Why no 7MM Dominos?

[smorgasbord]

Long time woodworker, new to Domino-ing. Going through setup and trial joints. For 20mm thick hardwoods I would think that a 7mm thick domino would be ideal - just a tad over the 1/3 tenon thickness guideline. It seems that many people choose the 8mm thickness for this application (and smaller 6mm to less dense woods).

Anyway, why no 7mm dominos? Just trying to keep things simple?

 

[Crazyraceguy]

I suppose that once you get that big, a 1mm step is just not worth the trouble?
They start at 4 and go in ones to 5 and 6, then in 2s, 8, 10, 12, 14.

 

[squall_line]

I'll probably get flak for this, but think of the Domino machine like a doweler that wags back and forth.

Standard metric dowels are 5mm, 6mm, 8mm, 10mm...  Those are the exact same sizes as the domino tenons when the machine was first introduced in 2007.

The 4mm domino came in 2009 to aid in drawer box assembly and around the time they switched from pins to flip stops.  The XL 700 came another 3 years later in 2012 with 12mm and 14mm and deeper 8mm and 10mm plunges.

 

[smorgasbord]

I suppose that once you get that big, a 1mm step is just not worth the trouble?
They start at 4 and go in ones to 5 and 6, then in 2s, 8, 10, 12, 14.

Yes, I understood that, but feel that there is a need for 7mm. I agree there certainly is not a need for 11mm or 13mm.

 

[ChuckS]

FWIW, the manual says 8mm tenons are common for 3/4"  (19mm) lumber (hardwood), while 6mm tenons for 3/4" plywood (1/3 of 19mm). If 8mm is good for 19mm hardwood, it sure is suitable for 20mm hardwood. For structural applications in 3/4" hardwood, I always use 8mm tenons, otherwise 6mm tenons because they're cheaper.

 

[guybo]

Hi, I think chuck s is on to something  4mm to 12mmply the1/3 rule holds for 15 18 24,and 30mm ply in respect to 5,6,8, and 10mm dominos not for the12,14 ply sizesfor those @35,40, and 45mm. just a guess

 

[Birdhunter]

I’ve been using loose tenons (both the 500 and 700) for years and never thought I needed another size tenon.

 

[Crazyraceguy]

FWIW, the manual says 8mm tenons are common for 3/4"  (19mm) lumber (hardwood), while 6mm tenons for 3/4" plywood (1/3 of 19mm). If 8mm is good for 19mm hardwood, it sure is suitable for 20mm hardwood. For structural applications in 3/4" hardwood, I always use 8mm tenons, otherwise 6mm tenons because they're cheaper.

Very similar for me, but I don't do much that I would consider structural with 3/4" hardwood. When it gets to that point, it's usually thicker stock. I'm almost up to the point of needing DF700.
I should just go ahead and do it. It took a while to justify the Lamello Zeta P2, but have never regretted that.
Although, I did see that Peter Millard (10 min workshop) does not get along with his?
Somehow, I think someone is missing something there though, whether it's him or me, I don't know?
He showed an example of rotating a cabinet carcass and it collapsing on him. It was a mitered unit with a shelf in the middle. He used the Tenso connectors, unglued, and it just popped apart.
My thought is that this is the worst case scenario possible? I understand the concept of knock-down (KD) fixturing, but is that really a thing with mitered corners? If not, just glue it and problem solved.
I approach it differently though. I never rely on Tenso alone. I use them as a clamping aid in situations where that is difficult and use Dominos as the main structural element.
In his example (even if you needed KD with miters) the Dominos would have held that together just fine.
I have used them together many times on large wall panels and they work great. The Dominos hold everything aligned and the Tensos snap them tight. This is why I buy the 6mm Dominos by the case, rather than the little retail display packs.

 

[ChuckS]

8mm tenons used in this credenza (sapele, 20mm thick).

Not an owner of the DF700. I use double twin 10mm tenons where applicable.

 

[ChuckS]

This is why I buy the 6mm Dominos by the case, rather than the little retail display packs.

Same here...after wasting so much money on the plastic packs! [embarassed]

I get the cases for the 6mm and 8mm tenons.

 

[JeromeM]

[I did see that Peter Millard (10 min workshop) does not get along with his?
Somehow, I think someone is missing something there though, whether it's him or me, I don't know?
He showed an example of rotating a cabinet carcass and it collapsing on him. It was a mitered unit with a shelf in the middle. He used the Tenso connectors, unglued, and it just popped apart.
My thought is that this is the worst case scenario possible? I understand the concept of knock-down (KD) fixturing, but is that really a thing with mitered corners? If not, just glue it and problem solved.

If you watch the complete video you will see that that situation just illustrates that the Tenso connectors are just bad.
They do not do the job they are designed for.

They do not clamp the joints tight enough for a good glue joint. They do not hold a dry fit well enough to move it as he illustrated, while a domino or dowel joint dry fill will not fall apart like that.

It is on his worst buy list as it doesn’t do the job he bought it for so at the price “for him” it is a lemon. He isn’t doing anything it isn’t supposed to do.

