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Kites! Kites! Kites! => Kite Building and Repair => Topic started by: NWFlyer on July 29, 2013, 09:52 PM



Title: Adjusting Machine for Light fabric sewing
Post by: NWFlyer on July 29, 2013, 09:52 PM
I'm getting ready ready to try making my first glider style kite out of some lightweight material - either some AirX 600 or 0.75 oz. RSN.  As I was doing some practice sewing runs with these options I found my Pfaff 2140 machine wouldn't grab either fabric and pull it uniformly like it does for heavier weight materials.  Do you pro's adjust sewing tension and dog pressure for different weight fabrics or pretty much leave things alone for all weights?  Wondering if it's a machine problem or operator error -
Thanks,
NWFlyer


Title: Re: Adjusting Machine for Light fabric sewing
Post by: Doug S on July 30, 2013, 05:34 AM
NWFlyer,

I don't know your machine to help you make adjustments.  In doing a little internet research, make sure your walk foot is engaged and working.  The material we are trying to sew is thin and slippery.  You need to hold the two layers of material together in some way to keep them moving together under the foot.  Some people use double sided tape or a glue stick.  I also have found using thin strips of low stick blue masking tape to work for me.  I use a plain seam most of the time and join the edges together by hot cutting off a very thin amount.  From your prior posts, I believe you are building an urban ninja that uses a lap seam.  In that case, double sided tape or a glue stick may be the way to go.

The other response I saw was about the same problem I have on occasion using my old Singer machine.  When starting a new stitch at the beginning of a run, there is very little material under the foot.  What I do is start in a little ways and back stitch, then proceed forward using the loose threads to help carefully keep the material moving under the walking foot for a few stitches.  During the forward stitch, I make sure the needle goes back into the same holes as the back stitch.

It would be my suggestion that you do a little research.  There are some stunt kite building projects on this website that can provide you with a little more detail on how to secure the layers of material together before sewing, by individuals such as Sugarbaker.

I hope this helps,

Doug


Title: Re: Adjusting Machine for Light fabric sewing
Post by: tcope on July 30, 2013, 05:54 AM
You should not need to adjust the presser foot or feed dogs if they are adjusted correctly to start with. If you are using a walking foot the fabric should not be much of an issue. My recommendation is to take a piece of fine Emory cloth folded over and run the folded edge  in the groves of the feed dogs. This can make a _huge_ differences in grip. Thread tension won't make a difference in feeding fabric.


Title: Re: Adjusting Machine for Light fabric sewing
Post by: NWFlyer on July 30, 2013, 06:43 AM
Thanks for the responses.  I'll give those things a try tonight. My machine was serviced a short while ago and I don't think it's the problem - just my technique and inexperience I'm guessing.  I've been sewing heavier weight RSN and bag material without any problem.
Thanks again, NWFlyer


Title: Re: Adjusting Machine for Light fabric sewing
Post by: thief on July 30, 2013, 07:43 AM
Gary Engvall has some notes about basic tnesion settings on his site: https://sites.google.com/site/kites4all/home/kite-sewing-101
and if you wander over into kitebuilder there are a number of pfaff owners in there....


Title: Re: Adjusting Machine for Light fabric sewing
Post by: nckiter on July 30, 2013, 08:14 AM
1.You have to keep the layers together by what ever means (hot tacks, adhesives,clips, DS tape, etc, etc). The kitebuilder forum has a lot of info for this and other kite building tips and tricks.

2. You have to guide this stuff into a Pfaff. Be sure you are not holding it back. Let the IDT and feed dogs do the work, just guide it in and keep it aligned.

3. If the machine will not feed itself evenly with you guiding the material you may need to have it looked at. It is possible for even a Pfaff to have feed issues between the upper feed (IDT) and the lower feed dogs.

Good luck and let us know how you get on with it.


Title: Re: Adjusting Machine for Light fabric sewing
Post by: Wayner on July 30, 2013, 07:34 PM
All good points.

I would add. Go slow..... Speed and accuracy do not go hand in hand.

Use a zig zag stitch when possible.  It will show less errors than straight stitches.  ;)


Title: Re: Adjusting Machine for Light fabric sewing
Post by: tcope on July 31, 2013, 05:59 AM
Use a zig zag stitch when possible.  It will show less errors than straight stitches.  ;)
I'd agree that it may show less errors but it's also much more unforgiving. That is, the timing/tension on a machine needs to be pretty much perfect for a zig zag stitch to come good. A straight stitch requires less of a perfect set up. Hope that made sense.

