Spiral Coffee Table

Intro:
    Welcome to the Spiral Coffee table Instructable. I hope you will enjoy reading this Instructable as much as I did in creating it.  I will also be providing all of the files and formulas used in the construction. Any customization of the table is welcome. Now, lets start off with the purpose and goals in making this project.

Purpose:
     The purpose of this design is to make a visually appealing and structurally sound coffee table.

Goals:
     Several main goals existed in this project:
       1)  To illustrate the steps of starting conceptually from a conceptual idea appealing furniture.
       2)  To utilize CAD for precise dimensions and assembly fluidity.
       3)  Create tooling that was easy to use for repeatable results.
       4)  Compare a Virtual-created model to Physical result.

Safety:
Power tools ,woodworking and stain/paints are used for this project, so please, use safety-glasses and gloves when appropriate.

Now comes the brainstorming the concept of the table.

Step 1Conceptual Design and Equations

Concept: 
    I started off on this project deciding on what would be a handsome table and was interesting from the top down-design. I choose the spiral design of the legs. I then had to support the structure, so I had designed each leg be supported by the previous, as well as an optional base for additional support.

Trigonometry:
     Coming up with an initial design wasn't too hard. However making an appeasing twist and correct height involves some trigonometry. The major factor of this table was the side length. An easily measured length was one driving fator(round numbers are nice!)
     1)  The projected length (c)  and side length (l) were used to find a suitable height for a coffee table (around 19" high)
     2)  Since the average coffee table is around 20" in height, choosing the correct lengths and angles were important in make an attractive table
     3) A Law of Cosines and a Pythagorean theorem later, and I had a useful formula to implement in the CAD software.
   
Next up, CAD:

Step 2CAD Modeling Steps

Creating the Base:
    To make the CAD model, I used CATIA. The steps are as follows:

       1)  A starting point was created. The second point's sketch plane and the height were controlled through the formulas and created parameters (Also known as Knowledgeware in CATIA). Picture 2
       2)  A line connecting the points was then rotated around a central axis. This allowed for the central placement of each arm as well as giving a quick preview of the base design. Picture 3
       3)  After some adjusting, I settled on 15 arms for the table, they are aesthetically to me attractive as well as more natural-looking.
       4)  A rounded rectangle was padded to get the general arm shape.
       5)  For the arms to be more stable, a notch was created on each arm to lay normal (they lean on one another).
       6) This was made via a pocket on a normal plane of the line previous to the pad. Picture 4, 5, 7
       7)  The tooling/base was created after projecting the arms onto a disk, and adding some tolerance around the part (so the arms can fit) and then pocketing the sketch.
       8)  The pocket was also patterned, and a hole removed the inner-part of the ring. Picture 6
       8)  The glass top was made just as as simple pad with two chamfers on it (AKA a Bevels).
       9)  The final step in creating the CAD model is the assembly, to make sure the to assemble the parts and check if any clashes (collisions of the parts) are present.

To make my assembly and each iteration of the base go together efficiently, global parameters were set-up at the assembly level that all of my parts used. It makes any change I make happen assembly-wide to make modifying the document MUCH easier.

Drawing Class.
The next step is the Drafting/ Tooling steps as well as working drawings. These make creating the physical part a breeze.

Step 3Tooling and Working Views

Tooling:
    One of the most vital things in this project is tooling. To make all of the parts, I am including drafted the plans for showing the accurate placement of the bottom tooling and notches. I also included the formats of: CatDrawing,  PDF (for printing even if you don't have CAD software) and DXF of the base for laser cutting. All of the other tooling/drawings can be sized to fit when printing.

Files:
    The files included are:
Technical Views- These are the dimensions for correctly positioning the notch on the arms,
Tooling- This drawing includes the necessary tooling to position the cutouts on the bottom bracer.
Tooling_Continued- Since Measuring an accurate 24 degrees (360/15 degrees) to space the holes on the bottom of the brace, I am including a template to make this easy.
Tooling_1- The include the notch templates on an 8.5X11 in sized paper for printing ease

All of the other tooling can be sized to fit when printing.

Now, it's just about to get real...

