Classic Car Auto Upholstery Series Part 2: Seams and Sewing Machine Accessories
By Chris Wantuck
In Part 1 of this series, we showed you how to properly set up a walking foot sewing machine, how and why to properly adjust the thread tension, and maintaining the machine by periodically oiling it. In this segment, we'll cover 1) Bobbin thread length, 2) Two types of common seams, 3) Thread color, 4) Stitch Length, 5) Presser foot pressure, 6) Thread tension, 7) Technique for changing thread, and 8) Some common attachments used in finishing your fabric to the desired appearance.
Bobbin thread length
Unlike the upper thread which is fed off a large cone and is visible, the bobbin has a limited amount of thread on it and it will eventually run out. This can be extremely frustrating especially when working with vinyl or leather, because once a hole is pierced into it, it's ruined. You have to know and gauge the amount of thread on the bobbin before your start a seam. A sure method is to replace the bobbin on every seam, but that would waste a lot of time and thread. While thread is relatively inexpensive, your time at the machine should be considered. In this simple exercise, take some scrap material and make measurement lines and practice your sewing (stitching) skills.
Photo 1 — Pictured here is a fully wound bobbin before being inserted into the bobbin case. This is part of an experiment to see how long your bobbin will last before running out of thread.
Photo 2 — Two pieces of scrap vinyl material are cut into rectangular shape and ten lines are drawn on it with a Sharpee marker. Each line is about 30 inches long, which is 300 linear inches long. This exercise provides practice in sewing straight lines while providing valuable information on bobbin thread length. Your practice sections can be longer to ensure you run out of thread. This exercise also allows you to practice stitching and turning a corner. Turning a corner is leaving the needle down through the material and lifting the presser foot (using the knee lever) and with both hands, rotate the material to follow the line. Suggest turning the hand wheel for those few stitches until you turn it again to resume the long stitch.
Photo 3 — Close-up view of the scrap vinyl being sewn in the bobbin length exercise. This is a good opportunity to adjust and refine your skills in running the machine at full speed while keeping the stitching exactly where you want it to go. The weight and size of the material can cause it to drag and make the stitches veer off the desired sewing line. Once you get the hang of it, you might not need a line to follow, but for now accuracy is important. After all, this is a practice exercise with scrap material. Practing on cheaper $2 per yard material is better than practicing on $60 per yard wool or leather. Hint: There is a problem with this picture. Can you spot it? Answer posted in the notes section.
Photo 4 — Pictured here is the result of the stitching past the running the line. Rather than stop, the stitching was angled to get back on the line. Articles such as this are about learning. In the above text, we recommended using the hand wheel to stitch the short segments in the bobbin thread length exercise.
Afterwards, inspect the bobbin and estimate the amount left (Photo 5). In this example, ten lines were drawn each 30 inches long. That's 300 linear inches of bobbin thread and the bobbin was more than half used. So, a safe estimate is that the bobbin can accommodate about 400 linear inches. You can't be penny-wise and pound-foolish. It is better to unreel a few yards of thread remaining on the bobbin than to have the bobbin run out of thread during stitching. To get a better understanding of how far you can sew with the thread on your bobbin, try setting up your test fabric so that it does run out. Then you can judge just how many linear inches you can expect from a full bobbin. Keep in mind that stitch length, fabric thickness, as well as thread thickness will all affect your results so use materials representative of your projects. You can purchase cheaper materials from the discount shelf of the local store for this testing and observe the differences in stitch length.
Photo 5 — After all ten lines were sewn, the bobbin is removed for inspection and this is how much was left on it. It doesn't look like much has come off. Looks can be deceiving; the bobbin ran out of thread only six short pieces of sewing while preparing Part 2 (this article). This is why we recommend you have a firm grasp on your machine's capabilities. Imagine ruining an $80-$100 piece of leather by poking holes in it while stitching a seam to have the bobbin run out. Don't make this elementary mistake.
Flat Fell Seam — The Flat Seam (or sometimes called the Flat Fell Seam) is a simple seam and is shown in Photo 6. It is made first by taking two pieces of material with the good (top) surface facing each other and sewing them together with approximately 1/2-3/4 inch selvage (see Photo 7). (Selvage is the material between the stitch and the edge of the material. It insures that the stitch from raveling.) Secondly, pulling the stitched materials apart now with the good sides up and tucking the selvage (flap) under the left side and sewing a second stitch along side of the first (Photos 8 - 10). This second stitch will be exposed, so care must be taken to keep it even. Be sure to not poke any unnecessary holes in it. You should consider using the hand wheel at the beginning and at the end of each stitch. See Photos 9-10. Flatten the pieces and firmly pull them apart at the seam in the middle leaving the selvage under the seam to be oriented on the left side. You could fold (tuck) the selvage under the right side, just make sure you top sew the correct side. The top stitch must go through the top and selvage layers (Photo 10). Using your hands with fingers stretched wide, put constant tension on the two pieces and align under the presser foot. This is where the knee lift method plays an important role, raising the presser foot while allowing both your hands to stretch the material.
