Sewing machine thread standard

[Clive SteerParticipant @clivesteer55943]

I have become interested in refurbishing sewing machines and have recently acquired a Pfaff 145 walking foot machine. This is in a poor cosmetic state, it have been left out in the open, but otherwise OK after cleaning.

Unfortunately virtually every screw has had its slot mutilated so I would like to replace them if possible. Unfortunately spare parts are reasonably expensive including the screws costing IRO £2 each.

The screw threads may be special to Pfaff or possibly a standard I’m not familiar with. One common screw thread appears to be 3.56 mm diameter and a pitch of 0.065mm. I’ve used metric measurements because the Pfaff 145 is German but the design is derived from a Singer machine. Singer machine also appear to have non-standard threads which may be special to them and Imperial.  The thread pitch appears to be 39 TPI and several screws have the same pitch but with different diameters.

So my question is does anyone anything about the threads as all my searches so far have drawn a blank.

Clive S

[JasonBModerator @jasonb]

Unless that pitch is correct I would be trying 4BA or 4 Thurey with a pitch of 0.656mm

[Neil AParticipant @neila]

The threads could be from the small unified series. 3.56mm x 39TPI is very close to No 6-40 UNF, which is 0.138″ dia x 40 TPI. The other threads could be from the UNC series.

As Singer started out as an American Company, this would be my first search.

Taps and dies are readily available.

Neil

[Chris KaminskiParticipant @chriskaminski64716]

How about this?

https://www.gewinde-normen.de/en/sewing-machine-thread.html

 

9/64″ 40 TPI  (3.572mm Dia 0.635 NOT 0.065mm PITCH)

[DC31kParticipant @dc31k]

The good people at AliExpress appear to carry some (I guess the more common) screws for Pfaff machines.

You could try ‘pfaff 145’ in their search. The screws also seem to be listed by Pfaff part number.

Have you tried searching using the part number and ‘drawing’, ‘dimensions’, ‘specification’.

Try to find a Pfaff- or sewing machine specific forum and do a directed search on that site

<<search term>> site:old-german-sewing-machines.com

‘pfaff screw dimensions’ finds some things:

https://leatherworker.net/forum/topic/67043-pfaff-metal-thread-type/

https://www.gewinde-normen.de/en/sewing-machine-thread.html

https://www.victoriansweatshop.com/post/pfaff-screw-threads-9722034

https://www.practicalmachinist.com/forum/threads/sewing-machine-screw-thread-sizes.225457/

I often wonder at the thought process of those who post these queries. Do you honestly believe, on sober reflection, that you are the first person in the whole of recorded history who has a requirement for this information?

 

[Chris KaminskiParticipant @chriskaminski64716]

Alternatively… how about that page:

https://www.singersewinginfo.co.uk/screw_threads

[Howard LewisParticipant @howardlewis46836]

As already suggested 4BA at 3.60 mm diameter and 0.66 mm pitch would seem to be likely, and still available, albeit not as readily or cheaply as in days of yore.

The thread form should confirm if BA, being quite different from Whitworth, Sellars, Unified (As we now know it) or Metric

Howard

[Clive SteerParticipant @clivesteer55943]

Many thanks for all the replies and suggestions of sources to search and I’m amazed that my searches on Google and other sewing machine sites didn’t find as many.

Much appreciated. Clive S

[Ian HewsonParticipant @ianhewson99641]

My Dad worked for Singers in the special applications department at Leeds in the latter part of his employment. I have all his taps and dies that he used on sewing machines, cameras and tanks when at RoF Barnbow.

All are ba, bsf and whitworth.

Regards

Ian

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