Table Drawing-ANSI_Technical_Views.pdf106 KB

Table Drawing-ANSI_Tooling.pdf69 KB

Table Drawing-ANSI_Tooling_Continued.pdf47 KB

Table Drawing-ANSI_Tooling_1.pdf47 KB

Table Drawing-ANSI.CATDrawing862 KB

Base.dxf29 KB

Step 4Let's Get Physical

    While all this talk of designing a table using a computer and mathematics is fine and dandy, I feel as though actual proof is required to show if a design is up to snuff.

From start-to-finish, this project should take around 1.5 days or a weekend. It can be a one person project, but friends to help are always nice! Here is a list of Everything needed to make the table.

Required Tools:
-Table Saw
-Jig Saw
-Drill (with a bit large enough to fit the jig-saw blade through, your judgement, I used 3/16 in bit)
-Chisel
-Scissors
-Sandpaper- rough (75) to fine-(300) grits
-Straight-edge/Ruler
-Level
-Pencil
-Clamps

Required Materials:
- 36" x ~18" x 1" sheet of the wood of your choice (preferably hardwood)  for the arms.
-18" x 18" x 1"  sheet of wood the base
- 20" x 20"  sheet of the material that will be the top surface
- 1 bottle of Wood Glue or equivalent adhesive
- Tape (scotch, electric)
- Scrap wood pieces

Optional:
- 1 can of Spray Paint, Stain or Clear-coat
- Rubber mallet
- Willing friend to help
-  Any Heavy weighted object (ie. bricks, textbooks, "willing" house-cat (not really))
- Glass would be the best material for the top of the table, but as a student, I'm on a limited budget so wood was my choice.


Helpful Tip:
Before heading out to the workshop or garage, print off the Tooling and Tooling_Continued PDF documents from the previous step and take them with you to save trips.

Step 5First Base

First,  let's start with the base tooling of the table. I used pine, this is definitely not the suitable wood for quality furniture, but resources are limited in college. Pine shows also that the table can still be created and sturdy, even with the inferior wood. Anyone who has the laser cutter and is using the DXF can ignore this step and move on.
Time: 20-40 min

1)  On the ~18" x 18" sheet, find and mark the center in both directions.
2)  Cut out the radial lines of the Tooling_Continued.PDF.
        a) Poke a small hole in the center of the radial lines.
        b) Align the center of the tooling to the mark on the wood.
        c) Tape down the cut-out.

3)  (15x) Extend the radial lines out to the edges of the sheet using a straightedge or ruler. Picture 2
4)  (15x) With the ruler, make a mark 7.5 in from the center of the radial spacing tooling.
5) Cut out the radial line tooling from the Tooling.PDF.
Cut close to the angled slot graphic Picture 3
        a) Extend the radial line on the cut-out to the end of the slot graphic. Picture 3
        b) Poke a hole in the .25 in from the back of the tooling, along the radial line. Picture 3
        c) (15x) Align the hole on the radial line tooling and trace the outline of the slot graphic. Picture 4

 6) (15x) Drill holes at the marked locations with the bit (drill a pilot hole if necessary). Picture 5

Next comes all of the cutting/sawing in the project. Stopping at this point for now and cutting everything at once should minimize the amount of clean-up required.

Step 6Do You Want to Play a Game?

Please, use Safety Glasses for this step
Time: 45-60 min*

On the Table Saw:

  1) (15x) With the 36" x 18" piece of wood, rip the pieces of the wood into 5/8 inch strips. Picture 2
  2) (15x) Rip the strips a second time to get the square side pieces. Picture 3

*Using the Chisel/Dremel:
  1) (15x) Position the Side tooling from the Tooling_1.PDF , by the dimensions on theTechnical_Views.PDF .
  2) (15x) Sketch the Top and Side profiles in the respective locations.
  3) (15x) Take the carving tool of your choice and start.

  I realize that carving the notch can be rather challenging. The flat surface will provide a solid surface for the glue to adhere to, provide an even sturdier table and a more professional result. The table isstill strong enough if one chooses to skip this step. So I will be showing pictures of the table with the notch not included for those unable to complete this step.

With the **Jig Saw:

  1)  Cut out the sketched outlines on the 18" x 18" base
  2) Take your time, fit the side pieces into the cut-out to see how they fit tight.
  3) Enlarge with the jig saw or sandpaper the cut-out if the side pieces are too tight (no more than a mallet love-tap should ever be required)
  4) If you are going to use the base tooling as part of the table, cut out the preferred radii, do not cut any closer than 1 in to the sketched outlines to insure the base holds during assembly.

