10×10 SilNylon Pyramid Design

[Chris Roane]

Hey!

I outline my plans for my pyramid below. Please take a look if you think I am missing something or if I am doing something you don't recommend. I'm using the article Jerry wrote to figure out the calculations, what I need to buy and how to put everything together: http://www.backpackinglight.com/cgi-bin/backpackinglight/myog_silnylon_floorless_2-person_tent.html

Dimensions: 10'x10' Pyramid
Pole Height: 72"
Dimensions of Each of the 8 Pieces: Height: 96.69", Width: 60", Diagonal: 108.74" (this was calculated using a 2" perimeter air gap and assuming the silnylon will stretch 2")

– My plan is to have 8 stake loops for the tent (using the stake loop design from the article). Four for the corners, and one for the middle of each side (one of which is the door).

– I will use a #8 coil zipper that will be about 81.5" in length from the bottom for the door.

– I will use a piece of 200D Oxford for reinforcing the apex that will hold the pole.

– For stability I want to use five larger stakes for the corners and the door (maybe MSR Ground Hogs???) and then lightweight titanium stakes for the remaining sides.

– I plan on strapping two trekking poles together for the center pole.

– In most cases, I envision pitching the pyramid so that there is a 2" air gap.

– I will attach NoSeeum perimeter netting that is 12" wide.

I am not quite sure what I am going to do about a floor and whether or not I am going to attach the floor to the pyramid. I have plenty of silnylon to make a floor…I'm just concerned that it will be way too slippery .

I'm going to be following the instructions in the article exactly for sewing everything together.

Assuming there is no issues with this (that you guys can see), I'll go ahead and order everything else this week and probably start putting things together in 2-4 weeks. I couldn't do this without the help from you guys (articles and useful posts)! Thanks.

[Ben Wortman]

I would skip the floor. With the netting around the perimeter, you should have no problem with bugs. (unless you have the door open) A simple groundcloth would give you alot of options vs. a sewn in floor. If it is raining, you will get water on your floor if is is not movable when you open the door. Plus, you would have to worry about your center pole poking a hole in the floor also if it is sewn in. I have used a simple piece of tyvek with good results.

You could always make a mesh panel the same size as your door opening, and use velcro to attach it. It would give the you option to take it when you need it or leave it at home also.

[Chris Roane]

I didn't describe that clearly. I'm looking at using a groundcloth, and not actually sewing the floor to the shelter.

My main thought was that I would attach the groundcloth to the shelter so it doesn't slide around (thinking of silnylon).

[Jerry Adams]

Dimensions: 10'x10' Pyramid
Pole Height: 72"
Dimensions of Each of the 8 Pieces: Height: 96.69", Width: 60", Diagonal: 108.74" (this was calculated using a 2" perimeter air gap and assuming the silnylon will stretch 2")

Pole height is 72 inches, subtract 2 inches for air gap and 2 more inches for silnylon stretch – height is 68 inches
Distance from center is 60 inches
Height of each of the side pieces is sqrt(68*68+60*60) = 90.69 inches (not 96.69 – only one digit off – maybe I made a mistake – I thought I made a mistake once but I was wrong)
When I have got silnylon that was "60 inches" it was actually a few inches wider, so when you get your fabric you can check this out and maybe make it a bit wider.
Width of each piece = 60 inches
Diagonal = sqrt(90.69*90.69+60*60) = 108.74

– My plan is to have 8 stake loops for the tent (using the stake loop design from the article). Four for the corners, and one for the middle of each side (one of which is the door).

Good – you might find after using it that middle stakes aren't necesary.
For the door, since you have an even number of people, you might want to put a tent stake loop one foot from the door in each direction so it opens in the middle, like it says in the article.

– I will use a #8 coil zipper that will be about 81.5" in length from the bottom for the door.

Good – #5 is all you need though and a tiny bit lighter than #8. Actually, the next time I might try a #3. When you get the zipper, put the pull on it and try it back and forth a bunch simulating what would happen in real life. I bought a #5 zipper and a pull, it seemed like it was the right size, but when I played with it a while it didn't fit right. Better to discover this before you sew it onto the tent.

– I will use a piece of 200D Oxford for reinforcing the apex that will hold the pole.

Good – Will the handle of the trekking pole be pushing against the top of the tent, or will the tip of the treking pole? If it's the tip, is it sharp? That might eventually poke through. Take a piece of the 200D and try to poke through it with the tip using some muscle, simulating a wind storm, and verify it doesn't poke through.

