Walking foot - feed dogs marking leather

[jakc3]

Hello,

I have a question regarding feed dogs marking leather.

I have a Pfaff 335 sewing machine with walking foot feed. On softer leather the feet marked it as well but I solved that by gluing thin leather on the bottom of the feet. 

I still have issues with the bottom feed dog marking the leather. It's smooth, without teeth and it moves only horizontally (maybe just a little bit vertically but it is a negligible amount - 0.05mm). What it does is it leaves a line, which can't be rubbed off, on the bottom side of the leather.  First I thought this is because the plate covering it was slightly higher than the feed dog so I sanded it down to the same height. This however didn't solve the issue.

Are there any solutions/workarounds to this?

Many thanks,

Jakob

[Uwe]

Try lowering your presser foot pressure. Many people have the foot pressure set much too high for what they're sewing. Many people don't even know how to change that setting (perhaps because the manual does not talk about it!) Dial back the screw on top of the head to the least amount of pressure that keeps the material from moving when it shouldn't.

Support the material with your hands as you sew so the machine needs just a little bit of force to move the material. Don't push or pull on the material, let the machine do the feeding. 

[Uwe]

So it turns out I don't know how to lower the foot pressure on a Pfaff 335 either! I removed the foot pressure adjustment screw on my Pfaff 145 and it made almost no difference at all in how strong the feet press down. This needs further investigation . . .  

[JerseyFirefighter]

 

So it turns out I don't know how to lower the foot pressure on a Pfaff 335 either! I removed the foot pressure adjustment screw on my Pfaff 145 and it made almost no difference at all in how strong the feet press down. This needs further investigation . . .  

I've never had any success with backing off the presser foot pressure on my ferdco either. One of those minor annoyances I have come to accept in life. Still curious on further insight. 

[dikman]

It was pointed out to me that the pressure screw was missing on my 335 when I posted pics here, so I found something that would fit to replace it. Funnily enough, it didn't seem to make any difference to foot pressure, so I figured I needed the correct screw. From what Uwe said it  now appears it was missing because it didn't make any difference.

Now I'm curious to find exactly what, if anything, does affect the foot pressure.

[CowboyBob]

Is the marking worse or only on the leftside of the needle?

[Uwe]

The Pfaff 335/145 series machines have two presser foot springs, one nested inside the other.  It appears that on the old casting machines the outer, strong spring is not adjustable. If it is adjustable, I don't really see how. The inner spring is adjustable with the thumb screw, but that spring makes almost no difference. Either I'm missing something or I don't understand the design intent here (other than purposely locking the operator out from making that adjustment for some factory/production reason or saving $0.50 in production cost by not threading the hole and the sleeve.)

Only my Pfaff 593 was cooperating in being taken apart to show the thin inner spring (pulled a little). On this machine the sleeve does not have a knurled top. I was able to loosen the set screw that appears to lock the sleeve in place, but the extension sleeve would not budge or move at all after loosening the set screw. 

 

On my Pfaff 145, the extension sleeve has a knurled top, which makes it look like it's intended to be manipulated somehow. Unfortunately the set screw that holds that extension sleeve in place is messed up and I can't loosen it. Maybe you are able to move that sleeve up and down to adjust the outer spring, and then lock the sleeve in place again with the set screw. None of my machines were cooperating in testing this theory. 

On the modern casting of Pfaff 335, the outer spring is adjustable and you can adjust foot pressure:

This archive picture of my former Adler 69 shows how on that machine the inner and outer spring on that machine are adjustable with independent, nested, lockable adjustment screws. This seems how it should be, quite frankly. Maybe Adler filed a patent on that design to keep Pfaff from doing it.

 

 

[jakc3]

 

Is the marking worse or only on the leftside of the needle?

As you noticed, the screw doesn't really affect the foot pressure. 

The markings appear only on the left side of the needle.

A temporary fix I found is to sew the piece with baking paper underneath and then simply tear it away. It is extra work though and would be nice if the leather wouldn't get marked in the first place.

[CowboyBob]

Well I was thinking since the feed dog doesn't go down as it goes foward & you have just the left toe foot on when the inside foot goes up the outside foot goes down & the feed dog goes foward the top left edge of the feed dog is being pushed into the leather underneath.The only fix would be to round off the whole edge or top corner of the feed dog.

[RockyAussie]

I will try and take some pics tomorrow of a 335 I have put away in a storage container. From what I can see it looks as though I have lifted the as Uwe calls the extension up about 1/4 to 3/8" and run with that. From memory I think it required vice grips and ample swearing.My 331 has a far nicer set up (Like the modern one a bit)  but inside of it there is a rod that when you screw the extension down it pushes the inner  spring down. As I use very small feet and on light duty leathers I take that rod out thus making the inner spring do nothing. I gauge the tension by lifting the foot by hand first then adjusting the pressure until the job will just not lift when the needle pulls up.When I use heavy veg I put it back in.