LumberJocks

looking for pointers on my bookshelf design

  • Advertise with us

« back to Designing Woodworking Projects forum

Forum topic by jamsomito posted 01-18-2018 08:27 PM 708 views 0 times favorited 23 replies Add to Favorites Watch
View jamsomito's profile

jamsomito

182 posts in 512 days


01-18-2018 08:27 PM

I have ~30 board ft of red oak that has been machined to 3/4” thickness. I would ideally like to make 6 bookshelves – 2 “large”, 2 medium, and 2 small. Below is my plan for the large one. The others will be smaller versions designed to match.

The top will be a glued up panel but the middle and bottom shelves will be 3/4 oak veneered plywood. The back is 1/4” plywood. Everything else is 3/4” thickness because that’s my stock thickness. I could glue-up for thicker legs or something else but I’d be stretching my stock I think.

My main question is about joinery. I don’t have a domino or dowel jig. I’m thinking that leaves me with mortise and tenons or pocket holes. Would pocket holes be strong enough for an almost 4ft long bookshelf full of books? I’m not yet certain in my mortising or tenoning skills but what better time than now to hone my skills…

Also, how would you join the X shapes to the frame of the bookshelf?

I was planning on the little angle brackets into some slots on the stretchers to keep the top fastened down since it will move more than anything else in the piece. The plywood back is set into a rabbet on the legs and stretchers.

Pics below. Thanks in advance for any tips for this humble beginner.


23 replies so far

View bilyo's profile

bilyo

276 posts in 1188 days


#1 posted 01-18-2018 09:58 PM

IMO, the ply back and the X bracing will give you adequate stiffness throughout the entire piece without depending on super strong joinery. So, I think that pocket screws would be OK. However, having said that, I think you should use this project as an opportunity to learn some better joinery techniques and, perhaps, obtain some additional equipment. A dowelling jig is not necessarily expensive and the skill level to make dowel joints is not huge. M&T joints are a little more difficult, but well worth learning to do. And, you need nothing more than and hand saw, chisel, and hammer to do it if you don’t have power equipment.

My opinion is that your design would look a bit better if the legs were somewhat heavier; even if you did nothing more than make a face frame.

I would make the X braces with a shiplap in the center. My first thought is to use biscuts or dowels to fasten the ends. Counter sunk screws with wood plugs would also work.

View Bill_Steele's profile

Bill_Steele

381 posts in 1817 days


#2 posted 01-18-2018 10:55 PM

I’m a novice woodworker—so consider the source of my “free” tips…....

A 4 ft span seems like alot for a 3/4” thick shelf—even with the hardwood edging I would think it might bow if filled with books. I would consider doubling the thickness of the shelf OR using a robust edging approach like one of these:

I would ditch the X braces—I don’t think they will add much if anything to the structural rigidity. If these are for style/design—I would experiment with a half-lap joinery approach for these. You could also experiment with a panel OR long vertical strips where the x-braces are currently—perhaps a solid strip horizontally where the 2nd shelf is located and then vertical strips above and below.

I think thicker legs would look nice too. Optionally you could join 2 pieces at 90° and form a leg at each corner.

I think the plywood backing will help create rigidity in the structure, but the shelves themselves as stressed members of the design may be sufficient (perhaps with edging all the way around).

Pocket hole screws and glue is certainly strong enough—but might be unsightly if you can see the pocket hole.

View LesB's profile

LesB

1791 posts in 3529 days


#3 posted 01-18-2018 11:01 PM

This projects leaves lots of possibilities.
First question answered. Yes the pocket hole screws would be strong enough but don’t skimp on the number used and adding glue will only help

Mortise and tenons for the main frame would be good practice in developing your skills so I would go for that.
The cross supports can be a lap joint at the center and pocket screws to fasten the ends. Or you can do more M&Ts at an angle.

The top could be fastened with pocket screws; I would put 3 on the front and back frame rails. Also you could make the top out of the 3/4 oak plywood and cover the edge grain with solid pieces of Oak…there are several ways to add this cover and it could be from 1/16” thick to as wide as you want; maybe mitre the corners but butt joints are OK too. Using plywood here would eliminate any concerns about movement and be less expensive than solid wood.

