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jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: David, Eugene and Jerry's ideas on 12/30/2011 07:34:55 MST Print View

"The x-box stitch is as large as possible, to distribute the load. Don't really agree with Ron Bell of MLD on this one, he said to just stitch along the edge - though I might be wrong."

The failure was at the junction between reinforcement and main fabric, or maybe it was just in main fabric.

So, stitches that connect grosgrain to reinforcement isn't critical. Stitch along the edge, x-box, zigzag - probably any of those are just as good.

Daryl Daryl
(lyrad1) - MLife

Locale: Pacific Northwest, USA, Earth
Re: Re: David, Eugene and Jerry's ideas on 12/30/2011 10:06:14 MST Print View

Daniel,

Thanks for the link.

"Have not had any sign of failiure yet."

So it looks like the 5 minute epoxy you used is holding. That's good news as it is readily available.

Daryl

David Olsen
(oware)

Locale: Steptoe Butte
grommets weaker, sewing above the hem stitch stronger on 12/30/2011 10:20:31 MST Print View

Sewing above the hem adds strength.

Notice where the fabric tore on the first test-
along the hem. Then when reinforced with extra fabric the grommet pulled from the fabric
rather than tear at the hem.

The z tack spread out the force and held in both cases without reinforcement.

There are a bunch of other factors involved too.
Kind and weight of thread
Size and kind of needle
Stitch length and pattern
Bias, Kind of fabric, stretch,size and shape of reinforcements as mentioned

Testing will sort out what works well enough and beyond which is just
unneeded labor.


Tie out test gromet vs sewn

Tie out test, grommet vs z tack over hem stitch on type 66


silTie out test reinforced gromet vs z tack over hem stitch

Tie out test, reinforced grommet vs z tack over hem stitch on type 66


copyright Dave Olsen, Oware

Edited by oware on 12/30/2011 10:29:01 MST.

Tim Zen
(asdzxc57) - F

Locale: MI
Re: Re: David, Eugene and Jerry's ideas on 12/30/2011 10:57:14 MST Print View

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Edited by asdzxc57 on 01/29/2012 12:58:57 MST.

Daryl Daryl
(lyrad1) - MLife

Locale: Pacific Northwest, USA, Earth
Good Advice on 12/30/2011 10:59:34 MST Print View

David,

I like your line:

"Testing will sort out what works well enough and beyond which is just
unneeded labor."

It is good for me to keep this in mind as I tinker away.

Daryl

Daryl Daryl
(lyrad1) - MLife

Locale: Pacific Northwest, USA, Earth
Its a Wrap on 12/30/2011 19:45:46 MST Print View

This reinforcement is a 2" wide by about 6" long piece of strapping tape that wraps around a square tarp corner. It feels very secure and incorporates many/most of the ideas we have been discussing here. I think I'm getting close to the "good enough" stage of this project.

here

here

here

Details

The "pattern" photo shows the shape of the single piece of 2" wide and 6" long tape used to wrap the corner of the tarp.

The puke yellow piece = parent fabric.

The whitish piece = the reinforcement made from 2" wide strapping tape. When the tape is wrapped arouind the tarp corner it forms a flattened cone. One side of the flattened cone has a straight edge. The other side of the flattened cone has a curved edge and extends about an inch further onto the parent fabric than the straight edge on the other side of the fabric. Heres a photo of the carboard pattern as it would be shaped if it were wrapped around the corner of the parent fabric like the strapping tape. In the photo one side of the pattern is pink and the other side is cardboard colored.

here

"A" = one side.

"B" = other side.

Black stitching allows you to see the shape of the other side from each side.

Reinforcement is two layers thick at the corner then transitions to 1 layer thick for about the last inch or so.

Final boundary of reinforcement patch is rounded.

Very easy to apply. This is the first time I tried it and it came out close to perfect. Only takes a few minutes.

Could be used for any width of reinforcement tape or fabric. You just need to make a new pattern which is very easy.

It is a little hard to grasp by just looking at the photos. It will be much clearer if you make one yourself. You can do so in just a few minutes. I've spent much more time writing this post than I did creating the reinforcement.

Edited by lyrad1 on 12/30/2011 22:37:10 MST.

Bob Gross
(--B.G.--) - F

Locale: Silicon Valley
Re: Its a Wrap on 12/30/2011 20:02:32 MST Print View

Strapping tape has good strong fibers, but is the adhesive that permanent?

Most of the stuff that I have would slide off on a hot day.

--B.G.--

Daryl Daryl
(lyrad1) - MLife

Locale: Pacific Northwest, USA, Earth
Re: Re: Its a Wrap on 12/30/2011 20:36:27 MST Print View

Bob,

I used strap tape to illustrate the concept but it isn't my first choice.

Based upon the ideas discussed so far my preferred material would be 2" wide .33 ounce adhesive backed cuben fiber tape....but I don't think it exists. As pointed out in some of the earlier posts, however, there are some adhesive backed cuben fiber tapes that are pretty close to this ideal.

Having said that.....I actually have a myog tent that is 10 years old and still has the strap tape on the seams that I applied when I made it. The tape is sewed also.

Daryl

Samuel C. Farrington
(scfhome) - M

Locale: Chocorua NH, USA
reinforcement patches on 12/30/2011 20:43:24 MST Print View

So for the corners, is it to be the straight or the rounded inner edge?

Theory: If the inner edge is rounded, to be equidistant at all points from the stress point, the force will be more evenly distributed than with the straight edge, triangular-shaped patch. Do you think?

Daryl Daryl
(lyrad1) - MLife

Locale: Pacific Northwest, USA, Earth
Re: reinforcement patches on 12/30/2011 21:41:37 MST Print View

Samuel,

It is both.

That is one piece of tape wrapped around both sides of the fabric at the corner. I think I need another couple of photos.

