Need Help With New Cowboy 3500

[JS22]

Could someone please explain to me the relationship between the length of my stitches and the thickness of material to be sewed. I am a sewing machine virgin. Have never touched one until last Friday when I recieved a brand new Cowboy 3500.Thye machine is similiar if not identical to a Artisan 3000 and Cobra class 3. I have stitched and stitched scrap leather for the past few days trying to figure this thing out. My first project will be of alligator. I can't afford to muff it up. My project is a wild buch rig for cowboy action shooting. It consist of 7/8, 9/10, and 12/13 oz skirting. The holster will be close to a 3/4" welt. The stitching looks exactly how I want on the lighter leather, but when I switch to the thick stuff ( 1/2" or more) I get little teeny stitches. Do I have to adjust this thing every time I switch leather thickness. Is there a tutorial on this somewhere?

Thanks!

[Art]

Where is the dealer you bought your 3500 from? He will setup the machine for you. These are needle feed machines and should not have a problem feeding, unless the presser foot pressure is too light and the material is pulling back because of lack of pressure to hold it. Your dealer can help you with this.

Art

Could someone please explain to me the relationship between the length of my stitches and the thickness of material to be sewed. I am a sewing machine virgin. Have never touched one until last Friday when I recieved a brand new Cowboy 3500.Thye machine is similiar if not identical to a Artisan 3000 and Cobra class 3. I have stitched and stitched scrap leather for the past few days trying to figure this thing out. My first project will be of alligator. I can't afford to muff it up. My project is a wild buch rig for cowboy action shooting. It consist of 7/8, 9/10, and 12/13 oz skirting. The holster will be close to a 3/4" welt. The stitching looks exactly how I want on the lighter leather, but when I switch to the thick stuff ( 1/2" or more) I get little teeny stitches. Do I have to adjust this thing every time I switch leather thickness. Is there a tutorial on this somewhere?

Thanks!

[JS22]

The machine was set up to sew out of the box exactly as I asked it to be. I have been in contact with Bob Kovar at Toledo sewing and he has been very accomodating. As I stated in my post, I am newer than new when it comes to sewing machines. I did not want to continually pester Bob with a barage of questions as I learn the machine. I thought maybe I could gain some insight here on the forum.

[Art]

That's what Bob is there for. He should get to know you on a first name basis. Being no form of keyboard daemons, it will take a long time to convey what can be done on the phone in a few minutes. Call him.

Art

The machine was set up to sew out of the box exactly as I asked it to be. I have been in contact with Bob Kovar at Toledo sewing and he has been very accomodating. As I stated in my post, I am newer than new when it comes to sewing machines. I did not want to continually pester Bob with a barage of questions as I learn the machine. I thought maybe I could gain some insight here on the forum.

[Rayban]

Could someone please explain to me the relationship between the length of my stitches and the thickness of material to be sewed. I am a sewing machine virgin. Have never touched one until last Friday when I recieved a brand new Cowboy 3500.Thye machine is similiar if not identical to a Artisan 3000 and Cobra class 3. I have stitched and stitched scrap leather for the past few days trying to figure this thing out. My first project will be of alligator. I can't afford to muff it up. My project is a wild buch rig for cowboy action shooting. It consist of 7/8, 9/10, and 12/13 oz skirting. The holster will be close to a 3/4" welt. The stitching looks exactly how I want on the lighter leather, but when I switch to the thick stuff ( 1/2" or more) I get little teeny stitches. Do I have to adjust this thing every time I switch leather thickness. Is there a tutorial on this somewhere?

Thanks!

I also just bought the CB3500 from Bob ( 3 weeks ago), and he's been very helpful.......but what you're dealing with, you shouldn't even have to call him....there's a manual right?

In it it shows you how to lengthen/shorten the stitch. Just turn the knob shown in this picture.

The relationship between the thickness of the leather you are stitching and the length of the stitch, is something out of "stitching 101", or to be more exact, Al Stohlman's " The Art of Hand Sewing Leather".

From that I learned that projects up to 1/4" thick look best stitched at 6 stitches per inch.......3/8" thickness, 5 SPI.......more than that, including your 1/2 or 3/4" thickness, 4 SPI......it's been a good rule of thumb for me when hand-stitching, and it's no different on the 3500.

I've made the adjustment several times already and it's really simple.....turn the knob, do a test on scraps that are the same thickness as you'll be stitching, adjust til you like the length of the stitch.

I'm by far no expert, but we're getting along (3500 and I ) very well, if you get stuck and Bob can't be reached, give me a hollar.

Edited March 9, 2011 by Rayban

[catskin]

Rayban,

I believe the question here is why are the stitches not the same length on thicker leather as on thin WITHOUT changeing the setting on the lever. I think they should be, so that when you sew from thick to thin or visa versa such as where you have leather overlaped the stiches stay the same length.

[JS22]

Catskin,

You are correct. I simply wanted to know why when I switch from one weight to the other does the machine sew different stitch lengths. Bob was very helpful in fiquring out the solution. As Rayban stated, I have to adjust the lever when I switch from one weight to another. I'm just trying to figure out why it does it. As new as I am to machines, I was under the assumption it would sew the same stitch length no matter what weight it was presented until I changed the setting myself.

