It is axiomatic that most professional repairman believe that at least 75% of the sewing machine problems that they encounter are caused by the operator. However, this could be true only to the extent that the operator is unfamiliar with a machine, inexperienced or uninformed. The purpose of this section is to present a few facts that will be a substitute for experience, and to inform you of a few basic procedures that will minimize operator-caused trouble. In the discussion, we will assume that you already have a sewing machine, or that you are contemplating buying either a new or used machine.
BUYING A NEW SEWING MACHINE
We earlier said that a new sewing machine is one of the most bang-for-you-buck quality items that you can buy. Currently, excellent new straight-stitch machines are priced from about $80; new zig-zag machines from about $125 (to as much as $900, however); and if you are a patient shopper, you can probably find an excellent used machine—often with a console cabinet for $50 and up. The prices of these new machines are representative of heads only—machines without cabinets.
The perplexing problem of whether to buy an inexpensive new machine, or a used machine that was obviously a top-line model when new, is one that can be solved only on an individual basis. And if your budget will allow it, the problem further becomes one of whether to buy a new economy model for as low as $125, or a top-line model for several times that amount. In making this choice, one general principle applies: Insofar as functional value is concerned, the additional dollars that you pay for a sewing machine are simply for convenience features, since there are few functional differences between the lower and higher-priced models. However, if you pay as much as $500 to $900 for a machine, you can reasonably expect more years of trouble-free service than you would get from the $125 model.
The purpose of this guide, however, isn't to tell you how to solve what is essentially a budget problem but to tell you how to get the best results from the machine that you do buy or the one that you already have.
Buying a new sewing machine implies that you will buy it from a dealer who deals in sewing machines more or less exclusively, although many sewing machine dealers also handle a line of small appliances-supplemented perhaps with a supply of sewing accessories and supplies. More importantly, he will most likely be able to provide repair and maintenance for your new machine, backed by a manufacturer’s warranty (usually a long-term, limited warranty) and service manuals.
Insist on a comprehensive demonstration, and don’t be put off by the fact that the dealer seems to have too many diversions to make a demonstration. A comprehensive demonstration should include showing you how to do the following
• Load an empty bobbin.
• Place the bobbin in the bobbin case and thread the bobbin case. In the case of the bobbin case as a separate component place the complete assembly in the machine.
• Select the correct needle plate for the particular sewing demonstration.
• Remove and replace the needle plate.
• Select the correct needle to match the thread and material being used.
• Clamp the needle in the needle bar.
• Top-thread the machine, matching the top thread to the bobbin thread.
• Select the correct presser foot for the particular sewing demonstration.
• Install the presser foot on the presser bar
• Select material and thread to demonstrate a certain sewing principle or machine function.
• Pick-up the bobbin thread with the needle thread.
• Adjust the pressure of the presser foot in accordance with the material being sewn.
• Adjust the top tension regulator.
• Set the stitch length regulator. When sewing, the stitch length regulator should be set through the complete range of stitch lengths, including 0, or no-feed.
• Select a cam pattern and stitch width, in the case of a zig-zag machine.
• Set the needle bar, and thus the needle, in the left, center and right positions in the case of a zig-zag machine.
• Start the machine.
• Sew, using all the functions that are available on the machine.
• Install a double needle, top-threading the machine accordingly, and sew.
When the demonstrator is sewing, ask him to demonstrate the following procedures:
• Sewing with the stitch length regulator set at 0. The needle should enter the material in exactly the same place on each stroke.
• Reversing the direction of stitching. In the case that reversing is accomplished with a push-button (as on most recent zig-zag machines), the length of the reverse stitch need only be approximately that of the forward stitch.
• Changing the setting of the upper tension regulator to demonstrate the effects of unequal tension between the upper tension regulator and bobbin tensioner, with the following points in mind:
—When the tension is correct, the stitch should be tight and invisibly interlocked.
—When the top tension is too loose in relation to the bobbin tension, the interlocking loops will show on the bottom of the material.
—When the bobbin tension is too loose, in relation to the top tension, the interlocking loops will show on the top of the material. The demonstrator will undoubtedly tell you that the tensions are equalized by regulating only the top tension regulator; however, there are times when regulation of the bobbin tensioner is necessary.
• Regulating the tension of the bobbin thread, and explaining in what circumstances you should make this regulation.
