Do you like this presser foot?

[Gymnast]

At the attached picture, you see two presser feet for Singer vintage sewing machines with normal feed dogs. I made a modification to the right foot by cutting a notch into the foot.

Have you previously noticed a similar presser foot?

Do you anticipate problems by using such presser foot?

I tried to sew tarpaulin near the limit for such a machine with a tex 135 thread. With the modified foot, I was able to reduce the thread tension to 61 % compared to the left foot in picture. Furthermore the required pressure on the pressure foot could be reduced to 52 %. In this way it became easier for the machine to handle the same job.

[Evo160K]

Good modification.  What thought process lead you to do that?

[Constabulary]

What is the modification - the short cut in the right foot? What is the advantage? 135 thread is quite tick for a Singer domestic machine. You calculate tension in percentage - are you a scientist? Maybe its just me but I don´t get what you want to say - but maybe its just me.

 

 

Edited April 27, 2019 by Constabulary

[RockyAussie]

Interesting . They are 2 different feet in that the one on the left is a hinged foot and has a fair bit longer body length than the one on the left. Like a stiletto shoe heel a lot more pressure is going down for the same weight applied which explains the reduced foot pressure needed. I can only assume that the slot cut may allow the thread tension to come in earlier to effect how the thread tension behaves. It may also be needed for the needle travel if the foot is for a different length than this machine.

2 hours ago, Gymnast said:

Do you anticipate problems by using such presser foot?

AS long as it is smoothed off well no and if it requires less foot pressure to do the job it should extend the machine life as well.

Thanks for sharing.

[Gymnast]

Thanks for your comments. I will try to answer your question in a later reply. But I need to give more details.

I made some comparative test with three presser feet. It was a normal presser foot, a modified foot with a notch to the back, and a wheel type foot.

The modified foot had been cut about 3 mm to the back to make room for the thread when maximum thread tension is applied in the sewing cycle. In this way the thread friction below the food is reduced. Furthermore the required traction for the feed dog is reduced due to the direction of the thread tension hitting the fabric. The wheel foot has the same kind of advantages.

The test was performed using a Singer 201k machine with a 140/22 needle and an Amann Serafill 20 polyester thread (Tex 135). Tension measurements were performed using an uncalibrated dynamometer. The tension was measured by pulling the thread before reaching the thread take up. The tension from the bobbin case was set to 0.5 N. The fabric was two layers of 600 g/m2 tarpaulin of good quality.

In each case the sewn stitch was examined, and the upper thread tension was adjusted to get a balanced stitch.

The traction of the feed dog was increased by increasing the pressure on the presser feet, so a maximum stitch length could be noticed. It was 4.4 mm for the two first presser feet and 4.8 mm with the wheel type foot. Then the pressure to the presser foot was reduced until 0.1 mm lesser stitch length could be measured. This pressure on the presser foot is named as the required pressure on the presser foot. The results are given in the pictures.

For some unknown reason the stitch length became 0.4 mm longer with the wheel foot compared to the other feet.

The pictures are taken in the stitch forming part of the sewing cycle, where the thread tension is applied to the upper thread (near max position of the thread take up).

Results:

With the modified presser foot and wheel presser foot, you are able reduce the thread tension to 61 % of thread tension with a normal foot.

The required down force on the modified presser foot could be reduced to 52 % of the normal foot. The required down force on the wheel foot could be reduced to 28 % of the normal foot.

 

 

[dikman]

Brian, I am more than happy to acknowledge your superior experience in these things, but I must admit I'm with Constabulary on this. The feet look the same type as those on my little 201K (domestic) and I'm blowed if I can see any advantage in filing out a notch like that. Plus, as you say they are two different type of feet, so to prove that cutting the notch makes a difference the comparison should be between two of the same feet, i.e. before and after.

Of course, I could be completely wrong......

I see you posted just as I did, Gymnast. Interesting tests, but as I said you should do the comparison between two of the same type of foot in order to get an accurate result.

