Catenary curves and such

[NJTroutstalker]

So I'm going to steal my moms old singer and put a tarp together. Can anyone point me to a good site on how to layout a cat curve and maybe some theory as to the dimensions?

Sorry ahead of time, I have a chronic disease. I'm an engineer.

[Man Thursday]

This might help: Cat Cut Tips

[Redoleary]

A true catenary is not essential, a bent piece of pvc or wood etc will get you close enough. Or tack a string to the wall between two points equal to the distance on the tarp and a depth in the range of 4-6% of the lengths is good. Trace string onto paper/cardboard. I thing Grizz has a catenary calculator around here somewhere too.

[oldgringo]

https://www.hammockforums.net/forum/...ighlight=chain

See post #2. Rat makes it easy.

[NJTroutstalker]

Perfect. Thanks. Exactly what I was looking for.

[hangNyak]

The easiest way I found is using 1" per foot of span. If the span between the 2 points is 5 ft., then find the center at 2 1/2 ft. now make a mark 5" in. Line up a piece of 1/4 round moulding on the two ends and bend in the middle to your 5" mark and trace. Easy, easy, easy. I don't get the whole tacks and dangling lines and chains. You're making it harder than it needs to be.

[bigfanboy]

The easiest way I found is using 1" per foot of span. If the span between the 2 points is 5 ft., then find the center at 2 1/2 ft. now make a mark 5" in. Line up a piece of 1/4 round moulding on the two ends and bend in the middle to your 5" mark and trace. Easy, easy, easy. I don't get the whole tacks and dangling lines and chains. You're making it harder than it needs to be.

That or the PVC route.

1. Use a thin wall PVC longer than your tarp edge.
2. Grab a bit of 550 or whatever, more than twice the length of the PVC.
3. Run the line inside and out of the PVC. Use a Fig 9 or something to secure the line loop together, this allows you to change bend of the PVC pipe.

This way you can lay it all on the ground, not have to hang it up on a wall. And you can play with the visual of different cat cuts..

[NJTroutstalker]

The easiest way I found is using 1" per foot of span. If the span between the 2 points is 5 ft., then find the center at 2 1/2 ft. now make a mark 5" in. Line up a piece of 1/4 round moulding on the two ends and bend in the middle to your 5" mark and trace. Easy, easy, easy. I don't get the whole tacks and dangling lines and chains. You're making it harder than it needs to be.

I was definitely looking for the depth to length recommendations. My engineer brain says the true cat will distribute the loads better, but I'm sure the thread injector process and my operation will negate any gain.

I'll try the bent stick method, first.

[Redoleary]

I think 5" over 5' is a little deep. All you're looking for is a tight pitch, too deep and you're loosing coverage. If you went with the 4-6% rule of thumb you'd be looking at 2.4"-3.6" over 5'...an even 3" if you went with 5% over 5'. Are you binding the edges or doing a rolled hem? Sil can be a bit squirrelly to do a rolled hem on a cat as it's all on the bias.

[hangNyak]

If you are able to get some large paper on a roll, you can make a template of one side of your tarp. This is what I did. It made everything super easy. I work in a body shop and we have rolls of 36" paper. I taped two 12 ft. Pieces together to make a template. This works good because if you make an error, it's on paper not your expensive material. If I can help any further, let me know.