domino sizing chart?

[MrMac]

I just bought the extra kit that goe's with the domino. I was wondering if there is a guide or chart that show's which domino is most appropriate for a given size of material. IE: my dealer yesterday said that the 6mm was the right size for 3/4" material.

That got me to thinking that I should find a chart or something to attach to my kit, so I use the correct size domino.

For instance, a few days back I'm doing "hard edge" it's just to complicated! LOL anyway it involves joining two pieces of 3/4" x 5" MDF endwise. By that I mean we needed 10' and the sheets of MDF that we have are 8'. The other guy's on the crew are using two biscuits to do the joining.

I used my domino, and a pocket screw - done! no waiting around for the glue to dry while the outside crew sneaks in to use our saws while walking all over the trim that is set aside to dry! ok, rant over

Anyway I used two 4mm domino's, and while that worked, it was a little bit of an iffy joint. That's what got me to thinking that I need to figure out what's the best domino for the given material.

I've searched this forum, but I don't see anything about a chart. I know there must be one, and it probably came with the domino, but it's lost in a mountain of paperwork

Anyone know of a chart like that?

Thanks!

 

[woodguy7]

Can't say I have ever seen such a chart but a general rule of thumb is one third thickness.

 

[jacko9]

Can't say I have ever seen such a chart but a general rule of thumb is one third thickness.

I second that, 1/3 the thickness is what I've used even when cutting mortise and tenons by hand tools.  Yes, I use a saw and chisel occasionally!

 

[Wood_Junkie]

It's not a chart.  But see page 10 of Rick Christopherson's excellent supplementary Domino manual:

http://www.waterfront-woods.com/festool/Domino_DF_500.pdf

Good highlights:  (copied directly from Rick's work, linked above)

When the strength of your workpieces is comparable to the strength of the Domino tenon (e.g. general hard woods) then the thickness of the Domino tenon should be approximately 1/3 the thickness of the workpieces.
► It is acceptable to use a tenon that is slightly thicker than 1/3 when the width of the Domino tenon is relatively narrow compared to the width of the joint. This is why 8mm Domino tenons are the most common for joining ¾-inch lumber.
► For softer woods, such as pine, the joint will be stronger when the tenon is 1/3 or slightly less.
► For plywoods, especially low-grade construction plywoods, the Domino tenon is much stronger than the surrounding wood, so it is best to maximize the strength of the substrate by minimizing the thickness of the tenon.

Domino Tenon Placement Guidelines
There are no steadfast rules on where tenons should be placed, especially when they are used for alignment purposes. For edge joining boards, a typical placement might be 6 to 8 inches apart.
However, when tenons are used to strengthen a joint, you might be tempted to place the tenons too close together. This can actually weaken the joint by removing too much of the substrate material.
► A wide mortise weakens the substrate, so it is better to have several narrow mortises with uncut space in between, than it is to have a single wide mortise with several tenons side-by-side.
► When placing several tenons close together, leave at least twice the tenon thickness between mortise holes. As a general rule, this means the minimum tenon spacing should be about 10 mm to 20 mm, but they can be spaced much wider.
► When creating stacked mortises for extra thick lumber, an extension of the “1/3 rule” mentioned above still applies. Specifically, the distance between mortises, and the distance between a mortise and the wood surface should all be equal to (or larger than) the thickness of the tenon.

 

[Jesse Cloud]

Junkie and Rick are right.  The 1/3 rule is a reliable guideline, but don't get anal about it.  A little more or a little less won't be a problem in most cases.

In MDF I would err on the side of smaller is better.  MDF really likes to swell when moisture is applied.

 

[VictorL]

6 mm tenons are NOT practical for 3/4" plywood and MDF. Thickness of 3/4 plywood is 18mm or slightly undersized (3/4 lumber is 19mm).  For 1/3 thickness rule 6 mm sounds good, but material (plywood or MDF) is relatively weak and splits easily. The weakest point is material, not domino!
Most important is that length of 5mm tenon is 30mm or 15 mm go into one part, 15mm go to another part. Length of 6mm tenon is 40mm, but thickness of material is 18mm and mortise will be cut through. In this  case 15mm goes in one part, 25mm goes to another part. You have to adjust  depth of 6mm tenon back and forth, and very often just ruin parts.
"The Standard Domino Unit" (one bag of domino for the same price) is 300 for 5mm or 190 for 6mm.
Conclusion: 5mm dominoes ARE more practical than 6mm dominoes for 18mm (3/4" nominal) material.

VictorL

 

[mouppe]

It also depends on the joint. For panel alignment, you can get away with smaller dominoes. For joints where structural strength is required, use a thicker domino, or even two smaller ones if they will fit.

For solid wood, 1/3 the thickness of the material is traditional, but as I said two smaller dominoes could be stronger. As Victor said, I reduce the domino size for MDF, but I never use it where strength is required anyway.

It would be hard to produce a definitive chart as so much depends on the particular application.

