Help please with PWM sewing machine pedal

[et...@whidbey.com]

I have an old Singer sewing machine. It is a model 221, AKA a
Featherweight. I got the thing at a garage sale for 5 or 10 bucks and
everything was there but the foot pedal motor control.
So I bought a modern PWM style control instead of an old carbon
disc style one because it was supposed to be better. At least I think
the new one is PWM. It is very light and doesn't get hot after lots of
use.
I think it may be under performing though because the little
machine seems to run too slow. I did go through the machine, cleaning
and adjusting it. It was dirty inside, had old congealed lubricants
clogging and sticking stuff up. Things were also really out of
adjustment so it would not have been able to sew even if it was
turning freely.
The machine now turns quite freely. It is oiled with the proper oil
and the motor, which I also cleaned and lubricated, is lubricated with
the proper grease.
So after all that the machine still runs too slowly. At least in my
opinion. The motor just doesn't seem to have much oomph and I'm
wondering if maybe the foot pedal control is not delivering enough
current and/or voltage. Since the control is PWM output would an
analog meter like my Simpson 260 be a good tool to measure the current
and voltage?
Or maybe someone here knows already about these machines and the
foot controls and can tell me what to expect from a properly
operating control. And the best way to check it.
Thanks,
Eric

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[peterw...@gmail.com]

Ummmm ..... PWM controls are for DC motors for the most part. When used on AC motors, they will cut speed by some amount just by being in place. Motors are funny things. They draw rated current even when throttled, which is why VFDs are preferred for AC motors. Not so much the control heating up as the motor heating up if fed with a PWM device.

https://www.amazon.com/Sew-link-Featherweight-Control-Pedal-PFW-196131/dp/B07DMSSF2R/ref=asc_df_B07DMSSF2R/?tag=hyprod-20&linkCode=df0&hvadid=241925305119&hvpos=&hvnetw=g&hvrand=4629272318479936685&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9007234&hvtargid=pla-466961777480&psc=1

Yes. There are some featherweight motors that are both AC or DC - but it will run better on AC.

Peter Wieck
Melrose Park, PA

[Pimpom]

I've seen designs - but not the actual product - of cheap motor
controls that can provide only half the power at full throttle.
This is because the phase-controlled device is an SCR without any
pre-rectification and conduct for only half of each AC cycle..
Maybe you have one of those.

[Phil Allison]

Pimpom wrote:

------------

>
> I've seen designs - but not the actual product - of cheap motor
> controls that can provide only half the power at full throttle.
> This is because the phase-controlled device is an SCR without any
> pre-rectification and conduct for only half of each AC cycle..
>

** SCR speed controls for AC/DC motors are brilliant things - cos they allow for back EMF feedback as well as very low speeds.

The feedback keeps the speed steady with varying loads - while trigger speed controls built into drills use triacs and give no such benefit.

The sewing machine foot controller is likely a triac type - which is a form of PWM too.


..... Phil

[Paul Drahn]

I bought one of those for my wife almost 60 years ago. She still uses it
for all her sewing. I bought a complete rebuild kit a few years ago and
still have the leftover pieces. The biggest problem is lint and dust
collection, but you have taken care of that.

Have you actually tried sewing cloth with the machine. My wife seldom
operates it at full speed. Sewing with the machine is an art, not a race.

And the foot control is a wire-wound resistor with a slider.

Paul

[et...@whidbey.com]

On Sat, 22 Aug 2020 12:22:34 -0700, Paul Drahn <pdr...@jodeco.com>
wrote:

Yeah, I do sew with it. That's why I bought it. I have a larger
machine that is really heavy and a real chore to set up. That little
featherweight is a joy to use. It is supposed to be able to sew
leather but the motor stalls. Looking online for information about
this machine I found out all sorts of folks collect them and actually
use them a lot. I also found a zig zag attachment that I use when
patching holes in my work shirts.
Eric

[tabb...@gmail.com]

Simple: connect it up without the controller to see how fast it goes.
Didn't know zigzag adaptors existed for ancient machines
Some early electric machines are quite slow.


NT

[Phil Allison]

Paul Drahn wrote:

=================

> >
> I bought one of those for my wife almost 60 years ago. She still uses it
> for all her sewing. I bought a complete rebuild kit a few years ago and
> still have the leftover pieces. The biggest problem is lint and dust
> collection, but you have taken care of that.
>
> Have you actually tried sewing cloth with the machine. My wife seldom
> operates it at full speed. Sewing with the machine is an art, not a race.
>
> And the foot control is a wire-wound resistor with a slider.
>
>

** Some Singer models use that and others have triac controllers.

One I saw recently had an "air controller" - model 6233.

https://www.shopgoodwill.com/Item/85245157

Yep, the foot pedal fed compressed air to the machine via a rubber tube.

https://www.perfecttimingsewing.com/product-page/singer-air-foot-controller

Not sure how that activated a triac circuit.



