In last week's primer, I discussed the highly specialized nature of industrial machines. While this holds true 99% of the time with industrials there exists a class of "artisan" industrial lockstitch machines often favored by tailors and costume shops that combine both the versatility of domestics with the reliability of industrials. Unlike their straight stitch only counterparts, these machines often feature zigzag and other features at the cost of a lower top speed.
Perhaps the most common "artisan" machine is the 3/4 sized Singer 20U which has been rebadged and cloned many times over. Today we'll be taking a look at the West German made Pfaff 138--a full sized straight and zigzag lockstitch machine.
Pfaff is known for fine engineering and the 138 is no exception. It is an internally gear driven, front loading, rotary hook machine designed to operate at around 2000 stitches per minute. This is, by all accounts, slow by industrial standards, and while it can be coaxed into sewing faster with a larger motor pulley or higher rpm motor, manual oilers* are not designed to sew at extreme high speeds.
*high speed industrial machines are called self-oilers and feature an oil bath with a wicking system for constant lubrication. The 138 is a manual oiler much like a domestic machine.
These Pfaffs were made in various flavors and either come equipped with a 4.5 mm or 6mm max zigzag width. This particular machine, a 138-6 / 21 BS, has the wider zigzag. Stitch length is adjustable up to 5mm and the machine is reverse capable. Like most zigzag machines, the 138 has an adjustable left, right and center needle position. The mechanism is very similar to the domestic Pfaff 130 and takes a little getting used to. You need to push the lever in and then flip it up or down.
Some models come equipped with a twin needle needle bar, which can be adapted to do single needle sewing. As I rarely work with twin needles, I leave one of my upper tension assemblies adjusted for a lighter thread and the other for heavier thread. I have a pair of bobbin cases on hand with tensions adjusted to match in suit.
As this is my primary machine, you can see I've loaded the cast iron frame with magnets to conveniently hold my thread snips, seam guides, and miscellaneous presser feet that I happen to be using for my current project.
Most industrials use an external bobbin winder which enables you to simultaneously wind a bobbin while sewing your project. All of this gets fed from a dual thread stand so you will never run out of bobbin thread. This particular bobbin winder was harvested from a vintage Singer and turns much smoother than the modern industrial bobbin winders available today.
How does she stitch? Absolutely beautifully with matching forward and reverse stitches as shown above. She does all of this, quickly and reliably as any good machine should.
Those of you who have been following this blog know that I'm a big fan industrials because of their knee lifts. Knee lifts are one of the those conveniences I just can't live without. The 138, however, takes the convenience factor one step further. It features a hands free reverse option! This is accomplished with an additional foot pedal.
Not all industrial machines are capable of this. In order to qualify, the machine must have a spring loaded reverse and be equipped with a means to mount a pedal chain. Below I've pictured the back of the stitch length regulator. There you can see a small hoop where I've installed the chain. The chain then hangs out the bottom of the machine down to the pedal. Stepping on the pedal pulls on the chain which flips the stitch regulator lever up causing the machine to reverse! My pedal has also been harvested from a cast iron Singer and bolts easily onto any of the slots on a standard K leg frame.
While it takes a little bit of coordination, foot activated reverse sewing is a real time saver and frees up both hands to control the fabric. I've configured my rig such that the motor is controlled by my left foot, while my right operates the reverse and knee lifter.
If you do decide to install a chain pedal reverse, you might consider removing the oil pan altogether or perhaps cut a larger opening for the chain to come through. As it is, the chain sometimes gets tangled up with the knee lift mechanism--especially when tilting the machine back.
The 138 is super smooth and outside of the constant hum of the clutch motor, is relatively quiet. I've installed this in my other table that has a servo motor and find it comparable in volume to a domestic and in some instances quieter. This is largely due to its streamlined internals. There's basically one long horizontal shaft that drives the needle bar with a Pitman arm to regulate the zigzag pendulum swing. All of the adjustments are easily accessible.
Unlike domestics, industrials like to be oiled often as they are running at much higher speeds. Oiling ports can be found all over and are marked clearly in red.
Perhaps my biggest complaint with the 138 and Pfaff's in general is the high cost and lack of availability of parts. This machine uses a proprietary super high shank foot. Unfortunately, my search for quality aftermarket reproductions was largely fruitless--all of which required adjustments to my presser bar which rendered my original foot useless. Thankfully, the 138 can also accept regular high shank feet which can be installed in the lower hole. This may or may not require adjustment to the presser bar height which is a really simple fix. Below, you can see a super high shank foot in comparison to a normal high shank 20U foot.
However, if you decide to go this route, you will find that there aren't very many options when it comes to high shank feet that will fit the profile of the extra wide 6mm feed dogs as most high shank feet are designed for straight stitch models with narrow presser feet. Additionally, the original 6mm Pfaff feed dogs uses a coarse three feed configuration which is less than ideal when sewing in reverse and near the edge of your material. As a result, I've resorted to switching out to a set of 4 feed 4.5 mm aftermarket feed dogs which are readily available. This narrower profile also accommodates a much larger range of high shank feet. Using the high shank hole and a 4.5mm feed dog, the 138 can basically use any foot that works with a 20U, with few exceptions.
In my quest to find a perfect sewing solution, I've come to accept that no single machine will do everything I need. That being said, the Pfaff 138 comes awfully close!
- High speed rotary hook
- Adjustable presser foot pressure
- 4.5mm or 6mm zigzag width
- LCR needle positions
- Hands-free reverse capable
- Knee lift
- External bobbin winder
Thoughts? Comments or questions? I'd love to hear from you. Till next time!