(Stupidly Ambitious project no. 2)

Here are my thoughts after making my own pavillion due to being too cheap to just buy one off one of the many fine tent purveyors such as Past Tents.

Basic info:

Cost and materials - 36m hopsack red canvas off ebay £50 inc postage, 10m red webbing off ebay £5.50 inc postage, D rings £3 or so, thread £2 or so, getting poles made/donated by Sean £50. Total cost £110? Owning your own lovely medieval tent: priceless.
Effort - I made the whole thing in three evenings, say 13 hours? Not counting poles.
Equipment - a perfectly ordinary sewing machine did fine for me. More space than my living room has as cutting the pieces is quite a faff.

How to do it

Design

First, and I can't emphasise this enough, DO YOUR RESEARCH! Some collected links which may be of use are listed in Daisy's del.icio.us tents tag. Decide what you want and design it. I decided that I wanted a medium (roughly 14ft diameter) minimum-fuss octagonal pavillion style tent with a central pole which would break down for transport. At this stage, I was planning not to use poles to support each corner and instead simply guy out the structure for strength. That's because I didn't realise how big 14ft really is. I'm not saying it wouldn't have worked without side poles but it would have taken up a huge ground area and probably sagged quite a lot. Some research into canvas showed that a common width is 5 feet (152cm) which is about perfect for the width of a single wall. You could buy narrower canvas and sew it into larger widths if you like - this would be good for a stripy pavillion.

Geometry showed that the minimum total length of canvas needed for an octagon with walls 6ft high and 5ft wide is about 32m. You can do it with less if you make the roof triangles up separately (cut a rectangle down the diagonal, sew together down the outside edge to make an isosceles triangle, this is one roof panel) - do your own maths for that. You really need to be careful with the maths on this - double check all your calculations. Octagon geometry link: http://mathworld.wolfram.com/Octagon.html Here's a lovely polygon layout calculator and another one. Too late for me, but very useful!

So, the maths. Obviously, your sides are easy, decide the length of each side and sew eight of them together (well, 7 and a door). Working out how big to make the triangles that make up your roof is the complicated bit. If you were making a flat roof, you'd need to find out the inradius of the octagon i.e. the distance from face to face, NOT corner to corner. This is the length of triangle needed to make all 8 triangle just meet in the centre. The inradius (r) = 1/2 (1 + sqrt2) * side length.

So, how steep do you want your roof? This defines how much longer than the inradius to cut the length of each isosceles triangle to make up the roof. I wanted a pavilion which was about 10ft high, meaning my vertical raise was 4ft. Easy Pythagoras sorts out how long to cut each roof section.

So, if you're making up the roof pieces from rectangles, cut 8 rectangles which are L x 1/2a, cut 'em in half down the diagonal and sew back together as triangles with base a and height L. Because I was in a hurry and had enough canvas, I just added the triangle on top of each side piece and cut 7 sides in a house shape (the rectangular 5ftx6ft side with the roof triangle on top, and one side which only had about 8 inches of flat bit on it to take the tension at the top of the door, whilst leaving a full side open. (See the pic at the bottom if you don't know what I mean. I think the 'door lintel' bit is important structurally to take the tension).

This means that my pavilion doesn't have seams joining the walls and roof. This is probably good for keeping drips out but may not be so good structurally as that is where all the tension is, so maybe a seam isn't a bad idea. I may at some point in the future add an internal 'extra bit' along the wall/roof join, more as something to pin my banners to than for strength but it all helps.

Assembly

So, you've cut all your pieces. Big aren't they? Somewhat surprising that the pointy bit is longer than the actual walls, but that's hypotenuses for ya. Right then, sew it together. All the webpages recommend using a flat-felled seam (like the one on denim trousers). Yeah, well good luck to you, there's no way you can fold that much fabric like that for the sizes we're working on. Other tent-makers seem to have managed it but not me, not on my little machine anyway. Nope, instead I used the much much easier and faster welt seam (sew fabric face to face, then on the 'wrong' side (i.e. the inside of your tent) pull both bits of seam allowance to one side and sew another stitch line through all three layers. Lovely and strong, and even better because all you see, even on the inside of the tent, is the nice finished edges of the canvas (assuming you're using a full width as the length of your sides). Pulling it all through the machine is problematic but manageable.

Reinforcing

I reinforced every few feet of stitching and at the corners, just in case the crappy thread I was using snaps at any point. Reinforce the corners and particularly the apex of the roof with webbing as you go along (it'll save you pulling 4 whole sides of the tent through the machine to do it once all 8 sides are sewn together). I reinforced each wall-roof angle with a straight bit of 1" webbing. I also put a straight bit of webbing on each seam leading up to the apex (not all the way up, about 6 inches for each strip). When all 8 sides were on, I added two additional bits of webbing which bridged opposite seams which makes a sort of 'cradle' to support the central pole - and mainly to distribute the weight fairly evenly across all seams. This was all done by guesswork, I've no idea how other people strengthen their apex but it seemed to work fine.

I covered some webbing with canvas and used a couple more 5" strips to reinforce the corners of the door where a lot of tension will be. The (guesstimated) principal of reinforcing I used was simply to think about where the stress points would be and then add webbing to spread the tension.

Guy attachments

I made guy attachments using webbing, which I covered with the canvas so they looked nice. I sewed about 5" of covered webbing vertically on, from the outside of each wall-roof corner, not forgetting to slide a D ring on before sewing down the second bit of the loop. OK, I forgot for one of them but it was sewed on so sturdily that it wouldn't come off. Ah well, does the same job. My sewing machine didn't really like going through two layers of webbing and several layers of canvas at the same time. This stage took longer than expected due to reluctant machinery. At the bottom of each seam I made a loop with a D ring on the end of a 5" strip, the free end of which I sewed over the seam itself. These are for pegging it to the ground. I only sewed the first inch or so of the webbing to the actual tent - this was because I had no idea how much my seam allowance might have affected the overall height of the tent (and didn't have the pole yet to test it). Leaving them hanging quite free meant that they could allow for height differences in the walls by either hanging vertical (maximum height) or being pulled out horizontal (minimum height). Gave me about 4" of adaptability.

