Has Technology Passed the small trim shop by?

[baileyuph]

Take a look at leather seating in a five year old car or so.  More specifically one that has light gathering of the leather in some seams.  It is done so perfectly, in that all seats are gathered the same.

Anyone with knowledge about the equipment required to accomplish this work in leather?

Very important for auto trimmers involved in seat repair where a repair has to match the rest of a auto interior.

Equipment vendors or someone with manufacturing experience probably could talk to this?  

Anyone?

Doyle

[MinUph]

Not experienced here but it would seem some sort of gathering foot is used to make it uniformed.

[bobbin]

The first thing that springs to mind is use of a shirring foot.  This presser foot has a "step" at the front of it and is cut away behind the hole for the needle.  It's typically used with a drop feed machine (where only the feed dogs pull the fabric under the needle) and they come in various sizes, with the "step" varying in height according to the fabric used in the gathering operation.  However, I would wonder if this would be the way to gather leather... it stretches more than wovens and that tendancy would indicate to me the practical necessity of a needle feed or compound feed machine.  I have never seen a shirring foot with a slot that would accomodate a needle feed machine's needle bar feed mechanism; also a needle feed machine is designed for smooth, uniform feeding of fabrics to avoid creeping and unwanted puckering.

I would then think of some sort of chain stitch machine (likely without knives) as those typically come with a differential feed adjustment.  Differential feed, once properly set will deliver a uniform "gather" (shirring) with speed and great accuracy on piece after piece.  It would require very little operator experience as the person patterning would likely work out the finer measurements along with an experienced operator/sample maker, before the production cuts and work began. 

I will be interested to see if someone with production experience responds to this question.

[baileyuph]

Differential feed, once properly set will deliver a uniform "gather" (shirring) with speed and great accuracy on piece after piece

Yes, and my general thoughts, based on inspecting this type of upholstery in auto work, reinforces that possibility.  Also, I have an 8 spool serger with the differential feed flexibility and it works very well on light weight fabrics.  However,  consideration of this machine for leather or vinyl, it is not the equipment for the job. 

The technology used maybe relatively new, but from observations has been in place for a few years.  Maybe a description will surface somehow.

One of the major seating corporations supporting auto manufacturers, for example, Lear, is a direction to look for information.  Their production operations are probably located where labor rates are low, just a thought.

Doyle

[bobbin]

Do they pre-shirr the leather to a backing (some sort of twill tape) before it's joined to the other piece?  Or is the shirring effected in the same operation that joins it to the other piece?

[baileyuph]

Good questions, yes preshiir with a twill backing in the seam is common.

When a shirred panel is seamed to a flat panel (non shirred), then the process appears to be two steps.

Doyle   

[scott_san_diego]

I had a job to make 100 motor covers.  The top was gathered and had a draw string inside a pocket.  The pocket was 17" wide and the top of the material was 22" wide.  Had to gather the top so it would end up being 17" in order to sew on the top pocket.  Along the 22" edge would run the edge through the sewing machine with the widest stitch length possible..  At each end leave about 7" inches of thread.  Then would carefully pull on one of the threads to bunch the material down to 17".  Then sewed on top pocket.  It worked well.  Have used the same process on fabric that has gathering at the seams on Lazyboy chairs.

[bobbin]

That technique for "easing" is frequently used on the cap of set-in sleeves on trimly fitted blouses or sport coats/blazers.  I also employ it to set the curve on "smile" windows in marine enclosures (that is when I'm "allowed" to use coil zipper and do them the way I was orignally taught).

[baileyuph]

It worked well.  Have used the same process on fabric that has gathering at the seams on Lazyboy chairs

That technique has worked for a lot of gathering requirements, wish I was good enough to adapt it to maching leather auot seats.  It appears that here is a differential feed machine, computer assisted, with software to accomplish this feat in modern auto interior production. 

Any leads on verifying this would be appreciated.

Doyle