Using a twin needle?

[Moondog55]

My little sewing machine can take a twin needle.
I've never used one before and I'm not sure how they work but I'm wondering if buying one and using it on the Silnylon tarp I am still to make would make strong seams any easier?

[gayet]

Most domestic sewing machines with twin needle use a single bottom thread so getting your tension right is vital - in my experience. Too tight and you create a ridge and that stresses the lower thread and it is more prone to breaking. Any strain on the seam and you still only have one lower thread to handle it.

In my domestic machine experience, I wouldn't trust it on thin material under any strain. But that is limited experience.

[undercling-mike]

These are pretty much for cosmetic purposes only, proper industrial twin needle machines have two bobbins.

[Moondog55]

These are pretty much for cosmetic purposes only, proper industrial twin needle machines have two bobbins.

And have at least 3 zeros in the price tag

[undercling-mike]

These are pretty much for cosmetic purposes only, proper industrial twin needle machines have two bobbins.

And have at least 3 zeros in the price tag

And take up a fair chunk of space. Unfortunately the twin needles for domestic machines are not much use for gear making, they seem to be for things like sewing jeans with the appearance of an evenly spaced double row of stitching.

I'm guessing you've probably seen this but just in cast this is a pretty good looking method: https://www.youtube.com/watch?v=sG10M_ipgO8 to be fair he's using a fabric that looks a lot more compliant than some of the lightweight silnylons I've used.

[Orion]

A "felling foot". That looks pretty cool, although having perfectly parallel seams is mostly (entirely?) cosmetic.

That guy's method relies on ironing to achieve folds in the fabric. I've gotten ironing to work with some silnylon, but not all. And other uber light fabrics have also resisted holding a fold when (carefully) ironed. Sometimes I've sewn a single stitch line to simply join the two pieces prior to folding; that stitch is invisible in the finished seam. One time I used glue, just one time. Usually I painstakingly pin the flat felled seam together prior to stitching. Arrgh. But I don't do this stuff very often.

I really liked that homemade aluminum lap seam folder jig that Evan of Terra Rosa Designs uses to sew seams in the video he posted. I wonder how hard it would be to make one of those? I can't see any reason why it wouldn't work with a single needle machine.

[rcaffin]

I tried using a twin needle on silnylon. Total disaster. The thread underneath puckered the whole seam up.
I dare say a twin needle works fine on something as heavy as denim, but not on tent fabrics.

Cheers
Roger
EDIT: on a DOMESTIC single bobbin machine!

[Moondog55]

Thanx for the input Roger

[Orion]

I dare say a twin needle works fine on something as heavy as denim, but not on tent fabrics.

Seemed to be working just fine for Evan in that video.

Wouldn't most tent manufacturers use a twin needle? I'd be quite surprised to learn that Hilleberg sewed the flat felled seams in my non-denim tent one line of stitches at a time.

EDIT: on a DOMESTIC single bobbin machine!

Edit: Thanks for the clarification. That makes more sense.
But it sounds like there's little point in even trying this with a single bobbin machine unless one is after a cosmetic effect.

[Moondog55]

There is a huge difference between a domestic twin needle with a single bobbin and an industrial machine with two bobbins
I was asking about the domestic machine double needle

[neilmny]

.........I really liked that homemade aluminum lap seam folder jig that Evan of Terra Rosa Designs uses to sew seams in the video he posted. I wonder how hard it would be to make one of those? I can't see any reason why it wouldn't work with a single needle machine.

It would be fairly easy if you got hold of some 1mm thick or less aluminium sheet.

No matter how many times I've watched that video........It's magic.