{Solved} Pfaff 545 stitch length problem, can’t get a max stitch length. What could it be?

[hugocrafts]

hey, people

So, I picked this older Pfaff 545, CLMN-8 which says it has 8 mm stitch length. However, the lever is all the way down, but the maximum stitch length that I get is about 6 mm or so, but not 8 mm. What could be the problem? Is it something messed up or? Has anyone experienced something like this before, getting a smaller stitch length than what it's supposed to?

Hugo

Edited December 16, 2020 by Northmount
Changed title for OP

[CowboyBob]

Is the feed dog lifting high enough it can cause a drag on your material if isn't? You can also check the needlebar by pushing it front to back & see how much play it has,also do this with the feed dog & then follow back on the shafts & you might find a loose or wornout part.

[Uwe]

Congratulation on your Pfaff, they are generally really good machines. 

The model letter code of your machine does not include a “P”, which indicates that your machine does not have a four-motion feed dog. The feed dog only moves front to back, but not up and down. This feed mode is often found on machines intended for binding operations. 

The feed dog does not drop down to get out of the way as it moves towards the front. Friction from the feed dog rubbing against the underside of the material as it moves towards the front may cause the material to slip a little and shorten stitch length. 

I’d recommend doing a stitch length test with a piece of cardboard or thick paper, and without top thread. You can print out this template to make it a little easier: http://docs.uwe.net/slg.pdf

You can also just measure the how far the needle moves front to back as you flip the reverse lever up and down. Turn the hand wheel until the tip of the descending needle is level with the throat plate. Then move the reverse lever up an down. Put a ruler next to the needle to measure how far the needle moves. This measurement is the max stitch length the machine can produce with current adjustments.

If the stitch length on paper is far below the 8mm target, you may need to look into timing of the feed movement. For example, if the needle penetrates the material before is reaches the very front of its feed movement, it will also shorten stitch length.

Get ready to take some clear close-up photos or better yet a video of your machine’s feed movement.

[hugocrafts]

hey, @Uwe. Thanks, I hope I won't regret purchasing this sewing machine. Here's a close-up video of the situation. Please advise on how to remedy this:

 

Edited September 17, 2020 by hugocrafts

[Uwe]

Thanks for that video - nicely done!

I really don't see anything obviously wrong that needs to be remedied. The feed dog definitely does not move up/down. But it has a pretty good front-to-back movement - try to measure that if you can. I have a feeling it actually moves more than 6mm. Then the real world decrease in stitch length may have to do with how much the material may slip during the stitching. Sometimes the act of pulling the knot tight also pulls the material forward a little if it's not held in place securely. Your current feet and feed dog have a fairly small footprint. 

Be careful not to run the machine under power with the throat plate removed (bad things may happen if the bobbin case rotates freely). Also make sure you align the tab of the bobbin case in the cutout under the throat plate when reinstalling it.

My recommendation would be not to obsess over the exact maximum stitch length for now. Just get the machine sewing as well as you can. Then you can fine tune things one step at a time.

One candidate may be the eccentric that generates the feed movement - it may not be perfectly "centered". Normally, when the hook is in hook-timing position, moving the reverse lever should NOT move the needle at all. I had one machine recently where that was the problem. I had to rotate the feed eccentric on the main shaft to center it with the hook timing position. 

I'm leaving on a camping trip shortly, so I may be offline for a while

 

Edited September 17, 2020 by Uwe

[hugocrafts]

@Uwe I took a measurement with a caliper and it's moving about 5.7-5.9 mm. It's a little frustrating, but overall, the machine is sewing great however. Regarding the eccentric, when the needle is at BDC, flipping the lever to reverse, the feed and needle they don't move at all, so that seems okay. While inspecting, I saw that the safety clutch on this machine is missing. Then, doubts started to creep in about the service history of this machine, like If the brass plate truly belongs to this sewing machine or maybe someone has possibly swapped it with another model of Pfaff, or perhaps the machine is not adjusted properly. I checked the lift height of the machine and I can confirm is H3 with fabric clearance of 11 mm. I don't know what else should I check to confirm any doubts.

Another 2 things: I have a feeling like the walking foot i.e. the alternating presser needs some re-adjustment and synchronization with the needle, because they don't arrive at the needle plate at the same time (if you can take a look at the video for one more time to judge and advise on that also). And last but not least, the pin (part no. 91-013 139-05 on the diagram below that releases the tension of the discs in the tension assembly unit is missing. By any chance, do you know the diameter and the length of this pin If I could fabricate and make it on my own perhaps, because its function is pretty basic i.e. just releasing the tension?

Thank you @Uwe, and have fun camping.

Hugo

 

 that releases the disc in the tension assembly is missing 

Edited September 17, 2020 by hugocrafts

[hugocrafts]

@Uwe, I think I did not read carefully what you pointed me with your last post so I answered about the position of the needle at BDC instead of the hook in hook-timing position. And If that's the case, then, thanks to you, it seems I found the culprit. When the hook is in hook-timing position moving the reverse lever up IT DOES move the needle in my case. Here below is a close-up video of the situation.

Please confirm for sure If that's the main cause, and advise on what steps should I take to remedy this situation, Uwe?

My best regards,

Hugo

 

Edited September 18, 2020 by hugocrafts

[Uwe]

I looked for more info on this. As it turns out, the correct needle position for no movement when flipping reverse lever is neither BDC nor hook-timing position - it's in between.

The manual linked below contains some service instructions at the end:

Pfaff 145 545 User Manual.pdf

The screenshot below shows the relevant feed driving section from that manual

 

The feed driving eccentric is shown this picture. You can loosen both set screws and rotate the eccentric on the main shaft to adjust the timing of the feed driving motion. Your non-P machine will not have the eccentric on the left, which controls lifting motion of the feed dog.

 

This video goes over how the walking foot lifting motion should be adjusted. Yours looks pretty good as it is:

 

[hugocrafts]

@Uwe, I just checked again as you suggested for the correct needle position for no movement i.e. between the BDC and the hook timing position and yes, the needle still moves, I measured this movement of the needle dog and It moves about 2 mm. So, If so far the maximum stitch length was 6 mm, I guess this tiny movement of the needle of about 2 mm is that lost maximum stitch length, If I guess right? So, I'll have to play with the eccentric to make it just right. Do you perhaps have a video on how to adjust the feed driving eccentric on some of the Pfaff models?

Looking at the photo you attached, yep, that connecting rod on the left is missing on my model. You mentioned also this before that the letter 'P' was missing on this subclass. Now, I'm wondering, how that's gonna affect the performance on this machine? I mean, is the difference so noticeable between CLMN and CPLMN? Will it shift the material badly? And, If It's that noticeable, then maybe I could get another one, I remember the seller also had a Consew 225 and Singers from the 111W and 111G class. Do these (Consew 225, Singers 111W, 111G) have a '4 motion feed' and perform better than this one that I already bought?

Edited September 19, 2020 by hugocrafts

[Wizcrafts]

8 hours ago, hugocrafts said:

I remember the seller also had a Consew 225 and Singers from the 111W and 111G class. Do these (Consew 225, Singers 111W, 111G) have a '4 motion feed' and perform better than this one that I already bought?

These all have 4 motion feed dogs. This is also known as drop feed and it is pretty much the standard feed system in both walking foot and straight stitch machines. Sliding feed is non-standard and is only useful on binder machines. Otherwise, it is an impediment in my opinion. Those who already have such machines either learn to make do with the sliding feeder or sell them off and buy a 4 motion feeder machine.