Pfaff 191-5 timing

[trash treasure]

It must be just stuck to the hook shaft - The parts schematic just shows those 2 set screws ....... Unless there's a screw-under-a-screw, Singer-style.    I don't see what else could be stopping  the hook shaft from moving.

Anybody else with guidance here?

[mollieelle]

@trash treasure I too share your suspicions that the gears are indeed just stuck. They just must be   I’ve loosened every other screw I could find to try. But afraid to go prying the gears loose unless I know that for sure - though it may come to that. This machine is an odd subclass of the pfaff 191. So it does vary a bit from the general 191 schematic. 

[jimi]

Hi, I must be missing something with this machine?? is it not possible to adjust the needle bar??

[Scoutmom103]

I had a stuck bobbin case assembly.  I used PB Blaster, heat and then unwaxed dental floss to literally floss between the stuck parts to loosen the gunk that was binding the parts.  I went slowly and just kept at it over days to not harm the parts with heat or force.

Edited December 20, 2019 by Scoutmom103
The floss was used after I had removed the screws. The screw removal took a while do to the build up of hardened oil.

[trash treasure]

Maybe try some heat and penetrating oil on that gear - All the machines I buy are old and crusty, never a new one :~) , so I often need to free stuck parts, using chemicals and heat (sometimes) - I like to use Kroil (Best, but smelly), or Blue Creeper (2nd best, but less smelly), but try something like that -

For heat, if you have a heat gun, that'll work well, or even just a hair drier (I have even been known to use a micro torch at times) - The heat will soften old grease, and make the penetrating stuff penetrate better - The gear WILL come loose eventually , and you won't hurt anything.

As far as jimi's suggestion of just re-setting the needle bar - That will work, IF that was the cause of the original out-of-time problem (A driven-up, or shifted needle bar), but you can really wind up chasing your tail with this stuff, if you're not careful - The normal procedure for timing a machine is to set the needle bar FIRST (To correct spec for the needle system, etc), and THEN time the hook to it.  If you just set the needle bar to accommodate the hook timing (whatever it happens to be) .......... Well,  It wouldn't be my first choice for a solution - Just sayin'.

[mollieelle]

Thanks so much @trash treasure and @Scoutmom103  I’ll work today to de grease those gears and free them. Probably a good thing to do anyway. 

Ive read the service manual for the 591, the 191s contemporary counterpart carefully and I am positive the hook itself is not timed correctly according to the timing requirements of the machine.

@jimi Unfortunately adjusting the needle bar alone is not enough to remedy the situation. The hook and needle bar each have timing requirements they have to meet. Changing the needle bar to meet the hooks out of time position is not fixing this timing issue. The needle bar needs to be at a specific place in its path (2mm from bdc in this case) to have time to form a loop that the hook can catch properly. I can change the height of the needle bar to meet the hook, however, the hook then meets the needle a hair after bdc (bottom dead center) which does not give it time to form a loop. The hook then barely catches the loop sometimes, slices and splits the thread sometimes because the loop is tiny and too tight to catch, or misses it altogether sometimes. 

[CowboyBob]

On most Pfaff's & I'm sure this one is the same way you loosen the screws on the smaller gear,the screws on the large gear go into a slot on the shaft,so re-tighten the large gear screws ,loosen the small ones & if it's stuck,very carefully put a screwdriver under the hook to hold it from turning & turn the handwheel & it should break free.

[mollieelle]

Thanks so much @CowboyBob I'm cleaning them up and will give that a go. To make sure I'm after the right thing - below is a photo. The smaller vertical gear is connected to my hook shaft. When the screws are loosened on that gear the hook shaft should rotate freely without turning that small gear - correct? So that should really be the only gear I need to loosen to free the shaft to rotate independently?

[mollieelle]

I got it!! That did it. Some fishing line, pb blaster, cleaning, and loosening the small gear only. I can properly time my machine now. Thanks for the early Christmas present all. Wohooo!

[CowboyBob]

Great, I'm glad to hear you got it loose.