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Refinements to glueing tarp

June 26, 2021 — BarryK

Continuing TreeHugger 1P Mark-2 project, previous post:

https://bkhome.org/news/202106/treehugger-1p-tarp-mark-2.html

Some issues have been identified, and solutions...

Glueing reinforcements

I have glued on the tie-out reinforcements, and it has, in some of them, been unsatisfactory. These reinforcements are at the tie-out points, where webbing is to be sewed on, to spread the tension. They are just pieces of the same fabric glued onto the tarp.

The procedure is to spread silicone adhesive on a reinforcement, using the fingers, then lift it up and place it onto the appropriate place on the tarp. Getting it to lay nice and flat, and in the right place, no ridges and no bubbles, is a challenge.

There is a video on YouTube where a guy shows how to do this, that I have linked to in an earlier blog post. However, I have concluded that his method is not suitable for me. Where is that video? Ah, here:

https://www.youtube.com/watch?v=Ec8YhQffRj8

He might have got away with it using heavier fabric, however, 10D silnylon is incredibly stretchy. Using the fingers to smooth out the piece of reinforcing, and push out bubbles, stretches it -- and here is the thing -- the underneath fabric does not stretch, or will stretch less. So, after attempting to smooth the piece of reinforcing, ridges can form in the underneath tarp. You might then battle to stretch the tarp to remove those ridges.

One factor though, in support of his method, he is using Gear Aid Seam Grip seam sealer.  In his case, the surface is PU, but for silicone surface, as for silnylon, Gear Aid have "Silnet", also known as "Seam Grip + Sil", which is a thinned silicone adhesive. Seam sealer, being thinned, is quite runny -- it is designed to seep into the sewn threads.
Silnet is far more runny that straight silicone adhesive from the tube, that you buy in a hardware store. The runny seam sealer has much less "grip" between the two surfaces, so you are more easily able to push the reinforcing around after placing it on the tarp.

Note, I have experimented with that Silnet. You buy it from camping stores, it is for seam-sealing tents. It is very runny. Also, it is much less "sticky". I found when folding the hem, that it was somewhat reluctant to stay down. The straight silicone, you fold the hem, and that's it, it is stuck.

So, using straight silicone adhesive and pushing the reinforcing around with the fingers, what you end up with is a weirdly distorted reinforcing.

Extra notes about the video:
Do not use bare fingers, as he has done in the video. Exposure to harsh chemicals may not have an immediate effect, but in the long term the body will react.
Also, I think the way that he has spread the seam sealer is inefficient -- dribble beads over the entire surface first, in roughly parallel lines, then simple sweeps with side of a finger can spread it.
Also, with care, the piece of reinforcing can be laid pretty much in the correct place, without all the wrinkles requiring to be pushed out as he has done.
He used a soldering iron and comments that it cauterizes the edge so won't fray -- however, as the reinforcing is glued to the tarp, there won't be any fraying -- besides, ripstop doesn't fray. Cauterizing will cause lots of little melted lumps -- notice, later in the video he trims some of them off. OK to cut out the circles with scissors.

I used this finger method on a few of the reinforcing pieces, then remembered that with Mark-1 I only used the fingers a little bit, then used the Uni-Pro seam roller. See photo of the seam roller here:

https://bkhome.org/news/202105/tarp-glueing-hems-and-ridgeline.html

Yes, this is the way to do it. Hopefully, lay the piece of reinforcing down accurately, so you don't have to pull it around, then run over with the seam roller.

So, some of the reinforcing tie-out points look good, some look crappy.

Spreading adhesive

I posted about a problem with spreading the adhesive for hems and ridgeline. A dribble of adhesive along the line to be joined, then use side of a finger to spread it. But of course the adhesive will spread out, and the problem I had was the chalk mark getting erased. I posted about this problem, with a suggested workaround to draw arrows:

https://bkhome.org/news/202106/treehugger-1p-tarp-mark-2.html

However, today I devised another solution. Bought 16x16x1.5mm aluminium channel from Bunnings, cut it at 45 degrees, and very carefully filed the tip so that (hopefully) a thin film of adhesive will be spread, only 13mm wide:

img1
img2

I filed so that an extremely thin film of adhesive will slide through. The channel is held with the index finger pressing lightly so that the sloped end slides over the fabric, following the marked chalk line, the sides keep the adhesive from spreading out. Adhesive still needs to be dribbled down the line-to-be-joined beforehand.

Length is non-critical, I cut off 14cm of channel, which fits nicely in the hand. Cut at 45 degrees because my hacksaw-jig thingy only does 22.5, 45, or 90 degrees. Perhaps a steeper angle would be even better.