A little further design evaluation: Your current design sort of looks like “warehouse” shelves. The cross braces only add to this image and are not entirely necessary. As mentioned earlier adding a face frame on the front and possibly 1/4” panels dadoed in the frame on the ends would help you change that. I would bevel the front edge of the front supports and the edge of the face frame so they fit together with no joint line (it would be hidden in the corner).
You did not give the height but if it is a book shelf I would assume it is about 36”. If it is taller you might want to design the middle shelf so it is adjustable.

Without knowing about our other pieces I don’t think you have enough Oak at 30 bd ft. Especially if you use solid wood for the tops.
That’s enough to think about for now.

-- Les B, Oregon

View jamsomito's profile

jamsomito

182 posts in 512 days


#4 posted 01-18-2018 11:04 PM

Thanks for the help so far. To clear a few things up:

If I was doing tenons, I’d do them on the table saw. I have a simple jig I made but it’s accuracy is questionable.

I could purchase a dowel jig, nothing against that I suppose.

I could also hide pocket holes pretty well on the underside and back sides of pieces.

I’m not worried about the shelves sagging front to back. I was thinking of gluing a 3/4” strip of plywood in the middle of the stretchers such that it supports the entire length of the shelves and they more or less drop in flush with the top of the stretchers. The stretchers are 2” wide, which I think might be ok… Maybe. (Is stretcher the right term here? Rails maybe?) If I was worried about the sagging it would be front middle. The bach has its own stretcher fully supported by the backing plywood too.

I already have the x shapes half-lapped. Can’t ditch the X’s unfortunately, wife’s request. Just not sure how I’d attach them to the legs.

View jamsomito's profile

jamsomito

182 posts in 512 days


#5 posted 01-18-2018 11:09 PM

30bf may not be enough. I really only need 3 (small medium large), the extras would be built along side these and either given to family or sold so it’s not imperative for 6 total units.

I’ve hemmed and hawed over a plywood top too. Could certainly do that.

View Terry Osnach's profile

Terry Osnach

32 posts in 1350 days


#6 posted 01-18-2018 11:39 PM

I agree ditch the x-braces.

View JBrow's profile

JBrow

1366 posts in 1006 days


#7 posted 01-19-2018 03:41 AM

jamsomito,

In addition to pocket screws (which I have not used) and mortise and tenon joinery, lap joinery could be considered for assembling the end frame’s top and bottom rails. The top front rail that supports the top could be attached to the legs with either pocket screws or a lap joint. I assume the center and bottom front rails are also part of the bookcase frame and therefore could be similarly attached.

An option for installing the x-braces would be to apply a thin piece of oak (3/4” x ¾” or ½” x ¾”, or even ¼” x ¾”) to the ends of the x-brace, top and bottom. The connectors could then be glued or pin-nailed to the bottom edge of the top end rail and to the top edge of the bottom rail. The x-brace ends would offer end grain as a glue surface so reinforcing the x-brace to connector joint with a mechanical fastener would make this joint stronger. The x-brace could also be joined to the connectors with a lap joint and mechanical fasteners would be unnecessary (shown in the sketch).

If the shelves are supported all along the length of the shelves at the back and front, most, if not all sagging would be mitigated. The center and bottom shelves could either set in a rabbet in the front rail (as shown by Bill-Steele) or set atop the center and bottom front rails.

A front to back 1-1/4” wide set on edge centered stretcher would offer added insurance against sagging. I would also be inclined to add cleats to the end frame bottom rails on which the ends of the bottom shelf would rest. While it may not be necessary, the center self let into a shallow dado in the legs and x-brace would add a little more support to the center shelf.

You mentioned an angle bracket and a slot for attaching the bookcase top to the frame. I assume you had tabletop fasteners in mind.

https://woodworker.com/table-top-fasteners-with-screws-mssu-879-223.asp

View jamsomito's profile

jamsomito

182 posts in 512 days


#8 posted 01-19-2018 04:08 AM

Ah, very interesting. You all have given me a lot to think about. Thanks.

I had not considered lap joints. I’ll play around with my model and see how they would play out. I’m already doing that where the x pieces meet in the center anyway.

Yes those are the fasteners I was thinking of, just what came to mind first.

I’ll consider a face frame or thickening the legs a bit probably just doubling up, so 1.5” thick. Could do 3 pieces stacked and rip down the middle for 1-1/16” (ish) thick also.

The overall dimensions are around 46 long, 36 tall, and 15 deep, so LesB was right on.

Thanks again. Give me a couple days and I’ll post a revised model follow up.