– For stability I want to use five larger stakes for the corners and the door (maybe MSR Ground Hogs???) and then lightweight titanium stakes for the remaining sides.

I use the thin Ti stakes. When I have done this in sandy soil they have pulled out so I put a big rock on each stake, which is not optimum but it got me through the night. If you're in sandy soil, yeah, probably the Ground Hogs are better. Your tent is a little bigger than mine so maybe it needs bigger stakes. There have been threads recently about better stakes for soft ground.

– I plan on strapping two trekking poles together for the center pole.

There has been a thread or two about how to do that.

– In most cases, I envision pitching the pyramid so that there is a 2" air gap.

That works for me. Minimizes condensation. There is only a small amount of air flow inside.

– I will attach NoSeeum perimeter netting that is 12" wide.

Sounds good. I've never worried about insect netting, but here in Oregon and Washington it's possible to avoid periods of heavy insect infestation

I am not quite sure what I am going to do about a floor and whether or not I am going to attach the floor to the pyramid. I have plenty of silnylon to make a floor…I'm just concerned that it will be way too slippery .

Silnylon is pretty slippery. I use a bivy. I think you're resolving this in another thread.

[Chris Roane]

Jerry:

Thanks for your detailed response! Especially on the Height calculation error.

– I'll take your word on the #5 coil zipper. I had noticed that Oware used a #8, but I really have no clue in the difference. When you say: "When you get the zipper, put the pull on it and try it back and forth a bunch simulating what would happen in real life." Is the pull something that comes with the zipper (I would get the #5COIL + Black here: http://www.owfinc.com/Zippers/zippers1.asp )? I want to make sure I order what I need in one shot to save on shipping.

You said: "Will the handle of the trekking pole be pushing against the top of the tent, or will the tip of the treking pole? If it's the tip, is it sharp?"

That is a good question. When I researched the black diamond pole connector, people claimed different things in whether it was the handle or the tip that ended up on top. That is a good idea to test the material to see if it will poke through before attaching it to the tent.

I'm a bit paranoid about tent stakes. I've got 8 titanium stakes from BPLight, but the trekking pole tent I was using last year ended up having the stakes pull out. I backpack in Montana, and so the ground is usually not too sandy. I may buy a couple different ones and do some testing that way.

[Jerry Adams]

"I'll take your word on the #5 coil zipper. I had noticed that Oware used a #8, but I really have no clue in the difference. When you say: "When you get the zipper, put the pull on it and try it back and forth a bunch simulating what would happen in real life." Is the pull something that comes with the zipper (I would get the #5COIL + Black here: http://www.owfinc.com/Zippers/zippers1.asp )? I want to make sure I order what I need in one shot to save on shipping."

#8 or #5 would work fine I'm sure, someone else might have an opinion, I've used #5 for many nights and it hasn't failed

You buy the zipper by the yard, and seperately buy the pull

You can get a pull that has a tab on both sides, so you can open it from outside or inside the tent

If, for example, you get a #5 zipper, and they give you a #8 pull by mistake, it's hard to tell the difference. You have to put the pull on the zipper and make sure it zips freely but it's not so loose it comes off.

That's what happened to me once – #5 zipper, pull that didn't quite match, I assume it was a #8. Probably a rare event that will never happen to anyone else. I'm just paranoid now.

[Chris Roane]

That is great to know! I just put in my order with OWF.

So this week I am going to begin by putting together the tool that you explain in your article in how to accurately measure that catenary cut. In the article, you said: "For each two-inch mark, measure the deflection from the table and mark a dot."

1. Is that measurement from the 95.5" straight line that you made? How do you verify that you are measuring a straight line from the 2 inch mark to the dot for the cat curve?

2. Do you staple the carboard to that piece of wood to make it easier to draw out the catenary curve line on the silnylon?

I know that some of these may be very basic questions, but I'm so out of touch with these things that any tips/advice will be helpful. Luckily my wife knows how to work a sewing machine and she is going to help me with this project. :)

[Jerry Adams]

1. Is that measurement from the 95.5" straight line that you made? How do you verify that you are measuring a straight line from the 2 inch mark to the dot for the cat curve?

I suggest you wait until you get the fabric so you know how wide it is. It's nominally 60 inches but might be more or less.

The diagnal was 108.75. That is the length of the ridge. That is what we want to be a catenary curve. You make your cardboard jig that length.

Mark a straight line. Measure a point every 2 inches. Then you do a deflection from the table in the xls file. Do it perpindicular to the straight line. Just eyeball it. Doesn't have to be perfect.