A little bit of experimenting, and it works well. The great thing about this is two-fold. Firstly, the chalk line is still there, so can see where to fold the hem, or overlap the ridgeline. Secondly, no glue is wasted.

That second point is very important. I have found when constructing Mark-1 and Mark-2, that the glue can very quickly become a significant part of the weight of the tarp. I would even say, that if you apply it liberally, you could even double the weight of the tarp-sans-glue.

A little thought about the weight compared to sewn tents. They need seam-sealer, such as Silnet, and you can very easily use up a 50g tube on one tent. My glued tent does not need seam-sealing, except where the tie-outs are sewed on, and the amount of glue used could be similar to, or less, than that used to seam-seal a sewn tent. As long as there is no excessive glue applied.

The 16x16x1.5mm (13mm inside width) channel is OK for the hems. For the ridgeline, need wider channel, but the biggest that Bunnings sell is 20x20x1.5mm (so 17mm inside width). Actually, the 3cm overlap that I have done so far for the ridgeline, is probably more than needed. Will think about that. Might shop around, see if can find slightly bigger channel.

Chalk marking

I have posted about using a fabric marking pencil. Still not happy about it. It is some kind of "chalk", but is too hard, and I have to press harder on the fabric than I would like.

What I am using now is a chalk bar, designed for use on fabric:

img3

https://www.spotlightstores.com/sewing-fabrics/scissors-dyes-accessories/sewing-tools-accessories/fabric-markers/birch-tailors-chalk-pack/BP80054557

https://www.spotlightstores.com/sewing-fabrics/scissors-dyes-accessories/sewing-tools-accessories/fabric-markers/birch-tailors-chalk-sharpener/BP80054555

...I bought the second one, because the first is out of stock at my local Spotlight. The inbuilt "sharpener" is a joke -- just use a blade, or any sharp edge.

I also bought some chalk from the kid's section in Kmart, but found it to be unsuitable -- too crumbly. It tends to come off in chunks rather than a nice line on the fabric. Maybe it is just the cheap brand -- "Anko", which is Kmart's own brand.

EDIT:
Bought 25.4x25.4x1.2mm, 0.45m long, "Connect It" rectangular aluminium extrusion from Bunnings. So that is about 23mm inside width. Cut it at 45 degrees. Here it is:

img4

Not yet tested. I think that it would be necessary to dispense the adhesive in a zig-zag pattern along the line to be joined, to optimize even spreading.   

Tags: light

TreeHugger 1P tarp Mark-2

June 21, 2021 — BarryK

Complete instructions for Mark-1 tarp are here:

https://bkhome.org/light/treehugger-1p-tarp-weighs-only-178g.html

Mark-1 was a learning experience, and hopefully Mark-2 will be pretty much what I want as the final product.

The original concept was to have a 25mm carbon fibre spreader-bar just above head-height, to give more head room. I was a bit nervous about how that would complicate the design and how the sides would hang, so Mark-1 does not have the spreader-bar.

With Mark-2, decided to "go for it" and construct as per the original concept, even though haven't quite figured out some details for affixing the spreader-bar.

This time, I am using 10D silnylon purchased via Aliexpress, from Rex Outdoors:

https://www.aliexpress.com/item/32625219053.html

Rex Outdoors only ships by China Post, which is very slow. Not sure, think that it took about 2 months to reach my doorstep in Australia.

Construction proceeded as per the Mark-1, this time with slightly different dimensions:

img1

4.8 metres of fabric is required, and the 2 pieces can be cutout efficiently like this:

img2

So, had 2 pieces, and together they weigh 133g. It will be very interesting to calculate the weight of the fabric in grams per square metre. From SolveSpace, the bottom-left angle is 87.3 degrees and top-right is 74.96 degrees, on the top image above. Then can calculate the area:

https://keisan.casio.com/exec/system/1322718508

Gives the 2 pieces 4.08 metre squared, which calculates to 32.6gsm.

Very interesting! The photo on the Rex Outdoor page states 28gsm, then further down they have 30gsm.

I really do need a reference weight to test the accuracy of my digital scale. It is only a cheap one from Kmart.

Note, I suspect that the manufacturer and vendor are just stretching the truth a little bit, by including the border of the fabric in the area calculation. Only suspect, not verified! There is roughly 1 inch along both sides of the fabric that are not silicone-impregnated, thus lighter. That's why, in the photo below, you can see the ridgeline of the first piece placed about 1 inch from edge of the fabric, because that is going to be cut off.