..... Phil

[Paul Drahn]

Wife has trouble patching denim with hers, if more than 2-3 layers
thick. Original motor is not powerful enough. She has to help the
machine by hand.
Paul

[Michael_A_Terrell]

Paul Drahn wrote:
>
> I bought one of those for my wife almost 60 years ago. She still uses it
> for all her sewing. I bought a complete rebuild kit a few years ago and
> still have the leftover pieces. The biggest problem is lint and dust
> collection, but you have taken care of that.
>
> Have you actually tried sewing cloth with the machine. My wife seldom
> operates it at full speed. Sewing with the machine is an art, not a race.
>
> And the foot control is a wire-wound resistor with a slider.

My mother hated those. She would have me install one of the carbon
pile type, because it gave a smoother control. I would save the old ones
and add a few extra disks to them to return them to like new condition.
The wirewound controller changes speed in steps, not in a linear
fashion. I also replaced old motors when they no longer had enough
torque for thicker material. She sewed six to ten hours a day, and wore
out eight commercial grade machines.


--
Never piss off an Engineer!

They don't get mad.

They don't get even.

They go for over unity! ;-)

[Clifford Heath]

Leather is much easier to sew with the specialised needles, which have a
sharp triangular point.

CH

[tabb...@gmail.com]

On Sunday, 23 August 2020 03:26:43 UTC+1, Paul Drahn wrote:

> Wife has trouble patching denim with hers, if more than 2-3 layers
> thick. Original motor is not powerful enough. She has to help the
> machine by hand.
> Paul

Damn. I once sewed 12 layers of denim with my oldest one, 1960. It struggled but got there.


NT

[Cydrome Leader]

et...@whidbey.com wrote:
> I have an old Singer sewing machine. It is a model 221, AKA a
> Featherweight. I got the thing at a garage sale for 5 or 10 bucks and
> everything was there but the foot pedal motor control.
> So I bought a modern PWM style control instead of an old carbon
> disc style one because it was supposed to be better. At least I think
> the new one is PWM. It is very light and doesn't get hot after lots of
> use.
> I think it may be under performing though because the little
> machine seems to run too slow. I did go through the machine, cleaning
> and adjusting it. It was dirty inside, had old congealed lubricants
> clogging and sticking stuff up. Things were also really out of
> adjustment so it would not have been able to sew even if it was
> turning freely.
> The machine now turns quite freely. It is oiled with the proper oil
> and the motor, which I also cleaned and lubricated, is lubricated with
> the proper grease.
> So after all that the machine still runs too slowly. At least in my
> opinion. The motor just doesn't seem to have much oomph and I'm

Did you mess up the timing of the motor by chance? The angle of the
brushes makes a huge difference.

> wondering if maybe the foot pedal control is not delivering enough
> current and/or voltage. Since the control is PWM output would an
> analog meter like my Simpson 260 be a good tool to measure the current
> and voltage?

maybe? How's the motor run with no speed controller?

[peterw...@gmail.com]

> Did you mess up the timing of the motor by chance? The angle of the
> brushes makes a huge difference.

> maybe? How's the motor run with no speed controller?

The brushes are sleeved and fit in only one way. About the only other 'unusual' possibility is that Eric has a Euro version - which has flat paper caps in the motor. They should be REMOVED and NOT REPLACED!

Peter WIeck
Melrose Park, PA

[Cydrome Leader]

It's only somewhat related to this, but I have a precision drill press
with a real goofy looking manufacturer supplied speed controller. I called
them up about something unrelated and and issue of weird bursts in speed
came up. You'd have no load on the motor and it would randomly start to
race.

The suggested fix was to open the speed controller and cut out a bridge
rectifier that turned the AC output of the triac speed controller and just
let the motor get AC.

It worked fine after that. I'm not sure why they added a bridge recitfier
in the first place, or why removing it made a difference but it did. The
motor is pretty similar is size to a sewing machine motor, and the
standard universal motor type deal. The whole controller is cobbled
together looking so I can't even tell if they added the rectifier or the
OEM did.

I'm sort of tempted to try the drill press with a properly designed
industrial speed controller (Dart Controls), with and without the bridge
rectifier to see how it behaves.