Choosing a sewing machine

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Details on how to choose a sewing machine for automotive work.
 
  
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Sewing machines are major contraptions
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Rube Goldberg would have been proud to make one.  Before we look at machines, we need to look at the stitch that they make. 
  
[[Category:Interior]]
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Basic Stitches
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The first stitch is called a “chain stitch”. In this stitch, the needle is pushed through the fabric and a loop is captured; the needle rises and goes on to make the next stitch. On the next stitch, the needle passes though the loop of the first stitch, which is released and the loop of the second stitch is captured and the process is repeated..  There is no bobbin or shuttle required, however it’s possible to pull a row of stitches apart by merely pulling on the end thread.  A variation of this uses a second thread wrapped around the first thread on the bottom side.  It improves the reliability of the stitch somewhat, but the problem still occurs.
  
Sewing machines basically join fabric (cloth, naugahyde, vinyl, etc.) by punching a needle through the material and knotting a thread to create a stitch. The issue is that sewing machines are't subject to the equal rights amendment, and some just don't cut the mustard.
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The second stitch is called a “lock stitch”. In this stitch, the needle is pushed through the fabric, this time the loop is captured by a rotating hook.  The hook wraps the loop over a bobbin; at a critical point the bobbin case is ‘upset’ allowing the loop to pass under the bobbin; essentially the bobbin is passed through the loop.  In the meantime, the needle recedes and an arm at the top of the machine pulls the thread taut, forming a stitch in the fabric. This type stitch will not easily come undone, but requires that the bobbin be small enough to pass through the loop.
  
'''How it works'''
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Moving Fabirc
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Most commercial machines only use one of three methods of moving fabric.  The first method has a claw on the base of the machine below the fabric.  It slides the fabric underneath the foot, into the path of the needle.  This is the basic method used by home machines.  The second method, called a needle feed, has the same mechanism as first, but also has the needle moving forward and down into the fabric.  The needle then moves back with the claw, pulling the fabric more reliably. The stitch is formed and the needle recedes.  The third method incorporates a ‘walking foot/ or /alternating presser’.  The foor is made in separate sections.  One section moves forward with the needle, while one section keeps the fabric clamped down. The needle works the same as it did with a needle feed, but when it gets near the rear of its stroke, the second section lifts and moves forward in a walking motion.
  
Ever since Mr. Singer figued it out, nearly every sewing machine works the same way. A thread is carried by a needle that pierces the fabric from the top. As the needle pokes through the fabric, a rotating bobbin [shuttle?] below the material catches the thread and magically knots it to a second thread carried in the bobbin. As the needle moves down vertically and pierces the fabric, the "foot" holds the fabric down for the stitch; when the needle moves up, the foot releases and the "feed dog" below the fabric pulls the fabric into position for the next stitch. The useful controls on most machines for our purposes control the stitch length (i.e., number of stitches per inch) and tension of the thread(s); normally a foot pedal (potentiometer) controls the speed of the machine.ost machines (home and industrial) will have a backstitch control, which enables you to overlap a few stitches at the end of a row by literally running the machine backwards. This ensures the row of stitches will not unravel.
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Machines to look at
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A typical home sewing machine isn’t strong enough to sew through multiple layers of upolstry fabric and foam. Although the simpler old machines have cast iron heads, they are only slightly better than the newer multiple stitch plastic and stamped sheet metal versions. Generally speaking, the more high-tech they are; the wimpier they are. Additionally, they use a 1/10th horsepower (or smaller) motor, whereas a commercial machine will have a half-horsepower or more.
  
'''Your wife's (sewing machine is) a problem'''
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In the late 1930’s Singer introduced their 111W & 112W series of machines, which have become the defacto standard for sewing machines.  The have been copied by several other manufacturers.  Some of the copies not only look like the Singers, but you can interchange parts!  In the 1970’s Singer introduce their 211W & 212W series of machines and production of the 111W & 112W ceased.  The 112/212 differ from the 111/211 machines in that they are double needle machines; they’re used to produce parallel rows of stitching, like on the outside leg seam of blue jeans.  You might see numbers like 212W139, 212W140 or 212U141.  The 139 has a walking foot; the 140 is the base needle feed and the 141 will do back-stitching (you cannot turn the hand-wheel backwards to back stitch, it just jams the machine up).  The letter in the number system tells where the machine was made, W is usually Tennessee (Singers home), U is USA, G is German, etc.  Other companies use other numbering systems so watch out.
  
