Making a shelf

[quakerboy]

So, I am in the process of making a shelf that extends out both ways from a corner.

I reasoned that, if the corner were 90 degrees, I could cut one board at 45 degrees, flip one side, and the pieces would match and fit into the corner.

So when the actual angle was 95, figured I should cut it at 47.5 degrees.

This did not work out. The back corner is in the right spot, but at the front of the shelf, they overlap.

What did I do wrong?

[Angry Dragon]

1. How did you come up with 95 degrees??

is the wall that out of square??

To get 95 degrees you would need to use two boards because just cutting one will only give you 90 degrees

[quakerboy]

2. I was hopeing they were square

But I used an old iron angle my dad gave me. The angle went in, and had a little extra room.

So I bought a Protractor/angle finder. Which gave me 95 degrees.

If you cut a board at a 47.5 degree angle, then you end up with a second piece that also has a 47.5 degree angle at the point. You can try it yourself, It works with a strip of paper. By sharpening or widening the angle of the pointed end of the angled cut, you can make the pieces fit together to make the combined outside angle more acute or obtuse.

[Wash. state Desk Jet]

3. Are yer us'en a hand saw or a electric compound

miter saw otherwise known as a chop saw ?

[quakerboy]

10. Hand Saw

Not the best one ever made, but its an old Stanley miter box with matched saw.

[jeff47]

5. Doesn't work that way.

Cutting and flipping the board will always form a 90 degree corner. Because your'e starting with a 180 degree "corner", also known as a straight board.

When you make one angle flatter (47.5), the other angle must become steeper (42.5) so that the result still adds up to 90 degrees*. You can't cut a straight board once and get two 47.5 degree cuts. It will take two cuts.

* The way this part works is a bit complicated to explain, especially without illustrations. You start with a 47.5 degree cut and a 132.5 degree cut, because we're measuring the angle from one side of the board and your cut split a 180 degree angle. Flipping the board over and measuring from the opposite side changes your frame of reference by 90 degrees. So that 132.5 degree cut measures as 42.5 degrees once the board is flipped and you measure from the opposite side. And 42.5 is not 47.5 so they don't come together perfectly.

[quakerboy]

9. Try it with a piece of paper.

I guarantee you are wrong on this. If you cut a straight board at a 45 degree angle, you end up with 2 boards that each have a 45 degree angle on the pointy end and 135 on the obtuse corner. Flip one side, put the cut ends together, acute corner to acute corner, obtuse to obtuse, you get a 90 degree angle inside.

If you cut it at 30 degree angle, you get two pieces that have 30 degree angles on the point and 150 on the obtuse corner. Putting that together, you end up with only a 60 degree interior angle.

I will agree with you that it is hard to explain without illustrations. Try it with 3 strips of paper if you don't believe me. Cut across one at 45, one sharper, and one flatter. Then flip them, you will get one right corner, one that is more obtuse, and one that is more acute.

[jeff47]

12. Well, one of us has shelves that didn't come together.

And it's not me. So how can you guarantee I'm wrong?

[quakerboy]

14. Because my shelves come together at an angle that is not 90 degrees

It just doesn't happen to be the 95 degrees that I was wanting.

Plus, math doesnt work that way.

[jeff47]

4. Walls are never perfect.

If it's not exactly 90 degrees, the joint won't come together, as you discovered. This is additionally complicated by the fact that walls are never straight, and construction techniques result in corners that get filled with extra plaster/joint compound. So even if the framing and wallboard are perfect 90 degrees, the finished surface will not be.

Easiest way to make it work is to cut one board at about 45 degrees, and stick it against the wall. Hold the 2nd, uncut board against the other wall under the first board. Run a pencil along the miter cut to mark the angle for the 2nd board.

[jeff47]

7. It is quite possible to make more than one cut

So leave the second board long, and do a 90 degree cut at the final length.

The issue is corners aren't corners. They're actually slightly rounded, because joint compound or plaster builds up in the corner. Which is probably the primary reason that this corner is measuring 95 degrees - the measuring tools are short enough to be greatly affected by the hump of compound/plaster.

In addition, it is extremely unlikely that the wall is straight over anything but a trivial distance. This also makes measuring the corner itself inaccurate.

So make your first cut at approximately 1/2 the angle, and use it to get the angle for the 2nd miter cut. Make a 3rd cut if necessary to get the overall length.

[jeff47]

11. I don't have to. I do it with wood.

Again, you can not assume that the corner is actually a corner where two flat planes come together at a single point. Houses are explicitly built so that this is not the case.

The corner will be slightly rounded, because you don't put plaster/drywall compound tightly in the corner. The compound/plaster is thicker in the corner. And unless your measuring device is about 3 feet long on each side, you are not going to accurately measure that corner. You are going to be measuring the angle of the rounded compound, yielding an angle that is too wide.

