Cobra 4 presser foot leaving marks

[aaron8771]

I've searched the forum and couldn't find much other than just live with the marks or handstitch. Both are not options for me. 

I'm sewing 12/13 oz english bridle leather from Weaver for belts. Great stuff. But the presser foot marks are killing me. I've been sewing wallets too. 4-5 oz veg tan. Some places are 4 layers thick, and I have marks.

I have the presser foot adjustment out as much as it will go. I haven't found much to help.

I did run across something for the cowboy 4500. They were having the same problem. Someone suggest they cut the spring down a bit to relieve some pressure from the spring. That has me thinking. It makes sense right? What are your thoughts?

 

[Uwe]

You must not have looked super hard - the topic of presser feet leaving marks has been discussed ad nauseam in this forum.

It all comes down to pounds per square inch of foot pressure. To get below the p.s.i. level that leaves marks, you can either lower the spring pressure or increase the square inches on the feet.

The discussions generally boil down to this:

1. Use the lowest possible spring pressure that will still adequately hold the material (modifying the spring may be required.)

2. Use feet with the biggest possible smooth footprint that still allow you to see what you're sewing.

3. Use a big, smooth feed dog, or skip the feed dog entirely and use a throat plate with a needle feed slot.

 

 

[aaron8771]

I'm sure every single topic has been discussed  ad nauseam in this forum. 

Thanks for your reply.

[JLSleather]

 

 

[dikman]

2 hours ago, aaron8771 said:

I'm sure every single topic has been discussed  ad nauseam in this forum. 

Thanks for your reply.

Not really, but some subjects come up quite regularly (and this is one of them). Generally, with a heavy duty machine it will be almost impossible to stop getting marks of some sort, it's the nature of the beast. Even light/medium duty machines will leave marks on veg-tan. If you try to minimise the marks by reducing tension/pressure settings then you soon reach a point where the leather won't feed properly or starts lifting as the needle comes up, which can then cause missed stitches etc.

Virtually every holster/belt that I've seen that has been made on a heavy-duty machine has had feed marks.

[RockyAussie]

Is it possible to use the blanket foot set with the teeth ground down smooth on that job? I would hesitate before reducing the foot pressure spring too far as in my experience the small foot footprint is likely more the problem. On that sort of thickness you could run into the job lifting up with the needle if you reduce the pressure too much. Another alternative is to get a wider foot from kwokhing like in this pic of mine and grind the side bit off if you don't want that guide part of it. http://www.kwokhing.com/

It is right on the last page in their catalogue from memory.

First pic shows small contact area of the standard feet

2nd pic shows the kwoking feet with about twice the amont of contact area

The picture below shows most of the range but you can get a wider front foot for a bigger gap and that may be a better one to cut down.

You may find some thing more about these feet in this post I did awhile ago.

Brian

[JLSleather]

footpad.mp4

[soccerdad]

Someone on the Cobra staff suggested using a single-foot setup and putting a strip of thin, dense cardboard under the path of the foot. The foot hits the cardboard and not the leather. Tried it once just to check it out, and it seemed to work pretty well. If you are sewing straight lines on belts, maybe you'd get the hang of it, though it was as fussy as it sounds first time out. 

I love bridle, but in my experience it marks easier than other leathers. When I was asking this same question about machine marks a couple of years ago, one piece of advice I got was to work with leathers that take the foot pressure without taking on a dent. We get attached to our materials, so that was hard to swallow. But I think there's a lot in it.

For me, it's about adaptations, tradeoffs, etc. For instance, although my machine stitches perfectly well, the stitch itself never looks half as good as a saddle stitch to my eye (and I try not to look at the backside stitch at all!). I remind myself of the massive time savings with machine stitching. Plus, precious few customers notice that particular detail and even fewer are willing to pay a fair price for saddle stitching. When it comes to the leather itself, using the machine has prompted me to experiment beyond the firm veg tans I hand-stitched and has opened up lots of new possibilities for high-quality work. Good luck. 

[aaron8771]

Thank you for your comments. Soccerdad, I'm going to try the cardboard since I have a few belts I need to get done today.

Rockyaussie, I'm going to look into a wider foot also.

I do realize that eliminating the marks is probably impossible. I'm ok with that. The marks are a lot deeper with with the Weaver English Bridle Leather than they are w/ Hermann Oak. Weaver's is noticeably softer.

[Wizcrafts]

47 minutes ago, aaron8771 said:

The marks are a lot deeper with with the Weaver English Bridle Leather than they are w/ Hermann Oak. Weaver's is noticeably softer.

Almost all of our belts are made of bridle leather. We just rub out foot marks and any other scratches or range marks with a modeling spoon, and sometimes even a teaspoon.