Photo 6 — Cross section diagram of a completed Flat (Fell) Seam.
Photo 7 — The beginning of a Flat Seam. Two materials are placed together with the good sides facing each other leaving the bottom sides exposed. The two pieces are aligned on the right side and placed under the presser foot. Shown is a handy gauge to measure selvage, the amount to the right of the stitching. Also note the magnetic edge guide on the right side, which helps control selvage. This is a handy device while learning the trade and some even use a piece of tape to mark the amount of selvage. After time, you'll not have to rely on such guides, but good to have in the beginning.
Photo 8 — The seam is sewn together and both the beginning and end of the seam are knotted together. Using a dental pick or similar pointed instrument, pull the last stitch up into a small loop, and then hold both thread pieces and pull the last top stitch through the hole. Tie tight using a simple double knot. This needs to be done at both the beginning and end of each seam.
Photo 9 — The Flat Seam is opened up and laid open good sides facing up. The selvage just sewn together is folded under one side or the other. It doesn't matter which side you choose, just remember to sew the top through the selvage. Whichever convention you choose, left or right, stick to it. The author recommends folding (tucking) the selvage under the left side (opposite shown).
Photo 10 — We're now ready to stitch the second stitch of the flat seam. Position the material under the presser foot and align the right edge of the foot with the fist seam. This will be the guide to follow. It is possible to use the right edge of the needle foot as a guide, but that would place the stitch too close to the first stitch. You could actually offset the stitch further if desired. Again, which ever convention you choose, stick to it. Finish by knotting the stitches.
In Part 1, we mentioned the use of the reverse bar to lock stitch the seam. Do not do this if the top of the seam is to be exposed. Nothing looks worse than two pieces of thread going through the holes (Photo 11). Instead, pull the top thread under and knot the ends at both the start and end of each seam. As the material is positioned, use an alignment method that best suits you. In this example, we show using the right side of the presser foot right above the seam (see Photo 10). Set the first 2-3 stitches by using the hand wheel and allow the machine to run at normal speed. As you near the end, finish with the hand wheel. In time you'll likely learn to operate the machine just by using the treadle to start and stop the machine, but for now, use the hand wheel. Using the hand wheel is perfectly acceptable. Materials are too costly to accidentally pierce holes into materials. The completed Flat Seam is at Photos 12 & 13 and Photos 14 â€“ 18 critique seams.
Photo 11 — This is an example to avoid, doing a lock stitch procedure on material which will be shown such as this Flat Seam. It might be strong, but the end which will likely be joined to another piece of material and will look horrible.
Photo 12 — A completed Flat Seam. The stitching ended near the end with the top stitch pulled through to the bottom and knotted. This could have gone one more stitch. That's why we recommend using the hand wheel at the beginning and end of every stitch.
Photo 13 — View of the bottom of the Flat Seam in photo 12. Note the top stitch has been pulled through and knotted. Also note the nice separation between the first and second rows of stitches.
Photo 14 — Preparing the top stitch for a Flat Seam this time using a sewing ruler. Note the 1/4 inch separation and how the seam lines up under the right side of the presser foot.
Photo 15 — Top stitching of the Flat Seam. Note the presser foot edge on the seam.
Photo 16 — View of the bottom of the Flat Seam in photo 15 with the ruler. Note the 1/4 inch spacing between stitches which is fine.
Photo 17 — A completed Flat Seam. Stitching is straight with a slight roundness of the material to the right of the top stitch. This is considered perfect.
Photo 18 — Here we show you an example of a top seam that the top stitch is too close. It may appear right, but over time the stitches could tear into each other.
