Learning How To Sew With A Machine

[Tree Reaper]

If you're ever in mid-Michigan, you're welcome to visit my leather shop

Wiz, when I'm in mid-Michigan I'll be taking you out for dinner.

Kevin

[SooperJake]

Be sure to take him some Canadian Beer, too!

Wiz, when I'm in mid-Michigan I'll be taking you out for dinner.

Kevin

[Cobra Tom]

Leather Machine Co., Inc. includes a DVD with the COBRA Class 3 and 4 machines. If you want to buy just the DVD we will include the machine at no charge. Same price either way. LOL.

[1911 Jerry]

I seam to have a lot of trouble adjusting the tension of the bobbin and top thread.

Sometimes I get loops on top.

When I do get it to sew right and have to change colors I have to start all over again with the tension.

I have a cowboy 3500 using 277 thread and #25 needles.

I didn't think you should have to readjust the tension every time.

[Wizcrafts]

I find that there is a bit of a balancing act you need to acquire to get the tensions in the ballpark. Once there, adjustments for new thread, or different thicknesses can be made by twiddling a knob. Let's proceed with a setup using #277 thread, top and bottom, with a #25 needle, sewing 1/4 inch of veg-tan leather.

Adjust the bobbin tension for a noticeable, but smooth pull, directly out of the bobbin case spring. Make sure that the bobbin is inserted so it feeds backwards, making a sharp turn off the bobbin, into the thread slot, then under the spring and out. Note, there is a tiny screw inside a hole on the case. That is a set screw that locks the tension screw into position. Good, bad, or ugly, you have to either use it, or lose it. To change the bobbin tension, loosen that little hidden screw, then turn the bobbin spring screw in or out to increase or decrease the drag. Tighten down the set screw when you are happy with the bobbin tension.

With the needle threaded, rotate the hand wheel and pull up the bobbin thread. Grab it and give it a tug. Is the tension about the same as with the thread feeding directly out of the case? It should be close to the same, but not jammed.

Next, go over the top thread path, from the spool to the needle. The thread should feed straight up off the spool, through the hole or guide on the upper bar, then on to the post on top of the machine. If the thread is too springy it can wrap around the top bar and cause the top thread to have way too much tension. It may even break the thread, or the needle, if it gets totally jammed from a wrap-around on top. I sometimes place a funnel over black thread to keep it from looping over thread guides on the thread stand.

If your machine doesn't have a lube pot on top, the top thread must be wrapped around the top post at least one time (in a hole, around the post and through another hole, then out to the top thread tension disks). Failure to do this can allow springy thread to lift up in the upper disks, losing their normal, or all of their top tension. The back pressure from thread wrapping around the top post should keep the thread deep inside the top tension disks.

Feed the thread through the thread guide in front of the upper disks, then up and around the disks, snapping it all the way into them.

Take the thread down to the lower disks and feed it through the thread guide, then backwards around the disk, 1.5 times. On the second revolution, feed the thread back up through the same guide hole, then to the right, through the movable thread check spring hole. From the check spring, feed it up, through the take-up lever eye, then down, through the snap spring guide plate, then down through the steel guide loop, then through the hole in the bottom of the needle bar. Finally, thread the needle from left to right.

Raise the presser foot by the foot lift pedal on the right on the floor board of the pedestal. If set up correctly, this should cause a lever to go between the top tension disks, separating them and releasing most of the top tension. At this point, if you pull down on the top thread that feeds down from those top disks, it should feed with very little pressure from the separated disks (mostly from being wrapped around the top post holes). If you have too much tension screw adjustment, those disks may not release enough, or at all. If this is the case, back off the top disk tension thumb-nut adjuster until you can pull the thread easily.

Next, test the tension on the secondary tension disk assembly. Can you still pull the thread around them on the way up to the take-up lever. If not, back off the adjuster nut until you can pull the thread around that adjuster, with just a little tension.

Now let go of the presser foot lift pedal. The top tension disks should have closed on the thread, putting pressure on it. Try sewing some leather and see where the knots are. If on top, back off the top tension adjuster, and/or the secondary adjuster. If the knots are on the bottom, either back off the bobbin case tension spring, or add some more top tension (from the upper tensioner). Once the knots are anywhere inside the leather, you can fine tune the position of them using the lower tensioner adjustment.

Sometimes, it becomes necessary to add a lot of bobbin tension to balance the knots. This usually occurs with heavy, or springy black thread. Black thread has a lot more dye in it than any other color. This makes the thread tougher to balance than white, beige, or brown thread.

There are times when your eye won't see that the top thread has erroneously gotten wrapped back around the secondary tensioner on its way to the thread guide below the take-up lever. This happens more often that you can imagine. When this happens you get loops on top, or broken needles, or frayed top thread. I have even filigreed heavy leather when the top thread got stuck around the second tensioner assembly.

BTW: A #25 leather point type 794 needle is correct for #277 thread, top and bottom. But, if the leather is very soft, like draft harness leather, the hole might be too big to properly position the knots. Try moving down to a #24 needle and see if that helps.

Bottom line: As long as the top thread is not jamming, or getting wrapped around something it isn't meant to go around, and the bobbin thread is not jammed, nor out of its tension spring completely, you should be able to get consistent stitch knot placement in the range of thicknesses you thread is best suited to. If you can't balance the knots properly, either the thread is jammed, or has come out of its proper tension disk or spring placement.

Edited October 18, 2012 by Wizcrafts

[Tree Reaper]

I had some suede to sew and dreaded changing needles and thread but sooner or later it's going to happen so I made the switch.

It seems to be sewing properly, I backed the bobbin tension way off and it still seems tight but it is working.

Occasionally it will skip a stitch when back stitching (not sure what's causing that) but the running stitch seems fine.

Is anyone using a thread tension gauge to measure the thread tension?

[Wizcrafts]

Another tip is when you wind a bobbin on the winder, always cut off the starting thread that sticks out as close to the hole as possible. A tiny amount of thread sticking out can affect the position of the knots as it rotates. This is especially so if the thread stub is on the inside, where the ejector spring resides.

[SooperJake]

An update from me : Things are going well. My anxiety with the machine is gone and I'm ticking right along. I just needed to tinker.

Now I'm ready to switch to the smooth plate because the tooth marks on the backside of my stuff is pissing me off.

Haven't made any holsters lately. I made a quiver belt hanger attachment for a family member and he showed it to a local archery shop and next thing i know I'm producing these things for them. Apparently crossbow hunters don't always like to carry the quiver attached to the crossbow.

Jake

[Rayban]

I've always thought there was something screwy about black thread...thanks for explaining why Wiz.

[SooperJake]

CAn anyone recall which forum thread contained the info about setting up the smooth plate and foot combo on the Cowboy Cb4500? I'm ready to do that but can't locate the thread in here where Wiz explained how to do it.

Thanks