Now we are ready for the gluing, and to see this pile of sticks come to life.
* The time was determined by skipping this step.
** Anyone who has a laser cutter can use the DXF file and make the base.

Step 7Bonding Together

Now that everything has been cut, it's time to move on to assembling the sides. The assembly is getting glued upside-down into the base
Time: Overnight, (8+ hours)

Assembling
1) Slide the side-pieces into the slots, each piece is slid under the previous one placed.
    *For those who made the notches, the correct orientation from Picture 1 is shown in Picture 2
2) Tap with the mallet (if needed), the pieces flush to the ground.
3) At this point the pieces should be free-standing in the tooling.
4) Carefully flip the stand over. Picture 4
5) Level, the base with the ground in all directions. (Since I was using pine as the base, some polite persuasion with a brick was needed to make my slightly warped boards level)
6) Space the arms of the base evenly with any spare wood Picture 4, 6

Gluing 
To make this assembly permanent, the wood-glue of your choice is needed.

1) Pour the glue into a cup
2) Apply to every side touching wood with a thin piece of wood (a cable tie worked good for me).
3) Clean up any drips that occur, this will make sanding easier.
4) Wrap the middle section with electrical tape. This is to make sure that each arm has even pressure bonding it together.
5) Wipe up any remaining drip 30 minutes after then wait for the glue to cure overnight.

So close,  you're almost done!

Step 8Finish Line

    Hopefully, you're refreshed from the previous steps, because the final product involves some sanding as well as painting. First things first, if you want to remove the base form the tooling, use the mallet and gently tap arms out. To do this gently, tap the arms out .25 in sequentially around base until loose.

With the rough-grit sandpaper:

1) Round the edges off of the on the top and bottom of the base Picture 2, 3  This helps ensure that any high-point on the arms is now flush to the table.
2) Sand flush any glue that could have run down the legs and dried.
3)  Also sand all of the exposed wood roughly.

With the fine-grit sandpaper

1)  Mark every side lightly with a pencil. Picture 4
2) Sand the marks of the pencil away. This will help you to know all of the surface is has the proper amount of sanding done on each side.

Now that the base is smooth, vacuum or blow off the base to remove any wood dust.Apply any finishing touches to the base. In the pictures, I used satin-black paint for my base.

As the last step apply the top of your choice, if the top is glass or some other slick surface Bumpons from 3M or something similar, will hold the top in it's place.

That's it, your done, enjoy your unique spiral in your house. I used pine and no notches and the table was still strong enough. This way the design can be built successfully if you want to skip the carving and/or use lower quality wood. These decisions depend on how high-quality one wants to go in building the table

*If anyone want's a custom size of table, I would be happy to modify the working drawings and send them. Also, included are the CATIA model of the whole assembly as well as STL and STP files for importing in other 3d programs.

A Very Unique Folding Chair

This chair design came to me after a failed attempt at re-creating a chair I had seen by Architectural Designer Robert van Embricqs. It was a very beautiful and stunning piece, but seemed to expensive to do it just the way he had. So I set out to make a less expensive version of his chair and it looked amazing, however it couldn't even hold my 95lb daughter. I was then left with about 70 pieces of 3/4" x 3/4 " wood in varying lengths. What was I going to do with all that wood?

A couple of days later, I remembered having seen a sketch of a chair in a book titled "Nomadic Furniture" by James Hennessey and Victor Papanek called a "Savonarola Folding Throne". After a quick search on the internet for better pictures of it, I thought I figured out how it was put together. Although I have only seen them in the open chair position and never folded, I could only imagine that the following is a pretty close (albeit very simplified) approximation of how it is done. 