Further, your walls are not flat planes, because making walls perfectly straight is hell of a lot of extra work and they won't stay flat as the house settles. They will be built "close enough". If a stud sits too far back near the corner, your measuring tools will yield a wider angle. Yet the shelf which goes past that stud will need a narrower angle to fit.

Because of all of these variables, you need to use the walls themselves as a template if you want a perfect fit. Otherwise, cut the wood at 45 degrees and you'll be close enough.

[Adsos Letter]

13. This.

Easiest way to make it work is to cut one board at about 45 degrees, and stick it against the wall. Hold the 2nd, uncut board against the other wall under the first board. Run a pencil along the miter cut to mark the angle for the 2nd board.

I used this method on the shelving in my garage, as well as the top caps on some fences and planters around the house.


edit: "excerpt," not "blockquote"

[Wash. state Desk Jet]

15. !

!

Well, tis true you will not find a place in the whole of the place that is perfectly square or perfecty level !And you will not get a measurement that is in fact perfectly clear !

The idea of cutting one piece at the 47.5 and holding it up in place than overlapping the first piece-with the 2nd. piece-,it too being held up on the wall and than using a pencil to make the line-sure than cut away,- yep that might work !

Buliding the shelf on a table using 45 degree cuts ,than just hang it. It always looks great that way, or so they tell me !

I really don't think you have enough hand tools to craft the shelf you may have in mind.

I would leave perfect out of the equation and simply build a shelf that looks nice ,on a table or work bench,than hang it on the wall.

!

And as a rule people put things on shelves ,isn't that so ?

!

[quakerboy]

16. Ive a few thoughts.

Unfortunately, I either waste a ton of boards, or I figure out how to do it right. After this shelf, there are 5 more.

I have a corner alcove that is a pain in the rear. Its inset 12 inches, and each side is 51 inches long Which means on a 8 foot board, I don't have a lot of room to spare in cutting a shelf. So, to fit right, I have to have it pretty close to perfect, otherwise I end up with gaps somewhere.

After cutting the one board, I have realized exactly how much of a pain it will be to do it manually with what my wife assures me is a very dull handsaw. Trying to figure out what tool I should get to replace it, and how to do it most affordably, seeing as I am time rich but cash poor.

I wanted to have it beveled, so it meets in the center of the corner. I suppose I could just cut at 90 degrees, and have one long and one short side, then trim the long side to 95. That might be easier, but its sure not as pretty in my mind.

[Wash. state Desk Jet]

17. My goodness !

Get yerself a long ,wide ,flat piece of cardboard -such as a giant card board box- yer can find those in the back pf supermarkets or home depots or lowe's or sears !

Than get yerself a good razor knife- box cutter what ever yer will call it.

You will need a straight edge or a 4 foot level fer a straight edge-and yer angle finder fer yer figuring angles,- and make a pattern fer yer set up out of cardboard- call that a template. Fabricate a template fer each shelf.

Got it- card board- a good razor knife -straight edge fer yer cutting guide,I use a ajustable speed square but I am sure you have yer own method of catching them cornors !
Make a perfect template than build yer shelf using the demisions of yer template. Of course yer will require a roll of duct tape ! What yer will be doing is creating in the rough a full scale model of yer shelf.

OK so, five dollars fer a razor knife-should come with at least five blades, and some duct tape another five. The duct tape and the razor knife will come in handy on other home projects ,so consider it a investment.

Now if you search in the warehouse section of yer local appliance store-home depot -sears what have you- you must know that they get diliveries fer large appliances and other huge items-big screen tv's so on and on ,and those boxs are broken down then these days recycled-however-some trusty worker or even the workers manager will be glad to give you for free a few large boxs fer yer project templates !

Furnature stores , carpet stores ,dumpsters all that,

Fallow the creative trail- when materials can be free-go for it.

Now you have an idea.

[quakerboy]

19. Not here

None of the neighbors would have such a thing. Most of the neighbors are apartments, and the others are Condo's. My dad would have one, but its probably 65 years old and rusty, stuck in the back of storage where it would take a moving crew a few hours just to get to it, with a cord thats been re-spliced 6 times after he accidentally cut through it. Thats how things go there. i remember he had any tool you could think of when I was a kid, but the last time I borrowed a drill, he had to instruct me on which parts of the handle you could touch and which would get you electrocuted. I decided just to buy a cheap one, as I didnt expect to need it for much.

I'm strongly thinking about getting a cheap miter saw from HD or lowes when I get ready to go past the trial stage of this project. The more I think about this the less desire I have to build 7 shelves with a dull handsaw that is shorter than the width of some of the shelves