Sewing Machine Primer

Another great primer from a member of the forum. This time it comes from HardCoil out of Denmark. He’s written a great article on the different types of machines and included pictures as well as video clips for description. He discusses home and industrial machines, different types of feed systems, motors and various features found on modern day equipments.

Machine types

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Sewing machines can be broadly categorized in two categories: Home machines and industrial machines. Most people have access to some variant of home machine, while getting an industrial is a bigger undertaking with regards to both money and space.

Home machines
For tactical sewing, modern home machines are not well suited. They are made of plastic, some of them even have plastic gears and other insides, and they are generally designed to do very advanced things to light fabrics. That being said, some people are still managing to coax these machines to sew plate-carriers, but prepare to spend a lot of time finding the way to do this.
Really old home machines are another story. These are typically made from cast-iron, with stainless steel insides. They lack all the fancy features of the modern machines, most of them can only do straight stitch and zig-zag. Some of the best machines were produced back in the 1950ies and were treadle powered.

Old pfaff machine with retro-fitted motor

Underside of the old pfaff machine. Notice how everything is made from high quality steel, and looks almost new after 60 years of heavy use

Those still in use today have usually been upgraded with an electric motor, that has a lot more power than the motor found in modern home machines. This combination of power and solid construction is why they are so useful for tactical sewing. When properly set up, they will typically be able to sew through up to 8 layers of 1000D Cordura, using #69 thread.
What they have in power, they can lack in control however. My old machine has no brake of any kind, so when going full speed, it’ll still sew up a few inches before coming to a stop when I let go of the pedal.

Industrial machines
While an old home machine can be used for tactical sewing, switching to an industrial machine is usually a natural progression, when one really gets absorbed by the hobby. Industrial machines are made to do ONE task, and finding an affordable one that’s made to sew many layers of Cordura is obviously a kind of holy grail for DIY’ers. Unfortunately these machines are often very expensive, so many people buy them used.

A selection of new and used industrial machines from my local dealer’s stock list

Since they are made to last, this is a really good idea. One should always test drive a used industrial machine with the appropriate materials before buying, and at different speeds. Just because a machine is huge and looks like it’s been just dragged out of a WWII era Soviet tank factory, does NOT mean it’s designed for heavy fabrics. I’ve seen huge machines made for sewing silk! The internals (hook and such) must be made to work with heavier thread. Still, there is a wide range that’s usable for tactical gear making, and getting one in the “lower” end may make sense if its limitations don’t matter to you, since there’s a substantial saving involved.

The prices for used machines vary wildly, and one can get really lucky on e-Bay. The price usually depends on age, brand and which features (see below) the machine has.

Feed types

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One of the most important features for tactical sewing is feed type, which describes how the machine moves the fabric along as it creates the stitches.

There are three basic feed types: Regular, top and needle.

Regular feed (or drop feed) moves the fabric forward by means of feed dogs under the fabric. This is what’s typically found on home machines. This system is not ideal for sewing heavy fabrics, and may result in stops, tangled thread or irregular stitch length. That being said, a used industrial bottom feed machine, which is designed for heavy fabrics, can often run really well, and will cost a fraction of what a more complex feed machine does. Because of the simple presser foot design, regular feed machines are also better at getting into tight corners than the more complex types.

Regular/drop feed

Top feed(or walking foot) is where the bottom dogs are assisted by a moving presser foot, helping the fabric along. This can be done in many different ways, some schemes have the top foot split in two and hop along the fabric, while the others have a large normal presser foot, with a smaller, walking foot inside. The downside to the top feed system is that the mechanics that control the top feed can take up a lot of space behind the presser foot, making it hard to make turns on bulky items like pouches. The presser foot mechanics often result in a relatively low presser foot clearance when lifted, which can also be problematic.

Industrial machine with top feed. Notice the large mechanism that controls the upper foot

Needle feed is where the needle moves during sewing, assisting the bottom dogs. This ensures an even stich length on exotic and/or stretchy fabrics.

Unison feed
Unison feed (sometimes also referred to as compound feed) is a combination of any of the above. On the most usable machines, the fabric is moved forward by the needle, the bottom dogs and a walking presser foot. Surprisingly this system is a lot less bulky than the top feed setup, and is usually considered the optimal for tactical sewing. Unison feed machines often have relatively high presser foot lifts as well. There are lots of differnet names for the combination types, and they are often used incorrectly by the advertisers, so one should check carefully what a given machine actually does. For a full explanation of the different feed types, refer to this page: http://www.industrialsewmachine.com/webdoc3/feed.htm

Unison feed with top, bottom and needle feed

While unison feed is probably the optimal type for tactical sewing, it also comes with a hefty price tag. Getting an old, used drop feed machine for $50 is a thousand times better than not buying anything. Do not get fixated on getting the best or think it’s the only way to go. The DIY tactical forum is filled with wonderful stuff being made on regular feed machines. With practice one can learn to work around the machine’s limitations.

Bobbin and hook size

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Something worth looking out for is the bobbin size. For normal sewing it is not that critical, but when using the heavy #69 or #96 threads, you can’t have many yards of thread on a normal bobbin. This is annoying, as it leads to frequent bobbin changes. Some industrial machines come with larger bobbins, which let you sew longer before changing. The larger bobbins also come with a larger hook, which increases stability with high-speed sewing.

2.5x size compared to normal bobbin

Motor type

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There are two motor types: Clutch and servo. Clutch motors run continuosly, and the clutch system transfers the power to the machine head when the pedal is pressed. Clutch motors are often quite noisy. A servo motor only runs when the user presses the pedal, and are almost totally quiet. Servo motors are the most modern type, and also offers more power and control.

Various features

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Lift Height
The heigher the presser-foot can lift, the better. A high presser foot lift makes it easy to navigate on bulky items. A machine for tactical sewing should have at least 3/8″ lift, but preferrably more. Some machines can lift almost a full inch!

Knee lift
Knee lift is a lift variant where you use your knee to lift the presser foot. This is a lot more ergonomic than having to reach the hand lift bar every time the operator has to make a turn. Most industrial machines come with a knee-lift option. Often the presser foot lift is higher when using knee lift.

Automatic lift
Automatic lift is where an electro-magnet operates the knee lift mechanism. The machine lifts when the operator presses backward on the pedal.

Synchronizer
A synchronizer is a device that communicates the needle position to the control box. This means that the machine can be set up to always stop with the needle down. This is a tremendous advantage when sewing tactical items, where many turns are the order of the day.

Automatic thread trimmer
An automatic thread trimmer is a set of knives under the bottom feed dogs. When the operater presses all the way backward on the pedal, both threads are snipped.

Controls
There are a wide range of control options available. Some machines just have an on/off button, other have simple controls like speed settings while some have fully computerized sewing control. The high end control panels aren’t particularly useful for tactical sewing. The simpler panels offer some good functionality like automatic start and close, where the machine sews a few stiches back and forth when the operator starts and stops sewing. These can often also be set up to do “automatic” PALS stiching. Another nice control to have is a push button reverse at the head, where a small button lets you reverse the sewing direction.

A simple panel with speed control and some automatic back-tack options

Reverse and needle up/down button

This reverse button has an extra function that lets you step forward ½ stitch at a time.

So that’s about it. If you made it this far, I hope you have an idea of how the basic features of sewing machines work, and what you’ll be looking for if you’re going buying.

You can view the original discussion in the forum here