Unfortunately, most home sewing machines are not adequate for an automotive upholstery job, although it can be done, but not well. Most home machines - Singer, Kenmore, etc. - can drive a needle through two or three layers of automotive fabric, but they don't have the horsepower to create a firm enough stitch in a suitable weight thread for our purposes. The result is that the seam will not be tight, and it will pull apart when under tension, like when your girlfriend sits on it. The typical beaded seam involves at least four layers of material, which is beyond the capacity of your mother-in-law's machine. If your wife has a sewing machine, find a new wife. In addition, padded seat or door panel fabrics may be too thick for your average machine. Tuck-and-roll upholstery and door panels have the thickness issue, plus are multiple layers thick. You could probably jam the material through a home machine, but it's not going to last. That's the issue.
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Singer is not the only manufacturer of good quality commercial sewing machines, in fact some of the clones are better than the original. Some of the other companies to consider are Bernina, Brother, Consew, Juki, and Pfaff. A brand new Juki DDL-8700 complete sells for about $3500, a used rebuilt machine from a reputable company like ‘Miami Industrial Sewing Machines’ sells for about $700, plain used (un-rebuilt) show up on ebay for half that. Singer 111’s go for $200 to $1500 depending upon the phase of the moon. Which ever route you go, make sure you get the table and motor too.
  
'''The solution is downtown, or by the harbor'''
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A word of caution
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Commercial sewing machines are fast and powerful; they can sew through a half inch of leather or your thumb with equal facility.
  
The solution to home machines is getting your hands on a used industrial machine, like an old Singer 111-W. Most cities worth the name have the remains of a garment district with dusty places that sell and service sewing machines, and I don't mean your strip mall Sears, or the Singer shop. Sailmaker supply shops are other places to look. I've seen used heavy-duty machines for $250 in New York, and there are places that rent machines. A sewing machine is a terrific addiiton to your man cave, and I bet you could get your (new) wife to agree to buying one a heck of a lot easier than it was getting her to sign on to the plasma cutter that you might use once again in your life.
 
  
'''What to look for in a heavy-duty sewing machine'''
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[[Category:Interior]]
 
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What separates a heavy duty industrial sewing machine is raw power and some other features that permit precise and strong sewing of heavy fabric, such as upholstery, leather, canvas, etc. The industrial machines normally are belt driven, with a separate electric motor, whereas a home machine normally has a puny built-in motor about as powerful as an aquarium air pump.
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A feature to look for in a man's sewing machine is what is called a "walking foot," which is when the foot that sits on top of the fabric acts in unisyn with the feed dog below to pull the fabric into the machine and position it for the next stitch. This practically eliminates fabric slippage, which is a problem with slippery automotive materials, and it helps ensure an evenly spaced stitch.
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A further refinement is a "needle feed," in which the needle actually acts in unisyn with the walking foot to pull the fabric forward, resulting in very precisely spaced stitches. 
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A "double needle feed" machine is the ultimate, in that it has a needle above and below the fabric.
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Any of these industrial strength machines will require a separate bench to mount the machine, its motor, and the foot control.
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'''Sewing isn't for pussies'''
 
  
These heavy-duty sewing machines are dangerous and need to be treated with respect. These machines can't exactly tell the difference between running a row of stitches across a seat panel or up your arm, which they will do. A double needle feed walking foot machine will suck your hand in and stitch it right to your tuck-and-roll door panel faster than you can say "waaa...?" So be careful. Try to stick a needle through your leather belt and you'll get some idea how powerful these machines are.
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Dan 2Lakes is a drunk

Latest revision as of 09:58, 24 August 2023

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