When you have all those deflection points done, take a careful look at them. They should be in a smooth curve. If you mismeasured a point you can see it by eye.

2. Do you staple the carboard to that piece of wood to make it easier to draw out the catenary curve line on the silnylon?

The piece of wood is so that the cardboard doesn't bend.

If you place the cardboard flat on a surface it bends up and down (obviously) but it also bends sideways some. This is in the direction of the catenary curve. This is going to screw up your catenary curve. That is why you have the wooden board.

Staple it a bunch of places to keep it stable.

[Chris Roane]

Yeah, I was just using the length that was in your article as a reference. I made a step by step process on a sheet of paper so I know exactly what to do to make the jig, with the correct length on there. I figure that time spent in making sure I am as exact as possible with this step will be well worth the effort.

Everything you said make sense. I feel pretty confident with your article and your descriptions. The way you describe using the permanent marker line for the line that you sew on with the sewing machine is genius.

I have a feeling that cutting everything is going to be the simple part…and the actual sewing part is going to be the difficult aspect of this project.

[Jerry Adams]

"The way you describe using the permanent marker line for the line that you sew on with the sewing machine is genius."

I think a professional sewer would just mark the edge of the fabric, and then use the scale on the sewing machine to get the seam exactly 1/2 inch in. But I'm not a professional sewer so I mark the seam line which works.

"I have a feeling that cutting everything is going to be the simple part…and the actual sewing part is going to be the difficult aspect of this project."

Take your time measuring and cutting to get it right.

When you sew make sure and sew a couple scrap pieces to get the tension right.

Then, it's difficult getting the lower and upper pieces to stay lined up, which is why you should pin it or do a couple hand stitches like I suggested.

[Chris Roane]

I still haven't received the silnylon yet. If the material ends up being exactly 60" wide, I'll just change my perimeter dimensions to be 59" per piece (making a 9.83'x9.83' pyramid)…which would allow a 0.5" seam allowance (like what is described in the article).

I'm gathering the materials to make that cat jig (but I won't make it until I get the material). I don't have one piece of cardboard or one piece of wood that will cover the length that I need (around 108"). I should be able to do it in two pieces of cardboard and two pieces of wood. It might be a little tricky in lining up the cardboard exactly. What I will probably do is ductape the two pieces of cardboard together and then cut the cat curve like that….so in theory, this should allow me to make the cat curve exactly as it is calculated.

I'll also ductape the two pieces of wood so that I make one stiff straight piece to staple the cardboard onto.

Is there a certain kind of cardboard that you use for this? I was going to use boxes, but I think that will be difficult to cut precisely.

[Jerry Adams]

I used corregated boxes cardboard

They weren't long enough so I did two layers, overlapping the joint.

Wood piece doesn't have to go all the way to the ends. Make sure any joint in the wood is not at the same place as the joint of the cardboard so it doesn't bend there, defeating the whole purpose.

[Chris Roane]

I received the material late afternoon yesterday. The material is around 66-68" wide. So I started putting the catenary curve jig together. This was actually harder than I thought it was going to be. It looks alright, but I'm convinced there are problems with it. Mainly with the straight line that I based the measurements on…I'm not convinced it is completed straight. And it took me around 2 hours to make the marked curved line (and I didn't even cut it out yet).

I'm going to re-do it this evening. I think if I can make a straight 108" line, I'll be set up for making a great cat curve. It is just figuring out how to make this long of a line straight. I used a measurement against my wall, thinking that would make a straight line, and I do not feel good about it. When I look at the curve, it looks alright. I need to realize that as long as the line is straight, it doesn't matter if it is going at a little bit of an angle.

What I am going to do this time is I am going to draw the main straight line using a 5' level (with help from my wife this time). I'm going to get a better 1' ruler to use for the two inch marks and the deflection measurements. I'm also going to do everything in a room that has better lighting.

After I finished drawing the line, I got confused at where I put the piece of wood. When I looked at what you made, I realized that after I draw the cat curve, I need to complete a rectangle off of the straight line, and put the piece of wood there.

I'll let you know how this turns out.

[James Marco]

Use a chalk line to get a straight line.

[Chris Roane]

Duh! I should have thought of that. I have one of those too!

[Jerry Adams]

Better to go slowly and if it's not right do it over.

You can eyeball for straightness – hold it up and look at it from the end

You can use a string tied to a point on each end

Best to have a straight edge that's long enough for your longest edge – 108 inches or whatever. You could probably find a wooden board – eyeball it to make sure it's straight. Or buy an aluminum straightedge from Home Depot or wherever.

