Correct Tension For Machine Sewing Stiff Leather?

[pellechick]

I only have experience with much softer leathers - lamb and cowhide. I have a particular veg tanned leather that I want to stitch with my machine but have trouble setting the correct thread and bobbin tension. My problem is that if the tension is too small the stitching is loose at the top for a few stitches and then at the bottom for a few stitches interchangeably. To get the stitch alright I have to set both tensions really tight - I mean really tight so sometimes the thread breaks mid seam. I can't for the life of me get it right. The leather is 1.5 mm - 4 oz. veg tanned leather and is very stiff.

If anyone could help me out I would really appreciate it.

[BillB]

Pellechick,

It is hard to answer your question directly since: 1. I don't know what type of machine you are using; 2. I don't know the thread or needle size you are using; and finally I don't know how many layers of leather you are trying to sew through.

What I can do is tell you what I am doing with the 4-5 Oz and 5-6oz leather I use in make leather bi-folds for 8.5" x 11" writing tablets.

1. I use a Toro 3000 sewing machine.

2. I use 207 or 277 industrial nylon or linhanyl thread

3. I use Schmetz 794 D needles of size 24 (CANU:53:20MF1, NM:180 Size 24, 794 D, CYX3 D)

4. The leather bifolds vary in thickness from one layer 4-5oz leather with liner (4 mm) to 3 layers of 4-5 oz leather with on layer of lining (8 mm) thick.

The tension of the needle side thread is very tight since it is dragged through the leather twice and then has to sustain the pull the "take up lever" when the stitch is set. If I grab the thread on the tensioner side of the "take up lever" and pull to create slack to remove the item I am sewing it does take a good steady pull. You can not create slack to remove the item to cut the threads by pulling the item away from the needle. The bobbin side thread is not tight and can be pulled easily but it is not loose either.

I do not have a pull scale to give you any idea about the pull strength I am talking about but it take a thumb and finger to pull the bobbin thread and a whole hand to pull the top thread and it feels like it is cutting into the skin.

I have include a picture of a bifold that I make and if you would like closer pictures of the actual stitching and thickness, let me know.

I hope you can use this description and compare it to what you are doing and resolve your problem.

BillB

Edited December 5, 2011 by BillB

[Jimbob]

I only have experience with much softer leathers - lamb and cowhide. I have a particular veg tanned leather that I want to stitch with my machine but have trouble setting the correct thread and bobbin tension. My problem is that if the tension is too small the stitching is loose at the top fkoor a few stitches and then at the bottom for a few stitches interchangeably. To get the stitch alright I have to set both tensions really tight - I mean really tight so sometimes the thread breaks mid seam. I can't for the life of me get it right. The leather is 1.5 mm - 4 oz. veg tanned leather and is very stiff.

If anyone could help me out I would really appreciate it.

Start setting ur bottom tension....pull on bobbin thread

this should be a pretty firm feel to the pull.....

Then make shure ur pressure foot has plenty pressure...

adjust top screw....firm leather needs more pressure...

now test stitch...make sure right size needle(use new needle)

Matches ur thread....possible go one size smaller...

then start watching ur nots apear or disapear on your

top stitch....knots on top is to much tension, try to oil

Or wax ur thread if u can.....

See if that gets u sewing...

Let us know details about ur set-up!!

Aloha

James

[TwinOaks]

Match your needle and thread sizes and set up the machine. Make your bobbin tension about 1 pound, maybe 1.5lb. It should pull out with just a bit of resistance, but not enough that you have to pull hard. Now, back your top tension off completely and make a stitch. You should not have any knot on the top - this tells you your bobbin tension is enough keep the top thread under the leather. Now, tighten the top tension to the point that you pull every knot to the top - consistently. You'll actually pass the point that you'll end up setting the tension, but this is to find the right range. Starting from no tension, adjust by full turns, counting them as you go. When you've got it set to pull to the top, start backing off your tension until you see the knot pulled into the hole. You should be able to adjust the tension at this point by 1/8th turn increments, until the machine pulls the knot to the center of the leather. Keep track of your adjustments and you can repeat them. Something along the lines of noting the leather thickness/type and the setting. Example: You could have a note card with "3 layers, 4oz vegtan, 207 thread top and bottom, 4+5/8ths turns from zero", and you can 'pre-set' the machine back to that point at almost any time. It saves a lot of trial and error.

This may or may not work on your machine, so let us know what you're using so we can tailor the answer to your situation.

[pellechick]

Thank you for all the input.

My setup is a JUKI DL-1181N

Using Scmetz needles NM:130 SIZE:21

Thread is size 40 - I'm not sure on the conversion - I think its metric.

I am sewing 2 layers.

I have decreased the presurre foot so that there are no nasty marks left.

[pellechick]

I have actually increased the pressure foot today to see what the effects would be and the seem to be above satisfactory.

Since I am self-taught, could someone indulge and let me know about the logic of this in regards to my problem.

Thank you.

Also, I have found the best results with bobbin tension at 100% and thread tension at 150% if that makes sense???

Thank you for all the input.

My setup is a JUKI DL-1181N

Using Scmetz needles NM:130 SIZE:21

Thread is size 40 - I'm not sure on the conversion - I think its metric.

I am sewing 2 layers.

I have decreased the presurre foot so that there are no nasty marks left.

[Art]

When running huge tensions, the top thread is very capable of lifting the leather despite the presser foot. This is why increasing presser foot pressure solved your problem a little bit. You now have to play with it a little and back off those high bobbin tensions, the top tensions will follow after you reduce the bobbin tension. Once you get the tensions right (lower than you now have) you can back off the presser foot pressure so you don't mark the leather as much. I can't think of any reason to set everything to maximum ++. Of course hard dense leather will really grab the needle so the high pf pressure might be the only course.

Art

I have actually increased the pressure foot today to see what the effects would be and the seem to be above satisfactory.

Since I am self-taught, could someone indulge and let me know about the logic of this in regards to my problem.

Thank you.

Also, I have found the best results with bobbin tension at 100% and thread tension at 150% if that makes sense???

[pellechick]

once I have the tension set suitably, I find that while sewing curves or corners the stitch becomes uneven - what gives?

[Ferg]

Try sewing the curves/corners by hand (turn the wheel by hand). You can often control the machine a lot easier doing this.

ferg

once I have the tension set suitably, I find that while sewing curves or corners the stitch becomes uneven - what gives?

[pellechick]

actually I do the corners or turns by hand. maybe it is a matter of momentum - using the wheel by hand but quickly and with a bit of force???

[Art]

The tighter you turn, the longer your stitch length will be in relation to a straight line of stitching. Your leather is moving faster. You can minimize this by only turning the leather when the machine is feeding (needle down and moving rearward). Move the leather only when the machine will let you. If you turn when there is a foot down, you will get wonky stitching. It just takes practice, remember, guide the leather, don't force it.

Like Ferg said, going slow helps this.

BTW, like any well designed machine, a quality sewing machine will do the same thing going fast or going slow. So, you can throw away the motor and turn it over by hand from now on if that's what you want, same stitch, generally no better or worse.

Art

actually I do the corners or turns by hand. maybe it is a matter of momentum - using the wheel by hand but quickly and with a bit of force???