Pfaff Timing Belt

[trash treasure]

This is NOT about a leather sewing machine, but it IS about industrial machine adjustment -

I recently picked up a couple Pfaff 463"s with tables & motors, for our shop - Cheap - Just plain high speed garment machines. One had a broken timing belt, and the other (in better shape overall) had a "newer" replacement belt installed.

So, I downloaded the service manual, and got the one with the belt set up, but there is an obvious problem - Although the hook / needle timing is on, and it picks up and makes a stitch, the tensions are so far out of whack, that the normal adjustments of the upper and bobbin tension, and take up spring make no difference.

At this point, I'm thinking that the upper and lower shafts may be out of sync, and as a result the take up arm is not acting at the right time. I know that Uwe said, in a recent thread, about timing the take up with the thread passing the furthest point of the hook, but I don't know if I want to trust that, as I think the hook may have been moved enough to compensate, somewhat, for the shafts being out. Also, this machine has a rather complicated bobbin case opener, timed to the hook, and the adjustments for that were not quite able to be set in the range the manual shows - So, I'm wondering .......

So - Is there some basic way to check the synchronization of the shafts ?

There is NOTHING about timing belt replacement for this machine in the service manual, NO marks on the bed or pulleys, and nothing anywhere I can find on the web

[Uwe]

I don't have a Pfaff 463, but from what I can tell it's a very different design  from the common walking foot machines we often talk about. The reason the service manual doesn't talk about the timing belt synchronization is because the adjustment happens in the link between the top shaft and the needle bar driver. On many machines the link between top shaft , thread-take-up lever linkage, and needle bar driver is locked in place and not adjustable. That is why the synchronization marks are used. 

This Pfaff 463 design is very different. The linkage in the head is adjustable and that's why it doesn't make sense to talk about synchronizing the upper and lower shaft. Instead, you adjust the relative position of take-up lever and needle bar, and then you adjust hook and feed timing based on the needle bar position. The relative positions of the top and bottom timing belt cogs are not really a factor in this.

I came across the diagram below as a loose leaf insert in another Pfaff service manual. Your machines may work the same way, but I'm not positive. In any case, it's a quick visual check to see if your machine is aligned like the diagram below shows. If it isn't, that may be a good starting point for investigation. Why that diagram is not part of the service manuals, I have no idea.

[trash treasure]

Thank you, Uwe !

This is very similar to the way my machine is set up - I will check this out, and see what's what :~)

It is a mystery why this info is not in the manual - Maybe they figure you're just supposed to know.

[Uwe]

I have a feeling the diagram is intended as installation instructions, not adjustment. There is apparently precisely one correct alignment for these parts and it should never change once assembled. However, if the alignment does change due to some forceful crash, part replacement, or a well-meaning tinkerer with a screwdriver, these parts need to be brought back into alignment in order for the rest of the machine to make sense.

Edited October 19, 2017 by Uwe

[Gregg From Keystone Sewing]

Not going to help with this here, but I've attached the Pfaff 463 service manual that does not cover belt install.

463 463H(3-86.pdf