None of that means that it is not the correct tool for different jobs

 

[Svar]

Long time woodworker, new to Domino-ing. Going through setup and trial joints. For 20mm thick hardwoods I would think that a 7mm thick domino would be ideal - just a tad over the 1/3 tenon thickness guideline. It seems that many people choose the 8mm thickness for this application (and smaller 6mm to less dense woods).
Anyway, why no 7mm dominos? Just trying to keep things simple?

I think 8 mm is ideal for 19 mm stock. 1/3 rule is just an easy to remember simplification and is just wrong. Tenon needs to be thicker than 1/3 for maximum strength, closer to 1/2.

 

[ChuckS]

Absolutely correct, Svar, which I learned not too long ago from a woodworker who is also an engineer.

 

[JeromeM]

Anyway, why no 7mm dominos? Just trying to keep things simple?

Probably because they would be redundant. Having been a domino user for well over a decade I have never found any desire or need for that size.

I also use the original Senica Domiplate for the vast majority of joints so many of them do not have the mortise centred in the board, this is never a problem unless I cut the domino referenced from the wrong face.

The centring of mortises is almost certainly a hangover from manual mortise cutting where a symmetrical mortise makes marking out mistakes less likely to happen, with a domino there’s no need for that.

 

[Crazyraceguy]

[I did see that Peter Millard (10 min workshop) does not get along with his?
Somehow, I think someone is missing something there though, whether it's him or me, I don't know?
He showed an example of rotating a cabinet carcass and it collapsing on him. It was a mitered unit with a shelf in the middle. He used the Tenso connectors, unglued, and it just popped apart.
My thought is that this is the worst case scenario possible? I understand the concept of knock-down (KD) fixturing, but is that really a thing with mitered corners? If not, just glue it and problem solved.

If you watch the complete video you will see that that situation just illustrates that the Tenso connectors are just bad.
They do not do the job they are designed for.

They do not clamp the joints tight enough for a good glue joint. They do not hold a dry fit well enough to move it as he illustrated, while a domino or dowel joint dry fill will not fall apart like that.

It is on his worst buy list as it doesn’t do the job he bought it for so at the price “for him” it is a lemon. He isn’t doing anything it isn’t supposed to do.

None of that means that it is not the correct tool for different jobs

I did watch the whole thing, I just see it as a misapplication of the Tensos. The really don't have any lateral strength, the flexible fingers are not tight in the space, like a Domino would be. They are not intended to do that, so it's not surprising that they don't. They do clamp nice and tight, but they just won't take lateral movement. You actually have to be somewhat careful with them when assembled, because they can be quite difficult to disassemble with a straight pull, especially when there are a few Dominos in there keeping things straight.
The Clamex connectors are much stiffer/stronger, but as mentioned, they do require an access hole.

 

[Brian Livingstone]

Hi All,

I have the Zeta P2.  I find that from time to time I don’t get as tight of a joint as I would like, and have to use clamps.  However, sometimes I do get a really nice tight joint.  I am building a new garage, and am using PVC trim.  For wall corners I cut two boards on a 45 degree bevel, add a Tenso every 12 inches, and the PVC snaps together perfectly.  For long runs I join two boards at the ends with a Tenso, snaps together perfectly.

I have the DF700.  Just finished using the Domino connectors for the first time.  Slick !  Highly recommended.

I had a DF500 for ten plus years, sold it when I bought the 700.  Found I missed it, and bought another one.  Obviously love it.

Brian

 

[JeromeM]

I just see it as a misapplication of the Tensos. The really don't have any lateral strength, the flexible fingers are not tight in the space, like a Domino would be. They are not intended to do that, so it's not surprising that they don't. They do clamp nice and tight, but they just won't take lateral movement.

It wasn’t a miss application but was a rather funny demonstration of the total lack of lateral holding power. Peter acknowledged that it wasn’t how they are designed to be strong but the total lack is very useful for prospective users.

As to clamping nice and tight that is not his experience he found he needed clamps which means that they do not even do the job they are designed to do.

I was not seriously considering buying that tool but now I am absolutely sure I don’t want one. My DF500 can do everything it can and far more, including a fixing similar to the Clamex

 

[ChuckS]

Snip.
My DF500 can do everything it can and far more, Snip.

Likewise here.

I don't do entrance doors or outdoor benches for a party of 12, etc. I have also found a way to make deep mortises (6mm, 8mm & 10mm) like the DF700 with my DF500 -- beyond the 28mm depth limit, and may be to as deep as 70 to 80mm -- except in a much less efficient way.

 

[Coen]

I have also found a way to make deep mortises (6mm, 8mm & 10mm) like the DF700 with my DF500 -- beyond the 28mm depth limit, and may be to as deep as 70 to 80mm -- except in a much less efficient way.

Tell us more  [huh]

 

[ChuckS]

Coen, Just use a drilling guide - shop-made or bought ($15 US or less):
https://www.festoolownersgroup.com/festool-how-to/entry-doors-with-a-domino-500/msg653755/#msg653755

Start with one end of the mortise, then the other end, and the rest with overlapping boring -- in the same manner you use a mortiser.

I've used this method in two projects so far, accounting for less than 0.1% of all the mortises ever made with the Domino Joiner.