View bilyo's profile

bilyo

276 posts in 1188 days


#9 posted 01-19-2018 04:15 AM


An option for installing the x-braces would be to apply a thin piece of oak (3/4” x ¾” or ½” x ¾”, or even ¼” x ¾”) to the ends of the x-brace, top and bottom.

The OPs design of the X brace provides angled surfaces at the top and bottom that fit flush against the legs. This provides good long grain to long grain surfaces for gluing. Also, slots for splines could easily be cut into these surfaces on the TS. Or, biscuits or dowels could be used if he has the equipment.
The x-brace ends would offer end grain as a glue surface so reinforcing the x-brace to connector joint with a mechanical fastener would make this joint stronger. The x-brace could also be joined to the connectors with a lap joint and mechanical fasteners would be unnecessary (shown in the sketch).

If I understand what they are saying, your last two sentences in the same paragraph are contradictory.

View jamsomito's profile

jamsomito

182 posts in 512 days


#10 posted 01-19-2018 04:18 AM

I do have a biscuit jointer. Didn’t think of it here because I need these joints to be structural, not just help aligning.

Bilyo, you’re right that on the leg side the x will have more long grain than end grain so just glue would probably be fine. Jbrows method would have the ultimte in strength but I don’t know if that’s needed. I like it though.

View JBrow's profile

JBrow

1366 posts in 1006 days


#11 posted 01-19-2018 01:57 PM

bilyo’s idea of simply gluing the x-brace to the legs would indeed result in a strong glue joint. Clamping this joint would require some creative thinking, but if successfully clamped, the x-brace should stay put.

My apologies for the awkward explanation of the two options for joining the connector to the x-brace. If the connector is joined to the x-brace atop the x-brace with a butt joint, the x-brace would offer end grain for gluing. Thus reinforcing the joint could be beneficial. This option was not illustrated in the sketch.

The sketch shows the second option, that of attaching the connector to the x-brace with a lap joint. In this case, both the x-brace and connector would offer long grain for gluing.

Biscuit joinery is frequently touted as a good way to help align a joint. Since it is a spline, it has the added benefit of reinforcing and strengthening the joint.

View bilyo's profile

bilyo

276 posts in 1188 days


#12 posted 01-19-2018 02:14 PM

I’m assuming you will build the two ends (two vertical legs, top and bottom stretcher, and X brace) as complete units and then join everything including shelves and long stretchers during the last steps. As you assemble the ends, the X brace will fit snugly into each corner, and when in place, will stiffen up the whole unit with only glue. However, splines, biscuits, or dowels will help keep everything in alignment during clamp up and offer some strength; less so for the biscuits. Be sure to do dry fits. With the X brace, you will not be able to adjust for squareness as you are gluing and clamping. Having said that, you should actually glue the center of your X first and make sure it is totally square first. It will control the squareness of the end units.

View jamsomito's profile

jamsomito

182 posts in 512 days


#13 posted 02-25-2018 07:37 PM

Ok, finally caught a break and sketched up a redesign. I tried my best to make a face frame work, but I just didn’t like the look no matter how I arranged it due to the open X’s on the sides, so instead I decided to make the legs bigger and I like this overall a lot better. It doesn’t solve my joinery problem, but I can decide if I want to do M/T, dowels, or pocket holes a little later when I actually start cutting my pieces.

Because my stock is only 3/4” thick, I needed to do a glue-up on each of the legs and the bottom side rails as well. Because I’m using more wood for this, I opted to make all the shelves out of oak veneered plywood, so I just made a quick mitered trim piece to go around the top. The x’s are half-lapped in the center and I’ll either glue them in on the ends or put a single screw through each and fill it. We’ll see.

View BenjaminNY's profile

BenjaminNY

131 posts in 1488 days


#14 posted 02-25-2018 07:43 PM

Break up the back panel into two pieces with a stile at the center of the two panels. You can place a screw at the center of each shelf that is connected to the stile. This one screw will go along way to preventing sagging.

View jamsomito's profile

jamsomito

182 posts in 512 days


#15 posted 02-25-2018 07:46 PM

I like the idea of adding the stile to break up the look, I’ll probably do that. But I’m not worried about sagging in the back – everything will be screwed to the back sheet. If I’m worried about sagging, it’s in the front right in the middle. Only thing I can think of there is adding another leg that goes the whole height of the piece from floor to top shelf, but I dont think I want to do that.

showing 1 through 15 of 23 replies

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com