Marking out this fabric has proved to be even more of a challenge than the previous fabric used in the Mark-1 tarp. This stuff is very translucent. Here is a photo showing the first cutout laid on the fabric to use as a template to mark-out the second piece:

img3

For Mark-1, I used these fabric-marking pencils:

https://www.spotlightstores.com/sewing-fabrics/scissors-dyes-accessories/sewing-tools-accessories/fabric-markers/semco-fabric-pencils/BP80401344

However, with this green fabric it is difficult to see the line. With Mark-1, I was pressing the pencil a bit too firmly onto the fabric and I was worried that it might be damaging the delicate fabric.

I have experimented with other markers. On the forums, the Sharpie metallic silver permanent marker pen is highly recommended. However, I think that it is unsuitable for a couple of reasons.
Firstly, it remains highly visible through the translucent fabric. Secondly, it may compromise the silicone glueing -- I have no idea how well the silicone adhesive will stick to it.

I also tried chalk, but when ran a bead of adhesive along with the finger, while glueing a hem, it also erased the chalk line. So I could not see where to fold the hem over to, and had to estimate it visually , which was not satisfactory.

Actually, I did use the Sharpie pen to mark-out the two pieces, as the marked line was outside where cut with the scissors.

For the hems, I went back to the Semco pencils. To make the line more visible, needed something dark underneath. This was the only dark fabric I had available:

img4

...the photo shows a length of wood being used as a ruler for the marker pencil. I took care to press the pencil lightly.

Running a bead of adhesive along with the finger does still partly erase the marked line, but enough remained for me to just make out where to fold the hem.

EDIT 2021-06-22:
Hmmm, no, not so good. Sometimes the marked line is completely gone. As had pressed lightly with the pencil, it gets erased when spread the adhesive with the finger. I think that it is chalk-based, and the particles get swept away.

Struggled through with the hems, but when got to the ridgeline, tried this...

I don't need a continuous line, just periodic visual cues showing where the other piece of fabric is to be pulled onto overlap the underneath piece. To achieve this, I drew arrows, about every 6 inches:

img5

Yes, this works. Even if the tip of the arrow gets swept away, I can still see where it is pointing to. In the photo, you can see the other piece of fabric at the bottom, the edge of which has to be pulled up to the marked line. Overlap is 3cm.     

Tags: light

Sewing neophyte slowly learning

June 14, 2021 — BarryK

What has plagued my sewing so far, is thread getting caught up in the bobbin area, and a rats nest of threads on the underside of the fabric.

Today I watched a couple of videos that have resulted in significant improvement:

Singer 4411 Heavy Duty 12 Tension Test:

https://www.youtube.com/watch?v=AfDNGOug7bY

Singer 4411 Heavy Duty 13 Holding Threads When Starting to Sew:

https://www.youtube.com/watch?v=qojD8LuHm2k

Following the instructions, I found that the tension setting is the culprit. I had it set just above "4". Changing it to just below "4" did the trick.

Incidentally, I am now using Guterman Extra Strong thread from Spotlight:

https://www.spotlightstores.com/sewing-fabrics/haberdashery/sewing-threads/gutermann-extra-strong-thread/BP80055520

No particular reason for changing from the lighter thread, except that it looks good.

And as before, a sharp/microtex 80/12 needle:

https://www.spotlightstores.com/sewing-fabrics/haberdashery/needles-pins/needles/klasse-8012-sharp-machine-needle/BP80529911

Another problem occurs when do a back-stitch at end of a line of sewing. The Singer 4411 has a lever, press that and then the foot lever, and sewing will go back. It is normal practice to do this at start and end of a line, however for me it results in messed up threads on the underneath of the fabric.

The hint I got from watching the videos, is, when get to end of a line, wind the wheel at right-side of sewing machine counter-clockwise, until the needle is up and the metal part comes up out of the top of the sewing machine, to it's highest level. That completes a sewing cycle. Then hold down the reverse-lever and sew backwards.

Not quite sure about that last paragraph, have to experiment some more.

EDIT 2021-06-15:
I have gone back to using standard Guterman thread from Spotlight, which is, I think, called "sew all" thread in some other stores.

Reason is, I cannot stop thread bunching underneath the fabric when sewing webbing onto the fabric. I messed around with tension setting, tried both walking foot and standard foot, to no avail.

