Tarp Corner tieout thread puckering undertension. - Help!

[wgonfan]

Well.. I guess its a "pucker". The stitches (straight, 6per inch) on my corner tie out reinforcements go slack and pucker up on top when the tarp (8x10) is tied out. The actual thread puckers, not the sil. My stitches look good otherwise and as far as I can tell my tension is balanced out as good as its going to get. I'm using an older sears 1403 zigzag machine, silnylon tarp with 1 piece of 200d reinforcement material on the underside and Tera 80 thread. Any idea how I can correct this? I've tried adding sticthes, zig-zag stich and increasing my bottom tension. Increasing my bottom tension helped a little bit but made sewing a nightmare. I'm sure the is something I'm over looking.


My ridgeline & side pull outs do not do this.

[The Old Boot]

Pictures please!

[VictoriaGuy]

Pictures please!

+1
It's hard for me to understand the problem....

[wgonfan]

OK. I'm at work so I did a few quick diagrams... maybe I can take some pics later this week.

The diagram is of the tarp corner from the top looking down.

Light gray = silnylon tarp body
Dark gray = area where reinforcement is (underneath sil)
Red = thread
Black = grosgrain tieout tab


This first diagram is without tension:



This shows the corner with tension. Notice how the thread is now loopy (relaxed?), but the sil does not bunch up. The underside with the reinforcement does not do this.




I know it's not a substitute for pictures though.

[SnarkyJosh]

The same thing happened on mine. The stitches look perfect until you setup the tarp. Pulling on the corners would slightly stretch the fabric, drawing the stitch holes closer together, which caused slack in the thread. I think the issue is that I had my machine set to 6 stitches per inch. If I were to do it again, I would change to 8 or 10 stitches per inch. I didn't feel like ripping out the stitches so I compensated by making the grosgrain tabs span the length of the reinforcement patch. Similar to your picture where the line of stitches that the grosgrain crosses stays straight.

[MAD777]

Ahh! Now I understand. I stitch mine with the stitches running radially out from the corner. (Not across the reinforcement). No puckering stitches that way.
And if you think about it, a puckering stitch adds no strength to the system. Whereas, the radial stitches are running in the same direction as the stresses, therefore adding strength to the system.

[wgonfan]

Ahh! Now I understand. I stitch mine with the stitches running radially out from the corner. (Not across the reinforcement). No puckering stitches that way.
And if you think about it, a puckering stitch adds no strength to the system. Whereas, the radial stitches are running in the same direction as the stresses, therefore adding strength to the system.

I like it! now, whats going to be weaker? the slack stitches as they are or pulling them & adding more holes by restitching radially.

[MAD777]

I would re-stitch it. Don't forget to add silicone seal which will both fill the holes and add additional strength. It will be fine. The stitches add a bit of unique character; call them embroidery!

[wgonfan]

I did restich last night & it feels plenty strong.... plus no puckering! thanks Mike.