Dominoes Versus Biscuits in case construction

[waltwood]

I have been using Dominoes exclusively for all joining for about 2 years including case construction. I have a large amount of cases to build now and I am considering biscuits. Here is why. I visited a friends shop a couple of days ago that builds large frameless cases for kitchens and he uses only biscuits using a Lamello joiner. I commented that the units looked as though they needed temp. support across the backs while being transported to the job and he showed me how strong they were. I thought about it and there would be more surface area with the biscuits than the Dominoes. Only a 5 mm Domino can be used on 3/4" ply because when cutting a slot for a larger one it will come through the ply. However a #20 biscuit can be used on 3/4" with about 3 times the surface area than a 5 mm Domino.  I have not used biscuits in about 5 years but for this application they seem like a better choice. I made samples of ply corners using both and the ply busted in both cases and not the tenon or biscuit. Any input for me because I start assembling the cases tomorrow. 

 

[leakyroof]

It sounds like you made your decision already once you built those test pieces. I used biscuits and my first Lamello machine for 15 years before the Domino came out. They are fast and strong.  You should be fine

 

[tiralie]

I think biscuits are faster than dominos to install.
Dominos are better for alignment.
Biscuits give you some flexibility in terms of alignment if you need to adjust the joint during glue up.
I wouldn't build a case without braces at the very least.
Tim

 

[semenza]

You can use a 6mm domino on 3/4"  if you want. Set face mortise at 12mm depth and end mortise at 28mm. I have done that in a few instances but usually use 5mm.  I guess the domino / biscuit  choice depends on the rest of your process. I like the dominos because I find it much easier to do the assembly by myself.  The pieces stay together without tipping over without need for support. I put pocket screws in to take care of the clamping, so no clamps to place , etc.  For me the glue surface area difference between biscuits and dominoes is negligible since I glue the entire edge.  

I think the speed will depend on the whole process not just the biscuit / domino choice.

Seth

 

[stvrowe]

I did my own informal testing of dowels/biscuits/dominos for the very application you indicated.  My conclusion was that all were adequate for the joint.  The dowel was the weakest, the #20 biscuit was the strongest and the 5mm domino was in the middle.  All joints were tested in shear and in all cases, the plywood failed and not the connecting element.  Whatever you choose will be fine.  Seth makes a good point on ease of assembly, the Domino will hold itself together while the biscuit will not. 

 

[Kev]

Lamello make some great "system" things that I wish Festool would catch up with. The Invis stuff looks really cool.

I'm tempted to get a Lamello, but not for the biscuits - for the systems.

 

[Peterm]

Lamello make some great "system" things that I wish Festool would catch up with. The Invis stuff looks really cool.

I'm tempted to get a Lamello, but not for the biscuits - for the systems.

+1. Very interested in the Clamex P connectors, just can't quite bring myself to spend that much (Lamello Zeta is £1300 GBP here) on a non-Festool 

 

[waltwood]

You can use a 6mm domino on 3/4"  if you want. Set face mortise at 12mm depth and end mortise at 28mm. I have done that in a few instances but usually use 5mm.  I guess the domino / biscuit  choice depends on the rest of your process. I like the dominos because I find it much easier to do the assembly by myself.  The pieces stay together without tipping over without need for support. I put pocket screws in to take care of the clamping, so no clamps to place , etc.  For me the glue surface area difference between biscuits and dominoes is negligible since I glue the entire edge.  

I think the speed will depend on the whole process not just the biscuit / domino choice.

Seth

The pieces staying together without tipping over is a good point. I also glue the whole joint but I don't think it does much on the end grain. I don't use any metal fasteners because if I make a mistake I can cut the unit down and reuse it without have be concerned about hitting any metal.  

EDIT> moved reply out of quote box.

 

[waltwood]

It sounds like you made your decision already once you built those test pieces. I used biscuits and my first Lamello machine for 15 years before the Domino came out. They are fast and strong.  You should be fine

I really hadn't made a decision but I gave more pros of the biscuits because this is a festool forum and I thought more folks would be for the Dominoes.
There is one thing in favor of the Domino; the support bracket that holds the machine 90 degrees to the workpiece when doing the sides of the cases. My 2 biscuit joiners don't have them. 

 

[semenza]

I have recut cases after glued assembly. In my case I just need to remove the screws before making the cut.

