

-- Regards Robert



5 comments so far

View Boxguy's profile

Boxguy

2180 posts in 1735 days


#1 posted 08-10-2016 05:31 AM

Rob, keep at it.

-- Big Al in IN

View Joe Lyddon's profile

Joe Lyddon

9451 posts in 3520 days


#2 posted 08-10-2016 06:36 AM

Rob, you’re doing a Fantastic job of making that table!

How many people is it going to take to MOVE it to it’s final location?

I’m wondering how the metal edging is going to be done… allowing for expansion, etc. ... Would it break a welded corner?

Thank you for the updates!

It will have time to expand & contract between now & December!

Now, I guess you’re going to make the base; which should be a piece of cake… :)

-- Have Fun! Joe Lyddon - Alta Loma, CA USA - Home: http://www.WoodworkStuff.net ... My Small Gallery: http://www.ncwoodworker.net/pp/showgallery.php?ppuser=1389&cat=500"

View prad's profile

prad

15 posts in 135 days


#3 posted 08-10-2016 03:51 PM

Those are some awesome joints under the table, looks like they can allow shrinkage/expansion. What about the edge banding, how does this work with expansions? Thanks!

View robscastle's profile

robscastle

3393 posts in 1672 days


#4 posted 08-11-2016 12:28 AM

Thanks fellow LJs.
Always nice to get some comments on bits and pieces

So some replies back

Big Al,
I found a textile shop that sells webbing so I bought a couple of long lengths to allow me to use “your”
clamps on bigger projects not that I am planning anything at the moment but i am now able to clamp them

Joe,
Moving this monster is a worry for me on my own I use the Skate to shift it around without too much worry but turning it from Vertical to Horizontal is scary due to it getting damaged so i see if my wife can help.
Otherwies it will go into the back of my table top Ute/Pickup for road transport to Sydney about 1000 Klm away. It will have to lie flat and be supported by EPE blocks (Expamded polyetehelene) along with total waterproofing all over.
A trip I am slightly worried about due to the overall distance and the state of roads.

prad
Your question regarding edge banding and the lack of room for movement is one that is a consideration on all timber projects of this size, usually breadboarding is used on the ends, however I chose to just have a small expansion gap underneath hoping that it will not expand too much and as a result blow out the miter edges as a result.

Its all a bit of a worry building something this big, but I guess time will tell.

-- Regards Robert

View crowie's profile

crowie

1499 posts in 1419 days


#5 posted 08-11-2016 10:50 AM

Good save Rob, looks very professional.
On the weight – even 65kg is a heavy table…

-- Lifes good, Enjoy each new day...... Cheers from "On Top DownUnder" Crowie

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