Back on the "sew all" thread, with tension setting just on "4", it is working reasonably well. Still not perfect, sometimes get small loops at start of a line of sewing, and when reversing. But much better than the mess I was getting with the "extra strong" thread.

https://www.spotlightstores.com/sewing-fabrics/haberdashery/sewing-threads/gutermann-polyester-thread-colours-0-99/BP80173074

One of the things that annoys me about Spotlight, is they often give inadequate specifications. See the above link. I determined from reading elsewhere what kind of thread it actually is. 

EDIT 2021-06-16:
I mentioned above about finishing sewing with the lever sticking above the sewing machine. This video shows what I mean:

"Singer 4411 Heavy Duty 20 Take Up Lever in the Highest Position"

https://www.youtube.com/watch?v=bpa7uJBCbnw

...she calls it the "takeup lever".

She advises to do it at the end of a line, before lifting the foot and removing the fabric.

But see in that video, she got to end of line, held down the backstitch lever momentarily and did a quick back-stitch. Didn't bother with getting that takeup-lever at max height.

So I still have the problem of some looping underneath the fabric when back-stitch. Forum member williwaw has suggested that I might need to adjust the bobbin tension. Will read up on that.

EDIT 2021-06-16:
Hey, she -- her name is Sara -- does have a video explicitly on back-stitching:

"Singer 4411 Heavy Duty 16 Reverse"

https://www.youtube.com/watch?v=q9U68lwkUuw

Interesting, she sews in reverse at the beginning. And does it real fast, like she doesn't even take her foot off the floor pedal.    

Tags: light

Catenary cut for tarp ridgeline

June 09, 2021 — BarryK

After constructing the TH1P tarp Mark-1 and erecting in my lounge room, then eye-balling it, I realised that it would be better if the ridgeline is joined in a catenary-cut. Previous post, showing photos erected in lounge room:

https://bkhome.org/news/202106/bottom-tie-outs-and-tarp-completed.html

It is not apparent from those photos, but the fabric either side of the ridgeline is loose, not taut. even though I pulled the cords fairly firmly at each end. The problem is, the ridgeline is never going to be a straight line, no matter how firmly you attempt to tie each end. It will sag.

This photo shows the sag in a straight-cut ridgeline. OK, it is a bit exaggerated, because the ends have not been pulled firmly, but the shadow does show you the effect of the sag:

img1

This sloppiness can be mitigated by having extra tie-outs on the sides of the tarp, but I would prefer not to have more stakes to hammer in.

There is a fix for this problem, to join the ridgeline in a curved shape, so when erected, the fabric either side of the ridgeline will be taut. This photo shows a tent which has such a curve:

img2

...you can see, a reasonably firm tension applied each end, the ridgeline has a sag, but the fabric each side is taut.

My apologies to whoever posted the above photos, for not acknowledging you. I downloaded them and don't recall the URLs. Ah ha, found one URL, but he also has "borrowed" the photo from somewhere else.

The curve shape is known as a "catenary". The Wikipedia defines a catenary as:

A catenary is the curve that an idealized hanging chain or cable assumes under its own weight when supported only at its ends.

So, it would be good to join the two halves of the tarp so that the ridgeline has this natural hanging shape. As I have already created a straight ridgeline, I decided to modify it to be a catenary.

Firstly, I need a formula for calculating the points along the catenary. Fortunately, 'XTrekker' has done it:

https://www.hammockforums.net/forum/showthread.php/85208-Catenary-Parabola-Curve-Calculator

...you can run the formula online, or download the Excel spreadsheet  -- which runs great in LibreOffice.

I have uploaded the Excel spreadsheet here.

Note, XTrekker's formula is for both ends of the tarp to be at the same height. My tarp is lower at the foot-end, but I don't think it matters if the cut is not to an exact catenary mathematical formula.

Back in an early post of these tarp construction instructions, I gave the dimensions of each side of the tarp, and the ridgeline was 222.2cm. After folding the hems, the final ridgeline length on my tarp is 215cm.

But the big question, how much "sag" to put into that formula? After a bit of reading other people's experiences of a minimal catenary, I chose 4cm. Tabulating the results from the spreadsheet:

Distance
Offset "b"
0 (centre)
4.0
25.0
3.8
35.5
3.6
43.5
3.4
50.0
3.2
55.5
3.0
61.0
2.8
65.5
2.6
70.0
2.4
75.0
2.2
78.0
2.0
81.0
1.8
85.0
1.6
88.0
1.4
91.0
1.2
94.0
1.0
97.0
0.8
99.5
0.6
102.5
0.4
105.0
0.2
107 (end)
0

I have modified my tarp, by cutting along the ridgeline, then re-glueing.