 

[Kevin Stricker]

In your application I find bigger is better. I see a big difference when end joining MDF with 6mm tenons vs 5mm tenons in the amount that the pieces shift when the pocket screws are driven home.  Always clamped but there is still always a creep and I find the larger tenon can better prevent the racking.

I have yet to have a problem with swelling of the MDF at the domino.  I do sometimes plunge a short domino in from the back side for the pocket screw to grab on to help with assembly.

I had to make up some 24' trim pieces in Rustic Alder which only comes in 10' lengths around here. Using the domino and pocket screw and a butt joint I was able to get pretty acceptable results, as in customer could not find the joint once the boards were stained.  The best part was that the dominos gave the joint enough strength for the boards to be moved around once the glue set.  For this application I don't rely on the pocket screws alone as end to end is about as weak as it gets even with the pocket screws.  With MDF once the glue sets the joint is stronger than the rest of the board. 

 

[MrMac]

Thanks! some good guidelines to follow.

Cheers!

 

[architect]

just joined the group...I am in the planning phase for a 4-posted bed. the posts are 2-1/2"x 2-1/2", the rails are 1-1/16"x 8", all milled poplar. Looking for advise on the size of the dominos for my brand new Domino 500: 10x50 or 8x50 or 8x40? I plan to use three dominos for each joint.
Thank you in advance

 

[peter halle]

just joined the group...I am in the planning phase for a 4-posted bed. the posts are 2-1/2"x 2-1/2", the rails are 1-1/16"x 8", all milled poplar. Looking for advise on the size of the dominos for my brand new Domino 500: 10x50 or 8x50 or 8x40? I plan to use three dominos for each joint.
Thank you in advance

Welcome to the FOG!

Are you asking about making all your joints in the bed with dominos or using them to construct the head and foot?  Bed bolts add a ton of strength.

Peter

 

[Holmz]

...
For solid wood, 1/3 the thickness of the material is traditional, but as I said two smaller dominoes could be stronger. As Victor said, I reduce the domino size for MDF, but I never use it where strength is required anyway.
...

[member=7882]RL[/member] What does "I never use it where strength is required" mean?

And specifically for MDF is it just to align?

 

[clark_fork]

This is another means to select a Domino Each Domino is seated 1/2 into the guide.

[attachimg=1]

Jig Guide

 

[guitar_ed]

I built a domino jig after seeing this.  Made the domino process a lot easier for me.  I highly recommend making of your own.

edg

 

[bkharman]

No offense to anyone... But do you REALLY need some sort of index for doing dominoes?  There are exactly 2 measurements.

The thickness:  3/1 is the normal measure and it is a pretty decent one. Move to metric and things will be easier.

Depth of domino:  if it says 40mm, you have half in each side by default or you split it up based on materials. Not all that difficult.

I have had my 700xl over 2 years now. I tried a LOT of test cuts the first week I got it. I figured it all out. I made a few mistakes and learned not what to do. Buy some cheap ply or poplar from your HD or Lowes and try some stuff.

Enjoy the equipment and again, no offense to other methods people have concocted. Just not my style.

Cheers. Bryan.

 

[Stone Message]

There is far more to domino planning than has been discussed and I would say that only the obvious rule of thirds (or near enough) has been mentioned. For that there is no need, as the previous poster said, to have charts or aides memoire.

The position or placement of dominos and relative spacing is far more important (given that the thickness of the domino is simple to work out). I am no expert at all but I spend a bit of time working out the best place to put dominos in a multi domino situation. Working out whether to have 2 instead of 1 domino between stiles and wider rails is also important. Whether to stack the dominos so that more than one will span the width needs some thought.

But how thick a domino should be in a piece of 3/4" or 40 mm stock is the easy bit.

To help me I have created a reference block that allows me to check the widths of all the dominos and it also helps me to eyeball (yes, non empirical) whether I need more than one in a given joint.

Peter

 

[sancho57]

I dunno to me it's not that big of a deal. For edge jointing, I'll use the stops on the fence, make the first mortise then evenly divide them down the edge taking in account any routing I have to do that might expose them. Same with shelves, etc.

I use the largest one that will fit and go on....

To easy.

I try not to over think this..

 

[mouppe]

...
For solid wood, 1/3 the thickness of the material is traditional, but as I said two smaller dominoes could be stronger. As Victor said, I reduce the domino size for MDF, but I never use it where strength is required anyway.
...

[member=7882]RL[/member] What does "I never use it where strength is required" mean?

And specifically for MDF is it just to align?

I meant that I would never use MDF where strength is required so any dominos used with it would just be for alignment, so I'd probably go with small ones.

 

[Cheese]

[member=49013]clark_fork[/member]
I like your Domino selector... [thumbs up] 

Right now I just have an assortment sitting on the bench, which means they tend to get lost.

 

[ART at WORK]

A trick I read here and have successfully used is to make a set of 4 Dominos for each size that are sanded down on all sides.
These are to help when checking a dry fit or making a mock up 0r test piece.
It saves you time and money having to pull the new ones out of the wood with some pliers.
I keep mine in small air lock/tight bags to reduce the mosture problem.
I use these to figure out which size to use in complicated joints.

Pip