Step 1Materials and tools

It has been my experience with woodworking that there is never just one tool that can be used or just one way to put something together. The first couple of these chairs that I made I did with just a table saw, miter saw, tape measure, drill with a few bits and some sand paper, so most hobbyists will have the right tools for this project. Once you read through this, you will have a good idea what tools you have in your arsenal that will work for this job. Here is a list of the supplies I have come to use for making these. (The chair in this instructable is number 10 including the first two prototypes)

Tools

-Table saw - for ripping lengths of pieces
-Miter saw with attached jig - the jig makes sure that every piece is exactly the same (and all without measuring)
-Router with 5/16" bit and attached jig - the router makes sure the holes are nice and straight and the jig makes sure the spacing on the holes are exactly the same on each piece (again, no measuring needed once you make the jig)
-Drill with varying bit sizes and a 3/8" boring bit for counter sinking screws
-Sander - this keeps the slivers out of our tender bits
-Philips head screwdriver
-Tape Measure
-Rack for applying stain and polyurethane, and also for drying
-Foam brushes for apply stain and poly
-Safety goggles and hearing protection
-Square for making sure things are squarish
-Vinyl paper for spacers - I'll explain these later
-Hacksaw - for cutting dowels to length in the finishing stages of the build

Materials

-Three 1"x4"x8' boards (actual dimensions 3/4"x3 1/2"x8') - These should be as knot free as possible because we are using such small pieces and if the knots span the width of the piece it will be very weak there (I am using pine for this build, but other woods work very well too, as you will see in later pictures)
-Two 5/16"x3' wooden dowels
-Thirty-four 1" screws (something reasonably appropriate for use with wood)
-Wood glue
-Wood stain - optional depending on type of wood used
-Polyurethane - again, optional depending on type of wood used

Step 2Ripping the Lengths

The first step is to cleanly cut the ends off your boards using the miter saw. These ends are never quite square, will sometimes have grade markings on them and they are also pretty rough. You shouldn't be making a very big cut, just enough to tidy things up.

Now set up the fence to cut all the boards into 3/4" strips. If you get it at just 3/4" and not a hair over (assuming you have a standard blade that gives you a 1/8" kerf)  you will be able to get 4 strips from each board without any waste. When you set your blade height, you want the teeth to just clear the top of the board as it comes through. This will give you a nice clean cut as well as keeping the saw from throwing a bunch of sawdust in your face as you cut.

If you've done everything right so far, you should have twelve 3/4"x3/4"x8' lengths of wood. This will actually be more than you need, but some pieces may not be desirable for this project, so you want to have a little extra. If you only ended up with nine of these and three thinner ones, do like the Hitchhiker's Guide says and DON'T PANIC because the nine pieces will be enough if you chose very carefully when you bought your wood. If you don't have any knots or there are only very small ones everything should be fine.

Step 3Cutting the pieces

This chair is, for the most part, just two pieces of wood repeated 17 times. There are the longer pieces that make up the sides that are 27" long and square on both ends. Then there are the seat pieces, which are square on one end and cut at a 40° angle on the other end. The short side of this piece is 15" and the long side of this piece is 15 11/16".

The most efficient way of cutting these pieces is to cut two side pieces and two seat pieces from each length. When you're cutting these you want to be aware of a couple of things. First of all, you don't want any potential structural failures due to weaknesses in the wood, so watch out for splits and large knots. Cut your pieces from either side of these types of imperfections. If you cut two long pieces and two short pieces from each length, you will have about 10" or so of scrap left over, so if you have to cut a knot or split out of the middle of your length, you will still have enough to get your four pieces. Don't forget that you also have a few extra lengths to use too, so don't be too stingy and use inadequate pieces.

The second thing you will want to consider is the grain of the wood. I don't think so much about the grain with the long pieces, but you will want to have the most interesting grain showing on the top side of the seat section. With the way I am going to cut these pieces on the miter saw, that means I will be picking my favorite side of the wood and putting that down ( the longer side of the seat pieces is the top side of the seat).

Another thing you will need to be aware of when cutting these pieces is the straightness of all the pieces. Your pieces have to be very close to perfectly straight stock in order for this chair to work well. I have made these out of pine, black walnut and red oak so far. The oak was by far the easiest wood to work for this project. It cuts easily, stays true and finishes easily. The pine usually works well, but can sometimes look good when I buy it and as soon as I rip the 3/4" pieces, the wood starts to warp pretty noticeably. The pine will also tear out on the bottom side of drilled holes and the back side of miter cuts more easily than the other two woods, so a very light touch is needed when drilling and cutting pine.The black walnut was the easiest to cut and is by far the most beautiful wood of all three, but what a pain in the backside it was getting the pieces to remain straight.