[Art]

That's strange. My Highlead sews 6 to the inch (according to my Campbell Bosworth gauge) and it doesn't seem to matter what I put in there. I don't think I have changed the stitch length lever except to go forward and reverse. Any chance your bottom stitch is hanging up on the needle (feed dog) slot in the needle plate? Maybe you could up your presser foot pressure a bit, and hold your threads tight till they get past the slot.

Art

Catskin,

You are correct. I simply wanted to know why when I switch from one weight to the other does the machine sew different stitch lengths. Bob was very helpful in fiquring out the solution. As Rayban stated, I have to adjust the lever when I switch from one weight to another. I'm just trying to figure out why it does it. As new as I am to machines, I was under the assumption it would sew the same stitch length no matter what weight it was presented until I changed the setting myself.

[catskin]

As Art stated other machines DO NOT make a different stitch length when you change thickness of leather under the foot. My OLD Adler 20-2 does not and it has just bottom feed and jump foot. I have a new 4500 Cowboy so I know what they are like.

I thought the new machines would be at least as good as the OLD ones as far as consistant stitch length is concerned. This might have to do with the linkages in the compound feed. I do hope someone will get on here and explain why this happens.

Catskin,

You are correct. I simply wanted to know why when I switch from one weight to the other does the machine sew different stitch lengths. Bob was very helpful in fiquring out the solution. As Rayban stated, I have to adjust the lever when I switch from one weight to another. I'm just trying to figure out why it does it. As new as I am to machines, I was under the assumption it would sew the same stitch length no matter what weight it was presented until I changed the setting myself.

[Rayban]

We need...

The Wiz !!!!!!

[buffalobill plus Ed D]

Are you running a regular leather feed dog?...or one of those specialized plates (slotted or holster plate) ?

[JS22]

The regular that came with the machine.

[Wizcrafts]

A pendulum always swings farther at the bottom, than higher up its shaft. Most modern sewing machines, including all of the 205 and 441 type machines, work on the pendulum needlebar principle. They pivot at the top, in an arc that is by nature longer at the bottom than up the bar. Once the needle penetrates all of the leather layers and begins to move them, the distance higher up must be shorter than if there were only a couple of layers to move. It may not be what you wanted to hear, but it is backed up by science.

Most upholstery class machines don't sew over 3/8" of anything, so the stitch length variance is less noticeable (but present). That is no longer the case when you move up to 3/4 inch. You must lengthen the stitch length adjuster to compensate for the variation when changing from 1/4" to 3/4".

Here are possible workarounds that you might be want to try out, in the hopes of getting the least variation in stitch length from thin to thick leather.

1. First, make sure that the feed dog is set to its highest position as it moves the work. It can only go so high before it makes contact with the underside of the throat plate.
2. Next, try backing off the top pressure on the pressor feet. You can only back off so far before the leather raises with the ascending needle and thread. Your machine doesn't have individual springs for the inside and outside feet, so one upper pressure adjustment serves both feet.
3. Try going up or down one needle size. A thicker needle won't flex as much as a thinner one, but requires more pressure to hold the leather down. A thinner needle penetrates the leather easier, but the knots may not be pulled up as easily.
4. Reduce the top and bobbin spring tensions equally. Less top and bottom tension makes it easier for the mechanism to feed the thick material.
5. Spray or wipe silicon or Teflon lube on the throat plate under the leather to reduce friction on the bottom.

There are sewing machines that don't exhibit the change in stitch length with changes in thickness. I own such a machine (ULS), but it is not for the faint-hearted. Such machines have what is known as square drive. This is not found in most sewing machines, as it is more complicated and expensive to implement than a pivoting pendulum needlebar. Square drive machines sell for more used than you paid for your new CB3500.

Edited March 10, 2011 by Wizcrafts

[catskin]

Thank you WIZ.

That does explain why my old fossil of an Adler with just bottom feed and jump foot is more consistant in stitch length regardless of how much is under the foot. It is because the feed dog moves the material the same distance regardless of how thick it is. I do understand now why this is as it is on the needle feed machine. And that it isn't just this make of machine that does it.

Edited March 10, 2011 by catskin

[Wizcrafts]

My friend's Cobra Class 4 does the same thing. We set it to the stitch length we need for various thicknesses. We also change stitch length for effect. It is not set in stone.

I can tell you with certainty that if you remove the regular throat plate and feed dog, and replace them with the slotted plate, that you will lose about 25% or more of the set stitch length in forward, and maybe more in reverse. That was my finding a few weeks ago when I tried that. I think a teflon strip taped onto the throat plate might help reduce the loss of stitch length from friction with the slotted plate.

I think that perhaps my recommendation about loosening both top and bottom thread tensions will help al lot when sewing tall leather loads. With less bobbin pressure a smaller needle size could be used and would still be able to pull the knots well up into the layers. The smaller needle exhibits less friction going in and out of the leather. With less friction on the way up, the top pressure spring can be backed off, making it easier for the machine to feed stitches of any length.