Shelf pins for bookcase with long span/heavy load

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I'm building a bookcase with adjustable shelves with a 46" span that will likely carry some heavy books.
To cover the load, I am making the shelves 1.5" thick (double 3/4" plywood).
I now want to make sure that the shelf pin setup I am using is as strong as possible.
- Can I assume that all other things being equal, 1/4" pins will support a heavier load than 5mm pins (since the diameter is larger)?
- Will using a "sleeve" in the shelf pin hole add strength and prevent tearout from too heavy a load?
- Would adding a third parallel column of pins on each side support *materially* improve the strength?
- Any other suggestions to maximize strength of a shelf pin setup? (note: I would prefer not to add any intermediate supports)
- Finally, any feedback on the Rockler Shelving Jig? (it seems to do the job, comes with self-centering bits, and is affordable)
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blueman wrote:

Why don't you use the standard metal shelf support rails (the ones with slots that use metal V support clips) that are dadoed into the shelf sides sides?
Sure 1/4" will support a heavier load than 5mm. 1/4" is about 6.4 mm. But you are talking about shear strength. I can't imagine how much weight a shelf would need to shear off four 1/4" pins (dowels). Probably more than one could put on a shelf using 12" high books.
No, don't use any kind of sleeve. just make sure the pins are snug in holes that are accurately at right angles to the shelf side and are drilled to a depth of 1/2" and the pins extend about 1/4" from the surface.
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Can I ask why you don't recommend the use of sleeves George? I've always used sleeves, both for added strength and neatness of appearance.
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I personally don't like the rails because they are more obtrusive.

Sounds like I will be OK with the 1/4" pins (though I have some sets of books that as big as 14"x12"_
My question was not so much about breaking the pins (which I imagine would be hard to do) as about tearing out the hole. What I really wanted to know is whether the 1/4" pin system is significantly stronger than the 5mm system to justify the bigger and more obtrusive 1/4" holes.

Do the sleeves add no strength advantages then?
Thanks
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blueman wrote:

I have torn out the 1/4" holes in plywood sides, but solid wood should be more resistant. I don't know which you're using.
BTW, my shelves were only 30". I tore out the pins by bracing myself on the shelf to get up from kneeling. I'm guessing that was only about 50 pounds of pressure on the shelf, but it was localized to a handspan near the pin.
-- It's turtles, all the way down
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Hmmmm... that's not too encouraging. For the sides, I am also using double 3/4" plywood which is why I was enquiring about sleeves. My thinking being that sleeves would better distribute the force and prevent tearout.
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blueman wrote:

You should have said the sides would be plywood! Sleeves would have to be metal at least an inch long which would be a pita.
Forget the pins and move to a different system if you stay with plywood.
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Per your excellent suggestion in another post, I do plan to do a test.
However, how much would I gain in moving from say plywood sides to poplar sides? Would the resistance to pin tearout be significant enough to justify the significant premium for 1x12" poplar?
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blueman wrote:

I would also do the test with a small piece of good plywood. A 9 ply plywood ?might? survive you test
In my opinion you would gain a lot with solid wood. OTOH, I don't much like poplar. But.... depends on prices of different woods where you live. In choosing boards that are relatively clear and straight, the difference in prices of cheaper and more expensive woods is often slight. Where I live poplar is not much cheaper that much better woods. Again, though, in my opinion, it would be criminal to put paint on oak, maple, cherry, mahogany, etc, so poplar would probably be a good choice. Check the prices where you are at a real lumber store, you might be surprised at what you can get.
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More generally, what type of wood would you recommend for the sides that would give good shear strength for the pins at an affordable price? I assume that I only would need the hardwood for the hole tearout so that 3/4" stock would be sufficienct since I could get additional stiffness by backing up the hardwood with a parallel piece of plywood side.
I am going to be painting the wood so I just need a wood that takes paint well. Also, I assume that since I am painting, it still makes sense to use 1.5" of doubled up plywood for the shelves (with poplar facing) and for other elements other than the sides holding the pins and the face frames.
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blueman wrote:

Almost any solid wood would do since you are going to paint it. Stay away from the very softest woods such as western redwood and cedar which you wouldn't normally consider. I've used ponderosa pine with no problems and that is probably as soft as any available to you. Any hardwood, including softer varieties such as Philippine mahogany would be fine but if you paint you probably want a tight grain. Personally, I would use solid wood of 1.5" thickness for the shelves. An alternative is to face (back and front) a 3/4" thick board with 3/4" x 1.5" or 2" strips (wide measurement would be vertical). The latter would provide about as much stiffness at the former and would essentially hide the pins.
I'm not a fan of painting book shelves. Just be sure that you use a paint that hardens well and has a high blocking rating (low blocking would mean that books will stick to the shelf).
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blueman wrote:

I suggest you make a simple test shelf. The shelf only has to be 3-4 inches high. Use the same thickness of materials sides, pins, and shelf that you want to test. The construction can be very simple just two uprights braced and nailed so they won't spread out. Knock it together then have one person stand in the middle of the shelf (150-200 pounds), then try two people near each end (300-400 pounds). If the pins break you only fall 3-4 inches.
Please note that you want the shelves to fit between the uprights with as little extra space as possible, just enough so that you can move the shelves.
BTW, if you keep books on the shelves, you will never see those metal rails, and even if you don't they won't be obtrusive if you paint them the same color as the wood.
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Just did the test today. So far, I put my own weight (~200lbs) on the middle and then on each of the ends and did some light bouncing without any tearout. I will add more weight (i.e. more people) later.
I built the test stand with off-the-shelf Home Depot 3/4" birch plywood but expect to use higher quality stuff for the real bookcase.
Also, I was thinking that I could further reinforce the holes by "painting" the holes first with a low viscosity epoxy (the type that is used as a wood hardener) and then inserting the pins. This should hopefully have the dual effect of hardening the wood surrounding the hole and also anchoring the sleeve to the hole so that it spreads the transferred weight more broadly to the surrounding wood.
Does the above sound like a good idea?
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I haven't been following the bulk of this thread where you've indicated how much weight you're going to be putting on these shelves, but to be honest, what you're proposing sounds a little like overkill. If using pins with sleeves still sounds like it's going to fail on you, then you're not using a proper support system for the weight you have in mind.
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I would consider maybe more support on the back sides of the shelves. Maybe a small cleat placed a foot or so apart the length of the shelf. You could use a small profile on the cleat and it will not be noticed.
I also think 46" is really pushing the limits on a case width.
blueman wrote:

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That's pretty big span

Plywood is not the most deflection-resiting material as half of the plys are going the wrong way to help. Solid wood will perform better. If I were you I would try it out an see how much deflection wou get applying hand pressure to the center of a test-shelf.

I think that is a fair assumption

Yes it would resiste the tendency for the hole to deform

By 50%.... 3 pins carying the weigh previously carried by 2.

You may not need to take any of these measures. The pins are not going to sheer off. Try a test to see how much weight it takes to significantly deform a hole. Just mock up something with a single pin in the proposed material and put most of your weight on it. I bet it will hold up pretty well.
-Steve
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Well, I plugged my dimensions into the "Shelf Sag Calculator" (www.woodbin.com/calcs/sagulator.htm) using the following parameters: Species: Plywood, fir (only plywood choice) Weight Load: 200lb, uniform load Note: this seems generous given that per the note, they claim that a fully loaded bookshelf weighs 20-25lb/foot. Which for me would have given a maximum of 96lbs. Width: 46" Depth: 12" Thickness: 1.5"
The resulting maximum deflection was 0.06" which is about 1/16". Again, according to the notes, the eye can recognize a deflection of 1/32" per running foot, which would translate into 0.12" in my case of a 46" span, again well within my tolerances.
For comparison, a "standard" 36" wide Eastern White Pine bookcase with 8" depth shelves under a load of just 25lb/foot would give a deflection of 0.13" or more than TWICE as much as my design.
ALSO, I am going to be giving each shelf a front edge facing of 1.5x0.75" poplar which should add strength, I imagine.
Assuming that all my calculations above are correct, I am now most worried about shelf-pin tearout which is why I was thinking that the wider pin (1/4" vs. 5mm) and the sleeves might help
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"blueman"

I have found that 90% of the time, one a shelf is installed, people rarely move it. And if they do, its only a little bit to accommodate a taller object. With that, I would only have a few adjustment holes in the general area where the shelf is likely to be.
For very heavy load and thick shelves, I would use a 3/8" pin, set deep in the side. To hid the heavy pin, I use a forstner bit and drill a 3/8 hole in the side of the shelf and chisel out a notch in one side for installation and removal. This hides the pin completely when in place.
As for the larger holes in the case, I cut 3/8 plugs and insert them in the holes aligning the grain. If the ever need to be removed, I drill a small hole in the end, insert a screw and pull them out for use in the now exposed hole.
Dave
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blueman wrote:

Huh? If .06 is 1/16, 1/32 should be .03. - .12 would be 1/8 (actually .125=1/8).
--
It's turtles, all the way down

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Deflection is .06" over 46" while eye can recognize 1/32" per RUNNING FOOT, which would translate into about 0.12 (or 1/8") over the 46" length.
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