With that said, you're ready to start cutting. First cut 17 pieces that are 27" long. I do this by cutting two pieces from each length until I have cut them all. That means you will have cut about 54" from each 8' length leaving you about 42". These long pieces are easy because they are just a nice straight 27" with no angles or anything.

With your miter still set for 90° angles, cut 4 pieces roughly 16" to 18" long. These will be used for the braces on the sides of the chair and will be trimmed up later to the exact length needed.

Next you will want to cut all 17 of your seat pieces from the leftover 42" lengths. First set your miter at 40°. Then you'll want to measure and mark a line 15" from each end of the 42" piece. Then, just go ahead and make all your cuts. What you will have left over will be the middle of the 42" length that is now a trapezoidal shape. Again, once cut, the seat pieces should be 15" on one side and 15 11/16" on the opposite side.

Next you will want to cut the dowels in half. This doesn't have to be exactly in half and most of the time I don't even measure this cut. These get trimmed up later to a more exact length so for now, close enough is close enough.

Step 4Drilling the Holes

The next step is to drill all of the holes. Each piece (side pieces as well as seat pieces) gets two holes drilled in them.  All holes are 5/16" holes and measurements are on center. I use a jig attached to my router for this step as well so that I don't have to do any measuring or marking. This greatly speeds up the process as well as ensuring that all holes are uniform from piece to piece. Uniformity is very key during every cut and/or drill section of this build. If you don't have every piece just the same as the last one, the chair will not end up working well. The chair seat may not sit flat or the chair itself might not sit level on the ground.

The seat pieces get holes drilled at 7/16" and 8 3/16" from the square end. The jig I use has a moveable stop so that I can drill all 17of the first holes, move the stop, and drill all 17 of the last holes.

Next, drill holes in the long pieces at 5 1/16" and 17 1/16". These measurements are from the same end, so you end up having a hole 5 1/16" down and one a foot away from it.

Step 5Sanding and Finishing

At this point the wood is ready for sanding and finishing. There isn't a whole lot of sanding to do, just clean up your saw marks a bit (I cut my pieces so that the saw marks don't face out on the chair, but will face another piece of wood, so they don't have to look perfect) and make sure all your edges are neat.

As far as the finishing, I'll keep that part kind of short. There are sooooo many options for this that I couldn't even begin to talk about them in a single instructable. What I do is choose a stain (some chairs get no stain) and stain it using a foam brush and a rack I built to do the staining. This rack allows me to stain all sides and all pieces at the same time without having to wait for a side to dry so I can lay it on something. Then, once the stain is dry (usually two to three days later) I put a polyurethane on it to protect the wood from weather or coffee spills or oil stains from the skin of people handling the chairs (trust me - people are going to want to play with this chair when you show it to them!). If it's a hard wood, I will usually just put one or two coats of poly on, but with the pine, I will do at least three coats because it is such a soft wood. If you don't know if you're using a hard or soft wood, the easiest way to tell is to scratch it with your thumbnail. If it makes a sizable imprint, it's soft wood. If it leaves a very light or no impression, it's a hard wood.

All seat and side pieces get stained on all sides and ends. The four brace pieces that are cut get stained on just three long sides and you'll see why  in the next step. Poly the three stained sides once the stain has dried.

Step 6Assembly and Final Touches

I hope you're getting excited, because we're really getting close now. We're just a little ways away from getting to see one of the most amazing chairs ever!

The first part of the assembly is to attach the dowels to the two outermost pieces of the chair. You do this by choosing one seat piece and one side piece. You will then spread some glue evenly around in the holes drilled in both pieces and stick your four dowels in the four holes. You want them to be nice and flush with the outside edge of the piece. I do this and then slide another corresponding piece on the other end of the dowel without any glue to hold it level while it dries. Use a square to make sure your dowels are coming out of the holes at right angles.

Once the glue has dried, begin assembly by removing the unglued pieces from the dowels and lay the two doweled pieces on your work surface with the dowels pointing up. Orient them so that the seat end hole and the top hole on the long piece are right next to each other with the short side of the seat piece touching the longer piece. This explanation might be a little awkward, so refer to the pictures for a clearer representation. I use spacers in between layers of wood so that I don't get the pieces too tightly packed together. This also gives the wood a little room to shrink and swell (as wood tends to do) without doing damage to the chair. If you push the pieces too tightly together, the chair will either be very hard or impossible to open and close because of all the friction between the pieces. I use spacers made of vinyl printing paper. The thickness is about the thickness of two regular sheets of paper, but because they are made of vinyl, they are very durable and can be used over and over again.