Edited April 27, 2019 by dikman

[Gymnast]

1 hour ago, RockyAussie said:

Interesting . They are 2 different feet in that the one on the left is a hinged foot and has a fair bit longer body length than the one on the left. Like a stiletto shoe heel a lot more pressure is going down for the same weight applied which explains the reduced foot pressure needed. I can only assume that the slot cut may allow the thread tension to come in earlier to effect how the thread tension behaves. It may also be needed for the needle travel if the foot is for a different length than this machine.

AS long as it is smoothed off well no and if it requires less foot pressure to do the job it should extend the machine life as well.

Thanks for sharing.

You are right - I have not used the same foot in the detailed Measurements. However i did earlier make some comparisons of the two feet, and actually did not find and significant differences. At the moment I do not have more feet of this kind, but I have ordered more feet. When I get them in about 3 weeks I shall make a better comparison. But I would like to see others try this modification.

The reason I did this modification was, that I discovered, that I needed less thread tension when using the wheel foot and started to investigate why.

[RockyAussie]

12 minutes ago, dikman said:

Brian, I am more than happy to acknowledge your superior experience in these things, but I must admit I'm with Constabulary on this. The feet look the same type as those on my little 201K (domestic) and I'm blowed if I can see any advantage in filing out a notch like that. Plus, as you say they are two different type of feet, so to prove that cutting the notch makes a difference the comparison should be between two of the same feet, i.e. before and after.

Of course, I could be completely wrong......

As you know I am guilty of using hammers and scales and fish scales etc but its funny how little things like this can make such differences in the operation of a sewing machine I reckon. The slot looks to allow the thread to be pulled through the needle on a more straight angle and that would therefore make the thread slide through the needle with less friction. The roller giving a longer stitch I think would be because there would be less resistance on the fabric when going through. The other 2 feet keep pressure down all through the job and create friction over their wider non rolling base than the other large roller foot. Now I sound like a geeeek again . I'll get kicked outer this here section yet.

[Gymnast]

3 hours ago, dikman said:

Brian, I am more than happy to acknowledge your superior experience in these things, but I must admit I'm with Constabulary on this. The feet look the same type as those on my little 201K (domestic) and I'm blowed if I can see any advantage in filing out a notch like that. Plus, as you say they are two different type of feet, so to prove that cutting the notch makes a difference the comparison should be between two of the same feet, i.e. before and after.

Of course, I could be completely wrong......

I see you posted just as I did, Gymnast. Interesting tests, but as I said you should do the comparison between two of the same type of foot in order to get an accurate result.

Thanks for your comment dikman. We need to be critical in order to try understan´, what is going on here.

I agree, that the different type of feet can make a change to the feed dog traction. Therefore the figures regading required down force on the presser foot may not be compareable. But how do you explain the difference in thread tension for a ballanced stitch?. When you compare the tread tension for the Wheel foot with the notch food, then they are equal. The only reason for me regarding the drop in thread tension from 7.2 N to 4.4 N is, that you add significant friction to the tread below the normal presser foot. Furthermore the thread tension direction is along the fabric and not more right up from the stitch hole in the tarpaulin, and it should add to thread friction as well.

With the added tension and direction of the tension in the thread pulling in the fabric, you need more traction from feed dog to pull the last half part of the feed dog motion with high tension in the thread. And the only way you can get more traction is to increase the Down force on the presser foot.

I actually did some Measurements with dynamometer on how much traction in the fabric you get depending of Down force on presser foot. A slump figure for this normal presser foot on this machine is, that you get about 1/3 more traction compared to down force. So if you increase down force with 12 N, you should get about 4 N more possible traction. So these traction values are compareable to the thread tension.

[trash treasure]

This is actually pretty interesting - If the modification results in that much less tension needed, then there might be a real benefit with pucker reduction for seaming some fabrics - I may have to do some experiments on my own ...........