Sewing vinyl to plastic

[tagal16]

I'm needing to sew a thin plastic strip on the bottom of a vinyl seat cover I made for an old GM vehicle to anchor it to the bottom of the seat frame. The problem I'm having is even with very loose bobbin tension and very high top tension set on my machine (Yamata FY5318 - same as a Consew 205RB) I can't get the knots in the stitches to pull thru the plastic (which is on the bottom while I sew) to make a satisfactory seam. I've tried sewing it with the plastic strip on the top but it turns out even worse. I'm using a size 20 needle and size 92 nylon thread, and I have the top thread tension set about as high as I can without the thread breaking. The only thing I can think to do (other than accept that the seam is going to turn out badly) is to use thicker thread so I can turn up the top tension even more to try to pull the knots in the seam up past the plastic to where they should be in the middle between the two pieces I'm sewing together.

Any thoughts or other suggestions on this would be appreciated. 

[MinUph]

Use a larger needle for a larger hole. A 20 is only equivalent to a 130. I would use at least a 140 and possibly a diamond point.

[kodydog]

I'm guessing you salvaged the plastic strip from the old seat. I had a similar situation with a camper canopy. The thread that holds the plastic spline to the canvas came undone. There was no way I was going to put this under my machine and the thread would not have been thick enough anyway. So I hand sewed it with a stout needle and thick thread. I used the old needle holes and painstakingly sewed it one hole at a time. This was a one time deal. If you're planning on recovering this type of car seat often, this method wouldn't be productive.

[tagal16]

I had that thought, too, that a larger needle might be necessary to poke a larger hole thru the plastic to make it easier for the thread to pass thru. Thanks for the confirmation of that.

Yes, I reused the plastic off of the old seat cover. I looked for something similar online thinking new plastic might be a little softer and easier to work with, but I decided without knowing what type of plastic it was that I was looking for buying something sight unseen would be foolish. There's a store in a city not too far away that carries surplus industrial goods like plastic (and you name it) so next time my travels take me there I'm going to stop in to see if they have something similar. I checked at an upholstery supply store and they don't have anything like this plastic strip.

[MinUph]

That plastic has to be very stiff so when you turn it into the channel it stays put.

[Mojo]

I would try a size 22 needle with 138 thread. If RiCat is around he may have another idea. He has done a lot of old classic cars
and knows a lot of tricks to the trade. If he doesn't pop on here and answer this post then send him a PM.

Rick is a great guy and always willing to help fellow stitchers.

Mojo

[RiCat]

Thanks for the kind words, Chris. Yes, I have done quite a few of the types of seats that have the strips of u channel to sew to the covers to refasten. I have been able to sew the originals back on with a #22 size needle and 92 thread. And I use a very narrow foot to do this to try to get back to the original holes. Machine: Juki LU563. An idea what I do sometimes. The principal is, if the plastic strips is sewn to the covers, there is no allowance to adjust the cover if needed. The plastic strip dictates where the cover goes, so one has to make sure it is sewn back on the new cover properly and the patterns are done precise. What I like to do if possible (if possible meaning hardware on the bottom side of the cushion is not in the way, and cushions is what i am mainly talking about and backrest can be more challenging) is to either make the vinyl longer and find some where to hog ring the vinyl or on the flat piece of metal that the plastic fastens to, drill some holes (maybe 1/4") about 4" apart and hog ring the cover to the holes. A principal I use is, I want to fasten that cover the way I want to and I am not concerned how it looks underneath the cover - I am concerned with what the cover looks like that is seen. When looking at a seat, observe it like when it is in the vehicle. That is different when looking at it on the bench.

Rick

[baileyuph]

Two things, #1 (your thread tension may be part, a big part of the problem.)

Get your thread tension adjusted for size 69  thread to test the machine on more
normal sewing.  When you get it sewing on normal materials, I bet it will then sew the plastic piece,
even with the 20 needle/69 thread.

Make sure you get the machine sewing on normal stuff with normal bobbing and needle tension.

This may be a machine needle problem but before assuming - verify it works on normal materials(vinyl)

I never have had a problem with a sewing task such as you describe.  If the machine will push the needle through the plastic (no thread for this test), then examine machine for thread tension and threading problems.

I sew these plastic retainers every day - no problem w/69 thread and or 20/22 needle.. 

Check your setup - something is not normal about the adjustment you have on your machine.

First keep it simple, check your machine (there is a problem in that area).  For example will your machine push the needle through the plastic -  not threaded?   If that is a "no".  Then it will not sew this until you do more checking to find out "why".


What year (GM) car are you working on?  What seat?  If the plastic is too hard to use, then that is a problem,


Doyle