For someone constructing the tarp from scratch and wanting the catenary curve on the ridgeline, I would like to theorize on a couple of ways it can be done. Let's call them "method-1" and "method-2"....

Method-1: variable overlap

This sketch explains theoretically how I think it could be done:

img4

The top sketch shows the two tarp ridgelines placed together, and the red dashed line is the pencilled catenary shape. There has to be some overlap at the ends, named "a", and in the centre there will be an overlap of "a" + "b", where "b" is from the above table.

One thing that I think you will need to be careful about, is not just to pull #2 side up to the pencil line, as the ridgeline will be slightly wonky. #1 and #2 edges need to be pulled equally. I think that a way to achieve a nice non-wonky join, is to do what I suggest in the bottom sketch.

I have indicated a sequence, 1, 2, 3, but you might find it better to do 2 first. That is, anchor each end firmly with weights, then pull the two edges so that they overlap and follow the pencil line. Then put in pins to hold the overlap in place.

Then step-3, glue. Tarp #2 will be sitting on top of #1, and you can glue it down. Usual procedure: dribble a line of silicone adhesive, then run your finger along to spread it, then press down. The only thing to be concerned about is that the spread of glue as you run your finger down, reaches the edge, so edge #2 is glued down all the way along.

Take out the pins, leave overnight. Next day, flip over and glue the other edge.  It is then wise to leave for several days, to fully cure.

Method-1 is wasteful of fabric and glue, and the tarp will be unnecessarily heavy, as the "b" value gets bigger. Plus, I am not sure how the ridgeline will hang with a large centre overlap.

I came up with that 4cm sag figure from reading forum posts, but those people were using method-2. So, "b" should be doubled for method-1, but 8cm fabric overlap is, I think, not the way to go. I am describing method-1 in this blog post, for consideration if you only want a tiny sag value.

The alternative is the traditional way, cut a catenary shape on the ridgeline edges of both tarps, and then join them with a constant overlap the entire length. This is Method-2...

Method-2: Catenary cut

Another sketch to show this:

img5

With this method, you mark catenary lines on both edges, then cut. This is shown by the pink dashed lines. If you used a "b" value of 4cm, as per the above table, then you are going to get twice the catenary effect than for method-1.

On side #1, mark another line for the overlap. I suggest the orange dashed line to be 3cm from the pink dashed line.

To glue the two sides, I think that you could still use the pins. So you would pull side #2 over side #1, pull each end and put weights, then pin, then glue.

Leave overnight, then flip over and glue the other edge.

I used method-2 on my tarp, and used pins. To make it easier to insert the pins, I hung the two tarp-sides near vertically, using a plank. The plank is dressed pine, 184x19x2400mm. Use a large crocodile clip at one end, to hold the two pieces of tarp together, with 3cm overlap, onto the end of the board. At the bottom end, you could use another crocodile clip to hold the tarp pieces together, again 3cm overlap.

Haven't got a photo of that, but it should be easy enough to visualize. That made it very easy to insert the pins.

I then laid it horizontal and glued. I left the pins in, but that is OK, next day flipped the tarp over and glued the other flap.

I had removed the tie-outs at each end of the tarp. Need to reconstruct those, then will take a photo of the erected tarp, and will update the tarp construction details here:

https://bkhome.org/news/202105/tarp-glueing-hems-and-ridgeline.html

This time, will use some heavier-duty webbing for the ridgeline tie-outs.

EDIT: TH1P tarp mark-1 with catenary-cut

I cut along the ridgeline, cut the catenary curves, re-glued, sewed new webbing tie-outs. Unfortunately, all this messing around has resulted in a lot more glue and some extra reinforcing bumping the weight from 178g to 218g, a jump of 40g. That is unnecessary extra weight, would have been less if had done the catenary-cut from the start.

Here is a photo:

img1

I am really not convinced that the catenary-cut is worth the effort. Yes, it does take up some of the slackness along the ridgeline. The tautness will also have an advantage when wind hits the side of the tarp, it will more readily flow over the tarp, instead of trying to push it over. Some people cut even deeper catenary, but then they are going to be loosing more height inside.

A straight-cut is probably preferable if you want to erect the tarp in other ways, not just as a V ridgeline.

For the tie-outs on the ridgeline, I have gone for a thicker webbing. This, 12mm wide by about 1mm thick:

https://www.aliexpress.com/item/4000126877988.html

...it is only available in black.       

