Bit of a diversion, making plans for a Book Tree

[WobblyHand]

My wife is a Librarian for our church. She was asked to look for new shelves for the kids library. She found a nice book tree that would work well. The cost of this book tree was a bit out of budget, at least for the one she found, but it was obviously made sturdy for the intended use. Looking on A***n there were several knock offs, but just judging by the weight and size we ruled those models out. They were obviously flimsy and wouldn't stand up to long term use. Knick nacks, maybe, but not books.

My wife was able to talk a congregant who is a carpenter. He said he'd be glad to take it on, but needed a basic plan. A plan bigger than a little picture in a catalog. So that brings me into the picture, who said, "You know, in one of my CAD lessons we traced out a design over a picture." Wouldn't you know it, my wife took me up on it.

My CAD tool of choice, (because it's the only one I have) is FreeCAD. It's not the easiest thing to work with, but it does work well enough, and the price is right. I built FreeCAD a couple of weeks ago from source from git, so I am using 0.21. It's pretty similar to 0.19, which is what I learned from.

So I started with this picture. In real life, this is supposed to be 59" high x 28.25" wide x 8" deep. I will make the shelves 10", as I think it is more practical for books.

I imported it using the Image tool. I placed the image in the XY plane at z = -13.7mm. The idea is to have the image in the background, so I can trace over it. FreeCAD assumes a dimension of 1mm per pixel. FreeCAD thought the Xsize was 211.7mm and Ysize was 211.7mm. I don't know why, but ok. I then increased the size of both Xsize and Ysize to 1600 x 1600. This enlarged the picture. Unfortunately, as it turns out, this was only 85% of real size, so I will have to fix that. However, I didn't realize this until I had done a lot of work...

I traced over the frame to make the main unit, and realized the image was crooked. How did I know? It was obvious that my vertical lines where not lining up with the picture! The image is tilted by about 1 degree. So I rotated the image until it looked better. Then I translated it a little in X to get closer to my model. Since this image is not part of the model, it didn't affect the design. Thought that was pretty nice. The camera view is not straight on, since you can see the depths of the shelves, but I winged it. This is what I have so far.

The arcs are b-splines that approximate the image curve. I made them symmetric, but they don't have to be. If I turn off the image plane, just the model is visible.
Here is the model with a slight rotationl, so it is not a dead on view. The tree portion is made of 1/2" plywood, whereas the rest is pine. In the back, or perhaps along one of the edges of the vertical, I think I will put in a section of aluminum or steel strapping so that the tree can be bolted to a wall stud. Wouldn't want it to fall over on the kids. The frame itself and the shelves will be attached to the backing. Probably will need some metal brackets for additional strength, but haven't thought about that fully yet. The non perpendicular angles will definately need some custom bracket, unless the vertical has some sort of slot cut in it. Think I will discuss that detail with the carpenter. I don't know this woodworking stuff all that well, I'm limited to stair treads and risers, not furniture.

When I am done, I will attempt to get it printed on D or E sized paper. But first I need to scale it to the final dimensions. I made the model out of 9 Bodies, so it will take a little bit. I obviously don't want to scale the thickness of the boards, but just the overall length and width.

 

[RJSakowski]

Bruce, you sure have a lot of irons in the fire! Those two middle joints look interesting. I was wondering how I would make them; probably a mortise and tenon with a dog leg on a tenon on the outer shelves. Biscuits could be used but they wouldn't be a strong.

BTW, how's the rear parting tool coming?

 

[rabler]

Screwed and glued to plywood, most of the board members should be pretty sturdy. Some sort of joinery will be needed where the branches meet. You picked up on the 90 degree uprights, the part I would worry about most is the bottom left leg as it has minimal overlap with the plywood. That will need some sort of enhanced jointing, finger joints would be my thought, but may also be a good candidate for a metal bracket.

As you already said, ask your woodworker what kind of jointing he is set up for, finger joints, biscuit joints, mortise and tenon, etc.

 

[WobblyHand]

Bruce, you sure have a lot of irons in the fire! Those two middle joints look interesting. I was wondering how I would make them; probably a mortise and tenon with a dog leg on a tenon on the outer shelves. Biscuits could be used but they wouldn't be a strong.

BTW, how's the rear parting tool coming?

Too many irons... Definitely got sucked into this one! The shelf that I'm a bit worried about is the bottom right. It is a right angle (I made it that way) but it doesn't have much support from the backer. All the rest of the shelves have 2/3 backing. This bottom right shelf only has 1/3 backing. Seeing as it is the lowest shelf, and we are talking about kids, I'd like to maybe extend the backer a little, maybe to get 50% backing. It's not like I need to make the tree totally symmetric, real ones aren't symmetric. Hope I don't screw up the looks too bad.

Besides my ELS project, my next project is the rear parting tool. I opened up the rear parting CAD model and looked at it. It seems I haven't drawn up the version that was similar to what you were suggesting in your PM. Once I get this book tree going (this week) I will make an attempt at that model. I'd really like to make the parting tool. Probably do it while I am waiting for the ELS pulleys to arrive.

Been busy with stuff. I did make the lathe compound clamp and that came out very well indeed. Noticeably more rigid. Fixing kitchen cabinets with custom brackets, back flow valves, a back plate, spanner wrench, lots of little things were done this year.

 

[WobblyHand]

the part I would worry about most is the bottom left leg as it has minimal overlap with the plywood

Yeah, that leg plus the bottom right shelf need attention.

I have the picture scaled now, along with the drawing. Wasn't that hard to adjust. Might play with the backer shape a little to help with the above.

 

[Boswell]

you could also add a brace between the bottom right leg and the bottom right shelf. It would add all the strength you need and create a nice triagular cubby space. Meet the bottom right shelf about 1/2 of it's length.

 

[WobblyHand]

I like the idea mechanically, but aesthetically not as much. It's a good idea though, maybe I can try something similar. I'll try it out and see how it looks.

 

[WobblyHand]

Here is a swag at slightly modifying the background tree "foliage" to give more support to the "branches". It also gives a bit more support to the bottom left leg. I left the background image the same, but you can see the new foliage is extended lower some, roughly by 2-1/4".

It just now hit me, there are two hidden shelves, or a masterful use of Photoshop. Notice the two groups of four books right next to the trunk, midway up. What's holding them up? I could add metal shelves there, otherwise those books can't be there, at least not like that!

 

[WobblyHand]

Looks like triangular blocks painted the same as the foliage. Sort of a trompe-l'œil. Well that's easy enough. Made the two blocks. Basic model is just about done. Now to create all the prints!

 

[WobblyHand]

Got them all done, save for the foliage. Got a little problem, as I made the shape from B-splines. It seems techdraw doesn't want to dimension them! Kind of frustrating. This design package has 12 technical drawings in it. 11/12 are no problem. But the foliage with the curves apparently is an issue for TechDraw. Posted on FreeCAD forum looking for some hints as what to do next.