Vintage pfaff 335G-h3 stitching problems

[tibee]

You're right, according to this https://www.manualslib.com/manual/1088170/Pfaff-335.html?page=25#manual , although that didn't change my problem unfortunately =(.

I am also threading the bobbin according to that same manual.

12 hours ago, RockyAussie said:

Also your thread return spring should just start to slacken off as the needle enters the leather.

it seems good ( do I have to change that every time I change thickness? )

I'm trying to understand the mechanism, is this right?: the hook catches the top thread, pulls it over the bobbin ( at this point, that thread is super taught ) and then at 3/4 around it'll jump out of that hook and get under the o pposing hook and is released from there as it passes under the foot.

here is a pic of my bobbin, it comes out quite a bit because it is pushed up by the little springs at the bottom of the bobbin case, but it does stick out either way.

the other pictures I took wile sewing without the motor by hand, and I noticed my bottom thread jumps out gets to where it is instead of in the track. I didn't seem like that's what was causing my loops,  but it could be a symptom of the same problem. 

[RockyAussie]

10 hours ago, tibee said:

22 hours ago, RockyAussie said:

Also your thread return spring should just start to slacken off as the needle enters the leather.

it seems good ( do I have to change that every time I change thickness? )

I don't usually have to but if it is not behaving well I do. I have to say that your bobbin appears to be sitting inordinately high up on the anti backlash springs and perhaps the bobbin slots are getting intermittently caught as the bobbin revolves. When the bobbin is in the machine and you pull the thread can you feel and catching as you pull the thread out? I could not find any manual specific on this machine and I am wondering if the thread/needle size is supposed to go this large. For instance from Pfaff on a 335 shown it says needle size 80-100nm  https://www.pfaff-industrial.com/en/portfolio/sewing-machines/cylinder-arm/pfaff335 That would mean a size 40 thread max.

I can run a 20metric or 138 in mine without any problems but it is not a G type like yours as shown in the picture below.

Given what you said about cranking your top tension to near max I would reduce my bobbin tension by about a 1/2 turn and see if that helps. Loosen your top tension to match.

[jimi]

On 1/11/2020 at 12:19 AM, tibee said:

I'm not sure what you mean by little finger

It´s the one in your last picture above the bobbin, where those two little screws are, but it looks like it is fixed and non adjustable? You could check to see if that has any kind of burr on it also?

[dikman]

Mine doesn't have an anti-backlash spring so I don't know how high it should sit but I thought it looked pretty high, which means when it's pushed in it's likely to have quite a bit of tension against the bobbin?

[tibee]

7 hours ago, dikman said:

Mine doesn't have an anti-backlash spring so I don't know how high it should sit but I thought it looked pretty high, which means when it's pushed in it's likely to have quite a bit of tension against the bobbin?

the antibacklash spring raises it quite a bit but I don't feel like it creates significantly more tension when I put it in the machine.

11 hours ago, RockyAussie said:

I can run a 20metric or 138 in mine without any problems but it is not a G type like yours as shown in the picture below.

I Beleive the G stand for great capacity bobbin which could explain why it seems to stick out so much.

10 hours ago, RockyAussie said:

When the bobbin is in the machine and you pull the thread can you feel and catching as you pull the thread out

it rolls smoothly when I pull =( 

 

The picture below are lines of stitches with no change in tension or anything whatsoever,  so it seems that the bottom material affect the stitch heavily.

3mm veg tanned with resined flesh side, + thick canvas.

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

Top piece: 2 layers of 3 mm veg tanned ( 6mm total)

Bottom piece: 3mm veg tanned + 2mm oil tanned. (5mm total)

 

so thinner leather gives better results and the ones with fabric or soft leather on the bottom give better results although there are still some loops here and there but maybe that will give someone an idea as to wth is going on. I live in a very isolated part of the country in France so finding someone to take a look is difficult so any idea is appreciated.

 

Thanks for the help 

[Constabulary]

The needle size these machines can handle often depend on the throat plate and feed dog the machine is set up with. With other words the size of the needle hole in the feed dog and the width of "thread gap" between hook and throat plate. Small holes and tight gaps will cause problems with larger site thread - so it depends... If you have bought a used machine you never know if it still is set up the way it left the factory. So its well possible when the manual says max 100 size needle that one of the former owners / users installed a different feed dog or throat plate to accommodate larger size thread - it could also be just the other way around. So machines of the same class & subclass may be set up totally different - it´s always trial and error wit used machiens. If a used machine is set up the way you need it - great - but I would not necessarily expect this.

When you add a soft layer on a harder material the knot is easier to hide because of the additional thickness and in softer material thread knots are easier to hide. I would guess when the soft layer is on the top you will still see the knots on the bottom side.

Try a needle 1 size larger if the hole in the feed dog is wide enough. or use thread 1 size smaller in the bobbin.

Edited January 12, 2020 by Constabulary

[jimi]

 Maybe like Rocky said, your thread could be too thick for your type of machine?? and what Constabulary also said, I use a feed dog with a wider hole for the size 40 thread i use in the machine. I also have one with a smaller hole for thinner thread, it is the same part number but the previous owner opened the hole?? If i have some thicker thread around i could try and see if it sews or not?

 

[tibee]

1 hour ago, Constabulary said:

Try a needle 1 size larger if the hole in the feed dog is wide enough. or use thread 1 size smaller in the bobbin.

58 minutes ago, jimi said:

Maybe like Rocky said, your thread could be too thick for your type of machine??

You  guys might be on to something. I didn't have a 140 but I tried 150 and it's just too tight of a fit in the slot in the picture ( don't know the name), so I figure 140 would be pretty close to the same and the 130 I'm already using is probably already a pretty narrow fit so maybe that's what is causing it. #69 thread in the bottom didn't change anything though. I'm going to try #69 top and bottom with a 110 needle and see what happens.

I appreciate the help guys. thank you, I'll keep you guys posted

[jimi]

Hi Tibee, here is what i have found just now. I had some 20´s thread so i have tried this in the 335 with a 130 needle ( i have not got any bigger for this machine). i have changed the thread and left all tension settings the same as was for the 40 thread i had in it. first try 3mm thick, then 2 layers 6mm thick both without touching the tension.then 1/2 turn to loosen the bobbin thread. next piece of leather approx 5.5mm thick 2 turns to tighten top thread, final 3 turns on top thread tension and 4 layers of 1.4mm oiled tan.

3mm and no tension changed6mm and no tension changedbobbin 1/2 turn loose

 

Edited January 12, 2020 by jimi

[jimi]

5.5mm 2 turns top tension top sidetop and bottom side4 layers 1.4mm oiled tan aprox3 turns total on top tension

Edited January 12, 2020 by jimi