To measure the 2 inch marks, use a tape measure that's at least 108 inches and leave it's end on the end of the jig. If you measure 2 inches from the previous 2 inch mark, you will accumulate error. Probably not critical but better to not use a process that adds unnecesary error.

When you lay out the fabric, make sure and have a flat area bigger than your biggest piece with room all around for you to walk without walking on the fabric. Carefully smooth out the fabric. Good to put weights on the corners (food cans?) to keep it positioned. But you don't want to stretch the fabric wich will affect the dimensions.

Sorry if I say anything obvious. Easier to just say it. Sometimes what seems obvious isn't and vice versa.

[Chris Roane]

Thanks Jerry. All of these are great tips!

[Chris Roane]

So I made the measurements and did the cutting. The chalk line made things way easier and a lot more precise. I will note that it is worth using a good ruler for the cat curve measurements. After I was done drawing the lines, I was very satisfied with how it turned out.

The cutting turned out alright. It was a little hard to do it accurately because I had to cut through the line twice to get through the cardboard (I used a razor blade). I can see that the curve is not 100% perfect…but I should be able sand down the obvious bumps. I think there are spots where I was off in my cutting about 0.5-1 mm from the measured line…so we will see if this has a huge effect on the end product.

Jerry: You were right in that the piece of wood needed a lot of staples through the cardboard to be secure. This not only makes the cardboard a lot easier to handle, but I should be able to use this to make several pyramids this size.

Now to get my wife to show me how to work the sewing machine and make some stuff sacks…

[Chris Roane]

Jerry: I ordered what I thought was the same hook and loop you used in your article. I ordered the H&L 1/2 listed here: http://owfinc.com/Hardware/Shardware/cuffs.asp

However, it looks like this is velcro? I verified that they did send me the H&L 1/2 that I ordered, but I guess I was thinking it was going to be something else?

Can you point to me to the exact item you ordered for the hook and loop on your pyramid (assuming what I ordered wasn't it)? Thanks!

[Jerry Adams]

Hook and Loop is the generic name for Velcro

Not supposed to use the name "Velcro" in articles, have to use the name "hook and loop"

What you got should work great

[Chris Roane]

Jerry: I attempted to test the zipper but we can't seem to get the slider to go up and down the zipper. Should I have gotten the top and bottom stops for the zipper?

I ordered #5CRD and #5 coil zipper on this page: http://www.owfinc.com/Zippers/zippers1.asp . I'm thinking I should have also ordered #5TSTCOIL and #5BST?

Or maybe we are just not connecting the zipper right? Also, can we cut the coil zipper with just regular scissors?

[Chris Roane]

n/m my last question. I was able to figure it out. I did have everything I needed to attach the zipper.

If you never attached a pull to a continuous coil zipper, this is a great article: http://www.questoutfitters.com/zipper_tips.htm.

Yesterday we measured and cut the 8 silnylon pieces. I'm a bit concerned at my accuracy…we'll see how this goes.

I'm now fairly comfortable with the sewing machine and silnylon. Tonight I am going to start sewing the pieces together.

[Eric Swab]

Chris,

I have been watching this thread and look forward to seeing the end result, getting comments on how much time it took, and if you would do it again. The bug netting seems like a scary thing to tackle, I would like to make it either removable or clip up. I have zero sewing experience myself but am really thinking about tackling this project.

Eric

[Ben Wortman]

Eric
I was in the same boat as you. I had no experience, and a 10x10x6 pyramid was my first project. It did not turn out pretty, but it is more tham funtional. I would suggest buying some light cheap fabric a make a 1/4 scale pyramid to practice on. I learned alot of valuable things doing this.

Here is my pyramid in a blizzard a few years ago. It amazed me that it was not shredded after that night. Since that picture I trimmed the corners so that it now rests tight to the ground insted of having a gap between the middle of each panel and the ground

It took me a weekend to complete, and I would do it again. After I made the small one and put a woodburning stove in it, I made a huge one that is 25 feet across and 13 feet high with a stove I bought from Ed T. This one took about a week and a half to complete.

[Eric Swab]

Ben,

Cool picture with the sideways snow and thanks for the vote of confidence. I like the idea of the small size practice tent first, and your "circus" tent, wow?

I have been wondering how the gap along the bottom between the stakes is set? If the catenary curve runs up the ridgelines then I assume the curved gap at the bottom is from stretch down the ridgeline to the stakes?

It seems that some pyramids have more gap than others even when the corners are staked tight. What was the reason for trimming down the sides? Were there any adverse effects?

Eric

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