I think I've found the problem.

[toxo]

I've been down in the mouth lately because my Adler 69 has not been playing ball. I even had to refund a sale because I just couldn't get it to work. I must've used up half a side of leather trying.

Now I don't wanna count my chickens but between you and me (I'm whispering now because I don't want the Adler to hear me.) I think i've found the answer.

It's the take up spring. I've got the hook meeting the scarf at just the right time and was still getting inconsistencies with the occassional missed stitch. I tried every thread size with every needle size, every top tension and every bobbin tension. I could only take a couple hours of getting beat up and I would have to come downstairs for a sit down and a cup of tea.

So after playing with the take up spring it gradually dawned on me that there's very limited adjustment on it and I couldn't get it to let go when I needed a loop. Then bing! the light bulb went off in my head and I realised that it doesn't matter how good the hook to scarf thing is it's never gonna work if you ain't got no loop right???

So tomorrow, when my brain isn't so fried I alter the bottom timing to coincide with a BIG loop.

Please someone tell me I'm right.

[jimi]

Have you tried turning it off and on again!!!  sorry, just remembered that ITT scene. Sounds like your going through a lot of tea bags Toxo!! I don´t have a adler 69 but a pfaff 335 which i think is the same, the take up spring should let go just as the needle hits the leather but apart from that i iam thinking if your machine was working ok before try to remember what was the last thing you changed?? It could be a twisty thread even'?? did you try another type of thread??could you maybe post a picture of your machine??

[toxo]

I've been having having niggly problems for a while and this would account for most of em. With the needle scarf meeting the hook, the take up spring is nowhere near letting go of the thread. I'm convinced I'm right but won't get on it till later cos my £213 quids worth of letters have arrived (been waiting awhile) along with the JB weld and I have an appointment later. I had to have a brief play and the imprint on veg tan is nice and crisp even with no heat so chalk that up as a positive.

I know the 335 and the 69 are virtually the same (binders) but does the 335 have the same back and forth feed dogs or do the oscillate?

You can see some of my machine in a thread recently about speed reducers. I found it.

 

Edited February 24, 2021 by toxo
afterthought.

[Uwe]

It sounds to me like your machine’s hook timing is considerably off. I recommend re-timing the machine as described on page 23 of the  Adler 69-373 Service Manual (assuming that is indeed your machine’s subclass.)

The tip of the hook does not merely need to meet the needle scarf at some point, it has to meet the scarf at precisely the right moment during the stitch cycle. On most machines that right moment is defined by the needle rising a specified distance from bottom dead center (2mm in your case.)  

After hook timing is positively correct, look at the check spring again.

On most machines the check spring (you call it take-up spring) has two functions:

1. Keep the thread taught while the needle is descending, to prevent the needle piercing the thread on the way down. Once the needle is in the material the check spring should rest on the adjustable ledge and no longer apply tension, until ...

2. It puts tension on the thread again as it wraps around the far side of bobbin case. This makes the thread slip through the passageway under the throat plate quickly to avoid snags.

Make sure the adjustable ledge under the check spring is in the correct position to apply and remove thread tension as described above.

The only time the thread should overpower the check spring is when the take-up lever is near the very top of its movement as it pulls the knot into the material and more thread from the spool.

  

I don’t recommend accepting paid work until you really have your machine figured out.

Edited February 24, 2021 by Uwe

[toxo]

12 minutes ago, Uwe said:

It sounds to me like your machine’s hook timing is considerably off. I recommend re-timing the machine by the book.

The tip of the hook does not merely need to meet the needle scarf at some point, it has to meet the scarf at precisely the right moment during the stitch cycle. On most machines that right moment is defined by the needle rising a specified distance from bottom dead center (2mm in your case.)  

On most machines the check spring (you call it take-up spring) has two functions:

1. Keep the thread taught while the needle is descending, to prevent the needle piercing the thread on the way down. Once the needle is in the material the check spring should no longer apply tension, until ...

2. It puts tension on the thread again as it wraps around the far side of bobbin case. This makes the thread slip through the passageway under the throat plate quickly to avoid snags.

The only time the thread should overpower the check spring is when the take-up lever is near the very top of its movement as it pulls the knot into the material and more thread from the spool.

I don’t recommend accepting paid work until you really have your machine figured out.

Thanks Uwe. Which is what I said I will do later.

You can teach me about sewing machines all day long Uwe and I'm very grateful but I promise you, you can't teach me anything about philosophy..

[DonInReno]

The thread take up spring only takes the slack out of the loose thread that might wrap around the tip of the needle right before the needle punches into the leather.  I’d bet lunch it’s an issue with the hook.

Maybe I missed it, but did you mention what kind of stitching inconsistencies?
Does the bottom tension seem extra tight off and on with the knot not pulling up into the leather consistently?

If the tip of any horizontal hook has been bent and damaged it causes two problems - skipped stitches because it’s not as sharp (even if the hook gap is tight) and once the hook clearance is readjusted now the hook crowds the thread path where upper thread makes its way around the bobbin case.  These tight clearances can make lower tensions seem random.  Some clearances may be listed in the service manual, but these may not be adjustable and the hook would have to be replaced.

What’s the history of the machine?  Did you recently buy it in this condition?

 

[toxo]

38 minutes ago, DonInReno said:

The thread take up spring only takes the slack out of the loose thread that might wrap around the tip of the needle right before the needle punches into the leather.  I’d bet lunch it’s an issue with the hook.

