Well, I just had to make those tarp tensioners part deux from Jeffs site. I almost gave up trying to get the surgical tubing (sling shot replacement kit) over the bights. Thank goodness I decided to try and heat the rubber up in some boiling water (keep the rubber off the hot pan). Perhaps it's just that I'm new to hammocks and working with these materials, but since a lot of the stuff that is probably common sense to most of you seasoned hanger DIY'ers, I thought I would do a quick write up on how I made them and the tension pounds and weight. The main instructions are on Jeffs site: http://www.tothewoods.net/HomemadeGe...ensioner2.html, I am only trying to explain where I was hung up following his instructions and offer some tips that helped me finally make them.
TarpTensioner_all_done.jpg
STEP 1
Materials for one tensioner is pretty straight forward (though I ended up cutting about 9 inches from the 36 inchers)
- One ~5" piece of surgical tubing
- A ~36" section of cord
- Two ~9" pieces of small string. I used inner core from 550-cord.
my comments - I got the surgical tube from Walmart (cut from a sling shot my son was very upset I bought just to destroy). Walmart doesn't have the slingshot replacement kit any more though, you will have to pay for a slingshot (or order surgical tubing online).
36" ended up being a bit long, but ok to start with. I too used the inner core from 550 cord. At first I didn't know what that meant, until I went ahead took a piece apart to find 7 strands inside that pulled out very easily - PHEWY.
STEP2
I formed the bight with an overhand knot
my comments - I embarrassingly had to look up what a "bight" was.
STEP3
Put the cord inside the tube, and pull the tubing up over the knot about .5".
my comments - ummmm, at least Jeff didn't use the word "just". This is where my initial problems started. I couldn't get the cord down the tubing to save my life. I finally used a hanger and dipped the surgical tubing in boiling water for a minute. It still took some major maneuvering, "massaging" the tube towards the knot I was trying to get over while pulling the end with pliers. Be careful not to cut tubing with pliers, but be patient, it will eventually go over, you just have to keep working it
STEP4
Whip the tubing to the cord with the inner core. If it's oriented like this picture (on Jeffs site), make sure the whipping is to the right of the knot.
my comments - Again, I am such a noob on this stuff, I had to look up how to whip. Found this video that really helped https://www.youtube.com/watch?v=QWoUbQXD65A. Having the whipping on the other side of the knot to keep the tubing from coming of the knot made sense
Here's where I am at in 4 different stages
TarpTensioner_early_stage.jpg
STEP5
Roll the end of the tubing backwards over the whipping.
my comments - Because getting the tubing over the knot was no fun, I didn't roll enough the first time and had to remove the whipping, reheat the tubing and pull more tubing over the knot this time. If you don't get the tubing to be able to wrap back over the whipping and contact more tubing it will roll back off the whipping too easy.
You can see the whipping is done and I have enough tubing left to stretch over top.
TarpTensioner_almost_done.jpg
STEP6
Stretch the tube down the cord to see how far it will go, and mark the spot (just pinch it between your fingers). That's where the knot needs to be.
Tie another overhand knot, making sure the knot ends up at the place you marked. You should be left with something like this picture.
my comments - In the picture on Jeff's site, I didn't understand why the picture showed such a long cord against the tape measure since I couldn't stretch my 5" piece of surgical tubing more than a couple of inches. I ended up just going with it and sticking to the main thing he said instead of trying to achieve what he had in his photo. I guess the slings shots these days are just a little more powerful? The main thing to remember here, is you want to set an ending knot where what ever tubing you are using can go to.
STEP7
Pull the tube down over the knot, whip it, and roll it just like the first end. You're done!
my comments - again, at least he didn't use the words "just pull the tube down over the knot". Holy crap this was difficult, even after I heated up the tubing. I did find that using 2 pliers at once helped, I'm really beginning to think that not all surgical tubing is created equally (Jeff's was apparently MUCH more stretchy than what I was using. Though mine did end up being almost the exact same length unstretched, but I guess from last picture his tubing would allow the system to stretch over 10 inches.
Also attaching the other end to something solid was key, you need 3 hands here.
Here is the 2 plier technique ;-)
TarpTensioner_pull_over_last_knot.jpg
They ended up being 8.5" each
TarpTensioner_No_Resistance_8_5_Inches.jpg
Fully stretched they are 12.5" each for a total stretch of 4". I'm not sure that will be enough stretch, mainly because I don't know how much re-tensioning is needed overnight??
TarpTensioner_Max_Resistance_12_5_Inches.jpg
All in all, the 4 tarp tensioners weighed in at 42 grams (1.48 ounces)
TarpTensioner_weight_42grams.jpgTarpTensioner_weight_42grams.jpg
Now to see how many pounds of force there is when stretching these. There seemed to be 3 positions when I pulled them. The first was and abrupt end to the easy pull. The second was the where the tubing maxed out. The third was the stretch of the 550.
The easy pull ended at around 7 pounds of force:
TarpTensioner_1st_Resistance_7pounds.jpg
The tubing seemed to stretch out at around 11 pounds of force:
TarpTensioner_2nd_Resistance_11pounds.jpg
The 550 stretched a tad past that until there was no more stretch at 47 pounds of force at which point it was like a solid rope:
TarpTensioner_Max_Stretch_47pounds.jpg
Thanks to Jeff from tothewoods.net for the article. I will let you know how these work, I plan on setting up the hammock tomorrow night.
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