One of the most time consuming parts of the project is making the khana (wall). The khana is basically a huge baby gate. It collapses down for storage.
Traditionally, the khana is about 4 feet tall, but that is not very practical when you are closer to 6 feet tall. You can make yours any height you wish to, but I will assume that you will be going for a 6 foot khana.
The first thing that you will need to do is figure out how long the slats need to be. The math for this uses the pythagorean theorem. I won’t bore you with the details, so here is the math involved. You start with the height of 6 feet.
(6 x 6) + (6 x 6) = 72
Take the square root of 72 (use your phone calculator) to get the length of your khana pieces.
Square root of 72 = 8.48 feet
Next, we need to figure out how many diamonds there will be. I recommend 10 inches on center for our project.
If your walls are a different height, subtract 4″ from the slat length and divide by 9. You might need to play with this number. Any size from 10-12 inches on center will work just fine. Find the best number for your project that gets you a size in the 10-12 inch range. Ex: 6.5 foot slats would work best with 7 at 10.5 inches.
For diamonds 10 inches on center, the width from tip to tip is: (10 x 10) + (10 x 10) = 200. Get the square root of 200 = 14.14. I’ll round to 14 inches.
From part 1, we know that the khana will be 47.75 feet, or 573 inches. Divide this by 14 to get the number of diamonds.
573 /14 = 40.92. Round up to 41.
Now, you will want to break the khana up into sections to make it easier to carry and set up. I recommend 3 sections. In order to assemble the khana, you will need to overlap at least one diamond per section, so we’ll add 2 diamonds to our count to end up with 43 diamonds total.
Multiply the number of diamonds by 2, and add 2, this is the number of full slats that you will need.
43 x 2 = 86 +2 = 88
Now, let’s talk about materials. You will need to buy lumber and rip it into slats. Don’t buy pine, you want a harder wood like poplar, which is fairly easy to come by. 2×4, 2×6, etc. lumber is easiest to get. I’ll assume you can get 2x6x8 poplar. Yes, we calculated 8.5 feet, but getting 10 foot poplar is not easy. It’ll just shorten your walls by a few inches, not a big deal really.
A 2×6 is actually 5 1/2 inches wide. You will be ripping 5/8″ slats, and the table saw blade will eat 1/8″ each cut, so you need 6/8″ (3/4″) per slat.
5.5 / .75 = 7.33 slats per board. Round down to 7.
Divide the total number of slats by 7 to get the number of boards you need to buy.
88 / 7 = 12.57 round up to 13.
Now, there will be knots in the lumber. You want to pick the boards with the least amount of knots as possible. Knots are weak spots, the slats will break at the knots. Also, there will be natural weak spots in the lumber, so I recommend cutting 25% more slats than you need. I’d buy at least 17 boards.
On the last yurt I built, we cut about 120 slats, and about 25 broke when we stress tested them prior to assembly. This left us with about 10 good spares for future repairs.
To cut your slats, set your table saw at 5/8″. I recommend a friend to help feed the saw. The finished slats will be 5/8″ x 1.5 x 8 feet. If you need shorter slats, shorten the boards before you rip the slats.
Measure 2″ from one end to mark your first hole, then every 10 inches make another mark. If you did this properly, your last mark should be 2″ from the other end. Now is your chance to fix the size of the diamond if you need to. Write down your final measurement. You’ll need this later when you drill the holes.
There are several ways to put the khana together :
- Rivets
- Bolts
- Lacing
There are pros and cons to each of these systems.
Rivets are fairly easy to use, and are very secure. They won’t loosen up over time. The downside is when you break a slat, you need to drill out the rivets on the broken slat. 1/4″ rivets should work. There is no forgiveness for sloppy hole spacing.
Bolts are the simplest to install, but the nuts tend to come loose, so you will need to keep some spares handy. They also don’t look as nice when it is set up. You can get by with 3/16″ bolts. There is no forgiveness for sloppy hole spacing.
Lacing looks really neat, and can be unlaced to replace a slat. The downside is that the rope tends to stretch over time, so you will need to retighten them every once in a while. I use 3/16″ woven nylon rope when I do this. There is plenty of forgiveness for sloppy hole spacing. This is my preferred method.
Now you are ready to drill holes in the slats for assembly. Mark the holes using the spacing that you measured earlier. Be as precise as you can be. A drill press makes this job much easier.