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Ankermann

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Posts posted by Ankermann

  1. Posted · Edited by Ankermann · Report reply

    I just picked up a few machines from an estate.

    I know one is a small press but what all can it be used

    for? It is an FH Smith brand Chicago.

    A leather cutter. about 16" throat.

    And a roll? My guess for leather belts?

    What do all these machines do and what are they worth?

    Also picked up a walking foot Consew and a Singer 7-34

    and A Singer 31-15.

    Ill post the other pics later when I can resize them to load...

    thanks for your help...

    Ankermann

    post-19629-050540300 1300059694_thumb.jp

  4. Posted · Report reply

    I have a friend who is looking at buying an Artisan 4400-25 walking foot machine.

    She is a professional upholstery/ boat cover sewer for the last 20 years.

    Are these good machines or should she buy a Consew or juki or ?

    I know this is not leather related, but I know there are some sewing machine

    guru's on this site. I would like some feed back. Thanks Mike

  6. Posted · Report reply

    This would be a good time to compare home vs industrial motors and needles. You depend on the turning power of the motor to get the first stitch into your material, and the horsepower determines how easy or hard that will be. Once it gets the machine sewing, almost any home style sewing motor will run a sewing machine at a decent rate of stitches per minute, up to its gearing limit. But, that speed is usually only attainable if you remain within the practical limits of material density, needle and thread size. The bigger the motor, and higher its horsepower rating, the more dense the material it can try to penetrate. Most industrial sewing machines come with either a clutch or servo motor, which is mounted under the work table, which the machine rests on top of. A v-belt connects the pulley on the motor to the pulley cast into the flywheel (handwheel) on the back of the machine.

    Industrial sewing machines are usually fitted with a motor pulley that best suits the intended work. Upholsters and garment makers want high speed, so they order a large motor pulley, somewhere in the vicinity of 3 to 4 inches diameter, inside the groove. The pulley on the flywheel of garment machines is typically around 4 inches diameter, so these machines are often running at close to 1:1. Industrial clutch motors run at 1725 rpm, at 120 volts, or 3450 rpm at 220 volts (3-phase), so a machine running a 1:1 ration to the motor will sew at that speed. If you were to purchase a used garment sewing machine, even with a 120 volt motor, a 1:1 pulley ration may be uncontrollable for the untrained sewer. A smaller motor pulley is the answer to that problem.

    Most leather sewing machines are equipped with a 2 inch motor pulley. This not only slows the machine down to a more controllable speed, but doubles the torque. This comes in as very important when you try to sew thick or dense leather, or bio-plastic projects, or plywood covered cases. Furthermore, if you sew anything other than garment/chap leather at the high speeds used in garment machines, the friction will heat the needle to almost red hot, melting the thread, scoring the leather and usually, causing the needle to grab inside the leather, on its way back up. This causes the leather to lift with the needle. When that happens at the moment the bobbin shuttle's pickup point is passing by the eye of the needle, you will get skipped stitches.

    The bigger the machine, the thicker the intended payload, the larger the needle and thread it uses, the slower it must turn. Therefore, distributors of harness stitching machines often include a speed reducer between the motor and the machine. This reduction is at least 3:1, or more. I have an Adler flatbed harness stitcher that was so geared down and its maximum speed was about 3 stitches per second, or 180 per minute. It sure could punch through 3/4" of belt leather at that speed and gear ratio!

    Now, on to the pictures. The first photo shows a home sewing machine motor next to a clutch motor. The home motor is rated at 75 watts and has a 1/2" pulley. The industrial motor is a 1/3 hp 300 watt motor, with a 2.25" pulley. The home motor is suitable for driving a home machine through cloth and denim. The industrial clutch motor can sew 3/8" of leather easily with that size pulley. A 2" pulley would give it even more torque.

    post-11118-127938857033_thumb.jpg

    Clutch motors always run at full speed, but they develop their maximum torque when you engage the motor to the machine. You control them by means of a floor pedal, about a foot square, with a rod connecting it to a movable arm protruding down from the bottom of the motor. When you move your toe downwards on the pedal, the clutch begins to engage, turning the machine. Skilled sewers learn to control the motor from barely turning the machine, to full speed. This takes a bit of practice and the amount of toe required to feather the clutch often depends on the density of the material, and inertial resistance of the machine's mechanism. Also, since a clutch motor always runs at full speed, it always consumes electricity. When it runs under load, sewing, it consumes its rated power draw. Most industrial sewing motors come in these ratings, with the smallest meant for garment machines only:

    1. 1/4 hp
    2. 1/3 hp
    3. 1/2 hp
    4. 3/4hp

    These motors have a 3/4" shaft and take pulleys made for them and the narrower, 7/16" v-belts they use.

    In order to make sewing on industrial machines more controllable, and to reduce the cost of operating the machines on 110 volt circuits, servo control motors were developed. The early generation were prone to premature failure and made a lot of noise as they started up. This has been improved and in some cases, totally overcome, by new controller technologies. Industrial sewing servo motors are available in a range of power capacities from about 1/2, up to 3/4 horsepower. Their wattage ratings vary, from about 300, up to 600 w. The nice thing about all servo motors is that until you press down on the floor pedal, they do not draw more than 1 watt. You can leave a servo motor turned on all the time and not notice it in your electric bill, unless you are actively sewing a lot.

    One of the shortcomings of many servo motors is a lack of startup torque. While they do produce their rated drive power at full speed, the opposite is true at slow speeds. That is another reason why many leather stitchers ship with a speed reducer pulley under the table. It doubles or triples the slow speed torque, while also reducing the maximum speed to one that won't burn up you leather and thread.

    There is a new type of servo motor that has been produced, to overcome the problem of low slow speed torque. It is a gear reduction motor, currently marketed under the brand name "SewPro." I have their model 500GR. It features a 2" pulley and a speed limiter knob on the back. It runs at a maximum speed of 1500 rpm. This machine only consumes 300 watts flat out, but has a 3:1 reduction system, giving it the same power as most 3/4 hp servo motors. I have one and love it. I can sew from under 1 stitch per second, to about 10 to 12 stitches per second (depends on the diameter of the flywheel pulley). It is a bit low for upholstery, but not unacceptable. It is perfect for leather, which is what I mostly sew these days. It sews marine vinyl like it is butter.

    Here is a picture of my SewPro 500GR servo motor, mounted under the table of my 75 pound National 300N walking foot machine:

    post-11118-127939072772_thumb.jpg

    Next, let's compare a couple of needles. The one on the left is a #12 home sewing machine needle, used to sew thin cotton thread into shirts and pants. The needle on the right is a number 25 needle (series 135x16), used to sew up to #277 nylon thread into leather holsters and straps. Home style sewing needles are not usually available in sizes bigger than #18, although I found some #20 on eBay. Series 135x16 (leather point) and 135x17 (ball point) are available in sizes up to #25. As a reference, #69 nylon thread, commonly used in upholstery and marine vinyl sewing, uses a #18 to 20 needle. Stronger results are achieved with #135/138 nylon or polyester thread, which requires a #21 or #22 needle. This leaves out all home machines, including the ones sold on eBay as "industrial strength."

    Here then, are the home and industrial needles, side by each:

    post-11118-127938907536_thumb.jpg

    Now that you have seen comparisons of the motors and needles used by home and industrial sewing machines, you'll have a better understanding of what is required to sew leather.

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