French Seam — A French Seam begins much like the Flat Seam with two pieces sewn together with the good sides facing each other. The selvage should be wider, say 3/4 to 1 inch. When the two pieces are pulled apart and facing up with the selvage under the seam split to both the left and right sides (see Photos 19 - 20). A strip of material is sewn under the selvage; the top stitch binds all three layers. This material can be the same material or of a more utility nature such as duck cloth or other binding. This strip is not seen and provides strength to the seam, so the recommended material should be thin as to not add additional thickness as necessary to the seam. This could become important when fitting your material and seam over a frame, especially an edge (Photo 22). Since the French Seam has two top stitches, it is vital that both top stitches be symmetrical to the center stitching. Whatever method or convention you choose, stick to it. Not all presser feet are equal in distance from the needle. And the stitching should travel in the same direction. There is nothing worse in appearance than a French Seam that has unequal top stitches. Photos 23 - 25 show more seam information.
Photo 19 — Cross section diagram of a French Seam. The seam starts like the Flat Seam by joining the two pieces together, good sides facing each other. Note the selvage under the seam is split with one folded under the left and the other folded under the right side. An additional strip is sewn under the stitching. This additional piece can be of the same material or of another utility material such duck cloth. This bottom strip is not seen and is sewn in place for added strength. The diagram shows large gaps between the layers for illustration purposes. When sewn together, the layers will be tight against each other.
Photo 20 — A French Seam begins much like the Flat Seam by sewing the two pieces together. However, the selvage is greater. Shown is the magnetic guide set to 3/4 inch.
Photo 21 — The completed first stitch of a French Seam. Note the generous selvage which will get folded under each side when we do the top stitch.
Photo 22 — Start of a top stitch for a French Seam. Note the binding material under the seam which will get sewn together with the selvage.
Photo 23 — Example of a French Seam that is not quite right. Note the slight curvature in the basic seam top stitches are not equally apart from each other.
Photo 24 — Top view of a perfect French Seam. Note that you'll have to device your own method to keep the seams equal such as using the edges of the presser foot.
Photo 25 — Bottom side of a French Seam.
Thread Color — So far in this series, we have used predominantly white and black threads to provide a strong contrast for the purposes of revealing pictures to aid in learning upholstering. The reality is that most times, you will want to have threads match your project's material. Sometimes thread colors are intended to add contrast to the materials, and other times you may want the thread to closely match the material so it blends in and visually disappears. You may notice that on the seams you've done so far, even when the fabric is sewn together threads can still be slightly visible. When purchasing the materials for your project, it is worth the investment to acquire multiple colors of thread in the one pound cone size.
Stitch Length — In Part 1, we mentioned the stitch length adjustment on the machine. Here we'll show you the effects of adjusting stitch length for your project. Vinyl and leather typically use longer stitches of 6, 7, or 8 mm long. If the application has the top stitch shown (for appearance), then a longer stitch looks more even. The other reason is that if stitches are too short, the thread can cut the material between the holes rendering the stitch useless. That applies to whether the stitch is exposed (seen) or is part of a hidden seam. Fabrics like wool or cotton should have shorter stitch lengths like 4 - 5 mm to keep the material together better along the joined surface. See Photo 26.
Photo 26 — Three different Stitch lengths are shown here. One would not normally change stitch length in a single seam, but this is the best way to illustrate the difference in a single photo. Pictured here is a Flat Fell Seam with the stitch varied from 6 to 8 mm during the stitching for this article. The 6 mm length is clearly too close, the 7 mm is acceptable and the 8 mm setting appears just right. Whether you are duplicating an existing upholstery pattern (to include stitch length) or creating something custom, you should feel comfortable with a length that delivers the desired result.
Presser Foot Pressure — There is a significant reason for addressing presser foot pressure and thread tension. If your project begins to show signs of a ruffled appearance, you may be experiencing "puckering". Puckering can be attributed to uneven movement of the materials being sewn together or thread tension. A short tutorial on this can be found at: Coats Industrial. Further research may find other references as well. We would encourage you to seek out reasons why the project shows signs of uneven results. The two we present here are pressure of the presser foot and thread tension (likely upper thread). See Photos 27 & 28.
Photo 27 — Top view of a French Seam that experienced puckering while being stitched. Its not obvious looking at the top, but the next photo shows it more clearly.
Photo 28 — Bottom view of the French Seam from Photo 27. Here you can clearly see the bottom strip getting bunched up while it was being stitched.
Thread Tension — In Part 1, we covered thread tension where we wanted the junction of the upper and bobbin threads to be in the middle of the sewn fabric. It is possible that too much tension on the upper thread can be applied causing the bobbin thread to be pulled up and visible in the top stitch. Improper thread tension can also lead to other problems, such as puckering. See Photos 29 & 30.
