Double Needle sewing machines?

Reverse is nice. Independent needles are nice. Fabric puller/roller can be helpful on sticky or slick stuff. Needle feed is very nice.
Oil bath if you sew a lot.

I recommend "Durkopp" German made. I purchased a used one 30 years ago for $300.00

It looked just like this one:

http://www.ebay.co.uk/itm/Durkopp-Twin-NeedleFeed-5-16-Gauge-Sewing-Machine-Reverse-/380371962776

Had reverse that worked smooth as silk. I used the machine to sew 1000 denier nylon.

Judy From LightHeart Gear here –

I have several double needle machines, they all work well, (several different brands) they all have pullers on them. and they all have folders for both forward and reverse lapped seams. My folders are all custom made – the standard ones are generally too open for 30 d silnylon and cuben fiber. just so you understand, custom folders , and you can't do a lap seam without one, can cost around $300.00 each. yes, you can get some off the shelf on ebay for less, and I have tried them – then bought custom ones – I sent my fabric off to the company that makes the folders so that they would work appropriately. The pullers are really what adds to the cost of the machine, racing pullers cost about $1500.00 or more. Also, with the folders, you need to have them mounted to the machine, so each machine I have has each of it's folders mounted to plates that slide into slots on the machines, as well as having plain plates for when I don't want a folder.

And I hope I'm not offending anyone – but a lap seam is different from a flat felled seam, a flat felled seam is done on a single needle machine with 2 passes, a lap seam is done in one pass with the folder folding your fabric. A double needle machine has 2 bobbins – they are drop in bobbins and the only thing I would say is to get one with 'large bobbins' Also, don't quote me on this , but I think they are all needle feed machines

Before you just buy a double needle machine, make sure you have someone who knows how to service them, time them and tweak them into perfection.

Judy – LightHeart Gear (who loves all of her very many sewing machines – and they all have first names)

Now that's funny, you collect sewing machines like some other people here collect equipment. Thanks.

Hi Judy,
Re: "And I hope I'm not offending anyone – but a lap seam is different from a flat felled seam, a flat felled seam is done on a single needle machine with 2 passes, a lap seam is done in one pass with the folder folding your fabric."

No offense taken – you'se da pro, I'se da MYOGer (pronounced my-OWE-gurr).
You can't pronounce it ME-owegurr, because someone might think you are an ogre and take a shot at you (more on this in the 'personal security" thread), or the someone might be an ogre themself, and attack you for impersonating an ogre.

Hope YOUR terms are right. The more I read about these terms, the more confusing it gets. "Lap felled vs. flat felled" would make it real simple if all the 'experts' accepted the terms.

But although the processes of making them is different, what is the real physical difference between the two after completion? Don't detect any difference from your post.

Can you enlighten us further? Thanks.

Quote" Hope YOUR terms are right. The more I read about these terms, the more confusing it gets. "Lap felled vs. flat felled" would make it real simple if all the 'experts' accepted the terms.

But although the processes of making them is different, what is the real physical difference between the two after completion? Don't detect any difference from your post.

Can you enlighten us further? Thanks. end Quote"

I cannot give you any scientific data on this – sorry – and, unlike in the other thread on this subject, I (this is personal I) do feel that a true lapped seam is stronger than a flat felled seam because each row of stitching is going through 3 layers of fabric (if it's done right) I feel it is more water tight because water would have to penetrate 3 layers of fabric to migrate through needle holes and /or would have to go through (over and under ) the lap to go from one side to the other side. Ogre's certainly can't get through a lapped seam.

So, I will now take back my words – I just checked the seam classification guides and while it is under "lapped seams" the specific one we are talking about here is called a flat felled seam http://www.garmento.org/751Astitchesandseams/LS.htm "LSC" is the seam we are talking about, and the link to the attachment will show you want a lap seam folder looks like.

Judy

Judy,
it's late, so I don't want to take the hour or so to do diagrams and post them; but I think we could be using different terms for different things.

What you were calling a flat felled seam, before you looked it up, may be what I call a faux felled seam. It looks like a flat felled seam without close inspection, but one of the two stitch lines, the one first sewn, goes through only two layers of fabric. And when the seam is stressed, the stitch holes in just one of those layers are exposed to the outside. Tried to show this in the diagram on the other thread.
From your discussion, I hope readers are getting a clear idea that the seams in your tents are not the faux-felled, but are the best quality.

Not having your skill and machines, I make the flat felled seam in the manner described on the other thread. Many don't like it because it requires developing a skill, and is hard. A lot of worthwhile things are hard, and I bet you know that as well or better than I. For MYOGers, the pins are necessary for the reasons restated by Roger on the other thread. Because the pins are pulled out before reaching the needle, and penetrate only through the four layers between the stitch lines, I have not found them to be a problem after sealing and making sure the sealer gets worked into the holes.

