Ever since reading R. Bruce Hoadley's article (44 years ago), I have not been a fan of dowel joints.   In addition, there is no room for error when doing multiple joints in a piece.  They need to be spot on.  Compare that with biscuits or mortise and tenon where the mortise is a bit longer than the tenon. And after getting into the furniture repair business, I have re-glued dozens of chairs with dowel joints.  Once I get the corner blocks unscrewed, they almost always just pull apart by hand.  Last Tuesday, I was taking a bunch of dorm desks donated to the furniture bank and converting them to a mini-dresser / nightstand by disassembling and sawing off the kneehole section, leaving a stack of 3 drawers in a cabinet.   The ones I worked on then had a stretcher along the back about 10" off the floor.  All the other stretchers and drawer supports had dowel joints and came right off.  But that stretcher would not budge.  So I started to saw off the joint and hit metal.  Turns out there was one screw on the outside panel that had a wood plug to conceal it and another from the inside of the cabinet.  Result: The one screw was holding much better than all the other loose joints with two dowels glued in.   

 

I got a BeadLock jig that I have sometimes used as a dowel jig, but very rarely.  I have a few hundred 3/8" dowel pins that I bought to replace non-functional dowels on chair reglues.  They will be in my estate sale.

 

I see people doing "tests" of strengths of dowel joints.   In my opinion they are flawed for two reasons: they only test one type of stress.  There is compression, tension, racking, and shear stress.  They test one, usually racking.  Two, they are done shortly after assembly and not after several seasons of humidity change (ref: Hoadley) and not accumulated stress.

 

i guess the best thing you can say about dowel joints is they  have slow failure and not fast failure.  If you are sitting on a chair with dowel joints, it will get loose gradually and not just dump you on the floor unannounced.

 

https://www.finewoodworking.com/project-guides/joinery/the-dowel-joint

Agree completely with your conclusions, based on roughly similar (if thinner!) experiences over the years.

 

I see dowels as joints to be a poor substitute for a mortise and tenon and I think they are largely used because that is what large scale furniture manufacturers do.  Such furniture lasts a few years only, make a few decades if lightly and rarely used - but those joints always seem to come loose eventually.  Somewhere I have a high quality dowel jig that a more experienced guy gave me 30 years ago, and I've used it as little as he did over the years.

 

On the whole, I have mostly replaced doweling with glued and pocket screwed butt joints where an M-T is overkill (NOT in chairs for example, there an M-T is required).  The tension on the screw shaft keeps the butt joint tight and the glue helps prevent the wracking forces that will work the screws loose.  I still don't see it as a century joint, but it works better than dowels where it works.

Agree with you also. I have never been a fan of dowel joints. And like you most failures in furniture I've seen are those type joints.

The only good use for a dowel in a joint, IMO, is to pin a tenon.   Many year ago, early in my teaching career, I taught a beginning computer class.  1982ish. As there wasn't yet a big monitor or projector in every room like there is now, I had to lug a PC with a big monitor back and forth from my office to the lecture room.  Made a rolling gate legged table to support a swing up hinged top. had to keep the whole table narrow to fit through doors.  Casters big enough to roll easily over variations in the wood floor of the ancient building I taught in.  Mortise and tenon joints between every stretcher and vertical leg were then  pinned with a 1/4" dowel through one side.  At some point as technologies advanced the need to roll a PC/Monitor around went away, so I brought the table home.  Thought I'd take it apart to salvage the wood used.  I suppose I could have drilled out the dowels.  Couldn't just knock them through.  The tenons had been snug and no rack every developed in the table despite it's rolling life adventures.  Finally I just cut the stretchers from the legs to get it apart. 

4D  

Still seeing a lot of YouTube videos about "the amazing DowelMax jig." Mmuh

I just ordered a bunch of 5/32" dowels from an outfit in Maine. They were cheap.

Going to use them for alignment pins, that is one thing dowels do well. I suppose I could also use them for pinned tenons but I don't often pin tenons, or if I do I make a contrasting pin since it's being used for detail as much as anything.

This reminds me I should go look for that dowel jig I have. Betcha I could sell it on ebay and buy something useful with the dough!

7 hours ago, JWD said:

This reminds me I should go look for that dowel jig I have. Betcha I could sell it on ebay and buy some thing useful with the doughnuts!

Fixed it.😉

Edited February 6Feb 6 by Grandpadave52

34 minutes ago, Grandpadave52 said:

Fixed it.😉

I wonder how an ebay donut would taste?

Girlfriend was trying to convince me to do this next time I'm out that way:

The Takeout

This Sugary Boston Tour Gets You Deeper Into Donut Territ...

Explore Boston's rich donut scene on Underground Donut Tours where you'll sample classic, innovative, and historic treats on this 2-hour excursion.

But I already know where the best donuts are out there! Except one possibility in Salem we haven't tried yet. The top two so far are going to be hard to beat!

For years I've been a follower of woodgears.ca. Matthias Wandel is an engineer who does woodworking like myself and a few times I've even had a bit of email dialog with him. His stuff is very interesting.

He has a great post about "Wood joint strength testing" ref: https://share.google/vcspoa9yBRUygkYHA

He tests dowel joints against other types of joints. It's a good read.

Check out out.

On 7/17/2024 at 3:47 PM, kmealy said:

I see people doing "tests" of strengths of dowel joints.   In my opinion they are flawed for two reasons: they only test one type of stress.  There is compression, tension, racking, and shear stress.  They test one, usually racking.  Two, they are done shortly after assembly and not after several seasons of humidity change (ref: Hoadley) and not accumulated stress.

 

i guess the best thing you can say about dowel joints is they  have slow failure and not fast failure.  If you are sitting on a chair with dowel joints, it will get loose gradually and not just dump you on the floor unannounced.

 

https://www.finewoodworking.com/project-guides/joinery/the-dowel-joint

Yes true but for the most part the concern would be the shear value. Racking as you say which is actually "bending moment" would be very little concern. The woodworker should be concerned when and where dowels should be used and not get caught up in the ease of using them everywhere.

Agree 100% Keith, it bears repeating.

Most joints in practical use need to resist all failure modes, not just the one or two that some magazine test executes. The one time I broke a tenon it was in tension. It was not in regular use, but it was a finished and glued joint with terrible grain orientation (mesquite, terrible grain orientation goes with that territory). The point is that a builder needs to understand that joinery is never one dimensional. The magazine articles are written to sell magazines first, and educate second. Consequently, there are some things we learn by experience - such as dowels are alignment tools with some utility in a joint that needs to last a few years rather than decades.

1 hour ago, MrRick said:

Yes true but for the most part the concern would be the shear value. Racking as you say which is actually "bending moment" would be very little concern. The woodworker should be concerned when and where dowels should be used and not get caught up in the ease of using them everywhere.

Thinking about all the furniture I've had to repair, I would say racking was very common. Pedestal table legs, chair legs that people have leaned back on, table legs where the table was dragged across the floor, interior parts of upholstered furniture. Shear stress would come in in bed rails, ladder steps, shelves supporting heavy items, horizontal beams on upholstered pieces, etc. (looking around the room I'm sitting in)