Biscuit joint suitable for breakfast bar?

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OhPinchy

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We’re going for a raised breakfast bar which will sit on top of angled chrome supports which are anchored just in from the edge of our walnut worktop (finally sourced the supports through the Panelling Centre – they ordered in from Hafele for €42 each).

They sent out the wrong ones though – the ones we have are for screwing into a wooden breakfast bar, but we had planned to use them for glueing a glass breakfast bar.

We’re now thinking a walnut breakfast bar would be fine, but we don’t have a cut-off long enough, so I’m thinking of cutting two pieces and joining them. It would be 2 600mmx300mm pieces joined in the centre to give one 1200mm x 300mm piece. The breakfast bar supports are at 500mm centres, and the centre join of the combined piece of walnut would be supported by the central support.

What would be the best way of joining the two pieces of walnut? It needs to be sturdy enough, but will not be taking very heavy objects, I think the supports can take max 20kg. Would biscuit jointing be suitable?

If I rent a biscuit jointer and cut the holes for the biscuits into each piece and then use a standard birch biscuit that you can buy, would this be a strong enough joint or should I run a strip of walnut on the underside to strengthen it? What glue, if any, should be used on the biscuit joint?
 
Yes, biscuit joint should be strong enough provided the two faces to be jointed are a good fit. Use the larger size 20 biscuits, and a good quality wood glue. Apply plenty of clamp pressure along the joint until fully cured. The resultant joint should be stronger than the wood itself.
Leo
 
If the walnut boards are thicker than 20mm you can have a double biscuit, that is a pair of biscuits, referenced from both faces at each location.
 
Thanks Leo,

I assume the biscuit joiner tool can cut for varying sizes and its just a case of buying the size 20 biscuits and cutting the correct size? I'll practice on test pieces before doing it for real.

Would mitre bond be suitable for jointing it (i.e. the 2 part glue which goes rock hard within ten seconds of applying the activator?
 
The glue you use should be water based if you are using a wood biscuit. I use Humbrol Cascamite for more arduous applications, but there are other types out there.
 
Thanks Carpenter,

The walnut is 40mm thick so double biscuits should be possible.

The joint is going to be 300mm wide so would 3 biscuits across the width be ideal (ie. 2 rows of 3)?

Would normal PVA be ok as its water based or should I go for the Humbrol Cascamite ?
 
A biscuit every 6-10 inches is recommended, so 2 x 2 should do. If you can get the Cascamite in a small quantity, it would probably be wise for this application. You need to go for a water based adhesive as part of the stregth of the joint comes from the fact that the biscuit expands into the joint in the presence of water.
Leo
 
Ah, makes sense now, thanks Leo. Yep, I'll try get my hands on the Cascamite as I might have use for it in the future, can think of plenty thinks biscuit joints might be useful for down the road.
 
I only bought a biscuit jointer myself last month and I have to admit it is a great addition to the tool kit. I've bought Humbrol Cascamite in a small tin for under a €10.
 
Hi Carpenter, where did you pick up the Humbrol Cascamite? (Got me first biscuiter in US last month!!).
Are there any other generic brands of the cascamite?
 
I bought it at a Homevalue Hardware store a few years ago, AFAIK "cascamite" is a generic term for this type of glue, the Humbrol variety may also be called "Extramite". It's weather resistant and especially suited for outdoor use. I generally use PVA most of the time for interior work, usually Resin W in the blue tub. There are other types of glues out there like "Titebond" and "Gorilla Glue" also, but don't know anything about these.
 
Thanks for that. found the "Extramite" at last! Fairly steep at €16, and was similar price on-line in UK.
Wasn't happy with biscuit performance using normal wood-glue on test pieces. Will see how this fairs out.
 
It has been suggested to me that sturdy dowel rods or the special worktop nut and bolt fittings would be better suited for joining these two pieces of walnut due to the sizes involved - 600mm x 300mm x 40mm x2pieces.

What do you think - would it be better to router out the holes for the bolts (unlikely to be highly visible) on the underside as opposed to going with biscuits?
 
I disagree with the logic- dowels are primarily designed as an alignment tool, the glue used actually provides most of the strength. Most engineered panels and laminated stock rely on a glue joint- the finger jointing only serves to increase the surface area for gluing purposes. Secondly the cabinet connectors you refer to are primarily designed to provide clamping force when the use of conventional clamps is not possible i.e. when joining cut a end to another end for example. I would be happy to use biscuits and a good glue, provided the mating edges are true and square and adequate clamping force is provided until the glue bond develops full strength. Dowels are difficult to position accurately and are not as forgiving as biscuits when it comes to glue up. I'd be interested in Leo's tuppence worth on this...
 
Thanks Carpenter.

If I can figure out how to apply the clamping force the biscuits should do the job. The joined piece will be 1200mm long so I'll probably need to get hold of a long sash cramp?
 
I'm with you on that one Carpenter. I'd be very much against the cabinet connectors, and I presume they suggested using them without glue. These connectors do the job they were intended for well, but they will only provide a clamping force in one plane. They were designed to hold two pieces of worktop together at a joint, but only where both pieces are supported vertically by attachments to the surrounding walls.

The biscuits will do the same, and probably better job than the dowels. As Carpenter says, all the strength here is going to come from the glue bond. Get a good glue bond and it will be stronger than the wood. I saw a piece on 'This Old House' where a timber frame manufacturer was testing glue joints on lengths of stock finger jointed together to form structural components. These were placed in a machine which pulled them apart with increasing pressure until they gave way, not once did the glue joint fail.

OhPincy, you could use some [broken link removed] if you can't get your hands on sash cramps. Protect the edges and corners of the worktop though. Also make sure the pieces remain alligned as you apply pressure. To ensure this, you could use a couple pairs of 2x3 or similar. Put one on each face, and use a G clamp on each end, if you know what I mean.
Leo
 
Great suggestion from Leo there on using straps for clamping. I'm assuming the walnut is prefinished? If so, allow the glue to off before trying remove and glue line on the surface. You should wait 'til the glue is "stringy"- it'll come off v-ery easily and won't mar the surfACE. sORRY 'BOUT THE TYPING MY LITTLE TERROR IS MESSING WITH THE KEYBOARD AS i TRY AND TYPE!!! tIME FOR SOMEONE TO GO TO BED i THINK.....
 
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