Dowel Joinery Opinions

[Phil Thien]

I am not against using dowels as long as we understand what we are doing and that we actually don't know the long term reliability of this type of construction. As I said before it will probably be fine in our lifetimes.

I just can't agree with statements like that. Mills used dowels for everything from entry doors to window components to whatever. Tens of millions of doors and windows have been (and continue to be) subjected to the most brutal conditions, and hold up very nicely, thank you.

These types of arguments kind of remind me of audiophiles arguing about interconnects and speaker wire. A sort of purist mentality that doesn't result in much enjoyment of music.

[Tom McMahon]

Phil, I agree with what you said about doors and windows. I was referring to using dowels to connect the bottom of a cabinet to the bottom of the sides of the cabinet, where gravity is working against the joint.

[Frank Drew]

[QUOTE=Phil, I agree with what you said about doors and windows. I was referring to using dowels to connect the bottom of a cabinet to the bottom of the sides of the cabinet, where gravity is working against the joint.[/QUOTE]

Unless the cabinet is as small as Krenov's seem to be, that's my objection, too. Gravity, plus any live load inside the cabinet.

I'm not sure when dowels became the joinery method of choice for doors and windows, but most millworks at one time, and not all that long ago, had single and double end tenoners and mortise machines (hollow chisel, chain, whatever). My first job in woodworking, in the early Seventies, was at an architectural millwork and virtually all the joinery we did was mortise and tenon.

[Jon van der Linden]

Unless the cabinet is as small as Krenov's seem to be, that's my objection, too. Gravity, plus any live load inside the cabinet.

I'm not sure when dowels became the joinery method of choice for doors and windows, but most millworks at one time, and not all that long ago, had single and double end tenoners and mortise machines (hollow chisel, chain, whatever). My first job in woodworking, in the early Seventies, was at an architectural millwork and virtually all the joinery we did was mortise and tenon.

This idea that stuff won't hold together is getting a little silly. First of all, we're not talking about large loads or roughly treated items exposed to weather. Second, we're not talking about poorly drilled tapered holes with out of round dowels held in with hide glue.

If we look at modern applications under stress, I can give a personal example where I glued a 16' 2x6 to two 4x4 posts without any mechanical connections as a test using a common adhesive. It was outdoors (a trellis with plants on it) and exposed to all weather conditions. After 12 years it was still holding just fine. In boats people glue winches in - epoxy in a round hole - and it holds just fine. The loads in these situations are much higher than we're talking about, and it's only the glue, no mechanical connection... and now there are even cars that are glued together, no welding or mechanical connections.

I'd bet that with a moderately good adhesive I could glue end grain to face grain and have it hold under a moderate load. The concern about dowels is way overblown.

[george wilson]

Airliners are also glued together,though that makes me a little nervous!! At least 1 roof section did pop off!! They must be doing incredible things with adhesives,gluing planes that will see exceeding low temperatures at 30,000 feet,and scorching heat on the ground. And,they glue on space shuttle tiles,too! In space,even!!

[Tom McMahon]

George that's the point. If any one has great glue it would be NASA and they have to re glue tiles in space that means that the glue failed. I can't even believe that this has turned into a controversy. Part of Krenov's genious is that he did thing that should not work and made them work, it does not make it good common practice and to pretend it is does a disservice to beginners. .

[Jon van der Linden]

George that's the point. If any one has great glue it would be NASA and they have to re glue tiles in space that means that the glue failed. I can't even believe that this has turned into a controversy. Part of Krenov's genious is that he did thing that should not work and made them work, it does not make it good common practice and to pretend it is does a disservice to beginners. .

You are kidding right??? Because adhesives fail over time with a particular material under particular circumstances i.e. 17,000+ miles per hour on reentry, and parts over 2,300 degrees fahrenheit. Comparing that to a the stresses on a cabinet is exactly the kind of silliness I was talking about... for one thing, I'd be more worried about the wood surviving the 2,300+ degree temperature.

