Thread: Help needed. Table top issues.

Hi DanSA,

Welcome to the forums!!

It looks like the centre boards weren't kiln dried and have shrunk. I guess you could replace the two centre boards with new kiln dried timber. It looks too substantial a gap to consider filling and you may still get some movement after you fill it.

Regards,

Rob

Thanks for the welcome mate I used this site a lot when designing the table - lots of great info here.

Re replacing the center board, I was hoping you weren't going to say that...

If I was to do that, any tips on the best way to approach it? It's biscuited both sides and at each end which will make it challenging.. Then there's sizing a new board to fit, and then refixing it - sounds like a major PITA. I knew I should have listened to my gut when i was building it, thought that board was suss.. Bugger.

I guess there has to be a limit as to how much it will keep contracting. I think ill wait until the end of summer and see where it goes before acting, in the meantime its a good crumb disposal opening i suppose..

Cheers

Originally Posted by DanSA

(biscuit every 250mm with cleats of the end, biscuited to every plank)

Can you explain this in more detail please

Sure DJ.
There is a biscuit joint every 250mm down the length of every board to the corresponding board. (Clamped and glued)
The end cleats are the same boards cut in half along their lengths. These 2 are tied into the main top via a biscuit joint into the end of each board. (See pics)
The idea was to close off the grain and to prevent any cupping or movement at the ends.
Does this help?

Sounds like you've glued the entire width of the cleat(breadboard end) to the end grain of the tabletop from the sounds of it which is a big NO NO, is this correct?

This following quote is taken from All About Breadboard Ends - Fine Woodworking Article

A breadboard end is a narrow piece that is mechanically joined to the end of a larger panel. The purpose is to support and maintain the rigidity of the panel, while allowing the panel to shrink or expand across the grain.

Possibly all the boards have shrunk a little and movement was at the weakest join. And as previously mentioned gluing the breadboard end along all the end grain it not a good idea. Sorry this post is back to front the table look's great hope you sort the problem to do justice to your work.
Regards Rod.

I agree with the suggestion that the crack is appearing in one (the weakest) joint, due to contraction in all of the top boards, and the fact that they have been biscuited to the ends.

The normal approach to breadboard ends would be to use a tongue and groove to maintain alignment and control cupping, and a series of pins to retain the end on the top. The significant difference from your biscuit approach is that only the centre pin is a firm fit in both tongue and groove. The other pin holes in the tongue are elongated to slots to allow for top movement around the pins. The further out from centre the longer the slotting to allow for greater movement. All of the pin holes through the end boards are a firm fit for the pins, for asthetic and pin retention purposes. The only glue used for the ends is a small amount for each pin near the top surface, so that the end and top can move freely at any time.

As has been said it sounds like a timber movement issue, typically timber will move 1 to 2% (species dependent) width wise so for a 1m wide top you need to be allowing 10 to 20mm movement overall, it would be OK to fully glue the biscuit to the center board (maybe two center boards at a push species dependent) and the corresponding breadboard slot but then each following board glue the biscuit into the board end and not glue it into the breadboard slot making sure that the slot is wider than the biscuit to allow for the movement.

The outer boards tho relies on the strength of the biscuit to control the top and only one (or two) glued biscuits, not a good solution, as Malb says a tounge and groove is a better solution, to fix your prob I'd rip the breadboards off down the join, then redo the failed join, then replace the breadboards with T&G, I'd be questioning the need for the breadboards before that tho, that might just be me, you have plenty of clips holding it down.



Pete

Interesting that this post came about the same time that I asked my own theoretical question about the same issue. Although my thread has so far gone unanswered it appears that most of the answers lie in this real-world thread about Dan's problem.
I read through the link about breadboard ends on the Fine Woodworking site and just want to confirm my understanding of the fixing method. I take it that the screws holding the end breadboards on go through the bottom of the table top close through both the tongue and the groove? I have attached a picture showing how I interpret the article. Is this correct? It seems that the end grain adjacent to the slots could get broken off quite easily if the tongue is only as long as the thickness of the top?

Hope you get your table fixed up without too much hassle Dan. I like the way you have joined the frame to the legs with the large mortice/tennon join. What is the joint method on the long side?

Thanks Johnz
The long rails that form the apron are mortise and tenon jointed into the end frames too.
I'll post up some build pics if u like. Just don't make the same mistake I did!

Some build pix.

IMG_2022.jpgIMG_2017.jpgIMG_2010.jpg

P1040278.jpgP1040495.jpgP1040517.jpgP1040271.jpgP1040491.jpgP1040503.jpgP1040270.jpgIMG_1964.jpgIMG_1989.jpg

I'm no carpenter or joiner as you can see, but I learnt a lot and hopefully the table lasts a long long time... I can't lift it whole, so hope we don't move soon
We have 2 kids , so wanted it to not be too precious, more a meeting place to share a meal and a drink with friends and family.

Regardless of the "ya shouldas" or "ya shoulden 'aves" your stuck with a big problem there, mate.

I suspect that the simplest fix will be to wait until the crack has opened up to it's widest, then rout a channel/dado down the length of the crack (squaring the ends with a chisel) and inlay a covering strip.

If the crack is in the middle of the table you could use a contrasting timber to make it into a feature. I'm guessing it's probably not... but there's nothing to stop you from adding a "mirrored" inlay on the other side to balance things up.

Good luck with whatever you choose to do; it's a nice looking piece of kit.

I think that the advice is a good solution and you he said it may add a great feature to the table.

Originally Posted by Johnnz

Interesting that this post came about the same time that I asked my own theoretical question about the same issue. Although my thread has so far gone unanswered it appears that most of the answers lie in this real-world thread about Dan's problem.
I read through the link about breadboard ends on the Fine Woodworking site and just want to confirm my understanding of the fixing method. I take it that the screws holding the end breadboards on go through the bottom of the table top close through both the tongue and the groove? I have attached a picture showing how I interpret the article. Is this correct? It seems that the end grain adjacent to the slots could get broken off quite easily if the tongue is only as long as the thickness of the top?

Hope you get your table fixed up without too much hassle Dan. I like the way you have joined the frame to the legs with the large mortice/tennon join. What is the joint method on the long side?

Johnnz,

As suggested in my previous post, the generally accepted method is to tongue and groove, and then set pins to retain the end on the table top tongues. People set the pins through from the top to highlight them or from the bottom to hide them. Thee are normally an odd number of pins (3 or 5 depending on top size). The centre pin (near the midpoint of the end is tightly pinned to both top and end, while the outer pins pass through slots in the tongue to allow the top freedom of lateral movement with expansion and contraction. The outer tongue slots should be long enough to cope with the expansion/contraction range anticipated for the top (plus a bit more) and wide enough to provide clearance from the pin widthwise, without being so sloppy that the end can bow.

From your sketch, it seems that you want to use screws instead of pins. I suspect that with this approach there is a danger of the sharp screw threads slowly chewing out the sides of the slots and making them wider, allowing the ends to bow over time. Personally I think you would be better to use pins rather than screws, but you could set them from below and passing through the three layers of T&G without penetrating the top surface (as per the screws in your sketch) if you wished to hide them.

For a moderate top thickness, (say 25mm), 6mm pins set 6mm clear of the edge of the end grooves (9mm to centreline) would leave 12-13mm of tongue beyond the slots which should be adequate to contol bowing in the end. This supports the suggestion of tongue length equalling top thickness, but you might want to increase relative tongue length for thinner tops or decrease it for substantially thicker tops.