Pegging woodworking joinery

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Used frame and panel approach to making a large outside gate using cedar. Has three "rails" (top/mid are 2x4 with bottom 2X6) and two "stiles" (left and right sides 2x6). Top and bottom joints are half- laps with "mid" cross piece using M&T. All glued with outside wood glue. (Yes, I know now I should have used M&T on all joints)
Because I want to put off sagging as much as possible, I want to peg all the joints. A couple of questions: a) what is general guideline to placement of pegs? b) for this dimension of lumber, how big should the pegs be? c) anything gained by using galvanized fasterns instead? If so, what are suggestions as to suppliers who can provide am Asian type look?
Chris
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"cc" wrote:

---------------------------------------
SFWIW, I like 1/2"-5/8" Dia pegs, maybe even 3/4", two (2 pegs)/connection minimum.
I'd use S/S not galvanized, if desired, but pegs should sufice.
Have fun.
Lew
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A pegged *diagonal* will do more to prevent sagging than any combination of fasteners on a purely right-angle design. You might want to add a diagonal turnbuckle brace right now... you'll need it soon enough.
Scott
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cc wrote:

Frankly, I don't think pegs would help prevent sagging. A diagonal, yes; pegs, no. If the lumber, joints and glue were decent, the joints are going to stay good. Just keep them painted.
However, if you just gotta do it, these are the choices...
1. Treenails ("trunnels"). These are best whittled from black locust but can be made from whatever. They are really good for securing a plank to another fixed piece of wood (one that doesn't move). Whittled because they need to be irregular so the irregularities will deform the wood into which they are being driven thus pulling them together.
2. Dowels. Those would hold the pieces laterally but if the joints are good they aren't needed. With both dowels and treenails you are getting exposed end grain, paint will always crack over them.
3. Screws. A couple of heavy - #12?, #14? - screws in the joints will hold them laterally and together. Lag screws could look good, paint the heads a contrasting color. Like black.
4. Rivets. Do the same as screws but look cool. I've riveted lots of stuff together using brass rod. Copper or bronze is good too. One drills the hole, counter sinks it on both sides slightly and shallowly then peens both sides over to form heads. It takes some practice to cut the rod long enough - but not too long - to make the head. The side opposite the one being peened needs to be supported; a steel block with an oversized hole the depth of the rod extending on that side can be clamped over it to keep the rod from being driven out while you peen the opposite end. Hole needs to be oversized because the rod will expand on that side too and you have to be able to get the bucking block off.
For placement, stay away from the ends and edges by 3/4" or so and don't put them "in line" which could encourage splitting. For example, on the center rail, put one at the top left corner, other bottom right corner, both 3/4" or more from any edge.
Size depends on what you use; wood needs to be bigger than steel. Just for appearance, I agree with whoever said 1/2 - 5/8.
Galvanized - hot dipped galvanized - is better than plain steel. I have no idea what you mean by "an Asian look".
--

dadiOH
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Sounds like a cool project.
I think pegging could help with longevity and you should put two pegs diagonaly on each lap joint. Assuming the lap area is square just think of it as divide it into three sections iwith like a tic tac toe hatch and place the pegs at two opposing corners where the lines cross. One peg would suffice at the mid.
However, since the crucial joints are lap joints and pegs are really best for M&T, the laps have a possibilty of peeling apart so I would use through fasteners in the same pattern. For a good asian look, find square head black hand beaten bolts. I had a source for those. I'll do a goggle and see if I can post a link.
Also, I woild oil the gate with Penofin clear or similar to keep that beautiful Cedar look. Give it a week or two to start to sunburn and red up a bit then oil it before it starts to fade.
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. I had a source for those. I'll do

Something like this http://www.vandykes.com/product/203930/square-head-screws
Or this http://www.blacksmithsdepot.com/Templates/cart_templates/cart-detail.php?theLocation=/Resources/Products/hardware/lag_bolt_black
But I would prefer a through bolt with a square nut to reallyhold the laps together. If you used lags, then maybe two on each side of the lap at opposing conners so you had 4 total.
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On 6/15/2010 11:14 PM, cc wrote:

