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sixleggedinsect
Aug 17, 2009, 10:11 PM
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Registered: Apr 14, 2004
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i was looking at one of my older camalots (a couple generations old, but not the u-stem ones). the sling (original nylon) features what looks like a tapered bar tack. that is to say- the outer tacks have what looks like one run of zigzag stitching, and the inner three tacks have what looks like two runs (on top of each other).
this makes sense to me as a possible way to avoid the oft-mentioned 'stress riser' at the end of each side of the bartack, possibly resulting in a higher breaking strength because there is less webbing damage or fiber deformation near the ends of the tack. and you coudl still have the ease of use of a bartacker machine.
was this on purpose? am i just imagining it? anyone have any ideas about the design decisions made here?
photo is attached.
thanks,
anthony
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rschap
Aug 18, 2009, 1:14 AM
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never mind
(This post was edited by rschap on Aug 18, 2009, 1:15 AM)
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minibiter
Aug 18, 2009, 1:17 AM
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If you flip it over are they tapered the other way?
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sixleggedinsect
Aug 18, 2009, 1:22 AM
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minibiter wrote: If you flip it over are they tapered the other way?
not sure what you mean- by necessity of how these types of sewing machines work, the two sides will be symmetric. the other side looks the same, albeit a little neater. the photo taken is the underside of the tack and its difficult to get machine thread tension high enough to 'suck in' the thread into the webbing.
blah blah blah. end sewing geekiness.
yes, they are 'tapered' (to re-use my invented term) on the other side.
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slacklinejoe
Aug 20, 2009, 11:08 PM
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sixleggedinsect wrote: was this on purpose? am i just imagining it? anyone have any ideas about the design decisions made here?
No way to be 100% sure unless you have more than one sample from the same lot but it looks like it was programmed that way on a digital bartack where it automatically does that on the first and last tack.
If it was just one end, I'd say it was probably their bobbin running out.
To be 100% honest, it could be that they knew their necessary stitches to reach said strength and used the top and bottom not being doubled again as a way of finishing it faster and still looking symetrical.
While it is possible that they were playing with the concept of stress risers, I doubt it. Instead, it would be more likely that they could have reached their strength with one less tack, but consumers who look at these things tend to count tack numbers as assume that five tacks is stronger than four tacks.
For the record, that's why I use ten instead of the six that I need, well that and I have to account for abrasion over the product life span.
(This post was edited by slacklinejoe on Aug 20, 2009, 11:10 PM)
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