For the next layer you will stack it the opposite of the first layer. The middle seat hole always goes on the same dowel, but the end hole will alternate from left to right dowel. Always put the next seat piece on so that the angled ends form a point with the layer beneath when looked at from above. If it looks like /||\ you are doing it right, if it looks like |\/|, your are doing it wrong. See picture for clarity on this step. Keep doing this - layer - spacer - opposite layer - spacer - layer......etc until you have all 34 pieces stacked up together. Once you have them all on, the two outermost layers should be oriented in the same way. If they are opposite, you either have two layers together facing the same way or you need to look for your lost pieces.

The next thing to do is mark the dowel so that it can be cut flush with the top layer. Just use a pencil or blade to make this mark. Then remove the top layer so the mark you just made is sticking out about 3/4" from the second to the top layer and cut the dowel at this mark using a hacksaw or some other small hand saw. If it's not perfectly flush, don't worry, because we can sand it once the top layer has been glued in place. Now spread glue in all the holes of the top layer pieces and place it back on the dowels and let the glue dry.

Once the glue has had sufficient amount of time to dry, cut the brace pieces to length. We haven't cut them yet, because the width of the chair can vary slightly based on actual width of individual pieces and how tightly we have pressed the pieces together. Lay the chair down with the spacers kept in place as much as possible so that it is resting flat on the work surface and measure across the outermost top and bottom of the side pieces. Again, the picture will probably help make this much more clear. I like to cut and screw on two pieces and then flip the whole thing over and cut and screw the final pieces. (That's right! I said FINAL PIECES! We're so close now....) This step is done with a scrap flat piece of wood under the side pieces I will be screwing the brace to. This makes gaps between the brace and side pieces much less likely and keeps the pieces from moving around while you are drilling and screwing. Start by drilling holes of appropriate size for the screws your are using (slightly smaller than the screw diameter) through the unstained side of the brace into the outermost side pieces keeping the brace flush with the ends of the side pieces. So, just two holes at this point. Then put a screw in each hole to hold the brace in place for the rest of your drilling and screwing. I then go across and first drill countersink holes in the brace at the center point of each side piece (I always just eyeball this instead of doing precise measurements and have always been happy with the outcome). Once all of those are made, I will drill the pilot holes for the screws in  the center of the countersink hole, being careful not to go so deep that I come right out the other side of the side pieces. Then I will screw the screws into the holes I made for them, remove the two outer screws, drill countersink holes for the outer screws and put the screws in place. Do this at the top and bottom of both sides and the chair is now a chair.

Go ahead and open it up, you know you want to! Awesome!!

Now we just have to put the finishing touches on. That would be sanding and staining the sides of the braces that were not yet stained and putting polyurethane on to match the rest of the chair. You will also need to do a little sanding on the ends of the dowels so they are flush with the outside of the chair. I like to put a little masking tape on the seat and side pieces before I do this so that I don't ruin the finish with the sanding. Use a fine grain sand paper (150 grit or so) and work very carefully even with the tape in place.

And there you have it.

Step 7The Finished Chair

I like these chairs because they look neat and most people have never seen anything like them. Although the basic design for the chair has been around for hundreds of years, modern materials and manufacturing techniques have turned this chair design into aluminum or steel poles with a canvas seat. I really love the warmth and beauty of wood though.

The final dimensions of this seat are fairly standard and make it comfortable for a very wide range of body sizes and shapes. The seat height is about 17 1/2", width is 15" and depth is about 13". Depending on the wood this is made from it can support a tremendous amount of weight. I had a gentleman sit one of the pine chairs (the weakest of the three woods I have made this out of) who weighs about 260lbs and it was able to hold him just fine.I am 200lbs and 6' tall and can sit in these for long periods of time and still be comfortable.  One of the red oak chairs I made was tested by another gentleman that is about 6'2" and weighs 370lbs and it was a comfortable size for him in all dimensions. It folds to about 3 1/2" thick at it's thickest point and is about 37" tall.

It's such a fun chair to make and show off to people that I would strongly encourage anyone reading this to make one if you have the time and the means. You really won't regret it.