Domino Strength Test

[Coen]

Domino, on the other hand, CAN NOT be operated without a vac.

Oh, since when?

But even so; good! If I ever get one of those newer sanders you can be sure I'll enable that feature that disables the motor when the hose is not connected. Not for me, but for those family members that borrow my stuff. To make them see the light of working dust-free.

 

[squall_line]

Domino, on the other hand, CAN NOT be operated without a vac.

Oh, since when?

But even so; good! If I ever get one of those newer sanders you can be sure I'll enable that feature that disables the motor when the hose is not connected. Not for me, but for those family members that borrow my stuff. To make them see the light of working dust-free.

I think this is a "functionally, it doesn't self-clear, so you need to use extraction", but not "there is a sensor that prevents the tool from running without extraction", the way some of the sanders do.

 

[ChuckM]

For just a few mortises, the DF 500 can be used without any vac. as can be seen in a couple of amateurish ahots out there. That. of course, isn't the proper way to use the machine, and the mortise quality can be affected. I wouldn't recommend it.

If you really really need to make a mortise or two in a pinch, and no vac is around, that's ok. BUT, don't try it with the 4mm cutter.

 

[Coen]

Domino, on the other hand, CAN NOT be operated without a vac.

Oh, since when?

But even so; good! If I ever get one of those newer sanders you can be sure I'll enable that feature that disables the motor when the hose is not connected. Not for me, but for those family members that borrow my stuff. To make them see the light of working dust-free.

I think this is a "functionally, it doesn't self-clear, so you need to use extraction", but not "there is a sensor that prevents the tool from running without extraction", the way some of the sanders do.

Yes I know it doesn't have a sensor. I just never heard about it not clearing the hole without dc.

 

[ChuckM]

I don't own the DF700 (pin-based rather than paddle-based), and have only used it with dust extraction. According to this fellow, he experienced some clogging problems:https://www.wallybois.com/the-festo...-problems-clogs-when-used-without-extraction/

I can imagine clogging problems if one uses one of the old DF500s with pins, or use the paddle-based DF500 with the cross stop without dust extraction.

 

[jaguar36]

The pins aren't really an issue.  The bit just doesn't clear the chips well and ends up recutting them and jamming them around.  Ends up with crappy mortises if you aren't careful.

I've done it without a vac before and as long as you go slow and don't try and force it, it works fine.  Certainly not ideal though.

 

[ChuckM]

The pins do matter if the tight setting is used for all milling which some prefer. The small chips in one or more mortises can throw the registration off and can compound the error. The pins may not matter if the tight/wide settings are used. But I expect unnecessary wear on the cutter if dust extraction is not used.

 

[bwhamilton]

I am always a bit miffed with these types of comparisons, because they tend be done "scientifically" without much of a hint of true comparability.

u/smorgasbord was on the money - the tests have to be highly comparable. Similar glue surfaces and spans, similar clamping pressures (if any), and as identical of setup as possible.

Pocket screws, by nature, "clamp" the two surfaces - likely drawing strong adhesion of the glue joint. I don't know how much in ft/pds or newtons, but it is likely significantly above the lazy clamping many of these tests do with other methods. Inherently, this biases the outcome more favorably.

 

[Packard]

I have a "Joint Genie" (made in the U.K.).  I have not used it for any other than butt and miter joints, it will work on any angle.  I got it through Amazon.com (USA) and it shipped directly from the UK in about 10 days. 

I was in the imperial system back when I ordered it (3/8").  If I had to do over, I would order the 8mm version.  My other main dowel jig is 8mm (for sheet goods only), CMT. 

Joint Genie gives you an approximate center.  It is not self-centering so you do have to orient the pieces or the edges won't align.  But after a few tries, that becomes easy to do.  I use the screws mostly (in place of the clamps) as they are less in the way and more secure. 

Cheaper than Dowel max.  It seems faster and easier to use.  (But I have not used Dowelmax).  They also limit themselves to how-to-dos in their instructions instead of making what seems to be overly optimistic joint strength claims. 

I found the a line voltage electric drill spinning at 2,000 or more makes quicker work of the dowel process.  I never use the battery powered drill for that.  Also the faster spinning seems to make cleaner holes. 

I don't understand why they don't post videos with sharper image quality.  It definitely detracts from the perceived value of the jigs. 