• Sewing a button hole. In the case of a straight-stitch machine, this will have to be done with a special attachment. However, you should be able to sew a button-hole with a zig-zag machine, either manually by selecting an appropriate cam and manipulating the stitch width, length and direction controls at your discretion, or automatically by setting dials or pushing buttons in a prescribed sequence. In the case of a zig-zag machine, the criterion for a button-hole stitch, apart from a tight, durable stitch, is that the stitch width and length is the same on both sides of the button-hole. Ask to be shown how to equalize, or balance the button-hole stitch (Fig. 2-1).
Sewing on a button is possible only on the zig-zag machine. There are several ways to accomplish 0 stitching; that's , no travel of the button:
— By setting the stitch length regulator at 0.
— By lowering or dropping the feed dogs.
— By using a special needle plate that's raised so that the feed dogs will not contact the underside of the material. Ask the demonstrator to show you all of these methods.
• Sewing different kinds of material especially rayon and denim to demonstrate the effects of regulating the pressure of the presser foot. When the pressure is correct, the material should be fed evenly and uniformly, without either slipping or puckering under the presser foot.
• Sewing a variety of decorative stitching (Fig. 2-2), in the case of the zig-zag machine, through a range of machine speeds from low to high. Also ask to be shown the effects on the appearance of the stitching caused by changing the needle position (left, center and right) and the stitch width.
• Sewing a straight stitch, through a range of stitch lengths, with the zig-zag machine. There should be no slight zig-zagging of the stitch.
The foregoing demonstration points are not suggested as a means for the dealer to show you the versatility or convenience of the machine (he will have his own demonstration procedure to point up these factors), but for two purposes: One is to familiarize you with the machine and the other is to reveal adjustment problems or defects in the machine which can be corrected before you take the machine from the shop.
If you buy a sewing machine from a mail-order company (such as Montgomery Ward or Sears), a dealer demonstration is generally available only if you buy the machine directly from the Ward or Sears store, but generally not available if you buy it through a catalog branch. However, dealer service will be available within the terms of the warranty.
When you buy a new machine, the manufacturer’s warranty is normally implemented by dealer service, within the specified warranty period. During this warranty period, if trouble occurs, read your Owner’s Manual and the first three sections of this guide to assure yourself that the trouble isn't one that can be corrected by simple changing a sewing technique, or making some minor regulation of the machine. Then, to protect your rights under the warranty, call a serviceman that's authorized by the manufacturer to provide in-warranty service under the terms of your new machine Warranty. In the case of a machine purchased from either Sears or Montgomery Ward, the procedure for obtaining in-warranty ser vice may depend upon whether your contact is with a full-service store or a catalog branch. In any case, you will proceed according to specific instructions. In the former case, you may be instructed to take the machine to the store for service; in the latter case you may be instructed to take the machine to either a designated service center in your area, or to an independent service center of your own choice. In either case, the service center will bill the firm from whom you bought the machine. Inmost cases, you will be required to take the machine to the service center yourself.
Owner Maintenance and the Owner’s Manual
When you are sure that your new sewing machine is in proper working order, and you have learned all the common sense sewing techniques possible from the dealer to prevent problems, ask him to give you some maintenance procedure suggestions. Ask him especially to explain when, how and where to oil the machine, and how to clean it. He may suggest that all this information is contained in your new Owner’s Manual, but owners’ manuals are notoriously superficial in maintenance instructions. They are, however, indispensable, in that they provide a wealth of information regarding the use of accessories, dial settings, etc., for certain sewing applications.
When you leave the dealer, you should have a basic under standing of whether or not the machine will require periodic oiling (most machines still do), and if it does, you should be supplied with sewing machine oil. Further, if you wish to perform a comprehensive periodic lubricating of your machine, as explained later in this section, you should also be supplied with sewing machine gear grease.
BUYING A USED SEWING MACHINE
The primary considerations in buying a used sewing machine are: model (the model, within limits, can be related to age); appearance; mechanical condition; and price. Unless you are thoroughly familiar with a variety of sewing machine brands and corresponding models, it may be difficult for you to relate the model to a reasonable used retail price. You can get this information, however, by writing to Bobette Industries, Dept. SN, 167 Elizabeth St. N.E., Atlanta, GA 30307 or call (404) 880-9400. Ask for the Sewing Machine Blue Book, which lists the suggested wholesale values of hundreds of the used sewing machines that are on the market today. There is a charge for the Blue Book, which you will have to determine by calling or writing Bobbette in advance of ordering the book. With this information, you can use your own judgment in establishing a relationship between the suggested wholesale price and what you might expect to pay for the machine on a retail basis. It is here that the appearance and mechanical condition of the machine must be considered.