Tags: light

Bottom tie-outs and tarp completed

June 05, 2021 — BarryK

Here is the previous post, in this "TreeHugger 1P tarp Mark-1" project, making the ridgeline tie-outs:

https://bkhome.org/news/202105/tarp-ridgeline-tie-outs.html

Today I sewed on the tie-outs along the hems. That is, the four corners and the middle of the sides.

I used the same webbing as before, nylon, just 10mm wide and 0.5mm thick:

https://www.aliexpress.com/item/1005001666741572.html

Cut these pieces, 16mm long, folded over about 35mm and sewn, with rubber o-rings, and one of them has a hook. The one with the hook is folded over a bit more so that the hook is the same distance from the tarp as the o-rings:

img1

The length of this webbing is a matter of personal preference, how high you want the tarp hem off the ground, and of course longer webbing will make the tarp wider when erected.

Note, when I cut the nylon webbing, I also use a flame to cauterize the ends. Important, otherwise the ends can unravel.

The o-rings are silicone rubber, 25mm OD, 4mm thick. They feel strong enough, however for future projects I intend to use o-rings made with EPDM rubber, as it is stronger than silicone rubber. Note also that EPDM is UV resistant. A cheaper rubber is NBR, and this is not UV resistant. This is what I have on order, 25mm OD, 4mm thick:

https://www.aliexpress.com/item/1005001631629585.html

The plastic hook in the above photo is a bit bigger than I wanted, so I ordered a smaller size. These are 3.6cm overall length, just what is needed:

https://www.amazon.com.au/gp/product/B08P14TWG1

They arrived after the initial writing of this blog post, and I swapped for the smaller hook. The EPDM o-rings also arrived, but will keep the silicone rubber ones on the tie-outs -- the EPDM ones can be for mark-2 tarp.

Sewed the tie-outs on, with my newbie wonky sewing, and erected the tent in my lounge room:

img2

The wooden frame is my "dressmaker's dummy", to make it easier to construct the inner-tent while inside the house.

The tie-out with the hook is front-right, as the tarp is intended to become a step-in and step-out tent, with zipper entry to the inner tent on the side.

Those o-rings are intended to go over stakes, and in the case of the hook, it will hook onto an o-ring. That is a detail that will become apparent when the inner components of the tent are constructed. For now, we only have the "stage 1" of the tarp, but still, you can see how the hook can be unhooked from the o-ring and folded over the ridgeline:

img3

Actually, even at this stage, the side flap is useful. If the high-end was tied to a tree trunk, the pole not used, the side flap is a convenient way to get in and out.

Here is a rear view:

img4

Now for the really interesting bit, what this tarp weighs. Wait for it...

Weight of tarp: 178g

Or, in Imperial measurements, 6.3 ounces. That is good.

What is planned next, is baffles for front and maybe on the low-end. The baffles are intended to facilitate exact spacing for the stakes, and to hold the o-rings firmly at ground-level -- so they will be less likely to be pulled up when wind blows on the tarp.

Planned erection procedure is you would stake out the tarp, with 4 stakes, then tie up the ends, with or without poles. I plan to use this without a high-end pole, as then the high-end ridgeline tie-out can be pulled up and tied to a tree, no need to have tension adjusters on the ground-level stake tie-outs. Of course, if you have a trekking pole, the length can be adjusted, so again, no tensioners required at the stake tie-outs.

The same principle holds for the low-end, but I will probably use the pole, as it might be difficult to locate a branch to tie to. Well, could use a stick, maybe with v-notch to run the cord over.

The front and rear baffles will also offer rain protection, and will have openings for ventilation.

These are future plans, but the tarp as constructed so far is quite useful. I cannot tell you how sturdy it is in windy conditions, as so far it hasn't been out of the house.   

Tags: light

Tarp ridgeline tie-outs

May 30, 2021 — BarryK

Continuing the "Mark 1" tarp construction project, this is the previous post:

https://bkhome.org/news/202105/constructing-short-pole-for-tarp.html

So far, the tarp has been constructed by glueing, no sewing, but now, I have sewed the webbing onto each end of the ridgeline. The webbing I used is this:

https://www.aliexpress.com/item/1005001666741572.html

With a cord tensioner:

https://www.aliexpress.com/item/1005002198346631.html

I am going for lightest possible weight, but uncertain if have taken it too far with this webbing. It is nylon, 10mm wide and only 0.5mm thick. Apart from nylon having limited UV resistance, it is very thin. Might be better described as ribbon, than webbing, but it seems strong enough. If it breaks, I suppose can sew on something else later.

I have a Singer 4411 sewing machine. Set it to zig-zag stitching, width "1" and length "3". Using standard Guterman polyester thread from Spotlight -- I think this is known as "sew all" thread at some stores -- Spotlight also have "extra strong" but didn't use that. Set the tension to just above "4". Using a walking foot.