Krenov did not do things that "should not work." His methods are very sound. Compared to 18th c. French furniture, or methods employed for centuries in instrument making, his techniques are simple and rock solid.

[Frank Drew]

This idea that stuff won't hold together is getting a little silly. First of all, we're not talking about large loads ...

Krenov-style slightly scaled-up doll house furniture (essentially, your description) isn't the only furniture being built; we are, in fact, talking about large loads some of the time.

Jon, you're free to build furniture or cabinetry any way you want; I like to have mechanical strength in addition to any glue strength in the joints I use.

[Tom McMahon]

Jon, I must apologize again for not expressing myself clearly. The point I was trying to makes is that I don't believe there is a magic permanent glue that doesn't fail over time, due to the seasonal moisture cycle or stress. I base this belief on 40+ years of repairing furniture, it's what I do for a living, I have worked on 300 year old pieces and pieces still in the furniture store that were not sold yet. All glue has the ability to fail, it may not fail but it may, for this reason I believe one should use joinery that will hold a piece together. If the glue was as reliable as you imply you would not need the dowels.

[Jon van der Linden]

Jon, I must apologize again for not expressing myself clearly. The point I was trying to makes is that I don't believe there is a magic permanent glue that doesn't fail over time, due to the seasonal moisture cycle or stress. I base this belief on 40+ years of repairing furniture, it's what I do for a living, I have worked on 300 year old pieces and pieces still in the furniture store that were not sold yet. All glue has the ability to fail, it may not fail but it may, for this reason I believe one should use joinery that will hold a piece together. If the glue was as reliable as you imply you would not need the dowels.

Agreed. All glues fail, and the wood does too at some point, even with the best of care under near ideal conditions. Sounds like a guarantee for future employment for you! With modern adhesives the problem seems to be a lack of reliable information on what will happen with a specific product over time. Obviously the failure of a winch being ripped out of the deck by a 70' tall sail is going to be a little more problematic than a shelf coming loose, but even there there seems to be little data - maybe the boats get junked too fast for the glue to fail!

Since we know that everything fails the real question seems to be how long is long enough? I may have mentioned earlier in this thread how I saw the front of a Riesener desk being destroyed. It seems that at a certain point fate has a lot more to do with what happens to something rather than how well it's made.

The moisture cycle is an interesting problem. Some glues are rigid and some remain flexible (at least in the near term), I think this would have some effect on the success of a joint that has movement in it. The long term is still the big question.

I might do a test just for laughs with some scrap wood to test a glue only butt joint. Probably a few days away before I can get to it, but it will be fun to see what happens.

[Phil Thien]

I'm not sure when dowels became the joinery method of choice for doors and windows, but most millworks at one time, and not all that long ago, had single and double end tenoners and mortise machines (hollow chisel, chain, whatever). My first job in woodworking, in the early Seventies, was at an architectural millwork and virtually all the joinery we did was mortise and tenon.

If you look at this site:
http://www.emeralddoors.com/Front%20..._questions.htm

You'll see them comparing their door construction to what is pretty typical in the mass-production entry door model. The mass-produced doors do typically use a simple cope and stick joint that is reinforced with dowels.

Here is a site where they show the method for making windows:

http://www.dynamicwindows.com/?actio...Join_ID=132870

I haven't demolished a ton of doors, but the few I have ripped apart have been held together with dowels. And they (dowels) haven't given up easily, even after 50+ years of service in a hostile environment.

I think dowels in doors and sashes became pretty popular with the post WWII construction boom. There are many benefits to this type of construction.

