Hello, Mechanical Sewing Machine

 I have written several posts about the trials of finding a good sewing machine.  I finally decided to buy an industrial model.  The store owner told me that it would last 20 years.  I think that he underestimates.  The way this machine is built, I plan to leave it in my will.  I mention it here as an example of heavy-duty design.  So much modern software and electronics are designed to be throw-away; the modern smartphone is designed to last for 2-3 years.  While disposable devices certainly have their place, I hope that we don't lose the ability to design solid, long-lasting devices.


English is not the first language of the manual.


This machine has an oil pan.  It uses splash lubrication just like a car engine. The lubricant is mineral oil.  It has a sweet smell and should stain less in the unlikely case that it spills.  I have read quite a few complaints on the Web about the plastic gears used in portable sewing machines and other home appliances.  As I understand it, plastic gears perform better in lubrication-free environments; I don't think the average homeowner wants to oil all their appliances.  I'd rather have good plastic gears than cheap metal gears.  But the drivetrain of this machine is impressively solid.

The speed control connection to the motor is a steel rod. The pedal on my portable machine proudly proclaims "Electronic."  No wimpy electronic control here.

This machine came with a servo motor. Older machines use clutch motors, which must have been both loud and a little smelly. This machine runs at 5000 stitches per minute---that's 25 meters per minute.  The knob on the motor allows you to set the maximum speed to a lower value.  I was a little worried about the sensitivity of the speed control, but it has proven to be easy to control.

You say you want vibration control? Just the head of this machine weighs 75 pounds.  Add in the motor and table and it tips in at over 100 pounds. That's vibration control technology straight from Sir Isaac Newton---a 100 pound body at rest tends to stay at rest.

This machine only makes one stitch, a straight stitch. It is also mechanically set for medium-weight fabric. To adjust it for either very light or very heavy fabrics, I have to use a screwdriver to adjust the feed dogs that feed the fabric. I also have to adjust the thread tension by hand.  Home portable machines have sensors and controllers that automatically adjust all aspects of the machine to adapt to the fabric conditions.  They also perform a lot of different stitches; high-end machines may perform hundreds of decorative stitches.  But their stitches aren't as uniform as the ones produced by industrial machines.  Building a machine to do one thing well has advantages.

Hello, Cyber-Physical Sewing Machine

The gearbox on my mechanical sewing machine broke.  It sounded like it was mixing gravel; I didn't investigate further.  I decided to replace it with a cyber-physical model but one that didn't have a lot of features that I wouldn't use.  I think this model will have a strong drivetrain as well as fairly reliable electronics, but only time will tell.
<p>
My first sewing machine suffered an electronics failure, and a rather mundane one at that.  As we integrate electronics and computers into all sorts of devices, I hope that system designers keep in mind that consumer electronics devices (cell phones, audio players, etc.) are designed with very short lifespans in mind.  In contrast, many of the cyber-physical devices, such as sewing machines, have much longer lifespans.  All the components should be designed to have consistent lifespans.  This means building printed circuit boards and chips to higher quality standards than those to which the electronics industry has become accustomed.  And, of course, more components of any type means more opportunities for failure.

Farewell, Cyber-Physical Sewing Machine!

I am retiring one of my cyber-physical machines---my sewing machine, to be precise.  You can see the source of the problem in the photo, namely the ribbon cable to the front panel.  The front panel is attached to the body with a very small tongue and a little adhesive.  When it comes loose, it pulls the cable out of its connector.  This little four-bit microcontroller costs $120 to replace; I know because it has happened before.

I have replaced it with an old-fashioned mechanical sewing machine, one built by Toyota, no less.  It has metal gears and no computer.  Toyota, of course, has had its own problems with cyber-physical systems, but I am confident that they know how to make a reliable gearbox.

While we are on the subject of sewing machines, let's take a minute to consider the genius of the sewing machine and its inventor, Elias Howe. The mechanism of the sewing machine performs a fiendishly complicated motion to perform what seems to be impossible---it wraps one thread around another.  Since Mr. Howe worked before the midpoint of the 19th century, he had no computers to control his machine.  He relied on simple rotating machines and cleverness.  150 years later, we still use his work.  As we design complex cyber-physical machines, let's remember that our goal should be to create designs that last.