The relationship between appearance and mechanical condition may be rather tenuous, unless excessive dirt or damaged outer parts reveal that the machine was poorly cared for. Therefore, if you are buying the machine as is, it would be advisable to operate the machine, or watch it in operation, before buying it. If you are planning to shop in flea markets or general second-hand stores, you should supply yourself with the following:
• Two or three needles, of the Type 15X1, size 14.
• A spool of 50 mercerized cotton, or a quality, cotton- wrapped polyester thread.
• Several swatches of light to medium-weight material. A small and a medium-sized screwdriver.
The Visual Inspection
First of all, inspect the machine to see that it has all the controls mentioned in Section 1. Also refer to Figs. 2-3 and 2-4. Remove the face plate (#6 in Fig. 2-3) and check the needle bar, presser bar and the needle bar and take-up lever mechanisms for dirt and rust. Tip the head of the machine back. In the case of a machine without a cabinet, you may have to remove the bottom cover, which should be held on by a wing nut; or, in the case of the free-arm machine, you will have to remove the free-arm cover. Inspect the mechanism under the bed of the machine for dirt, rust, obviously missing parts, broken screw heads or screwdriver marks which would indicate ineffectual repairs. Inspect the drive belt to determine its condition and tension. (The procedure for adjusting the drive belt tension will be explained later in this section.) With the needle removed and the presser foot up, rotate the balance wheel (always toward you) to see that all the mechanisms are working freely. At the same time, you can determine if the machine has the vibrating, oscillating or rotating shuttle. If it's a zig-zag machine, ask the dealer to remove the cover from the top arm, which will reveal not only the zig-zag mechanism but also sections of the main drive shaft, oiling points, etc. Disengage the balance wheel, and turn it by hand to determine that it will turn freely without turning the drive shaft. Inspect the electrical cord and plug for broken or disconnected wires.
If all the above inspections seem to reveal no problems, you can replace the face plate, re-engage the balance wheel and assume that the machine is operable provided that there are no hidden mechanical or electrical problems.
If the dealer is for some reason unable to demonstrate the machine, your only recourse is to do it yourself. First, run the machine at a slow to moderate speed, with the needle still removed and the presser foot still up. At this point, if the machine is dirty or gummy from old oil you may be misled to believe that the motor control is sticking. In this case the machine will start as if under a heavy load, or start abruptly only after you have depressed the motor control past the position that would normally start the machine at a low speed.
If the machine appears to run all right under these conditions (some sluggishness would be acceptable if you have reason to believe that the mechanisms need cleaning and oiling), you are ready to:
• Load a bobbin (Fig. 2-5).
• Install the bobbin, remembering to thread the bobbin case (Fig. 2-6).
• Install the needle. Note that the shank of the needle has one flat side, which will generally allow it to be installed only one way. However, if it can be installed more than one way, assume that the flat goes to the back or right side and that breaking of the thread indicates it's wrongly installed (Fig. 2-7).
• In the case of a zig-zag machine, note that the needle plate and presser foot are cross slotted.
• Rotate the machine a few rotations by hand to see that the needle doesn't strike the presser foot or needle plate.
• Top-thread the machine in the following sequence:
— Place the spool of thread over the spool spindle, nothing that in the case of horizontal spindle, there must be some provision for retaining the spool in place.
— Lead the end of the thread through the nearest guide that will direct it to the tension regulator.
— Loop the thread around and between the tension discs (Fig. 2-8), noting that in the case of a double-needle machine there will be two sets of discs (three discs in all, and it makes no difference which set you use.)
—Pull the thread through the tension discs, noting that with the presser foot raised, there is no tension on the thread.
—Pass the thread through the eye of the take-up lever.
—Pass the thread through every thread guide that you can see between the take-up lever and the needle.
—Thread the needle, inserting the thread in the eye of the needle on the side of the needle opposite the flat of the shank. Pulling 7 or 8 inches of thread through the needle eye.
