Secret Bookcase how to question

[Mark Gibney]

I'm designing a secret bookcase that will be about 34" wide x 80" tall, the shelving will be between 8" and 12" deep - the client hasn't made this final decision yet.

I'm going to use pivoting hardware (as opposed to hinges) to allow this to open. I'm thinking of using 6/4 cherry, so the case sides will likely be about 1 1/4" thick. One shelf will be fixed in place so it can be pulled to swing the bookcase open, the others will be moveable (unless this is a bad idea and they all need to be fixed in place to add rigidity).

My main concern and question is about the strength of the bottom case member (rail?) that takes the weight of the whole bookcase on the pivot - how do I make sure it doesn't deflect under the strain? Do I need to make a steel brace to span underneath the bookcase and catch the stiles?

If I don't need the brace is 1 1/4" cherry strong enough, or should I look at starting out with 10/4? I could also suggest using plywood (cherry veneered show face with BB multiply layers to get to the desired thickness?) if that would be structurally better, but this client loves real wood.

My other concern is that this hardware is designed for doors, and doors are trimmed to fit the framed opening, unless they are metal of course. I will have very little room to trim the bookcase sides, and I'm wondering if any of the pivot hardware out there has any adjustability built into it?

If anyone has any experience working with this kind of thing and has any pointers for me I'd very much appreciate anything you can tell me.

I also figured I can hold of on tying the framing to the house studs until the bookcase is installed and this will allow me to manipulate the gap to where i want it (the framing that takes the top pivot will need to be secure from the get go).

[Rick Lizek]

This has been covered several times on the pro-forums on the www.woodweb.com

[Mark Bolton]

http://www.thisiscarpentry.com/2012/05/11/hidden-pivot-bookcase-katz/

[Walter Plummer]

These guys may be good for some ideas. You can download the instructions in PDF. https://www.cshardware.com/hidden-door/invisidoor.html

[Mark Gibney]

Thanks all. I had read the Katz piece. However it doesn't address my concern about the weight of the bookcase causing deflection at the pivot point, and whether or not there is any adjustability in the hardware to compensate for the fact it's not a door and can't be trimmed.

I'll look into the woodweb and hardware links.

[Dan Rude]

Wood magazine, just ran an article about this a few months back. WOOD Issue 236, November 2015. They addressed some of the issues you have. Dan

[John T Barker]

I think I'm understanding your concern and I'm wondering if fixing some hidden wheels to the base might help with carrying the load. If you have any trim on the base this could very easily hide wheels.

Adjustable shelves were common in the bookcases I sold in my retail furniture days. Most manufacturers I saw used veneered plywood for these and a fixed shelf seemed an industry standard of 30" high.

[Mark Gibney]

John, I was going the hidden wheel route, but then figured it might leave a visible track on the flooring. And great to know about the height of the fixed shelf, I had settled on 32" so I was in the ballpark.

Dan, thanks, I'll look up that Wood magazine issue this weekend.

[Mark Henshaw]

Mark,
I have built several of these using 3/4" veneered plywood with 2 1/2" face frames. I used fixed shelves that are glued and screwed into the sides and the 3/4" plywood back. I used home made pivots from 3/4" bolts and bronze bushings. Some have been in used for over 10 years and have not sagged or moved more then a few thousands of an inch. They probably support 75 pounds of books. The bookcases are very difficult to identify as a secret door unless you really are looking close. I have tried to make earlier versions with a wheel and have found that they will always leave a telltale mark on the floor or carpet. I can try and make a short video of the door opening and closing for you if you would like.

Mark Henshaw

[Mark Gibney]

Thanks Mark, I'd like to see any kind of video you can take.

And good to hear you've had no sagging, very reassuring.

[Sam Murdoch]

I have built and installed several of this using the Rixson Pivots. A 3/4" solid wood bottom laminated to a piece of 3/4 ply would be helpful but 1-1/2" of plywood is even better. Essential is to add a back that is rabbeted or otherwise securely fastened to the frame of the box. Plywood is better for the back than solid wood but if the owners must see solid wood you could add a thin veneer of boards to the ply back. Fixing one of the shelves will help a lot considering the 80" height. Framing above and below the bookcase needs to be solid too. You don't want to be securing the pivot to just a 3/4" subfloor.

The last time I did this I built the bookcase and installed it within a plywood box making certain that all the clearances were good. Then when it came time to install in the wall I simply secured the outer box perfectly flat/level/plumb to the RO. Glue in shims so that the outer box becomes part of the framing but of course be careful not to distort the outer box. The bookcase after all, is pre- fit to the outer box.

In such a case you can eliminate door casing type trim altogether. Just pull the drywall off the surrounding wall and apply new drywall to return over the exposed edges of the outer box. You can do that nicely with metal or vinyl corners.

I found that using Sketch Up I was able to determine the exact clearances needed and the precise position of the pivot in order that everything worked. This made the set up foolproof.

As for the solid wood construction - your client preferences notwithstanding - my inclination would be to use 3/4" ply on the outside with 1/2" or 3/4" solid wood on the inside. A double layer bookcase inside the outer box previously described. This way you can secure the back and the horizontals of the case with screws and glue to the ply outer frame and the inner solid box can essential float (well held in place with minimal fastenings) to allow for wood movement. You can add a face frame to flush out with the front insides and outside edges of the layered carcass. You could do all this without the inner solid wood bookcase but in deference to your client's wishes this would be my compromise.

Steel in the bottom is not needed following my suggestions BUT you do want a good solid landing block for the closed bookcase. I used a block that started out with a bit of a taper and ended up with a deep flat top. I covered that block with a strip of UHMW Plastic secured with euro screws. Worked great. I'll see if I can locate some photos. I

The Gary Katz article from This Is Carpentry was informative.

[Sean Troy]

I've seen a 1/4" recessed plate of steel (painted) used on the hinge/or what ever you prefer side. You actually never see the steel if it opens outward. It was actually on some sort of ball bearing system.

[lowell holmes]

I just have to ask, is a secret book case a matter of need?

[Mark Gibney]

Thanks Sam, that's exactly the information I needed to read.

[Mark Henshaw]

i took a quick video but the system will not post it. I limited to under 30 seconds but no luck. The door still opens smoothly only needing a finger or two to open it. As others have said, the real key is to use a 3/4 inch back and screw and glue it as much as possible. Pivot hinges are a must.
Good luck
Mark