sewing HMA

[polarbear 1]

I did a search on this an couldn't come up with anything. Anybody know if there is special technique needed for sewing HMA? I figured I'd use a straight stitch with E-thread and just hand-walk the machine to make sure I stayed in the middle of the line.

Anybody know anything? Do I need a certain needle size?

"Holy s*** that was f***in' cold!"

[Spizzzarko 0]

I would think that a dull needle would do better in that aspect than a sharp one as a dull needle would seperate the weave instead of sewing through a carrier. This is purely subjective thought though.

[darkwing 4]

I'll defer to the experts, but I'd probably use B-thread.

-- Jeff
My Skydiving History

[Rdutch 0]

I wouldn't go for a dull needle. Dull needles will grab and tear the fibers. If you do sew Hma with a straight stitch (PD uses a bartack, but I have seen Precision canopies with a straight stitch.) you have to be very carefull to make every stitch the same length. While there isnt any reason why you cant straight stitch it, a bartack is more consistent, but you will need a machine that will make a small enough bartack. Also the very small hma is prone to breakage where the fingertrap ends so make sure you have a very sharp pair of scissors and make the cut very long. Hma isnt the easiest line to cut.
Good luck!

Ray
Small and fast what every girl dreams of!

[riggerrob 558]

Similarly, remember to full straighten out the cut end.
HMA is a "zero core" line, so even a tiny fold-over will weaken the outer line.

[riggerrob 558]

... dull needle ...

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Bad idea.
Dull needles usually have bent tips, sharp edges, etc. that cut fibers.
Why not just continue to use the "ball-point" or "universal" needles that we normally use for sewing nylon?

Oh!
And a size 16 needle will do fine for sewing thin HMA lines. No need for the size 22 needles that we use for harness or container repairs.

Similarly, skinny "B" Thread will work better on skinny HMA lines.

[precision 0]

Quote

I have seen Precision canopies with a straight stitch

Precision does not use a straight stitch on HMA. It might look like a straight stitch, but it is a zigzag. It is imperative that you use a zig-zag stitch to prevent thread breakage. The zig-zag doesn't have to be much, but a straight stitch will definitely break on fingertrapped HMA.

We use a new needle with every HMA lineset.

George Galloway
Precision Aerodynamics

[Spizzzarko 0]

I was un aware of that information. Sharp needles only then folks!