• Pick up the bobbin thread as follows: Leave the presser foot in the up position and in your left hand hold the end of the thread that has been threaded through the needle. With your right hand rotate the balance wheel toward you. If the timing of the shuttle hook is correct, the top thread should interlock the bobbin thread in one complete rotation of the balance wheel. A little difficulty in picking up the loop is tolerable, however, since the loop doesn't form readily with no material in the machine. Still holding and pulling the thread in your left hand, when the interlocked threads appear above the needle plate, pull them through the slot of the presser foot, so that they are both under the foot and toward the back of the machine (Fig. 2-9).
• Make an initial setting of the top tension regulator. For most normal sewing applications, a setting about halfway between the lowest and highest setting will be correct. Further regulation may be necessary after you have examined the stitch.
• Make an initial setting of the presser foot pressure. If the material is light to medium-weight cotton, a setting about halfway between the lowest and highest setting of the dial will be correct. Further regulation may be necessary when you see how the material is fed through the machine.
The machine should now be ready to sew. At this point, no written instructions can replace on-the-spot judgment regarding the operating condition of the machine. In general, however, problems can be classed as either those that can be corrected by making some external adjustment and modifying a sewing technique, or those that can only be corrected by going into the machine to make internal adjustments or repairs.
Troubleshooting the Used Machine
Faulty or Non-starting of Machine Motor. Tithe trouble symptom is faulty or if there is a non-starting of the machine motor, the underlying cause may be:
• broken wires or loose connections in the electrical circuit.
• worn motor brushes.
• motor in need of lubricating.
• worn motor bushings.
• sewing light is removed or burned out.
Noisy Running. The underlying cause of a noisily running machine may be:
• a dirty, corroded, incorrectly oiled or gummy machine. Assuming that corrosion is superficial, this problem can be corrected by cleaning and oiling the machine.
• a needle that's glancing the edge of the presser foot, the edge of the needle plate or the shuttle hook. The needle will most likely break, however. This may be caused by a bent needle. If the needle is bent, you are not able to get the smooth sewing. To check the bent of needle, place the flat side of needle down on a straight and flat surface as shown in Fig. 2-10. Or it may be caused by a needle of an incorrect type or size (selecting a needle for a few of the older European-made machines can be problematic); or you may be pulling on the material as it's being fed, thus springing the needle to the side; or the needle bar height may be incorrect; or the timing of the shuttle hook may be incorrect. Correcting the latter two problems will be explained in Section 3.
• A faulty mechanism. This would indicate an internal correction.
Stitch Skipping. This may be caused by:
• a needle that's incorrect for the machine, or for the thread being used; or a needle that's bent, incorrectly installed or incorrectly threaded. The Size 14 needle and 50 mercerized cotton or cotton-wrapped polyester thread should be compatible, however.
• incorrect needle bar height.
• incorrect timing of the shuttle hook.
Breaking Needle Thread. This may be caused by:
• any of the needle problems discussed above.
• the Use of poor or knotty thread.
• a burred hole in the needle plate. You can correct this by smoothing the hole with a fine emery cloth.
• sewing through too many thicknesses of material, or stitching too many times in a no-feed position.
• a shuttle that's dirty, needs oiling or has thread snarled around it. This may indicate a minor problem, inasmuch excessive lint, snarled thread, etc., can sometimes be easily removed. Or it may indicate a slightly more serious problem, inasmuch as the accumulation of offending material may be so severe that the shuttle will have to be disassembled and cleaned. One method of cleaning the shuttle will be discussed in this section, and disassembling the shuttle will be discussed in Section 3.
• too much tension on either the top or bobbin thread or both. This can be caused by incorrect regulation of the top tension; lint or dirt between the tension discs of the top tension regulator; the use of certain polyester threads, which might cause tensioning problems in either the tip tension regulator or bobbin tensioner incorrect regulation of the bob bin tensioner; or an incorrectly wound bobbin. To be sure the bobbin is level-wound, pass the thread through the bobbin winding guide, rather that letting it slip through your fingers as the bobbin is wound, which might result in cross layering of the thread. In any case, for best sewing results, use the same type and size of thread for both the bobbin and top thread.
Non-Feeding or Erratic Feeding of Material. This may be caused by:
• incorrect pressure of the presser foot. This would be in the case of erratic feeding assuming that the presser bar spring isn't broken. This spring is visible behind the face plate in many models. If it's not visible, you can make an approximate determination of its tension by lowering the presser bar and lifting it by pushing upward on the presser foot, while at the same time changing the setting of the presser bar regulator screw. In general, the setting is determined by the texture of the material. Lightweight, soft fabrics and piled fabrics, such as velvet require a lower setting than a heavy or crisp fabric. Alternatively, the presser bar might be sticking where it goes through the machine housing, which can probably be corrected by cleaning and oiling.