They are nicely machined.  But note that plating does not "throw" well inside hollows, so it is not likely that the entire interior of the dowel holes will have plating.  This is a product of the plating process and not a fault in manufacturing.  The plated jig is still preferable to a black oxide finish that we see on some other jigs.

 

[jaguar36]

I am always a bit miffed with these types of comparisons, because they tend be done "scientifically" without much of a hint of true comparability.

u/smorgasbord was on the money - the tests have to be highly comparable. Similar glue surfaces and spans, similar clamping pressures (if any), and as identical of setup as possible.

Pocket screws, by nature, "clamp" the two surfaces - likely drawing strong adhesion of the glue joint. I don't know how much in ft/pds or newtons, but it is likely significantly above the lazy clamping many of these tests do with other methods. Inherently, this biases the outcome more favorably.

The goal of the test is not to determine which is stronger is some perfect idealized lab situation.  The goal is to determine which one is stronger in the way that most folks use them.

I would like to test how clamping pressure effects lap joint strength though.

 

[Packard]

I once made a face frame using half-lap joints. Instead of clamping, I used a single screw with a fender washer at each joint. 

Then I removed the screws.  What to do with the ugly hole in each joint?  I used my mortiser to cut square holes and I then pegged the joints. 

They were probably the world's strongest face frames.  I never did that again.  Too much work.  Now I use pocket holes as long as they don't show, otherwise, dowels.

I also did a full saddle joint on the drawer fronts.  (Not pegged, though.)

I am trying hard to not overbuild my projects.  I was proud that I was able to make a reasonable medicine cabinet using butt joints and a nail gun. [big grin] I was fairly amazed at how solid it felt. 

I may post a shot of that here. 

In my opinion, DowelMax makes the most outrageous strength claims.  It is almost as if they believe they invented the dowel joint. 

The key for validity of tests is "repeatability".  Since none of the online tests I have seen have been anything but a one-off, the repeatability is still a question. 

I did read a test run by the RTA (ready to assemble furniture association) where they tested various fasteners for (basically) sheet goods.  Dowels topped the crop.  It did better than screws (but not better than Confirmats).  It did better than dadoes, quarter-turn fasteners and those hidden nut fasteners. 

The kitchen cabinet association came up with similar results, with dowels topping the strength (again, mainly for sheet goods). 

They both concluded that the dowels should not be within 2" of the end of the joint. 

The kitchen cabinet test was less interested in racking strength because most of the cabinets used a wall as part of the structure. 

Surprisingly (to me) the dado joint did the most poorly of any joint tested.  I used to assemble cabinets using dadoes.  Now I dowel.  With the  right jig, is is just as fast and just as easy.

 

[Cheese]

I would like to test how clamping pressure effects lap joint strength though.

Along those lines I ran across this article and they mention that too much clamping pressure can actually squeeze the glue out of the joint.
https://www.woodmagazine.com/woodworking-tips/techniques/skills/take-it-easy-with-clamping-pressure

[attachimg=1]

[attachimg=2]

[attachimg=3]

[attachimg=4]

 

[ChuckM]

I've never experienced glueline failure due to overclamping. As long as enough glue is applied to BOTH mating surfaces, I don't see how clamping can remove glue so much that it causes a starved joint.

 

[Packard]

I can imagine it, but I have not experienced it.

I've bought "project boards" at Lowes.  This is some sort of "white wood", probably some species of pine.  The surface is a slick as a sheet of glass. 

I can imagine that almost no glue gets absorbed into the surface because of the slickness and lack of porosity. I have no documentation to support that, however.

I have not seen any real studies that support that either.  The "tests" we normally rely on in the woodworking field, are typically one step above anecdotal.  They are likely indicative of what they are testing, but not proof of those tests. 

There are really only manufacturers' associations that finance real testing, and those tests are specific to the types of construction used by the members.

The only really good tests that I have seen have been conducted by ready to assemble industry (think "Ikea") and the kitchen cabinet industry.  Both mostly interested in assembling particle board and plywood. 

 

[ChuckM]

Snip.
I can imagine that almost no glue gets absorbed into the surface because of the slickness and lack of porosity. I have no documentation to support that, however.
Snip.

I've not used any wood like that, but if almost no glue can get into the wood (pores), then even moderate clamping wouldn't help.

I've "overclamped" edge joints (panels) or butt joints (carcases) a lot, if not all the time, because of the clamps I use, and not one single joint has ever failed. The jaw clamps in my shop can exert well over 1,500 lb of force.