FWIW, your choice of a half lap joint for a gate will more than likely prove unsatisfactory over time.
ALL lap joints, being one of the weakest joints, will benefit from mechanical fasteners of some type ... pins, nails, etc.
If it were my gate I would think seriously about a couple of carriage bolts at each joint ... if you want to get creative you should be able to find some wrought iron or decorative 'corner brackets' for opposing sides of each joint that will kill two birds with one stone ... "pins", in the form of bolts, through the joint; and some much needed extra reinforcement against the inevitable racking forces inherent in gate components.
YMMV ...
--
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Last update: 4/15/2010
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I didn't know that. I actually thought they got a good test review in some ww'ing mag lately. Probably highly dependent on how well the gluing surfaces mate and what adhesive you use.
JP
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Jay Pique wrote:

Here are some tests; unfortunately, they don't include lap joints. My opinion is that lap joints are very strong against pulling forces, less so against shearing ones (but still not terrible).

http://www.youtube.com/watch?v=DhLfb7m9Fug

--

dadiOH
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Nice!
The shear tests were done very unscientifically. It was more like a random torsion test. Nothing was constant. The wood materials were not constant, the joint styles were not constant and the distance from the joint were not constant. Poorly done, for any comparison. The idea was good though and you get the idea.
The pulling tests were quite good, with most untested quantities fairly constant on those ones.
Thanx
Here are some tests; unfortunately, they don't include lap joints. My opinion is that lap joints are very strong against pulling forces, less so against shearing ones (but still not terrible).

http://www.youtube.com/watch?v=DhLfb7m9Fug

--

dadiOH



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They can be OK, so long as you do something with the fasteners. If you attach a big steel plate to one side, spanning both parts of the joint, you can convert the wooden half-lap into something that's more like a bridle joint. This will work a lot better and more long-lasting than the simple half-lap.
I'd attach this with bolts, probably coach bolts (round pan head with a square beneath) from the timber side and nutted down onto the steel plate.
I wouldn't use wooden pegs unless it's M&T or bridle joints. Wooden pegs are good in shear, but not good for bending, as their holes will work bell-mouthed. So any load on them needs to be a symmetrical pure- shear load, not an asymmetrical load from a half-lap that tends to tilt them. Bolts don't enjoy this much either, but at least bolts can be tightened for some axial compression, pegs can't.
If you are using pegs, buy or make a dowel plate. If it's big pegs in oak, make this a good dowel plate with a range of hole sizes, and star- shaped holes to help bring the pegs down to size. Although you can rough whittle, a plate is faster and more accurate for final sizing.
Most of the time I'd recommend bridle joints (two sides, but no top) for a simple gate rather than M&T. They're a lot easier to cut, as you can saw them from the end without needing to work down a mortice, and they're nearly as good as the M&T.
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wrote the following:

Here ya go: http://fwd4.me/T8h
Since cedar isn't strong enough to handle pegs for a LARGE gate, you'll have to use an anti-sag kit. I swear by 'em. If you don't like zinc, smear some RBS on 'em.
--
Impeach 'em ALL!
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RBS?
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wrote the following:

Reddish Brown Shit, aka "stain" that some folks around here like to put on perfectly good wood.
------------------------------------------- Stain and Poly are their own punishment
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I have built dozens of gates and have found that they typically don't hold up regardless of how you build them. Wood shrinks and cedar does especially. When it shrinks the gate loosens and sags.
Solution,, A gate kit that has steel right angle brackets that hold every thing square no matter how much the wood shrinks. Having built 8~10 gates with this kit I have yet to have a gate sag.
http://www.rockler.com/product.cfm?page 584
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BTY, DO NOT use the screws that come with this kit, use your own quality square drive screws.
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"Robertson" head screws typically fit the bits properly.

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??
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To clarify, when the US released "square head screws" the standards were not followed and the heads broke off, or did not fit properly in the square head drivers, and stripped from slipping off the drive bit.
Robertson, was a defined and patented standard using colour coded sizes. These problems did not exist until "square drive" and "square head" arrived on the scene and violated the standards set up, accepted and used for years.
Stick with Phillips, slotted or follow the standards already followed elsewhere. Quality has been compromised.

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I am still confused? What point are you trying to make?
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