• an accumulation of lint between the rows of feed dog teeth.
• a worn-smooth top surface of the feed dogs, which can be corrected by replacing the feed dogs.
• a special needle plate that has its top surface above the top edge of the feed dog teeth at their highest point.
• feed dogs that have been lowered so as to be inoperative for previous darning, embroidering, etc.
• a stitch length set at 0.
• a faulty feed drive mechanism.
Faulty Stitching. Faulty stitching may be caused by:
• incorrect thread tension, if the interlocking is incorrect. Loose stitching, with the interlocking appearing on either the top or bottom of the material is incorrect. If you can't correct this by regulating the top or bobbin thread tension, you may have to clean the top tension regulator or the bobbin case.
• poor or Knotty thread. Use the best thread you can buy, and if you use polyester thread, you may learn that certain brands create tensioning problems. In any case, good quality mercerized cotton or cotton-wrapped polyesters give consistently good results if the machine is operating correctly and the tensions are correctly regulated.
• incorrect needle for the type and size of thread being used.
• a faulty or sticking zig-zag mechanism or needle bar in the case of a non-uniform zig-zag stitch. This may be corrected by cleaning and oiling the machine or internal adjustments and repairs may be indicated.
Binding or Sticking Mechanism: This may be caused by:
• engaged bobbin winding mechanism.
• snarled thread between balance wheel and the bushing.
• snarled thread around the shuttle mechanism.
• a dirty gummy machine.
• a faulty mechanism, or one that has been ineffectually repaired.
• an oil-soaked timing belt. Generally this is only applicable if the material of the timing belt is fibrous.
• slipping or binding drive belt from the motor to the balance wheel. A belt that's too loose will slip around the drive pulley. A belt that's too tight may put too much pressure on the bearings.
In this section, you’ll remember, we have been discussing what factors to consider when deciding whether or not to buy a certain used sewing machine. You will have noted that we referred to possible problems that would require internal adjustments or repair procedures, but without explaining the procedure. When you read Section 3 you will discover that there are a few more trouble symptoms and causes which we never referred to at all. This is because the purpose of this section is to give you enough elementary facts about trouble symptoms and causes to prevent you from buying a used machine that seems to have only a minor problem, but which will prove too expensive or impractical to repair, or conversely to prevent you from passing up an excellent used machine that appears to have a major problem, but which can be corrected by cleaning, oiling and making adjustments.
For example, timing a shuttle hook or adjusting the needle bar height may sound like a formidable task, but will sound simpler after you have read Section 3. Cleaning and oiling a machine is a simple procedure which can eliminate many trouble symptoms. A machine may not feed material simply because the feed dogs have been dropped for a certain sewing application. Perhaps the most risky buy is the machine that won’t operate, especially if it's evident through broken screw heads, etc., that repairs have been attempted on it. The danger in such a case is that certain vital parts may be missing and you will not be aware of it. Even experienced repairmen ponder the possibility of missing parts when it's obvious that repairs have been attempted on a machine. Similarly, you can assume that replacing a timing belt that extends from the lower mechanism to the main shaft in the upper arm of the machine will be a major job, or a challenge, depending upon your point of view.
Finally, when you do decide to buy a used machine, make an effort to obtain the owner’s manual that was supplied with the machine when it was new. If it has been lost, you may be able to obtain a manual from the manufacturer or distributor. The owner’s manual will not give you an in-depth service or maintenance instructions, but it will provide oiling instructions, as well as general operating instructions which may keep you from creating operator- caused problems with an unfamiliar machine.
In the remainder of this section, we will tell you how to initiate an ongoing maintenance program for your sewing machine, without the help of an owner’s manual; how to select and use threads, needles and materials to get optimum machine performance; and how and in what circumstances to make external adjustments, which will also give you optimum machine performance.
READYING THE MACHINE FOR SERVICE
If the shop demonstration proved the machine to be operable, the initial steps that you take at home to ready it for use will simply be a part of the continuing maintenance program on that machine. The electrical components should be checked, the drive belt tension should be adjusted and the machine should be cleaned and oiled.
|Top of Page||PREV: Basic Sewing Machine Mechanisms||NEXT: part 2||Home|
Thursday, 2016-06-23 1:55