Seth

 

[waltwood]

I used dominoes for assembling the cases and of course it worked good. I have never used the support bracket until yesterday and Boy have I been missing out. I never had one with all my biscuit joiners so I did not think it was necessary and it really works keeping the tool square when putting Dominoes on the top face of ply or a board. Everyone else probably knows this but in case you have not used it give it a try.

 

[jacko9]

I have used both Domino's and Lamello Biscuits to build solid wood cases with equal success.  With the Domino I have used combinations of cutter sizes and Dominos from 4mm to 14mm.  I have also used the Domino cutter to cut the mortise and used integral tenons.  With the Lamello I have used all sizes but mostly the #20 biscuit however I did some heavy duty construction using the #6 biscuit which requires a double plunge.  For really sturdy construction a double stacked row of #6 biscuits is rock solid construction.  I also have the Lamello support bracket which operated a lot like the one that I have for my Domino machines.

Jack

 

[waltwood]

I used to double stack biscuits when I used them also, and I do it with the Dominoes now. I just glued up a door this week using 10mm double stacked Dominoes.

Walt 

 

[jacko9]

Walt,

I find that using a double stack of 4mm dominos is very useful for small cabinet drawer blades.

Jack

 

[tjbnwi]

I'm building a bunch of cases right now. There are 4000 plus mortices per group. It takes me just over 3 hours to make all the plunges. The sides, tops and bottoms are plunged at 12 mm the edges at 20 mm. Edges plunged on the narrow setting, sides, tops and bottoms mid setting. Not only area the Dominos there for alignment, I am also using them to secure the parts in racks for transport.

I just ordered my second lot of 9,000 Dominos. By the time this project ends I will have gone through over 21,000 Dominos.

I'm not a fan of biscuits, to much play in them.

Tom

 

[Custard]

I have never used the support bracket until yesterday and Boy have I been missing out. I never had one with all my biscuit joiners

Just an aside, even though Lamello is a great tool their brackets are a PITA, too easy to get misaligned. The Festool brackets are better thought out

 

[waltwood]

I'm building a bunch of cases right now. There are 4000 plus mortices per group. It takes me just over 3 hours to make all the plunges. The sides, tops and bottoms are plunged at 12 mm the edges at 20 mm. Edges plunged on the narrow setting, sides, tops and bottoms mid setting. Not only area the Dominos there for alignment, I am also using them to secure the parts in racks for transport.

I just ordered my second lot of 9,000 Dominos. By the time this project ends I will have gone through over 21,000 Dominos.

I'm not a fan of biscuits, to much play in them.

Tom

Wow! That is a serious amount of Dominos. My current project has 200 in them and I thought that was something.

 

[ShawnRussell]

I'm building a bunch of cases right now. There are 4000 plus mortices per group. It takes me just over 3 hours to make all the plunges. The sides, tops and bottoms are plunged at 12 mm the edges at 20 mm. Edges plunged on the narrow setting, sides, tops and bottoms mid setting. Not only area the Dominos there for alignment, I am also using them to secure the parts in racks for transport.

I just ordered my second lot of 9,000 Dominos. By the time this project ends I will have gone through over 21,000 Dominos.

I'm not a fan of biscuits, to much play in them.

Tom

You have clearly cut more dominos per project than I will cut in a year or two. Have you kept track of how often you have replaced your cutters?

 

[Custard]

I think biscuits are faster than dominos to install.
Dominos are better for alignment.

I agree with Tim.

You always want speed, but sometimes you want alignment more.

Let's say I'm making a writing desk out of veneered ply or MDF. There will be a top, a base, and a couple of drawer dividers...all with a thick solid wood lipping at the front. I could use either dominos or biscuits to joint the drawer dividers to the top and base. But I absolutely need those solid wood lippings to line up precisely, so dominos would be the better choice as when it comes to the glue up you don't have to worry about the drawer dividers slipping out of place.

 

[Ted Miller]

I always felt biscuits were weak but they were only used for alignment purposes. Yes they were fast to install. Back in the day I would use a slot cutter on a router and groove the entire front edge of the carcass, then place biscuits where I wanted them on the face frames and alignment would be simple.

Since the domino hit the US, I don't rabbet, groove or dado much anymore on carcass work unless it's prefinished or melamine.

One side of the material I will make the plunges tight and the opposite material to join I will make the 2nd wider plunge. Now I still have some room for adjustment...