Despite my overclamping practice, by putting glue on BOTH mating surfaces, I've never had any joint failed on me in builds from chairs to tables to cabinets to frames, etc.

Putting glue on only one surface (which I've seen some do) is not something I feel comfortable with.

 

[Packard]

I clamp until the glued joint closes up.  Sometimes that requires a lot of force,  in other instances very little.  My opinion is that a gap in the joint is worse than over-clamping.

But again, I have no studies to back that up.  It is just going on my feelings. 

In the last several years I have been using dowelled joints mostly.  The fit of the dowels really controls the amount of clamping pressure required.  Once the joint is "closed", I stop adding pressure.

 

[smorgasbord]

Yet another test of the strength of various joints:

Joint Test

Result still frame:
[attachimg=1]

"That was a surprise. Based on this one test we should be building everything with dowels. But I want to emphasize this was an informal experiment."

I wonder what happens when two dominos are used (assuming the stock is wide enough).

 

[ChuckM]

I've used double and twin dominoes in a table build in the form of a butt joint.

Fine Woodworking did a joinery test back in 2009:

[attachimg=1]

 

[Packard]

The problem with these seemingly “scientific” tests, is that they appear to test just one sample of each.

When I was in the metal stamping business, and we had to test parts for weld strength or hook strength, we always tested 10 or more pieces and recorded the values for each. There were sometimes outliers that tested higher or lower.  The ones that tested lower still had to remain within the strength tolerances. 

One sample makes good magazine or you tube fodder.  I don’t find it convincing.

On the other hand, various industries (think ready to assemble furniture—IKEA; and the kitchen cabinet trade association) do contract testing laboratories to test joinery.  Those results are based on multiple tests.

(It is the reason I changed from dado assembly of cabinets to dowels.  Dowels were vastly stronger, especially in racking strength.  Dominoes are not used by large cabinet companies as they cannot automate that process, so they are not included in the tests.)

 

[mino]

It was already said, but I will add some more cruft that may help some hobbies:

TLDR ref. the "joint system strength" game:
IF one needs to ask "which joint system is stronger", one is asking the wrong question.

Instead, one shall go learn more about grain, about wood expand/contract, about glues chemistry, about mechanics etc. etc. When one will no longer see such a simplified (stupidified?) "test" as "enlightening", then one knows to have got the answers needed.

Some more mumblings of mine:
------------------------------------
The main advantages of the DOMINO system are:
- easy/speed of use FOR AD HOC manufacturing /such flexibility is actually a detriment (!) in series production/
- secondary function of ALIGNING the pieces /a non-issue in CNC-based mass manufacturing/
- secondary function of ALLOWING EXACT FIT tuning /a detriment in CNC-based mass production/
- flexibility, where one tool handles a WIDE RANGE OF APPLICATIONS /try joining 10 mm thick pieces with a 8mm dowel system .../

A dowel is:
- cheap
- not adjustable /a boon for mass manuf, a major issue for one-off custom work/
- needs way more specialist machinery*) /basically a doweling machine/ to do time-cost-effectively

Of course a dowel configuration with no (time)cost spared will be better. Like 2x better. It will simple have more glue surface. That is why I use dowels with a doubled 32mm system for joints I need to have absolute maximum strength. But boy, are such joints expensive on mantime and overkill for 99% of cases.

To the contrary, the usual semi-dense DOMINO arrangement is about as strong as a /semi-dense/ dowel setup.

This means:
"Testing strength" between DOMINO/dowel/etc. is completely pointless:
- if one needs maximum strength, cost be damned, then a well-balanced joint with both DOMINO and dowels will be stronger than the wood being joined
- besides all the "tests" I saw so far were just scratching the surface and thei results were confusing at best and misleading at worst

DOMINO is the king of the hill on ad-hoc low volume custom production where it shines on time efficiency.
- it is also very forgiving for free hand use

Dowels are the king of the hill on material cost which makes them ideal for series/mass production.
- but are complete time disaster for one-off or ad-hoc work as need custom precision jigs etc.

DOMINO is the only /industrial/ game in town for narrow stock.
- there are other options for 10-12 mm stock, but mostly manual work

*) DD40 excepted, that tool is a "Dowel DOMINO" in some ways, lacking the adjustability loose tenons provide