Photo 29 — Close-up view of a stitch length where the upper thread has too much tension and it is pulling the bobbin thread up. Those little black "specs" in a stitch should not be seen.
Photo 30 — Close-up view of a stitch length after the upper thread tension was reduced. It improved, but a few black "specs" are still visible. Ensure your tensions are set correctly using scrap material before starting your project.
Changing thread — It is common to have to change thread in a project. Here is a tip for quickly routing the thread through the machine for the top stitch. Cut the thread above the machine and tie a simple knot in the new thread and the thread that is already routed through the machine. Either with the knee lift or the presser foot lever, lift the presser foot to relieve the tension on the thread. Gently but firmly pull the thread from the needle end to pull the replacement thread through all the tension disks and loop holes. The last thing is to cut off the knot and thread the replacement through the needle. You may have to give a firm tug to help knot through the tension disks, but this an easier than manually re-threading through each part. After a few times, you'll appreciate the advantage of this simple method. See Photos 31 â€“ 33.
Photo 31 — Changing thread quickly will be a common procedure while sewing your fabric panels, so here is a quick tip on how to do it quickly. Cut the thread before it enters the machine and tie it to the new thread.
Photo 32 — Pull the threads tight to form a small knot.
Photo 33 — Lastly with the presser foot raised (either via the lever or the knee lift) pull the thread out of the needle and pull the thread all the way. This should pull the new thread. You might experience some resistance as the knot passes through the tension disks, but that is to be expected. Pictured here is the knot as it emerges from the machine. You still have to thread the needle, but is much quicker than threading manually.
Attachments — Here we'll introduce you to two types of attachments for your machine:
Welting Foot (sometimes referred to as a piping foot) is a special presser and needle foot combination. They replace the regular presser feet. The purpose of the welting foot is to produce a nice, tightly-wrapped material around a round form and include it in the stitching process (Photo 34). This requires welting material such as the 5/32 roll from a supplier like American Trim (see Photo 35). Referring to Photo 34, and after the correct size welting foot is attached to the machine (see Photos 37 - 39 ), Step 1 is to align the base material and a strip of the welting material under the presser foot and carefully stitch the two pieces (three layers) together. Keep the edges flush to ensure the seam doesn't wander. Upon completion, tie the top and bobbin thread as you would with any other seam. Step 2, place the other piece of material face down over the welted piece just sewn. Allow the welting foot to do its job by pressing over the welt in Step 1. Again keep the edges flush while stitching. Tie off the threads. Step 3, pull apart the material pieces to reveal the welting in the middle (Photos 39 & 40). An importent tip is to keep these welting feet in a marked bag as delivered from the supplier. It is easy to mix up presser feet and needle feet.
Photo 34 — Cross section diagram of a welting seam, shown as three steps to form this seam.
Photo 35 — This is a 500 yard roll of 5/32 welting cord. It's not very expensive, approximately $20 per roll. Common sizes of cord are 4/32, 5/32, and 6/32.
Photo 36 — View of two welting feet. Shown are the back of the feet to show the cutout in the presser foot and the slight cut out in the needle foot. On the left is the 5/32 foot and on the right is the 3/16 foot. When attaching these to the machine, ensure the needle foot is straight and does not interfere with the presser foot. They should move freely with touching each other.
Photo 37 — View of two more welting feet, this time notice the large portion that is removed from the heel. This is intentional when doing a project where the welting needs to make a tight turn.
Photo 38 — Welting feet come in many sizes. This is a 1/2 inch welt foot set. This size and type of welting could be used in door jamb applications on closed cars of the 1930's and 1940's.
Photo 39 — Top view of a welting seam. Here a black material was used around the welting cord to show a contrasting color combination. Depending on your project, the welting color could be contrasting, complimentary or exact (same) color to the base material.
Photo 40 — Close-up view of the same welting seam in Photo 39.
Binding folder — Binding is a trim item that finishes off the cut edges of many fabrics usually two or more layers sewn together. Most bindings have a configuration of Two-Edge-Turned. The Two-Edge-Turn means that both edges (sides) are turned onto itself. When Two-Edge-Turn binding is routed through a binding folder, it puts the folded binder in front of the sewing needle to be sewn onto the fabric layers. The other type of binding is One-Edge-Turned. The One-Edge-Turn means the binding is purchased with one side turned onto itself leaving the other side as a flap to be fitted under that fabric that is not seen. A good example for this is to bind carpet which is generally thicker than just a few layers of material. Binding attachments are designed for specific size and type such as 3/4 inch Two-Edge-Turn or 1-1/4 inch One-Edge-Turn. This has to do with whether the binding is simply folded over as in the case of the Two-Edge-Turn or if the binding attachment turns one side over leaving the flap untouched. Photo 41 shows several types of Two-Edge-Turned and One-Edge-Turned binding samples and Photos 42 â€“ 44 illustrate a Two-Edge-Turn binding attachment mounted on the sewing machine and the results. Additionally, since the process of applying binding adds more drag to the material, special binding feet are employed to firmly grip the binding as its being sewn. More on this in Part 3 of this series.
