Thread: Dowels v Biscuits for edge jointing

We have laminated tassie oak boards with biscuits here and it was fine. Very easy. Are your biscuits a snug fit in the slots? Doesn't sound so if there is play in the joints. Ya still have to have long clamps either side of the boards and stuff. Don't know about the burning dust. Doesn't sound good. Was there evidence of burnt surface in the slots? Perhaps the bit wasn't sharp even though it was new.

Either way, dowels or biscuits onlyline the boards up. I wouldn't bother with them on such a small table top. Just glue and clamp the boards. Much less noisy all round.

One thing about laminating kwila, It is a very oily timber isn't it? You may have to wipe the surface to be glued with thinners or acetone so the glue can take. Had to do this on a little thing I was doing.

Jill,
My experience with dowels and biscuits is similar to yours (except I haven't started any fires yet )The one big minus with dowels is that you have to get them EXACT as, unlike biscuits, there is no play when assembled.

Sooo..if you can get them EXACT then you won't have to use cauls to keep the surfaces even BUT that problem pales into insignificance if you don't get the spacings EXACT as you won't be able to get the two faces to meet up ...even a fraction of a mm error in the spacing will make life difficult.

Take care to keep the biscuit joiner as stable and vertical as possible so that the slot is no wider than it needs to be but you will need cauls and a bit of sanding to finish off.

I'd personnally keep away from the dowels but that's just me

Ian

Thanks for this tea-lady, the biscuits are not a snug fit. I just went and had another look. The slot is 4.7mm wide, but the dry biscuit is only 3.8mm thick.

Interesting that the blade is 4mm thick, but it cuts a slot 4.7mm wide

I used a sheet of thin plywood on my table saw as a workbench, and the Ryobi joiner base sat on the work surface. The timber butted up against a 19.1mm piece of timber in one of the tablesaw slots, so there was no vertical movement to cause the extra wide slot.

Anyone got any ideas on this please?

Thanks for your reply, Ian. I use an old Silex #30 dowelling jig fitted with a 10mm ID bronze bush from Blackwoods. It is a pretty accurate tool, but I take your point, it is easy to be a fraction of a mm out, and no amount of cauls will pull it back into alignment. Out with the belt sander

Jill,

I'd say the blade on the biscuit jointer needs sharpening or replacing. It's not cutting timber but trying to grind through it. Hence the smoke and the enlarged slot.

All the buscuit joints I've done the biscuit fits snugly and there is no slop.

If there is smoke when cutting the holes it's possible that the blade is put on the wrong way and is not cutting correctly. DAMHIK. Or the cutting teeth are damaged or not sharp.

Also there are different brands of biscuits (Triton and normal ones) and there are different sizes of normal biscuits depending on the depth you cut the slots.

Finally the slots should be slightly bigger than the biscuits for when the moisture in the glue reacts with the biscuits they swell up to normal size and make a tight fit. If the slots were the same thickness as the biscuits you would end up with raised lumps on the surface where the biscuits are.

Peter.

Thanks Peter, I just checked and the blade is on the correct way, but it is not very sharp. And it is not TCT either.

If this blade is causing soft pine to burn, what is going to happen with hard kwila?

There is no evidence of burning in the slots in the pine.

I am now sourcing a new blade, 100 x 22 x 4, preferably TCT

Originally Posted by Sturdee

when the moisture in the glue reacts with the biscuits they swell up to normal size and make a tight fit. If the slots were the same thickness as the biscuits you would end up with raised lumps on the surface where the biscuits are.

Peter.

I remember reading somewhere that you shouldn't glue the biscuits anyway cos of the wood swelling problem. You'll end up with a bump or a dind over where they are. You just have glue on the edges of the boards. The biscuits are just to align them. I still reckon I wouldn't bother with biscuits on such a little table top. Something 1 meter by three meters yes!

Originally Posted by JillB

Thanks Peter, I just checked and the blade is on the correct way, but it is not very sharp. And it is not TCT either.

If this blade is causing soft pine to burn, what is going to happen with hard kwila?

There is no evidence of burning in the slots in the pine.

I am now sourcing a new blade, 100 x 22 x 4, preferably TCT

Jill,

A trip to the hardware store will solve that. Even Bumblings have them ... Ryobi blade and TCT as well.

If you get no joy at the hardware store PM me and I'll post one up to you. Got about 5 of them.

Biscuits are designed to swell when glue is applied. This can cause uneven tensions within the timber close to the joint and may cause joint failure. A small top such as yours should be able to be coaxed into alignment without the need for locators. A tip for easier alignment is to plane the edges ever so slightly hollow in their length (one stroke of the plane.) Then, when the boards are being clamped up, they come into contact from each end. This tends to make them self align. It also helps prevent end cracking in the joints as the top continues with seasonal/atmospheric movement over time.
Buscuits are for coffee.

I use both, and actually quite enjoy dowels, despite their finicky nature. Matching metric drill bits and dowel stock with an old Silex jig adds to the drama.
I have a similar problem with regard the slop with biscuits, quite simply it is a function of the cheap Ryobi machine. It is not a quality machine, and the plastic slides allow far too much movement as the cutting head is pushed in. Perhaps its a matter of paying more to get a better built machine.
The ease of aligning parts is the one positive!!

Cheers,

I have been using triton biscuits for about 14yrs. I bought a 50mm (would need to double check diameter) x 4mm slot cutter from carbitool and have just used that in a small 1/4" router either free hand or in the table ever since. A bit of sharpy around cutter head serves as a reminder about the depth required.

It has always given me nice snug pockets for the biscuits. I have never had any problems with swelling. Yes they do swell in the joint (part of the reason I like them so much) but we are only talking about tiny amounts that are soon sanded back. I would be careful with veneered timber and maybe try a test on the substrate depending on thickness. The thinnest I have glued was 10mm pine. No bulging from memory and there is only 3mm of pretty flexible wood sitting there...

One drawback with the router is not being able to plunge into the face of a carcass, but have not found that to be a huge limitation. It gives great control, and if you already have a small router you are most of the way there. In the table with some guides clamped for mitered frames is very fast and accurate (and good dust control).

I leave about 100mm to the ends of the boards to avoid the mentioned splitting, and have never had a split from the biscuit expanding. between biscuits I leave 200-250mm, maybe less if the boards have moved a bit after planing.

I glue them in by applying glue to the surface, the pockets (leaving applicator/biscuit in as i go) then the other surface bringing the two together before everything expands and grabs. Then it's on to the next board. Clamps across the whole assembly at the end.

I too was using dowels, and the setup for biscuits was so much more accurate vertically and forgiving longitudinally that I have not used another dowel since (although I do like the look of the kreg system, no clamps!)

All the best in finding what works for you

There is really no need for biskets/dowels in edge gluing. Long grain is the ideal surfrace for glue to hold. Use cauls and all of this becomes so much easier and spot on.
Check Mike's web site and see hoe easy they are to make

.Shop Made Cauls by P. Michael Henderson

Hi Jill, haven't read all the posts but I only use dowels. I have an old Stanley 59 I got off ebay for about $20. I drill my holes on one edge then instert Haron dowl nipples available at Bunnings to line up the opposite edge, fit the 59 back to the new edge keeping the depth the same from the face surface (I run a line with a square accross the edge through the dot to make it easier to line up) God sounds complicated when I write it but is realy is very quick simple and you don't have to buy a biscuit joiner etc. If you look at my web site, all my work has been done with dowels.