Erm, that's it. The finished tent: isn't it splendid? It is shown here erected with the poles on the outside as I haven't put holes in the corners for the spikes to go through yet. Worked fine though.

Future tasks

• Make holes in each corner for the spike on the corner poles to go in. Use grommets to reinforce? DONE!
• Add a velcro strap for holding the poles next to the seams.
• Make a door?
• Straps for hanging lanterns off?
• Make a bag? DONE!
  

Lessons learned:

• You need side wall poles if it's anything much larger than a 'sentrybox'. We used tents nearly as big without side poles when I worked for a medieval circus in Portugal, but their weather is better for a start. I wouldn't recommend it.
• No seams = difficult to find a place to pin your banners! A better solution involves running string between the wall poles.
• Some things I did the way I did because I was making the tent in a hurry and without any of the poles to erect it. Certainly I would test it more before adding the peg loops if I had had the opportunity. I was lucky and it measured out perfectly but it might not for you!
• All the web advice says you have to wash all the canvas in hot water to prevent it shrinking. I tested a piece and it didn't shrink at all. Maybe I'm speaking too soon, or maybe it's 'cause it's pre-dyed but there was no way I could wash 36m of canvas in time to make the tent so I didn't bother...

Overall verdict

I used this tent all summer at Maelstrom and man, do I love my tent. I really had The Fear for this project - a big cash outlay for something which either works or it doesn't... but it was much easier than I thought it would be. Buying in the poles certainly helps... and at £500+ for a similar size professionally made it was my only option really. It does leak in incredibly heavy rain, and the walls get wet to the touch but don't drip in steady moderate rain. It has not shrunk or gone mouldy (yet)... and it's had some pretty rough weather to deal with. It's a sturdy tent and copes well with wind.

Improvements

It's now next year and the tent has not only survived a treat through several wet weather events and not gone even a bit mildewey but had some improvements!

Yes, I added holes so that the poles (which have a spike on top) can go on the inside instead of the outside which will make it look a bit neater. There weren't any washers or eyelets big enough for the spikes to go through so I made my own out of spare bits of wonderflex (a kind of plastic that I had hanging around the house). Sewing them on was a bit of an irritation - I painted some PVA glue onto a bit of spare canvas and cut out doughnut-shaped pieces big enough to cover the plastic. Then I made a hole in the existing canvas which frayed a LOT. So after that I painted glue onto the tent as well, then sandwiched the plastic washer between the two non-fraying canvas bits, then sewed around the outside and inside of each doughnut. I will at some point add either velcro or simply ties at the bottom of each pole to keep the tent from blowing about too much as well.

I also added eyelets to each corner where the top of the side poles are. This was initially because I thought that the spike would fit through them (doh!) and it didn't. But all is not lost because I'm going to thread rope through them to hang the internal banners off. It'll be nice and easy because each end of the rope will simply loop over the protruding spike outside the tent. That'll save me safety-pinning them direct to the canvas and risking tears.

More pavillions a.k.a. Jude's Thoughts, By Jude

I made a similar tent along these lines in black and white heavy cotton calico. I double sewed my seams, first with an overlocker/serger then with a straight seam on a regular machine. This certainly seems sturdy, but I'm yet to see how it stands up to use. On the second and third tents I sewed a welted seam, which was troublesome but probably worth it. One thing I found is that you lose quite a lot of height on the side walls in the process of sewing them up, so if a true six foot height is what you need, it's worth adding a few inches. I didn't use webbing, just folded over a strip of the fabric and overlocked the edge, so we'll see how that stands up to the strain, and I didn't use D rings, figuring that they'd probably be ok without.

I made the poles - the centre one is a one inch diameter dowel, and the wall poles are planed 1 inch by 1 inch pine. It's very soft and liable to warp, so we painted them with wood seal in a nice oak tint. The centre pole is split into two for ease of transport, and joined with a locking collar of a cylinder of metal, just larger in diameter than the dowel. It's a bit bigger to allow for potential swelling in the wet. I got this from the Metal Supermarket, found here: http://www.glasgowonline.co.uk/info/17005/ which was very helpful, and was £7 for 2x two foot lengths of mild steel pipe. Two bolts and wing nuts used to attach it.

The outer poles have a spike at the top and the bottom. At the bottom this lets you drive it into the ground, which makes pitching the tent slightly easier. The spike at the top is for either feeding through the loops (for poles on the outside) or through the eyelets at the top (for poles on the inside). These were made by drilling into the end grain of the poles, and screwing in long screws. The heads of the screws were too big to fit through the eyelets, so we got rid of them by hitting them hard and repeatedly with a lump hammer, which breaks the head of the screw off, leaving the shaft and thread intact.

It's worth mentioning that the wood for these black and white ones (nicely planed 1inch square wall poles and finished dowl), ropes for guys (waxed cotton), screws, nails and eyelets cost around £200 for all three tents. She also applied some waterproofing to one of the three. We tested one of the un-waterproofed tents when it was damp and it didn't keep out a hosepipe on its roof (unsurprisingly). We've yet to ascertain whether the waterproofing will be worth the £45ish it cost.

With the leftovers after two pavillions, I made this one. The lighter tents do leak worse than the red one but are fine in light/moderate rain.