There are great animated GIFs that show how the sewing machine works but just in the bobbin area it's pretty complex. The needle goes down into the bobbin area and then moves back up, just slightly. With the grove in the needle this creates a loop in the thread at the needles point. The bobbin hook then circles around to the top and catches that upper thread loop. It pulls the loop all the way around the bobbin. This is what locks the upper thread and lower thread together. You then have the thread take up arm that pulls the upper thread back up and makes it tight. All of these movements are done with slack thread. So things need to be pretty much perfect. The bend of the thread, the tightness of the bobbin tension, how close the bobbin hook is to the needle, etc. Open up your machine with no thread and press the pedal. Watch how fast that bobbin and needle move! It's crazy to think that everything above takes place several times a second. Then you work in several other mechanical movements for zig zag and reverse stitches. Crazy.


Title: Re: Adjusting Machine for Light fabric sewing
Post by: glk47 on August 01, 2013, 03:17 PM
Some advice from my wife that worked for me getting seams started in RSN: put a couple of layers of tissue paper under the starting point, extending out ahead of it. This seemed to give my Bernina enough to work with. When you're done, the tissue paper is perforated along the seam and tears away easily.

Speaking as a real novice kite sewer, Larry


Title: Re: Adjusting Machine for Light fabric sewing
Post by: tcope on August 01, 2013, 03:21 PM
I like things that service two purposes. When you get done on a long seam and discovered that you need to seam rip the entire thing that tissue paper can be used for the tears that follow.


Title: Re: Adjusting Machine for Light fabric sewing
Post by: Lou on August 01, 2013, 03:31 PM
I like things that service two purposes. When you get done on a long seam and discovered that you need to seam rip the entire thing that tissue paper can be used for the tears that follow.

My goodness that made me laugh and at the same time put such a fear in me that I pray I never have to seam rip that much at any one given time!!  ???


Title: Re: Adjusting Machine for Light fabric sewing
Post by: tcope on August 01, 2013, 03:36 PM
I've done 16' and 21' seams. Most of the time when I realize what I've done I need to walk away for a few hours and then come back and do a few feet at a time. When you have that much fabric it's tought to even know if the kite is right side up or upside down.


Title: Re: Adjusting Machine for Light fabric sewing
Post by: NWFlyer on August 01, 2013, 06:46 PM
Ok, you guys.  The thought of taking apart 20 plus feet of a seam has me thinking twice about tackling something that big.  I'll stick with smaller stuff for now until I get better with my sewing.  I tried some of the suggestions offered and they seemed to solve the problem I was having.  I also used lighter weight thread and a slightly smaller needle and I can't say that was the sole cause for improvement but the results were better.  Thanks for everyone's help.
NWFlyer


Title: Re: Adjusting Machine for Light fabric sewing
Post by: Doug S on August 02, 2013, 07:37 AM
On the opposite side of a large build, I was building my 20 inch Hawk last week out of the light and fragile Cuben fabric.  With this fabric, one mistake and you have to start over from scratch.

With the first leading edge done, I was working on the second leading edge.  I had it folded and the tip reinforcement in place with double sided tape.  When I went to stitch, I realized that I had leading edge material folded on the wrong side of the sail.   :'(  It was interesting removing the tip reinforcement from the sail without damaging it.  A little rubbing alcohol worked wonders to get the glue residue off of the Cuben Sail.  I was day dreaming because I have built a number of my Hawks using the same type of construction.

I keep examples of my mistakes hanging in my work shop as a reminder that sometimes your mind is not engaged and you just have to walk away for a while.   :-[

Doug


Title: Re: Adjusting Machine for Light fabric sewing
Post by: Lou on August 02, 2013, 04:09 PM
I've done 16' and 21' seams. Most of the time when I realize what I've done I need to walk away for a few hours and then come back and do a few feet at a time. When you have that much fabric it's tought to even know if the kite is right side up or upside down.

 I have no words for what I just read.... 21 feet of seam ripping....  you sir are truly dedicated to the art of kite building.  I see gasoline and flames if that happened to me!  :'(