Dowels vs mortise & tenon

[ted van halen]

I'm considering using 3/4" poplar dowel (2 per joint) on on the head & foot-board of my king size bed project. I was planning on M&T joints but don't have a good confidence level for them. Nor do I have a mortiser. I do feel a little more sure about a designing & building a jig for hole placement using the dowel. It's 4" wide stock so I think 2 per joint would be my limit. Thoughts?

[bigsteel15]

I'm considering using 3/4" poplar dowel (2 per joint) on on the head & foot-board of my king size bed project. I was planning on M&T joints but don't have a good confidence level for them. Nor do I have a mortiser. I do feel a little more sure about a designing & building a jig for hole placement using the dowel. It's 4" wide stock so I think 2 per joint would be my limit. Thoughts?

Check this out.
http://www.dowelmax.com/

It's a little pricey, but works great.
In the case of your project, you could place (9) 3/8" dowels with no problem and that gives you a lot more holding power than (2) 3/4" dowels.

You'll also find many other uses for it.


I'm a little biased, as I own one and it's Canadian made.

[drumpriest]

You may also want to consider mortise and loose tenon. If you have a plunge router, you can make this joint, it's 95% the strength of integral tenon.

[Tarheel]

I agree with Bigsteel15.

The DowelMax jig is one awesome piece of "machinery". I bought mine about 1.5 yrs ago and can give it nothing but praise! I use mine for every project calling for a M&T joint - just add a couple more dowels as he suggests in your case. Also, great for faceframe construction. I have a Kreg pocket hole jig, but most of the time I prefer using the DowelMax.

True. It was a little pricey initially, but I think that it was worth every penny!

Wayne

[btv]

I've wanted to try this beadlock. You put it in with a drill. It looks easy but i've never used one before.

http://www.rockler.com/product.cfm?page=5392

[rickd]

mark me down as a big dowelmax fan too. i bought one a couple of years ago, and yes it is a bit pricey, but in my opinion worth every penny. i use it for most joints that would normally be mortise and tenon unless it is a 'thru-tenon' obviously.

as for strenght, dowelmax claims their doweling system is every bit as strong, maybe even stronger, than conventional mortise and tenon joints.

[drumpriest]

I have the beadlock. I find that it's easier/cheaper/better to setup my plunge router for loose Mortise and Tenon if I'm going to be cutting a bunch of joints. If I'm only doing 1 or 2, I grab the beadlock. Thing is, usually it's more like 16 or 32 mortises, depending upon the project.

The beadlock is also excellent for repair, as the drill is 3/8" or 1/2". If you have a 1/4" tenon fail, you can drill out the mortise with the 3/8" bit for the 3/8" tenon, and it'll work, and be stronger.

As to this project, I think it'll depend upon how wide your slats will be. If they are wide enough for biscuits, that might work also. Double dowel certainly does a good job also.

I would somehow doubt that a double dowel joint would be as strong as a true mortise and tenon joint. But I have no evidence either way.

[rickd]

I would somehow doubt that a double dowel joint would be as strong as a true mortise and tenon joint. But I have no evidence either way.

hi,

i'm not so sure about a 'double' dowel joint either(i presume he means 2 dowels per joint) in a strength comparison to mortise and tenon. however, dowelmax did hire an engineering firm to test their dowel joints vs mortise and tenon. here is a link to the test and the method used:

http://www.dowelmax.com/test_results.htm

the quick story is that under hydraulic pressure each joint finally failed at 275 psi and the engineering firm determined that the joints were equal in strength. it should be noted that the dowelmax joints used 5 x 3/8" dowels making the joint 3 1/2" by 3/4" - the exact same as the mortise and tenon.

so, that still doesn't answer the question about the 'double' dowel joint, but i agree, using just 2 dowels per joint, i doubt it would be as strong as a mortise and tenon. i use the dowelmax system all the time but i usually use as many dowels as the joint size will allow.

[gsmittle]

I used the Beadlock system to make a drafting table last summer, and I had a devil of a time getting the tenon to fit in the holes. I'm wondering if my 3/8" bit is a hair undersized. I ended up having to sand the tenon until it fit. A frustrating experience!

I do like the idea, though. When I get some time, I'll try it again....

g.

[drumpriest]

One beadlock suggestion is to make sure that you keep evacuating the jig of sawdust by plunging the drill in and out. You will get cleaner cuts that way. The first couple that I did were not as good as they are at this point, but I still use it only occasionally. If I have 16-32 mortises, a spiral upcut bit and a plunge router are just faster.

About the dowels, yeah if you do enough dowels to have similar glue surface, that makes sense that they'd be as strong. 2 dowels for alignment would be my minimum for use, and just about any jig will handle that.

[JimD]

I looked at the dowel joint test. I think it is misleading. I do not make joints to stretch the length of boards. That is essentially what was tested. In addition, the test was to the shear strength of the joints. Big deal. If you make end to end joints in boards like this maybe it tells you something. I do not make these kind of joints. If they has tried to pull the two pieces apart along their length, if the mortise and tenons were cut properly they would be much stronger.

Either Fine Woodworkding or Fine Homebuilding (I do not remember which) tested doors like you have in your home made with dowels, mortise and tenon, and biscuits. Dowels were the weakest and it was not close. Mortise and tenon were the strongest but biscuits were surprisingly close. For something easy to make, use biscuits. If you do not need much strength, dowels are OK. I have a jig but never use it since I got a biscuit jointer and, more recently, a dedicated mortiser.

The problem with dowels is you do not get much long grain to long grain contact. That is what makes for a strong joint. If you cannot cut good mortise and tenon joints (or do not want to) but need strength, use biscuits. I think biscuits are the easiest to use and also significantly superior to dowels.

Jim

[ted van halen]

I may need to clarify a bit. The dowels will be for assembling the head-footboard rails to the corner posts. Don't know if it's relevant or not.

[rickd]

I may need to clarify a bit. The dowels will be for assembling the head-footboard rails to the corner posts. Don't know if it's relevant or not.

hi ted,

i've used dowels(using the dowelmax) in the same type situation you are describing and would do so again. i would just recommend using as many dowels as the length of the joint will allow, that's the nice thing about the dowelmax jig - perfect joints without having to measure.

as far as jim d.'s comments about dowels and strength vs mortise and tenon, i would simply like to say that i found the strength tests done to be pretty persuasive and the engineering firms conclusion that the joints were equal in strength to be supported by the facts outlined. i haven't seen any other facts to contradict or dispute their conclusions.

[Russianwolf]

another alternative that I enjoy is Miller Dowels. www.millerdowel.com Nothing complicated at all. glue joint, drill hole, drive dowel. I've made a couple footstools and they don't have any problems under my heavy load.

[drumpriest]

Honestly, unless someone is going to sit on the rail, you'll probably be ok with any of these joint techniques. Dowels, use a bunch. Biscuits, double them if you can, they get crazy strong. Mortise and tenon, easiest is loose tenons, and is crazy strong also.

Biscuits require - a biscuit cutter (dedicated joiner or router setup for it)
Dowels require - a drill
Mortise and Loose Tenon require - a plunge router, and a plunge bit. (spiral carbide recommended).
Mortise and Integral Tenon require - don't get me started, too many ways to cut them.