to biscuit or not to biscuit

[steviem]

Just wondered what the general concensus was.
I've made numerous tables and unit tops and generally speaking I tend not to bother biscuiting the edges. Just a good plane and some decent glue and clamp for 24 hours.

Who biscuits and who doesnt?
Just wondered

Steve

 

[OPJ]

There is a suggestion that, if you use a glue which can creep (like PVA) then, biscuits (or a similar aid to alignment) are essential as they'll keep the boards flush with one-another, should any of the joints 'creep'.

I use biscuits purely to help with alignment when assembling a table top. On smaller items though, you can get often get away without them, if you like.

 

[steviem]

Interesting thought that. And I suppose it makes sense in an application where the boards are potentially self supporting.
Maybe wouldnt be as important where a tables rails would support each board equally.
Cheers

 

[Mr Ed]

Mostly I go without biscuits, because I find it easier to align the boards under partial clamp pressure with small mallet taps - if there are biscuits that for whatever reason are not cock on you loose that ability to adjust.

I've done many joints this way and have yet to have one fail, or appear to creep perceptibly.

Ed

 

[woodbloke]

If you look back to how it used to be done using hot hide glue, biscuits weren't used (they weren't even invented!) as the joint was simply 'rubbed' together and left for the glue to cure. That we choose to use them to align boards is a recent innovation but not necessary...if your boards are straight, the joining surfaces are well shot in and your cramping regime is sound, you don't need biscuits to align the boards. I like to use biscuits for all sorts of stuff (dunking one right now in me tea :lol: ) but edge jointing ain't one of them - Rob

 

[MikeG.]

The only time I use my version of biscuits..........actually loose or floating tongues, done with a routered groove and some ply off-cuts.......is if there is a particularly difficult or long-winded glue-up in prospect, or if I need to use a quick setting glue for some reason.

As has been said, they remove the option of clamping a couple of boards across the work at each end to pull everything into perfect alignment. They contribute absolutely nothing to the strength of the join.

Mike

 

[Paul Chapman]

I would always use biscuits (or Dominos ) or loose tongues. Despite what some say, in my view they add considerably to the strength of the joint and, if you do them properly, result in flat jointed boards that need a minimum of cleaning up.

Cheers :wink:

Paul

 

[BTR]

I tend to agree with paul i always use biscuits nice straight joints and i beleive they do add considerable strength to a joint

 

[Waka]

I would always use biscuits (or Dominos ) or loose tongues. Despite what some say, in my view they add considerably to the strength of the joint and, if you do them properly, result in flat jointed boards that need a minimum of cleaning up.

Cheers :wink:

Paul

Me to.

 

[woodbloke]

I would always use biscuits (or Dominos ) or loose tongues. Despite what some say, in my view they add considerably to the strength of the joint and, if you do them properly, result in flat jointed boards that need a minimum of cleaning up.

Cheers :wink:

Paul

...but suppose your board is only 8mm thick as in the back panels of this cabinet:

or this one:

No doms, no biscuits...just shot in true and edged jointed. A loose ply tongue (aka Mike G) is probably the best way to increase the strength of the joint if required. A favourite technique btw of the late, great AP - Rob

 

[L Harding]

I dont buy into the theory that 'back in the day!' edge jointing with hide glue was strong enough, so why use biscuits now.

You've got to move with the times, modern glues were invented because animal glues have limitations for certain applications. Biscuit joiners were invented to give a quick and easy way to strengthen joints. Of course biscuits strengthen the job. Surely the only argument is weather you think the joint needs that added strength or not?

I love using the traditional option as much as the next maker, but only when it is still the best option. For example Rob: I agree you couldnt of used biscuits in your 8mm back panel, but wouldn't a veneered panel of been the more stable option?

 

[woodbloke]

I dont buy into the theory that 'back in the day!' edge jointing with hide glue was strong enough, so why use biscuits now.

You've got to move with the times, modern glues were invented because animal glues have limitations for certain applications. Biscuit joiners were invented to give a quick and easy way to strengthen joints. Of course biscuits strengthen the job. Surely the only argument is weather you think the joint needs that added strength or not?

I love using the traditional option as much as the next maker, but only when it is still the best option. For example Rob: I agree you couldnt of used biscuits in your 8mm back panel, but wouldn't a veneered panel of been the more stable option?

