Double vs Triple feed for vinyl

[RaSk]

Hi,

After reading on the subject, including various posts here, I'm a bit confused about the pros & cons of double vs triple feed.

I understand that one of the big differences is that triple feed usually has a smoother presser foot that prevents damage on leather. I guess that the needle helping to drag the material allows a softer grip on the pair of feet.
But on the other hand double feed seems to integrate newer technologies (like computerized stitch length) and is much cheaper.

As a sewing beginner, one of my issues with my current triple feed machine is when sewing on top of quick-changing thicknesses, like topstitching at the intersection of 3 pieces where it goes from 3 layers to up to 8.

One of the benefits of double feed and drawbacks of triple feed mentioned by Sailrite is this "bump" issue with compound/triple feed.
But one other manufacturer that offers both mentions the opposite on their brochure when choosing between both models (2030 vs 2060).

I'm not using leather yet, so I'm considering buying a double feed to complete my set of machines. Would it solve my problem with bumps? Any other drawbacks to consider regarding double feed for upholstery?

Best regards,

Alex

[Wizcrafts]

Dual feed machines have teeth on the feet and feed dog to claw the work forward (and backward if they have reverse). Teeth leave permanent marks in leather and possibly in some synthetics, like pleather. Compound feed machines usually have teeth on the feed dog but not on the feet. This leaves some marks on the bottom but not much on top.

As for positivity of feed, dual feed really locks it in. However, the layers can slip a little until the needle penetrates them. Also, compound feed machines have a swinging needle bar, like a pendulum on an old clock. The thicker the seam, the shorter the stitches compared to the thinner layers. It is called The Pendulum Effect. This doesn't happen on dual feed machines with a fixed position needle. So, the stitch length is more consistent on a dual feed machine. Those machines are best limited to sewing cloth and synthetics. Leather is best sewn with a compound feed machine, unless it is chrome tanned and doesn't retain tooth marks.

[DonInReno]

What about the “bumps” are you having problems with? 

We normally talk about leather here, but triple feed machines are not limited to only smooth feet.  Most professional vinyl sewers I’ve come in contact with use a triple feed machine because it feeds all kinds of difficult material well.

My experience with rather hard and shiny vinyl such as for outdoor spa covers and such, with matching thread color so stitch uniformity isn’t an issue, is that it’s a constant struggle to keep enough traction to climb up and over thick seams.  The triple feed was noticeably more capable than the walking foot that lacked needle feed.   Both machines had rather aggressive feed dogs and serrated feet.

If you will be sewing canvas or vinyl regularly it comes in handy to invest in different feet/feed dogs for that vs. leather.    

Feed dogs will often be labeled inconsistently as to how aggressive they are - one company’s heavy/coarse model is another’s medium.  I’d get two heavy sets - leave one for heavy canvas and things that don’t show teeth marks at all.  The second would be sanded down somewhat so the teeth aren’t sharp and won’t leave marks on vinyl.

Even if you like to keep the same feed dog for everything from leather to canvas, definitely invest in separate feet.   Canvas and vinyl feet can, and I’d say should, be serrated for extra traction - I have one set that is so coarse it can only be used on canvas and another serrated set for vinyl.   The seams on outdoor vinyl are often quite large so a bit of angle on the nose isn’t a bad thing to help getting on top of things, whereas leather feet often benefit from being rather blunt to have better access for tight areas that are difficult to maneuver around. Foot pressure needs to be heavy enough that the serrations can get a grip.

If you are having a hard time getting on top of seams keep technique in mind.   As the nose of the walking feet contact the seam you need to carefully pull on the material enough to make the stitch, but not so much the needle bends or stitch gets out of alignment.   On really big seams it’s not unheard of to go one stitch at a time and lift the feet if need be so the needle goes where it should.   On the downhill side it’s lazy sewing to just let the foot slip off creating an extra long stitch - pull back on the fabric as need be and always watch where the needle is going.

I’ll bet your seams are thicker than they need to be.    Layers of material under the surface layer of things like multi layer handles and loops can often be trimmed back directly under the seam reducing bulk and not affecting long term strength.  While it may seem cleaner to double fold an edge to hide the ends, it greatly increases bulk and might be better to sew tape on the edges.  Often handles and loops are added after seams are sewn so there’s no need to sew up and over them.   Same with leather - areas that create a large bump are often shaved down to reduce it.

Best of luck and don’t get too frustrated - it all seems difficult until it doesn’t.  :-)