Maybe I missed it, but did you mention what kind of stitching inconsistencies?
Does the bottom tension seem extra tight off and on with the knot not pulling up into the leather consistently?

If the tip of any horizontal hook has been bent and damaged it causes two problems - skipped stitches because it’s not as sharp (even if the hook gap is tight) and once the hook clearance is readjusted now the hook crowds the thread path where upper thread makes its way around the bobbin case.  These tight clearances can make lower tensions seem random.  Some clearances may be listed in the service manual, but these may not be adjustable and the hook would have to be replaced.

What’s the history of the machine?  Did you recently buy it in this condition?

 

Hi Don. I only use the machine intermittently and with different threads. I mistakenly thought that if the hook is meeting the needle scarf properly it should be good to go. It was only after closely investigating "the check spring" and it's limited adjustment that I realised it must be the bottom end that's out of time. I hope it will be back to it's old self once I re -  time it.

[jimi]

On 2/24/2021 at 1:34 PM, toxo said:

I know the 335 and the 69 are virtually the same (binders) but does the 335 have the same back and forth feed dogs or do the oscillate

Yes, Back and forth.

[toxo]

32 minutes ago, jimi said:

Yes, Back and forth.

Do you find that the stitch length changes when going from say one layer to two layers?

[Constabulary]

Thats the pendulum effect on most needle feed machine - the thicker the material the shorter the stitches.

 

[Frodo]

Have you checked the machine for correct needle length? 

My machine acts like yours when the needle is to short

 

[jimi]

7 hours ago, toxo said:

Do you find that the stitch length changes when going from say one layer to two layers?

Yes as Folker said, this is the pendulum effect, so the thicker you go the more you will notice the stitch length shortens. I would say this has nothing to do with the forward and backward motion of the feet because your outside foot holds the work while the inside foot and needle come into position.

Edited February 26, 2021 by jimi

[toxo]

1 hour ago, jimi said:

Yes as Folker said, this is the pendulum effect, so the thicker you go the more you will notice the stitch length shortens. I would say this has nothing to do with the forward and backward motion of the feet because your outside foot holds the work while the inside foot and needle come into position.

So does this happen with oscillating feed dogs also?

[jimi]

2 hours ago, toxo said:

So does this happen with oscillating feed dogs also?

No, this only happens on the top side of your Adler where your material is.

[Constabulary]

Open the face plate on your machine, the pivot point of your needle bar rock frame it on the top so the needle bar moves back and forth in an angle and the thicker the material the shorter the stitches. You have the same effect on patcher sewing machines. Or draw a triangle and move the ruler from the bottom further up. The distance between the legs becomes shorter the higher the ruler goes.

Maybe it´s of interest:

There are needle feed machines which have an even stitch length no matter what thickens you sew but there are very few. So far I only know two (I owned both). One is the BUSMC #6HM (and similar models) and one is the Singer 108w Class (and similar models). That is because they have no pivot points on the top and their needle bars are always straight (not in an angle) when feeding the material.

[toxo]

Thanks Folker. You said this before but fool that I am was hoping you might be wrong duh!

The problem I'm having is definitely the check spring. Maybe Frodos point about the needle bar is worth looking at because there's no way I can get that spring to let go of the thread early enough to get a loop on the way down or take up the tension on the way up. It was sewing ok in the past and I know it must be something I've done. Maybe I've asked too much of it at some point and moved something? 

Just looked at the book and I think I've got the presser feet to high. I'll have another go later. It's ok. I'm calm. Getting used to getting beat up by a sewing machine but I'm wondering why there isn't a "Fine tuning sewing machines for dummies"? Start here, you MUST do this first and then do that etc.

[jimi]

26 minutes ago, toxo said:

The problem I'm having is definitely the check spring

I would take off the check spring and have a good look and give it a clean, there might be a groove worn in there somewhere or you might see something catching?? On the 335 you have the small plate for adjusting the travel of the spring, adjusted by the small screw, and you also have the knob in the middle for the tension of the spring. I am sure you will find out what it is Toxo if the problem is there.

Edited February 27, 2021 by jimi

[amuckart]

On 2/25/2021 at 3:32 AM, Uwe said:

On most machines the check spring (you call it take-up spring) has two functions:

1. Keep the thread taught while the needle is descending, to prevent the needle piercing the thread on the way down. Once the needle is in the material the check spring should rest on the adjustable ledge and no longer apply tension, until ...

2. It puts tension on the thread again as it wraps around the far side of bobbin case. This makes the thread slip through the passageway under the throat plate quickly to avoid snags.

Make sure the adjustable ledge under the check spring is in the correct position to apply and remove thread tension as described above.

The only time the thread should overpower the check spring is when the take-up lever is near the very top of its movement as it pulls the knot into the material and more thread from the spool.

I reckon this bit should be made a pinned post on this forum. I’ve not seen such a succinct and useful explanation of check spring function and setting anywhere.

[toxo]

The spring on my 69 wasn't in the best of condition and college didn't have one. Folker suggested the spring on my Durkopp 239 would psobably fit and if so I could order a Singer one but I couldn't get the damn spring out of the Durkopp I was pulling as hard as I dared but I didn't want to ruin it. The 69 worked fine until it had done around 3/4 inches of sewing and then it would miss a stitch. I reasoned that the spring was catching somewhere so I got the needle nose pliers on the job to ensure it wasn't touching anywhere. Job done. No more missed stitches.