Animal glue does have some distinct disadvantages for sure (ie interior use only) but it does have huge advantages as well (ask any furniture restorer)...I don't use it btw, but use it to illustrate the point about not needing biscuits.
Biscuits do strengthen the joint (in the same way as a ply tongue) but in most cases they're not needed for that application (ie edge jointing a board) In some applications you might need that added security (the top of my bench which is 75mm thick beech across the whole width has ply tongues to strengthen the glue line) but as I say, for most applications, a line of biscuits or dominos isn't required, provided that your jointing techniques are sound.
On the other hand, if you can't plane two bits of wood so that they mate properly, then you may well need biscuits to align each piece.
As for the veneering issue, I chose to have solid panelled backs in a frame on both of those cabinets rather than use veneer, a more complicated construction but equally as stable - Rob

 

[Paul Chapman]

If you have a copy of "Cabinet Making - The Professional Approach" by Alan Peters, I think it's worth reading the section 'Adhesives and solid wood construction' where he discussed` this whole issue. In a nutshell, his view was that wood never stops moving and this needs to be the major factor in construction and glueing techniques. He concluded that the best adhesive was PVA because of its flexibility (many other adhesives are just too brittle to cope with the movement) but that some sort of mechanical device should be included as well. In many cases this mechanical device would be in the form of dovetails or M&T joints, but where butt joints were concerned, something like a loose tongue should be added.

For me, what Alan Peters had to say was one of the best things I've ever read on the subject and made complete sense. It's why I will always, wherever possible, use biscuits, dominos or loose tongues and PVA adhesive when jointing things like table tops.

Cheers :wink:

Paul

 

[Paul Chapman]

Animal glue does have some distinct disadvantages for sure (ie interior use only)

I must lend you my copy of "Hide Glue - Historical and Practical Applications" by Stephen Shepherd. He explains how to make hide glue waterproof http://www.toolsforworkingwood.com/Merc ... ide%20glue

Cheers :wink:

Paul

 

[woodbloke]

Paul - you cant' really argue with AP 'cos he's 'the man' but I still think that it's a 'belt and braces' approach which in most cases, is not really needed. As you know, I use PVA all the time which gives sufficient flexibility for an edge joint...
The other thing about hide glue of course is that it's easy to take the joint apart again, something which is almost impossible with modern adhesives without destroying it - Rob

 

[Paul Chapman]

The other issue in all this is the practical one of how you stop the boards in, say, a table top slipping about all over the place when they have glue on them and you tighten up the sash cramps :? Say you have a table top and two of the boards cramp up 1/16" out of alignment at one end. They are also likely to be out of alignment 1/16" the other end. That means you have to plane off 1/8" to get them flat. And 1/8" on the other side of the boards which adds up to 1/4" overall. That could mean failure because the boards are now too thin. Biscuits stop all that and result in a far more relaxed glue-up.

I know some say you can adjust the boards with a mallet as you cramp them up but I just don't need that sort of aggro - and bashing them with a mallet or hammer is hardly precision woodworking, is it?

Still, each to their own - I'm very happy with how I do it

Cheers :wink:

Paul

 

[woodbloke]

The other issue in all this is the practical one of how you stop the boards in, say, a table top slipping about all over the place when they have glue on them and you tighten up the sash cramps :? Say you have a table top and two of the boards cramp up 1/16" out of alignment at one end. They are also likely to be out of alignment 1/16" the other end. That means you have to plane off 1/8" to get them flat. And 1/8" on the other side of the boards which adds up to 1/4" overall. That could mean failure because the boards are now too thin. Biscuits stop all that and result in a far more relaxed glue-up.

I know some say you can adjust the boards with a mallet as you cramp them up but I just don't need that sort of aggro - and bashing them with a mallet or hammer is hardly precision woodworking, is it?

Still, each to their own - I'm very happy with how I do it

Cheers :wink:

Paul

That's easy...put a panel pin in the middle of the board at each end, snip the end off so you've about 2 or 3mm showing and push the boards together. No slipage :wink: ...try it, it works :lol: I'd also only ever glue up one pair of boards at a time - Rob

 

[steviem]

interesting discussion this one and some well considered points raised from both camps.
I personally have used both methods successfully. These days I tend to discount the biscuits simply because its just another process that I feel isnt really necessary. I appreciated that the sanding may take a little longer because of the "step" that can sometimes occur but in my mind this is the only advantage of using biscuits.

Each to their own I reckon and many thanks for the replies.
Steve

 

[L Harding]

Rob - I wasnt implying animal glue was a bad glue to use, it does have some advantages (as you said, the ability to reverse it with heat for one). Having said that i not a big fan, would always pick something like titebond over it for 90% of jobs.

I appreciate your solid jointed back panels are surly more than up to the job, but no matter what your thoughts on MDF and alike i dont think it can be argued a solid at that thickness can be as stable as a veneered panel

 

[woodbloke]

Rob - I wasnt implying animal glue was a bad glue to use, it does have some advantages (as you said, the ability to reverse it with heat for one). Having said that i not a big fan, would always pick something like titebond over it for 90% of jobs.

I appreciate your solid jointed back panels are surly more than up to the job, but no matter what your thoughts on MDF and alike i dont think it can be argued a solid at that thickness can be as stable as a veneered panel

Sure...I'm a convert to TBIII now so that gets used for most things now. For those two jobs either would have been OK for the back, I just chose to use solid material as opposed to veneer (which I have used for other pieces) - Rob