Photo 41 — Different types of Two-Edge-Turned and One-Edge-Turned binding materials: #1 is 3/4" Two-Edge-Turned black vinyl face up, #2 is 3/4" Two-Edge-Turned dark blue vinyl face up, #3 is 3/4" Two-Edge-Turned taupe vinyl face up, #4 3/4" Twp-Edge-Turned taupe leather face up, #5 1-1/4" One-Edge-Turned taupe vinyl, face down, and #6 1-1/4" One-Edge-Turned dark blue face up. The #4 leather Two-Edge-Turned binding was a specially processed product made from leather strips to have the binding match other portions of the upholstery project (See Sources).
Photo 42 — 3/4 inch Two-Edge-Turned binding attachment is screwed on to the base of the machine using 8-32 machine screws. It is positioned in front of the presser foot and vinyl binding is inserted into the rear of the attachment. Note that the attachment has both front and back and side to side adjustments. Set the attachment so it is right in front of the presser foot and that the foot operates without interference.
Photo 43 — Side view of the binding attachment with 3/4" Two-Edge-Turned black binding inserted into the rear of the attachment.
Photo 44 — Close-up view of the #1 binding in Photo 41 sewn onto scrap red vinyl. Note that even though the binding is vinyl, it is textured to give the appearance of cloth. As with any project, binding color, texture, and thread color are selected to suit the project.
- Practice, practice, practice. This can't be emphasized enough. Purchase close-out lots of vinyl or other like-weight material and practice these seams. As a beginner you'll make mistakes, this is part of the learning process. It is better to make a mistake on a $2 per yard piece of vinyl, than risk ruining a $40 per yard specialty fabric.
- Request thread color panel boards (aka sample board) from Superior Threads to get aquatinted with the different colors that are available. It is worth ordering thread in both slightly lighter and slightly darker than your project requires.
- Make up simple projects for yourself. Purchase some clear vinyl from the local store and make up a cover for some items in the shop like a cover over the MIG welder and cart. Make templates out of brown paper and transfer them to the clear vinyl. Then sewing them together is a practical exercise. Don't forget to leave extra for selvage on your templates.
- Familiarize yourself with welting attachments and what size welting you might use in your project. It is up to you to know what size of materials are available and what you want to order.
- Investigate the different types of binding attachments available and what type of binding you will use. Make sure you correctly match the attachment to the material.
- Investigate and understand the different types and composition of binding available from suppliers. There are many cloth and vinyl bindings used in auto and marine trades that maybe suitable for your project. If possible request samples or sample cards and keep track of them by supplier.
- When in doubt about your machine for things like needle size and thread routing, rely on the manual for your specific machine. Superior Threads is a good source but is by no means the only one that offers many references to thread size and needle selection. Don't be afraid to ask. The dumbest question is the one you didn't ask. It's okay to tell them you are a beginner and that you appreciate all the help you can get. Everybody is a beginner at some point.
- Pay attention to the straightness of the stitches and the location of the stitch on the material. Learn to stop the machine short of the end and place the last stitch as close to the end as possible. This is especially true for the French Seam which must have uniform dimensions on the straight and curved sections of the seam.
- Think about the task to be performed and what you need. If you are sewing the binding onto the edge of a pickup truck Tonneau cover that is about 25 linear feet around, make sure you start with a full bobbin. Running out of thread in the middle of stitching is an elementary mistake you can easily avoid.
- Did you figure out the mishap cited in Photo 3? The seam was sewn with a welting foot instead of the regular presser and needle foot combo.
In Part 3 of our Upholstery Series, We'll make a Tonneau cover for a pickup truck.
Sources and References
- Superior Threads offers a wide variety of different types of upholstery threads and needle supplies including valuable references and an education section.
- Special binding and trim. Hidem, 1 edge turned or 2 edge turned binding, or Wire-on from customer supplied material: L'Cars. Cory Cook at 715-520-3776.