I alluded to this in my previous post.  A number of years ago, the power switches for the Pfaff 1222 type machines went “NLA” or No Longer Available.  As usually happens, it takes a while for existing stock to disappear so many of us didn’t know until it was too late.  Around the middle of 2020, it finally happened.   Not long after my first order went unfilled, I started playing with the idea of rebuilding the switches.  The reason being that it’s a single piece of (sometimes 40+ year old) injection molded plastic that fails.  Every single time. Could it be 3D printed? After all, several years ago, I’d determined that the rest of the switch is high quality, modular and relatively easy to rebuild. In October of 2020, I received 4 Pfaff 1222 machines in for service and you guessed it, there was a broken switch among them and I had no more switches in stock.

After a series of unfortunate (family/personal) events that Fall, I finally began on Christmas Day 2020, and by a couple of days into the New Year, I had a working design and it took me about 15 minutes to disassemble the machine, disassemble the unnecessarily complex switch, replace the defective part, reassemble the switch and the machine.   This could be a viable solution! The problem was that I had no idea how long the 3d printed part would last.  In “in lab” testing, they did very well once I got a strong design with a strong filament.

Note: NONE of the links in this post is an affiliate link, they’re all to further information – usually on this same website.

FYI, I am aware of the one on Thingiverse.  It is NOT my design but did show up a few days after mine was designed and I had shown it in the Vintage Sewing Machine Study FaceBook group I run.  That was demoralizing and I shelved the project shortly afterwards because of it. Worse still is that the one on Thingiverse is not a strong design and will fail for a couple of reasons. (More on that below) That will lead many folks to conclude that 3D printing “sucks”, the switches can’t be repaired, etc. 

See, the part that fails on the originals is the collar of the switch.  It fails for a couple of reasons:

1. The part is very small and the walls where the threads are is very thin.
2. The part does double duty to secure it to the control box and if over-tightened on install, it becomes weakened or breaks before it’s ever used to power the machine.  Failure is inevitable. Failure is hastened by any rough “pokes” to turn the machine on or off.

It’s the first reason that makes the collars borderline unsuitable for 3D printing. At the end of the day, most current 3D printing requires bulk for strength.   On average, an injection molded part will almost always be stronger.  If the design of the collar for printing doesn’t take into account how thin the walls are, there will be holes in the smallest parts of the threads and it will be excessively weak.  This is what my first designs looked like and also that other one in the wild.  It took me what looks like one try to get the basic design and 22 minor revisions to finally get a strong design with adequate clearances.

It appears that I didn’t keep the very early designs – most likely because of the holes that were in them.  This screen capture (click to see it full size.  The text will make more sense.) from the slicing software (prepares the CAD design for printing) shows holes in the Thingiverse collar on the right – and the slicer gives a warning about it. “Support” isn’t an option in this print.  The clearances don’t allow it. Note the lack of holes on the left.  The design on the left is mine. Even at the absolute finest I can print a layer, there are still holes in the one on the right. It’s possible I could eliminate the holes with a smaller nozzle but that will still mean extremely thin walls – which means weak walls. In practice, there’s a good chance the one on the right would break before it was installed. This is compounded by the fact that many people would try to have the collar printed at a library or such and they would almost 100% of the time be printing in a brittle filament that tends to degrade and fail at about the 1 year mark even if it were to be successfully installed.

Here’s a closer look at those 2 sets of walls:

This is a large part of the reason I started designing what I wanted in CAD a few years ago instead of downloading already designed items from the Internet except in the case of very specific designers.  So many projects are unfinished or untested and often not fit for purpose.

Around the time that I was starting to test the working collars, I mentioned to my rep at SMS what I was working on.  When he asked for more details, I uploaded a video (since deleted) for him on how I was rebuilding the switches.  He said that they had been trying to have these switches re-made for years – since stock went NLA – because they were a high sell item. He thought that there was a switch with the component parts that had failed testing electrically but that the injection molded parts should be around.  Maybe they could send broken ones to me to rebuild.  After some investigation and pleading with the manufacturer to just produce the plastic parts, it became a non-starter when the manufacturer refused.  I went back to considering how to get the part molded myself – after all, the CAD work was already done.  Now it was a matter of how many units I’d have to order for someone to make the mold.  I inquired with my rep because they do way more of that sort of thing than I’ve ever considered.  He didn’t think it would be feasible so it landed on the back burner for a second time.

Periodically over the next almost 2 years, we’d talk about the switches and what made them so hard to replace.

Mostly that comes down to the dimensions – they have to fit in the control box and it’s tight in there! Naturally, also – there’s no spare wire to manoeuvre things easily.

And here’s what that box looks like from the outside.  Please excuse the appearance of my parts machine.  I have no idea what sort of creature felt the need to scratch all of that paint off. It was like that when I got it.:

If one were to try to reproduce the switch exactly as Pfaff had designed it too, it’s a 28 piece switch.  Yeah.  Classic German over-engineering.

Other than that, it’s a relatively standard configuration if not terribly common switch.  The dimensions were what made it impossible to grab something off the shelf.

About 6 months ago, I think it was – I heard whispers that SMS had something in the works.  The switches were likely coming back! A proper injection molded switch.

In the meantime, the 2 machines I had test collars in did perfectly fine.  I would actuate them periodically when I walked past them. For almost 2 years.  The collars were lasting for at least 2 years with light use. The problem was, I knew that if I did a pilot of them, there was a good chance of high failures because if the nut is tightened down too far, the collars will inevitably fail – a lot like over-tightening a lug nut on a car tire.  It doesn’t fail right then but the threads are damaged and it is very likely to fail in the future.  Plastic will fail far more reliably than that metal will under those conditions.

In late August, I got the official word.  Switches would be in stock in a couple of weeks.  So, with the return of the switches, it’s safe to shelve this project for the 3rd time. Hopefully it won’t need to be revived for a fourth. SMS is really good about trying to get parts that are in high demand though – even if it means having them made.

As of this weekend, I’ve installed one of the switches into one of my 2 personal 1222s and it works as expected.  I also installed a replacement presser bar lever and a new camstack.  If it tests well, it’s the final machine that will be up for sale that I mentioned back in August.  I don’t need 2 – Pfaff 1222s and it should be used.  I choose to see this as growth – instead of feeling overwhelmed by the number of machines I had here that I wasn’t exercising enough. I felt like I was going to end up on an episode of Hoarders, maybe after the house sunk noticeably from the weight!

With that said, Pfaff Switches can now be found in the shop.  For now, there are only a couple but I can order more at will and expect to be putting in an order in January.

With my sincere thanks to my rep, Jason at Sewing Machine Services Canada for keeping at it and getting these switches back into our hands and helping us revive these machines.  And also for putting up with the mounds of info I supplied him when he just asked for a few details.

Today’s post title inspired by Eurythmics – It’s Alright (Baby’s Coming Back)