One more thing, used a sharp needle, size 80/12:

https://www.spotlightstores.com/sewing-fabrics/haberdashery/needles-pins/needles/klasse-8012-sharp-machine-needle/BP80529911

...apparently, the standard needle that comes with the sewing machine, has a slightly rounded point, designed to push-aside threads, which is (apparently) not the best for sewing ripstop.

The reason to stitch zig-zag is that polyester thread is far less stretchy than nylon. This means that a straight thread may break when the tarp ridgeline is pulled very tight. At least, that is advice I got off the Internet.

The original plan was to sew a nylon washer underneath, for the support-pole to slot into. I did that, but it doesn't look sufficiently robust:

img1

Scrap that idea. The carbon-fibre pole has a rubber end-cap, so there is some spread, but what is needed is something to keep the pole in place. I want the pole to be right under the webbing.

Found a length of 25mm nylon webbing, cut two pieces, clamped them together, then used a soldering iron to make a hole:

img2

Good, created a hole into which the pole end-cap can be inserted, with side-walls high enough to keep the pole in place. Then glued it to the tarp:

img3

Looks good. Could have gone even further, with 3 layers of webbing.

Note, glued a tiny piece of ripstop underneath, so the pole is not rubbing directly on the webbing.

Note, if that sewing looks a bit wonky, it is. I'm a sewing newby, was experimenting with different zig-zag widths etc., while doing it. Yes, did try on some scrap fabric first, but still had to play with settings while doing the actual job.

Will do the same for the other end. Then will do the tie-outs on the bottom of the tarp. A bit of delay there, as ordered plastic hooks, that go onto end of webbing or cord, and they haven't arrived.

Some other items ordered from Aliexpress also haven't arrived. Then I made a discovery. Although I had chosen "Aliexpress Standard Shipping" when ordering, these non-arrived items were shipped by China Post -- which is considerably slower to Australia. The vendors took the extra money that I paid, and then posted by the cheapest means.

I have complained to two of them, asking for a refund of the difference. Anyway, I found another vendor of those plastic hooks on Amazon, placed an order.

EDIT 2021-05-31:
The above picture is for the ridgeline at the low-end of the tarp. The high-end is a different story, as the walls form an acute angle. The "cup" that will hold the pole will have to be as narrow as possible. I oriented along the ridgeline and also trimmed the width a bit with scissors:

img5

...it is 4 layers, 3 of them form the "socket" into which the pole will be inserted.

Still concerned that this is too wide. Maybe also too fragile. Anyway, will see how it performs when in use.

Though, I don't intend to use a pole at the high-end, so the fragility might just be an academic issue. Most interested in erecting it in "tree hugger" mode.

Ideally, want the "socket" to be no wider then the webbing. An idea is a plastic screw-on top off something -- like the screw-top on a tube of toothpaste, but it would have to be wider. Then drill tiny holes in the base, so that it can be sewed onto the tarp. Or even glued to the webbing with epoxy resign. Maybe will do that for tarp "Mark 2"! 

EDIT 2021-05-31:
Thinking about it some more, a narrow "socket" for the high-end could be achieved by these silicone end-caps:

https://www.aliexpress.com/item/1005001609758449.html

I already have some with 7.7mm ID, 11mm OD, which would be just right. As they are silicone, they can be bonded strongly to the webbing. A bit of reinforcing around the end-cap could enhance the bond integrity. Maybe even some epoxy resin in the bottom, to spread the force. Just making a note of this alternative, a possibility for the "Mark 2" tarp.

EDIT 2021-05-31:
Hey, why not? I cut the 7.7mm ID silicone end-cap a bit shorter, and glued it into the hole previously created:

img7

Now, just insert the metal pointy-end of my carbon-fibre pole (or a trekking pole), and we are good to go. The ridgeline width is still a concern, but we shall see once it is up and in use. The CF pole I am referring to, is this one, purchased awhile ago (125cm, 5-segment):

https://www.aliexpress.com/item/32918962406.html

img8

Actually, I have two CF poles, see report here, but the other one is not suitable for this tarp, as shorter:

https://bkhome.org/news/202103/two-cf-straight-tent-poles-compared.html 

EDIT 2021-07-04:
I am now favouring a simpler method for the "sockets" in which the poles are inserted. Just glue the silicone end-cap onto the webbing. That's it, nothing else. See details here:

https://bkhome.org/news/202107/treehugger-1p-mark-1-tarp-deep-catenary-cut.html

img10      

Tags: light

Constructing short pole for tarp

May 27, 2021 — BarryK

Continuing construction of an ultralight tarp, this is the previous post:

https://bkhome.org/news/202105/tarp-glueing-reinforcing.html

The tarp has a ridgeline, with a high head-end and a low tail-end. The head-end can be tied directly to a tree-trunk, branch or can sit on a trekking-pole or a 125.5cm carbon-fibre pole.

