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Holding power of pocket hole joinery

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Forum topic by jstewart posted 2177 days ago 9937 views 0 times favorited 12 replies Add to Favorites Watch
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jstewart

141 posts in 2689 days


2177 days ago

Topic tags/keywords: pocket hole

I’m planning on doing a project that will involve using pocket hole joinery to connect a sheet of 3/4 Oak plywood to 1×4 Oak boards at the four corners of the sheet. In other words, the plywood shelf will be held up by 8 pocket hole screws, two at each corner. Does anybody have any guess as to how much weight a joint like that could hold? I plan to place a TiVo and an Xbox 360 on this shelf. I think I might cry if I lost these two pieces of equipment because I screwed something up (no pun intended). I know they that have a combined weight of under 30 pounds. I would like the joint to be capable of holding 60, just to give it PLENTY of extra strength. (I plan on also using some wood glue in those joints before setting the screws, in case that matters.)

-- Joshua, Olathe, Kansas


12 replies so far

View Randy Sharp's profile

Randy Sharp

348 posts in 2271 days


#1 posted 2177 days ago

Joshua,

Pocket hole joinery should work just fine. You won’t have a problem with that amount of weight. Use glue and follow this rule: Screwing into solid oak, use fine-thread screws. Screwing into plywood, use course-thread screws.

-- Randy, Tupelo, MS ~ A man who honors his wife will have children who honor their father.

View Zuki's profile

Zuki

1404 posts in 2675 days


#2 posted 2177 days ago

Pocket screw joinery is quite strong. I use it in just about every one of my projects, however i do not use glue. Randy is correct . . . fine screws for hardwood and course for softwood.

-- BLOG - http://www.colorfulcanary.com/search/label/Zuki

View SawDustnSplinters's profile

SawDustnSplinters

321 posts in 2379 days


#3 posted 2177 days ago

I second all of the above….would not use anything else..

-- Frank, Dallas,TX , http://www.allthingsrustix.com , “I have a REALLY BIG chainsaw”

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JimJ

16 posts in 2196 days


#4 posted 2177 days ago

I also use and love pocket screws. There was an article in Wood magazine or American Woodworker (the 2 mags I take) within the last few years that had an article on testing a variety of joints including glued mortise and tenon, dowels, pocket screws and maybe a couple of more types. They did destructive testing (loaded to the point of failure), including sheer forces (like weight on aprons on a table). As best I can remember, pocket screws were right behind mortise and tenon joinery. Very strong.

I read this before I had ever made a mortise/tenon and was immediately sold on pocket screws. I haven’t used a dowel since then, nor have I made a mortise/tenon.

The article is worth finding if you can. I look around and see if I can find it and post here the mag, date and page published.

Jim

-- JimJ - Oakton, VA

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Ads

15 posts in 2237 days


#5 posted 2177 days ago

Pocket screws can be very strong. I’ve built a few things using them and the most important thing seems to be to make sure to have a very strong positive connection between the pieces you are joining. The more play you get, the more likely the joint will come out. i found copious clamping to to help a lot.

View Douglas Bordner's profile

Douglas Bordner

3960 posts in 2662 days


#6 posted 2177 days ago

If your planning on using edge banding, you might consider using a wider than 3/4 strip of solid lumber glued face grain to the plywood edge to insure against sag. You can even pocket hole it on, screwed in on the shelf bottom. Pocket Holes work great.

-- "Bordnerizing" perfectly good lumber for over a decade.

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edp

109 posts in 2559 days


#7 posted 2176 days ago

I use a boat load of pocket hole screws in my work. I don’t however, rely solely on the screws to maintain the joint. I think of the screws as disposable clamps. I really wouldn’t trust an unglued joint.

Ed

-- Come on in, the beer is cold and the wood is dry. www.crookedlittletree.com

View kolwdwrkr's profile

kolwdwrkr

2821 posts in 2188 days


#8 posted 2176 days ago

Pocket screws are an efficient joint, but if it’s exposed it’s pretty ugly. You should always glue your joints unless you want to take it apart at a later date. You could edge band the plywood and pocket screw the hardwood to the plywood so the seam is on the side not the top. This way the weight rests on the hardwood not on the joint. Then you can do cart wheels on it and it won’t break. Not that it would anyways. Does that make sense?

-- ~ Inspiring those who inspire me ~

View Slacker's profile

Slacker

178 posts in 2299 days


#9 posted 2176 days ago

Be aware of sag… I think that 3/4 ply will not sag at 32” long. There’s a web site to help you calculate sag (the sagulator).

-- Adapt, improvise, overcome

View snowdog's profile

snowdog

1132 posts in 2581 days


#10 posted 2176 days ago

I just bought the kit
http://www.woodcraft.com/family.aspx?familyid=5374

Never used it before but it looked like a pretty good idea and if Norm uses it then it must at least be fast and solid.

Now I have to find a few vids on best practices for use.

-- "so much to learn and so little time"..

View Kipster's profile

Kipster

1076 posts in 2351 days


#11 posted 2176 days ago

Thanks for all the info everybody. I won’t hesitate to use pocket hole joinery from now on.

-- Kip Northern Illinois ( If you don't know where your goin any road will take you there) George Harrison

View mhawkins2's profile

mhawkins2

51 posts in 2166 days


#12 posted 2165 days ago

I used pocket hole screws to build a frameless cabinet out of 3/4” birch plywood (including the back) it currently holds a little less than 200 lbs worth of electronics and such. I use screws and glue. I also have a shorter cabinet that is to hold 300 lbs. In both designs I have at least 3 pieces of 3/4” thick vertical supports to distribute the load plus a 3/4” back. I tested each piece before putting the electronics on them with the very scientific method of having myself and friend hop on them. With the 3/4 back them seem exceptionally strong with no sign of racking with a load of over 400 lbs. There is no design that can’t be over designed :).

I find them very strong when spaced 6” to 8” apart as the manual recommends. The manual has lots of good information in it. As long as you either plan to hide the holes or spend the time to lay them out and fill them in an attractive manner they should work great.

-- mhawkins2 - why does my wife keep parking her car in my shop :)?

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