[Dave Anderson NH]

Great discussion folks. On the subject of adhesives there are many applications in the transportation industry including trucks, buses, and aircraft where structural and trim components are both held by adhesives without any mechanical fastners involved. Examples of this incllude the body panels of Greyhound buses, Navistar stucks, and the stainless steel rub strips on the flaps of the Airbus 320. All use a special acrylic pressure sensetive adhesive for speed of assembly and cost reduction. A further and more important reason for the use on large parts like these is the ability of the adhesive modulus to absorb the size changes of the parts caused by wide variations of temperature. Other than the space shuttle, I can't think of a more unforgiving environment than an airliner sitting on the tarmac in Phoenix on a hot summer day when the surface temperaturee of the wing reaches 130+ degrees and then having the same plane 5- 10 minutes later at 30K feet where the air temp is -40F. Properly engineered, specificed , and applied adhesive have amazing properties. To absorb temperature and humidity variation the adhesive chosen must have a high flexural modulus.

[Kent A Bathurst]

........an airliner sitting on the tarmac in Phoenix on a hot summer day when the surface temperaturee of the wing reaches 130+ degrees and then having the same plane 5- 10 minutes later at 30K feet where the air temp is -40F. Properly engineered, specificed , and applied adhesive have amazing properties..........

I recall seiing - this goes back a ways - a video clip if the SR71 Blackbird. Still has the record as world's fastest aircraft > mach 3. If they sensed a missile fired at them, they just stepped on the gas and outran it. Ceiling at 80,000 feet.

Anyway - the point - the thermal expansion of the components was so great that they had to be very loose-fitting on the ground - like inches [?], and the plane just sat there and fuel ran out of it. Not a drip, but not a gusher either - somewhere like a moderate, steady leak. They'd launch, climb fast to heat up the skin, and then refuel mid-air. I thought those guys had to be over-the-top nuts to fly something like that. But, what do I know?

[Jon van der Linden]

Of course there's the argument that the adhesives used for airplanes and space vehicles are both unavailable and prohibitively expensive. Bringing this back down to earth... I glued up a test block with a common epoxy to simulate the load on the edge of a cabinet with 3/8" sides.

Test piece: red oak scraps, surfaces planed and cut over two years ago, surface prep was two passes with 60 grit sandpaper to clean off any dirt. Dimensions: 3/4" x 1" end grain. The gluing is a little sloppy and I didn't use clamps (hey, I was busy doing other things). The adhesive cures overnight, but I tested it after two hours (full cure in a week).

gluetestblock.jpggluetesthangning.jpg

You can see a volunteer hanging from the 3/4" x 1" block glued end grain. I was able to get both of us on there, but no one to photograph it. The point here is that with no connection other than the adhesive an end grain connection (with 3/8" sides) can easily hold over 150 lbs. I think that's more than enough for fine furniture. The adhesive forms a rigid glue line (no creep) but it is also flexible, so it's doubtful that any amount of wood movement will cause failure. In essence it proves that a dowel connection should not be a major concern, and if it is, there are ways to make up for it.

Regarding failure from aging, I have contacted several major manufacturers but none have any aging concern except when the product is exposed to UV. The product that I use happens to have a UV inhibitor in it. Anecdotally, I was informed that there were boats over 40 years old constructed with a glued lamination technique without problems.

[Phil Thien]

The commonly available hinges are 3/16" and 1/4". It's common practice for the hinge to be half the thickness of the door and you can see photos of this in Krenov's books, so his work is obviously not an exception. There would be no need to go to 3/16" hinges if the door wasn't well under 1/2".

Where are you seeing 3/16" and 1/4" wide knife hinges? The smallest I can find are 5/16":

https://www.brusso.com/Product/instr..._st_pivots.pdf

I don't believe you could use any knife hinge in 3/8" thick material. By the time you account for the depth of the hinge mortise (1/8"), and screw bite (1/4"), I think the minimum side top/bottom would be about 1/2".

What do you think?

Not trying to belabor the point, I'm actually curious how thin those cabinet components are.

Have you personally seen any Krenov (made by Krenov, not in the style) cabinets with knife hinges where the top/bottom/sides are 3/8?

I seem to remember seeing some units (pictures, not in person) where the top/bottom were thicker than the sides. Perhaps that is how he handled it.