Author Topic: Thread size application  (Read 954 times)

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AtelierCodeRouge

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Thread size application
« on: February 01, 2021, 12:09:10 PM »
Hi guys,
i'm sewing bags with my industrial machine. I usually sew using V69 thread. I want my bags to be durable and not falling appart. When sewing my bag I sew twice with V69 to be sure each panel will stay togheter.
I just want to know if double stich with v69 is something you guys do? Is it overkill?
Do V92 be a better choice for stiching panel togheter?

Let me know what you are using and for what application.

Thanks!

AtelierCodeRouge

Disturbed

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Re: Thread size application
« Reply #1 on: February 02, 2021, 11:09:49 AM »
I use 92 Nylon Bonded thread for most load bearing applications.  Are you binding?  Standard practice for me is to close up with 92, bind with Mil-T-5038 and 92 thread and then bartack any straps exiting the seams.

A double stitch is stronger than a single stitch but it needs to be offset, I have done 12mm seams and then sewn again at 6mm for 90 liter backpacks, binding went over the top of that and then bartacks as needed.

You can calculate your seams strength using the formula at the link

As long as you are using 7 stitches per inch and T70 Nylon Bonded thread your calculation would be 7 x 5.4kg x 1.5 = 56.7kg.  That means your theoretical seam strength is 56.7kg over 1". 

Sailrite breaks down load bearing stitches in webbing fairly well here

Hope that helps

AtelierCodeRouge

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Re: Thread size application
« Reply #2 on: February 02, 2021, 04:16:22 PM »
thanks for sharing Disturbed!
I'm going to switch to V92 Tread very soon for all the seam of my bag. The color choice is not as good as with V69. Just the time to find the right color I need.
Yes I have to bind all interior seams. The material i'm using fray a lot.
I do not have access to Mil-T-5038. I don't know if it's available in Canada. I will do a research.
I do binding using 1 inch black ''Grosgrain''  but I have not great success with my binding attachment. It's the swing away 1inch from sailrite.

Just like you I have 12mm seams but I do not offset. I will try it for sure and finish with binding. For the bartacks I have not that type of machine unfortunately.
I like the fact that you gave me a calculation. Sounds like you're an engineer  ;)
I sew exactly using 7 stiches per inch so it's nice to know !

AtelierCodeRouge

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Re: Thread size application
« Reply #3 on: February 09, 2021, 12:17:26 PM »
I just finish sewing a bag using the offset double stich with V92 and it works great. It feel really strong. I will be doing bag this way in the future. Thanks for the tip Disturbed !
The only problem to solve is the binding attachment. I have found an old post of Gear Dynamics talking about a compagny call : http://bjattachments.com/ in Montreal specialised in manifacturing custom binding attachment. I have give them a call and they have create a special binding for my sewing machine. I have drop them a strip of fabric I sew with and the binding tape i'm using at there head quarter. I'm going to take the binding attachment back on friday. Can't way to try it! I'm pretty much sure binding will not be a issue now. Everyone that have experience binding know it can be fucking pain !  >:(


Disturbed

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Re: Thread size application
« Reply #4 on: February 09, 2021, 02:50:51 PM »
Awesome, glad to hear it worked well mate.

N8Smith

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Re: Thread size application
« Reply #5 on: March 20, 2021, 05:08:16 PM »
ACR, I'm a little late but size 69 thread is perfectly acceptable for almost all bag applications. I make all of the Marine Corps freefall parachute kit bags with size 69 and they're carrying 70-100 lbs with zero issues.