Daryl

Edited by lyrad1 on 12/30/2011 22:38:05 MST.

Daryl Daryl
(lyrad1) - MLife

Locale: Pacific Northwest, USA, Earth
It's a cone on 12/30/2011 22:24:12 MST Print View

Wow, illustrating this in two dimensions is way harder than making it.

When the 2" X 6" piece of strapping tape is folded/wrapped around a 90 dgree corner it forms a cone. I've folded the cardboard pattern and made one side of it pink to illustrate in these photos:

here

save

save

Do these photos help?

I've also edited the original post to see if it is easier to understand.

Edited by lyrad1 on 12/30/2011 22:51:48 MST.

Daniel Sandström
(sandstrom.dj)
Re: Re: Re: David, Eugene and Jerry's ideas on 12/31/2011 04:04:46 MST Print View

I read a lot of threads here one BPL before and during the design of the tarp. Hoverer I don't know how many of the contributors actually have experience in real material engineering - on the other hand, they might have practical experience. And to be fair, I think this is mostly theory, as I have yet to hear of very many actual tarp failures.
One thread I found while researching is this one
Skip down to Lance Marshall's post Re: "Still, the math is interesting" on 10/18/2009 21:55:47 MDT

On the materials. Cuben fiber is close to a stable fabric, naturally it too has some elongation or creep if put under constant pressure, but I think it will hold up well in a shelter situation, in comparison to the first intended use, yacht sails. Silnylon on the other hand have more stretch so one needs to do separate calculations for either fabric.
I talked about the subject with my math doctor last year while still in school. We planned on visiting the architect teacher who had the appropriate software. Sadly we ended up not doing it as I don't have the material specs nor an exact model of the tarp. With that in mind, we concluded that the most important part for a "catenary cut tarp" is the smooth curve of the ridgeline and edges. The calculations would be done under controlled circumstances while the tarp would be set up on uneven ground, attached to trees and subjected to uniform winds, also providing I could produce an exact replica of the model tarp. Therefore I think trial and error, i.e. manufacturing experience, is a more suitable approach. Non the less, I am sad I didn't put the hours into it, as I've now finished the polytechnic university and would have loved the whole experiment - after all, I am an engineer and thus gear and experiment freak..

That kind of took up the subject of patch design. But if one would make a force model of a tarp in action I'd estimate that for a well built caternary tarp, the forces spread along the edges. For a flat tarp it would depend more on the pitch, the reason for the usually sloppier look. Basically it comes down to Newton I, where the force vector goes along the taut tieout line to the ground and secondly into the tarp. There's just too many factors in a real world situation. Hence, uniform 1/4, half circles.

Daryl Daryl
(lyrad1) - MLife

Locale: Pacific Northwest, USA, Earth
Re: Its a Wrap-more photos on 12/31/2011 09:40:16 MST Print View

Here are a few more photos to help you visualize this latest reinforcement patch. I wrapped the carboard pattern (pink outside and black inside) around a transparent 90 degree corner.

here

here

here

Daryl Daryl
(lyrad1) - MLife

Locale: Pacific Northwest, USA, Earth
Re: Re: Re: Re: David, Eugene and Jerry's ideas on 12/31/2011 09:42:56 MST Print View

Daniel,

My latest reinforcement patch would be like having your rounded edge patch on one side and then a smaller straight edge patch on the other side.

Daryl

Lesha Y
(leshka) - F
cuben fiber tarp Tie Out on 05/09/2012 09:49:39 MDT Print View

Has anyone considered using double folded 1.5oz cuben fiber for the tieout loops instead of grosgrain? Thanks

Karple T
(ctracyverizon)

Locale: Mid-Alantic
"Tarp Tie Out Logic Check" on 05/09/2012 10:15:27 MDT Print View

It works great.

I sandwiched the tarp between the tie out ends and put patches on front and back over the tie out.

It was strong enough in testing that I have not sewn bar tacks.


tarp tieout

Edited by ctracyverizon on 05/09/2012 10:19:25 MDT.

Lesha Y
(leshka) - F
Re: "Tarp Tie Out Logic Check" on 05/09/2012 10:54:32 MDT Print View

Thank you, Craig. Wonderful news!

Steve B
(geokite) - F

Locale: Southern California
So how would you... on 05/09/2012 21:55:03 MDT Print View

So how would you do that same kind of reinforcement with tape only (no sewing) for the ridgeline of tarp with beaks? It would be harder to sandwich the tarp, unless the beak wraps around underneith the tape.

I've been thinking of this for weeks and haven't come up with anything great.

Steve

Edited by geokite on 05/09/2012 21:56:34 MDT.

Karple T
(ctracyverizon)

Locale: Mid-Alantic
"Tarp Tie Out Logic Check" on 05/10/2012 09:14:35 MDT Print View

I am not sure I understand your question.

I am using tape for everything now. I find it easier and faster with plenty of bond strength for my needs.

For patches I just lay out the tape in strips across the patch and cover the whole area.

If you are adding patches at the top of the ridge line to hold the top of the trekking pole on a beaked tarp here is an idea : )

You could do this on the inside and outside.

I find a football shape wraps around the beak edges and therefore no split over the beak ridge.

beak4

patch5patch6

Edited by ctracyverizon on 05/10/2012 10:12:14 MDT.

Tyler H
(ctwnwood) - F

Locale: Utah
re: Tarp Tie Out Logic Check on 05/10/2012 12:00:48 MDT Print View

Craig-

Your design is awesome. Thanks for such a clean description of exactly what you're doing on your tarps. I wish I'd have seen this before I started my tarp! I used Hysol and triangular patches, was not easy or elegant.

Thanks

Edited by ctwnwood on 05/10/2012 12:01:33 MDT.