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Posted (edited)

Good Morning Good people!

 

I have a Mitsubishi CU-865 cylinder arm that I've been fussing with for a little while. (factory servo with box style reducer via Toledo)

Lately I tend to make bags, but was hoping that it would help with some other work as well.

My first question, SHOULD this machine be capable of tensioning the thread (138) well enough

to properly sew two layers of 6 oz veg? As of now it won't...I'll stop here. Snagged this photo from another post just for reference.

 

Thanks...Cliff

image.png.9e41627d9a2b254235f35dd425e4560e.png

Edited by sportycliff
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Posted

If the upper tension regulator won’t provide enough tension even when adjusted as tight as it will go, there’s a good chance the tension release is improperly adjusted not allowing the tension disks to fully engage the thread.

Thats assuming the lower thread tension is correct, and the needle size is large enough to allow the know to be pulled up.

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Posted
14 minutes ago, DonInReno said:

If the upper tension regulator won’t provide enough tension even when adjusted as tight as it will go, there’s a good chance the tension release is improperly adjusted not allowing the tension disks to fully engage the thread.

Thats assuming the lower thread tension is correct, and the needle size is large enough to allow the know to be pulled up.

#1 Checked and OK

#2 Bobbin tension OK, tried needles up to two size larger than called for (24)

Posted

I’m betting #1 is still your problem.   It’s very hard to just look at the tension disks and tell if the tension release is preventing the last few .001” of disk pressure.   I’d also check for deep grooves in the tension disks that might be preventing them from firmly gripping the thread.    Perhaps the tension adjusting nut is bottoming out on something?   Aftermarket tensioners are so poorly made, if it’s ever been changed any number of things could be wrong.

Have you had the tensioner apart lately?   Is the machine new to you?  Do you have a picture showing how it’s threaded?   Is the thread down between the disks and not ridding up on the outside edges?

If you can physically pull thread through that tensioner with bare hands when it’s tightened fully, it’s definitely something in there.

 

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Posted
49 minutes ago, DonInReno said:

I’m betting #1 is still your problem.   It’s very hard to just look at the tension disks and tell if the tension release is preventing the last few .001” of disk pressure.   I’d also check for deep grooves in the tension disks that might be preventing them from firmly gripping the thread.    Perhaps the tension adjusting nut is bottoming out on something?   Aftermarket tensioners are so poorly made, if it’s ever been changed any number of things could be wrong.

Have you had the tensioner apart lately?   Is the machine new to you?  Do you have a picture showing how it’s threaded?   Is the thread down between the disks and not ridding up on the outside edges?

If you can physically pull thread through that tensioner with bare hands when it’s tightened fully, it’s definitely something in there.

 

With the foot down there is a gap between the actuating rod and the rearmost disc, no contact.

Had tensioner art several times, perhaps minor scuffing on the plating, but no discernable wear. 

New machine yes, but not new to machines. It's threaded properly and you cannot pull thread when engaged.

IMG_6665.JPG

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Posted

Bottom thread full tension...2 layers 2.3 mm

IMG_6673 (1).jpg

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Posted

Try to cop a boo at the thread as it goes around the bobbin case and comes up to see if it is snagging on something. Also, check the hook timing to see if it is retarded and too close to the eye. If it is close, advance the timing a bit so the hook is about 1/16 inch above the eye at pickoff time. Also, make sure the hook isn't hitting the needle and that the needle easily clears the hole in the feed dog..

Q: Are you using a leather point or round point needle?

Posted IMHO, by Wiz

My current crop of sewing machines:

Cowboy CB4500, Singer 107w3, Singer 139w109, Singer 168G101, Singer 29k71, Singer 31-15, Singer 111w103, Singer 211G156, Adler 30-7 on power stand, Techsew 2700, Fortuna power skiver and a Pfaff 4 thread 2 needle serger.

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Posted
30 minutes ago, Wizcrafts said:

Try to cop a boo at the thread as it goes around the bobbin case and comes up to see if it is snagging on something. Also, check the hook timing to see if it is retarded and too close to the eye. If it is close, advance the timing a bit so the hook is about 1/16 inch above the eye at pickoff time. Also, make sure the hook isn't hitting the needle and that the needle easily clears the hole in the feed dog..

Q: Are you using a leather point or round point needle?

Leatherpoint, brand new. I will chk the timing.

 

Posted (edited)

Those are definitely twists in the thread or the thread is untwisting as it forms the knot - not a tension issue.   Sorry to drag you through all the tension stuff - I should have asked for a picture.   
 

What brand and type of thread is it?   To be honest, if I don’t know anything about the bottom problems I’d still think your thread doesn’t look right on top - like it’s not bonded and a loose twist - not the normal dense bonded nylon we usually use.   The good news is, a different spool of thread will probably solve the issue.

I’ve attached a random picture of 138 size thread - look at how twisted your top thread is compared to how it lays down flat in the pic.

B4C8378D-73EF-48EB-97BE-AA3BC6F30024.jpeg

Edited by DonInReno

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