Using a lapping attachment and double needles as you are skilled and able to do, it of course goes much faster. But for both of us, the stitch holes are going through three or four layers of fabric. On mine of course, the stitch holes are not as neat. That's why I carefully select the thread color to blend in with the fabric, and if the materials are different colors, will even use different colored threads above and below the seam. I also spend a lot of time to make sure the stitches are loose enough to not pucker the seam, and allow the silnylon to stretch; but are also tight enough to lie flat aganst the fabric with no slight loops that will eventually find something to catch on and break. The outcome just looks a whole lot better, especially when an amateur sewer is at work. But I get a product that is exactly what I want, and can't be bought for any amount of $. Now that is worth plenty, IMO.

You may be right about the flat felled seam being stronger than many others. The silicone coat on the nylon reinforces it somewhat, but if stitches are close to a raw edge, and enought tension is applied, they will pull right out through the edge of the fabric coated or not. But I think the problem with the faux felled seam, sometimes called the 'rolled' seam, is the single layer of fabric with stitch holes that are exposed to the elements.

Best wishes.

PS – Judy, Looked through the many seams illustrated on the link you posted, and the closest one to what I called the 'faux' felled seam is labeled 'LScs' near the bottom of the scroll. But the diagram fails to show what happens when the seam is tensioned. Was trying to show that in my diagram on the other thread. Perhaps I will call it the 'rolled' seam from now on. I can understand why some folks might not like their work being referred to as 'faux.' It is better than some of those seams on the link, which are pretty awful. May use it to connect a vestibule cover and insect netting door to a main canopy, but not on the canopy itself over my head.

Usage varies an amazing amount.

There are, for instances when it matters, actual standards for specifying seam construction and for the sort of stitching used to make them, from both US standards orgs and ISO.

That's because what Judy is calling a lapped seam isn't what most people I know call a lapped seam. To us, a lapped seam is two pieces of fabric, right sides up, slightly overlapped, and stitched together (usually with a coverlock or flatlock). But there is a large contingent that uses Judy's usage.

The old US standard, 751.a, has a whole set of seams made by lapping two pieces together. A plain lap seam, in my usage, is an LSa seam[1]. Judy's lapped seam (a trued felled seam) is an LSc[1] seam; the mocked felled seam is an SSw1[2]

American & Efird (a maker of high quality industrial threads) have a very useful little booklet: http://www.amefird.com/wp-content/uploads/2009/10/Seam-Type.pdf that explains these, shows diagrams of them, and tells where they're commonly used.

http://www.amefird.com/wp-content/uploads/2009/10/Stitch-Type-Matrix.pdf is also useful, it's an explanation of the various sorts of stitching used.

[1] Properly, all these seams need more specfication. You need to specify the stitch type, the number of needles, and the sizes. The seam used on most jean inseams is then a 401-LSc -2

[2] note that it's not a lapped seam at all, it's a seam done by superimposing the fabrics, so SS.

Sam,

You are right in everything you said. and in certain parts of my tents where I transition from a zipper to no zipper, I often do a 'fake' felled seam – or a rolled seam (a rose by any other name?) .

It depends really onthe stresses that are being applied to that portion of the item as to how to reinforce or sew something.

I am anxious to see your finished tent when you get it done.

Judy

Judy,
Thank you. There is so much terminology, and so many varieties of seams, I can see now the need from now on to include a diagram when talking about seams. This site is for enjoyment, and it is no fun to play 'Who's on first." Couldn't imagine trying to fold zipper tape into a flat felled seam – haven't seen any tent with that.

Will send you info when tent is done, but must warn that it is the longest term project that I've got going. You can visit the concept, though, at:
http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=45631

Since then, I found better carbon shafts for the poles, finished designing the front and rear vestibules, and changed the design to include a full net liner that also makes the canopy and liner into a giant pole sleeve that eliminates the need to attach elbows to the inside of the canopy. Just that small bit of bulge on each side of the canopy adds a great deal of head and sitting up room. The net liner will be pulled out and attached at the pole crossing points to take advantage of that extra room under the canopy. A similar approach is taken with the net liners in the newest TarpTents.

My apologies to the OP, as this is supposed to be about double needle machines. Will take the other topics over to the other thread.

The most common machines are drop feed, or for upholstery, compound (with both a walking foot and needle). Needle feeds
split the difference and work well with light and slippery fabric. They are also known as "backpack" sewing machines. I use very
light feed dogs and consider them blackpacking light machines.