Pocket vs. M&T

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Pocket screw setups look much easier than mortise & tennon and, apparently, are just as strong. Unless a through tennon extending beyond the rail is required for structural or decorative reasons, are the two systems actually interchangable?
FoggyTown
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foggytown Feb 18, 6:38 am show options
Date: 18 Feb 2005 06:38:12 -0800
Pocket screw setups look much easier than mortise & tennon and, apparently, are just as strong. Unless a through tennon extending beyond the rail is required for structural or decorative reasons, are the two systems actually interchangable?"
No. Pocket holes work extremely well in some instances, such as face frames, but are close to dead worthless in others. For example, I'd never use pocket holes to attach legs to a table apron when that table is going to get any heavy use. For headboards and footboards of beds, M&T is much more secure. I like pocket holes for face frames, but don't use them for much else.
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Short answer: No.
My gut says that M&T will be considerably stronger, but PH is plenty strong enough for all but the very most demanding applications.
IMHO pocket holes look like sh*t.
If you aesthetics matter *and* the joint shows, skit PH and use M&T
Otherwise PH is fast and effective.
Exception: IMHO, PH does not belong in heirloom quality construction, because "style" counts even where you can't see it.
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On Fri, 18 Feb 2005 10:12:46 -0500, "Stephen M"

that's a little too broad a statement. get underneath some really nice 100 year old furniture and you'll see pocket screws holding cleats and the like in place.
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Point well made. Hoever, the pocket holes used in quality antiques were made with big-ole honk'n screws with 1/4" shanks on them. Although it is a screw in a pocket, they are nothing like the "the kreg system".
Which, BTW, is not a slam at the Kreg system, I think mine is great, it's just like comparing a Honda Civic (had one of those and loved it too) to a Hummer.
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Yes, I'd say something that's well made and efficient, compared to something that's oversized and unnecessary, is a valid comparison ;)
Love my Kreg jig too, but there's times for doing it other ways.
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Dave Hinz wrote:

great, it's

too) to a

Reminds me of my favorite news group signature
"Get rid of the Range Rover. You are not responsible for patrolling Australia's Dingo Barrier Fence, nor do you work the Savannah, capturing and tagging wildebeests." --Michael J. Nelson
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Don't laugh, but I actually live near a school where a guy teaches off-road driving to dentists, Wall Street suits, etc... in Range Rovers.
Rover provides vehicles to the school. The guy has been featured in several magazines and makes an excellent buck doing it. I see it as no different than the Richard Petty Experience for Outback wannabees. <G>
The school is in East Haddam, CT.
Barry
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On Fri, 18 Feb 2005 14:23:56 -0500, "Stephen M"

not meaning to be in a flame war or to be too picky about language or whatever, but I guess that:

should have been:
***Exception: IMHO, Kreg screws do not belong in heirloom quality construction, ***because "style" counts even where you can't see it.
I think we are really in agreement.
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snipped-for-privacy@all.costs wrote:

Yes, they do.
Barry
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I love pocket screws and use them where ever I can.
But don't forget they are a mechanical fastener. If you aren't able to get several in over a reasonable length, anything subjected to torque will gradually move more and more, until you have failure. I have used them where there was room only for one screw, but only when no torque was possible; like a divider in a very rigid frame.
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As opposed to M&T that is non mechanical?
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Just for emphasis, I agree completely with Charlie and toller. Pocket holes aren't as strong, durable, or attractive as mortise and tenon joints.
foggytown wrote:

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"foggytown" wrote in message

For the *right* application, PH joinery can be hard to beat. However, and for my way of working and what I make, that "right" application is almost exclusively limited to face frame construction.
--
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Last update: 11/06/04
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Swingman wrote:

For me, add shop jig construction to the face frame work. I've also started to use pocket holes more than biscuits for finish (trim) work.
Furniture gets more traditional joinery.
Barry
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Well... PH's are not as strong as M&T, I agree they are ugly and they are not a good replacement for all M&T but my experience says they are not as bad as some portray.
Look at http://www.sonomaproducts.com/Furniture/JL-ET-RO.htm
It uses pocket screw joints for all the upper aprons, pockets under the shelf and one screw up at an angle from under the lower spreaders arch up into each leg. Combined with dowles in the pickets and the top attached with table buttons this unit forms one hell of a strong frame.
I have proof of this, one that I shipped was destroyed by a FedEx Ground contractor. It was eventually returned with fork lift tire marks on the box. The top was broken from the unit, two pickets were completly dislodged and the frame was still solid and stands on all four legs as flat as when I shipped it. I intend to repair it someday.
Would M&T be stronger? Yes. In fact I plan on building a set of this line for my home and I'll be using M&T, but pocket screws can save time and provide a strong joint.
I also use them occasionally on solid wood case work, table legs-to-aprons (with added transvers braces), etc. and have not had any problems. On occasion I'll add longer screws if using a soft wood or landing in an over-running panel dado.
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no.
pocket screws leave butt ugly holes. fine for hidden locations and rough and ready shop furniture.
pocket screws are strong in one direction, weak in the other. M&T are strong both ways.
there is really very little overlap in application.
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Pocket screw joints are strong but I would not use them for everything. The primary advantage of pocket screw joinery is speed of construction. Personally, I would not use pocket screws in fine furniture and find the oval holes plain ugly. A mortise and tenon joint is load bearing, handles compression well, resists tension and racking, and still holds up well after years of abuse. A M&T joint usually gives a warning before failure, unlike most other joints. I don't have any studies showing the pocket screw is just as good as the M&T, but I'd be interested in learning more about this. Many woodworkers shy away from metal fasteners, only using them as a last resort.
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I guess at the end of the day a pocket hole joint is nothing more than a reinforced butt joint and, if well done, shouldn't look any different to an M&T. The strength of the joint is another matter and I'm not competent to comment on that. Any structural engineers in here? :)
FoggyTown
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----------------- I have a Trend PH jig and use it quite a bit. It's quick and easy but not suitable for everything. So, when a MT is required I use another gizmo: BeadLock. It is a loose tenon gizmo that lets you make perfect fitting and very strong MT joints with minimal skill and just an electric drill and clamp. Like the PH it meets all the requirements, as in quick and easy. If you've got both options you're pretty much covered.
Check it out: http://www.beadlock.com/
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