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wood joint strength test

#558 by bashfulbob » Tue Oct 03, 2006 2:26 pm

Hi
Well in this issue of WOOD (November issue 173) there is an article titled Wood Joint Torture test. In short they put several joints to a destruction test both in shear and pull apart forces.

The bottom 3 finishers were, in order of weaker to stronger, Unreinforced Butt Joint, Butt Joint with a # 0 Biscuit and Butt Joint with 2 pocket Hole Screws. :eek: Then after that came 5 different sizes of Mortise and Tenion Joints using 3 inch stock.:rolleyes:

You might want to visit woodmagazine.com/jointtest for a video of some of the tests.

You all have a good day you hear.

---

Life is what happens in between Plans.:)

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Face Frames Joinery

#574 by Unregistered » Thu Oct 05, 2006 11:02 pm

No doubt WOOD MAGAZINES test is accurate and I'm not a fan of pocket screw joinery.

However, I'm building kitchen cabinets from scratch with my SS, a router and a circular saw - and pocket screw joinery in a face frame works! After all there's no stress on the frame, it's cosmetic feature. I was able to assemble an 84" face frame with 9 drawer caveties, in a couple hours. (I've never done a kitchen before) If I'd been making mortice and tenon joints (like I'll use on the doors) gluing and clamping, I'd be days doing it.

The purist in me always wants the mortice and tenons and the realist says we better get on with this or I'll never have time to enjoy the kitchen.

I guess what I'm saying is there is more to joinery than strength. Berry in St. Paul

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#575 by Bruce » Fri Oct 06, 2006 10:30 am

I guess what I'm saying is there is more to joinery than strength.


Gee, you'd think from your statement that pocket holes are no stronger than mitered corners. I know that they are biased, but Kreg says an independent lab tested shear strength and found the pocket hole joint to be stronger than M&T. I'm just getting started with PH joinery, but so far it meets my needs in the applications it's designed for, as long as they are not visible. A M&T is a better way to go in visible applications.

Bruce

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M & T made easy

#584 by Greenvilleguy » Tue Oct 10, 2006 11:15 am

I use all three; biscuits, pocket screws and Mortise and Tendon joints depending on the application. Just to throw in another ringer, I use contrasting colored splines on mitered joints like picture frames, athough I'll be the first to admit that sometimes it's just showing off! My answer to the age old question of which is better is "It depends". Biscuits are great for joining cabinet sides, pocket screws are great for face frames and M&T are the only choice when there will be side to side pressure such as on a table or chair.

Occasionally, I find something new in woodworking that makes me say, Wow, I'll never do it the old way again. A few months ago, I bought the SS tendon jig and the SS mortise attachment on one of their email specials. I just finished a copy of an antique table my wife liked. The table has four spindle turned legs only connected at the aprons and drawer rails. Obviously, only M & T would do, so I pulled out my new "toys". Wow! I'll never go back to hand chopping mortises again and the tendon jig allowed me to cut perfect fitting tendons with only minor hand work. I was able to complete all of the M & T work including the double tendons on the drawer rails in a couple of hours.

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#588 by Bruce » Tue Oct 10, 2006 12:30 pm

That's good to know. I have not attempted any project using mortise and tenon yet, but hope to soon. Have you used a standalone mortiser before? What is the setup time for the SS mortiser?

Bruce

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Setup time for SS mortiser

#591 by Greenvilleguy » Tue Oct 10, 2006 6:46 pm

No, I've never used a standalone mortiser. The setup time for the SS mortiser is not too bad once you have the SS in the drill press positiion. The SS mortiser attaches to the SS like the saw guard. It does require a non standard allen wrench. The standard drill chuck goes inside the attachment. On the 520, the holddown attached to the standard fence via a T-nut.

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#599 by Unregistered » Wed Oct 11, 2006 4:49 pm

I read the article and was not too impressed. I remember reading in an old old book, written by a socalled expert of his day, that dowels were never designed to hold anything together and should only be used to align the boards. When you think about it does make sense.

One thing which was not mentioned in the article, is that sometimes you need a weak joint to act as a sacrifice. A butt joint is easier to repair than one where the wood has been destroyed. For that reason I will use a "blind" 1/2 lap on many projects.

Sorry for the ramblin

Joe Mohnike

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