The pole for the tail-end is to be 48.5cm, and I want  it foldable, no longer than 25cm so as to be able to lay flat in my backpack or lumbar pack.

The tarp is intended to have in inner mesh tent permanently sewn in, and the tail-end pole will also be sewn-in. The 2 pieces of the tail-end pole could have bungee cord to keep them together -- that is the usual method -- however, being sewn into the tent, think will be able to avoid a bungee cord.

I have carbon fibre tube, 4x6mm (IDxOD) and 6x8mm (IDxOD), the latter to be used as the joining sleeve. Here is a picture:

img1

Those 4x6 tubes are 24.8cm long each (without the end-caps), and I cut 3cm length of the 6x8 for the joining-sleeve. There are rubber end-caps, that add a couple of millimeters on each end.

When pulled apart, the two pieces will fold to be the same length, close to 25cm. To achieve this, one of the 4x6 poles had to be cut short, to 23.5cm (including the end-cap) -- this is the piece that will have the 3cm sleeve glued onto it -- inserted 1.5cm onto the 4x6 pole, thus giving a total length of 25cm.

For the 23.5cm pole, I wrapped electrical tape around it, then sandpapered the surface so that the glue will adhere better. The photo shows this, and in the middle is the 1.5cm piece that I cut off the pole:

img2

I discussed on the Aussie bushwalking forum what glue to use:

http://bushwalk.com/forum/viewtopic.php?f=53&t=35123

...decided on epoxy adhesive. It turned out well.

Here is where I bought 4x6 and 6x8 carbon fibre tube:

https://www.aliexpress.com/item/1005002341116771.html

The silicone rubber end caps:

https://www.aliexpress.com/item/1005001609758449.html

Just a little detail, the 4x6 does fit inside the 6x8 tube, but is a tight fit, and I used some 4x6 that had purchased earlier from another vendor on Aliexpress (here), as it is a slightly looser fit inside the 6x8 sleeve.

The epoxy adhesive is a very cheap brand from Bunnings:

https://www.bunnings.com.au/utility-25ml-slow-setting-epoxy-adhesive_p1662637

Getting closer to the weekend, when I will have waited long enough for the silicone sealant to cure, and will be able to sew the tie-outs.  

Tags: light

Tarp glueing reinforcing

May 23, 2021 — BarryK

Continuing with contructing TreeHugger 1P Mark-1 tarp. Here is the previous post:

https://bkhome.org/news/202105/tarp-glueing-hems-and-ridgeline.html

Reinforcing is to be at the tie-out points. I used the same 10D silnylon, and two plates from the kitchen to cut circles. I cut out two sets of circles, 15.5cm and 21cm diameter -- nothing special about those sizes, they were what I had in the kitchen that seemed about the right size.

Here is a sketch showing where the reinforcing is to be applied:

img1

"A" is glued on top of "B" on the ridgeline, for extra strength.

Here is one of the bottom corners:

img2

The reinforcing on the ridgeline were larger pieces, more of a challenge to glue down. You can see the ripples, somewhat less than a perfect job:

img3

One good thing: it will be very easy to sew. If I decide to reinforce with some sewing later on, won't have to grapple with two pieces of thin slippery fabric trying to go off on every direction.

I was reading a post from someone, can't recall the link, who glues-on reinforcing, and he said to wait several days before sewing. The reason is, the silicone will cure quickly at the edges, but underneath the two layers of silnylon, it will take many days to cure. He said, if you do it too soon, it will gunk up your sewing machine -- especially around the bobbin.

Next, I will sew on the webbing tie-outs. But, oh no, I will have to wait several days! Hmmm, maybe work on EasyOS or something.

Now the really interesting bit: I have been weighing this tarp as construction progressed, and the weight is now 158g. This is so good. I estimate the webbing and a bit of hardware, such as cord-tensioners, will add another 15g, bringing the estimated total up to 173g. That is just the basic tarp, but I do plan to add more features, such as rain-baffles on each end, plus an inner mesh tent, but I do now expect the total tent weight to be well under my original goal of around 500g.     

Tags: light