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Lokahi

Pulling my hair out over tension issues with Consew 206rb

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I know I'm beating a dead horse, here...but I promise, I really have searched the forums (and youtube) on this topic, and tried to solve this seemingly common issue myself.

The issue I'm having is that there seems to not be enough tension on the top thread.   As in, I can see the top thread, on the bottom of the workpiece.  I'll go into what I'm sewing, and with what, and then what I've already tried.

The machine is an 'original' Consew 206rb (the plate with the model # on it only says "206rb", no "-1" or "-5").  It was purchased used, obviously, but had been serviced, and seems to have seen very little use in it's past.  There's almost zero wear at all on the bed of the machine.  Bearings were re-packed, timing checked.  I have no way of verifying that the guy who did this servicing knew exactly what he was doing, but I also have no reason to doubt him.  I'm using Schmetz needles, which I only just realized as I'm writing this, are NOT diamond/chisel point.  I've been using 135x17 serv7 needles in sizes 21, and 22, with #138 nylon thread.  (I'm going to scream if this whole time the issue has been that they aren't chisel-point needles).

I'm sewing mostly light-medium weight leather, generally a 3-4oz veg tan with another thin (1.5-2.5oz) garment leather on top of that.  I've also done some sewing with 3oz chap leathers.

With my stitches, the best result I seem to be able to get is to have the top thread slightly peeking through the bottom side on nearly every stitch.   I'm also getting a pretty ugly bunching of thread on the under/back side any time I do a backstitch...though changing the feed dog seems to have helped some with that.  I've also noticed that the presser feet will not raise higher than about 3/8" (and that's with the hand lever.  It barely lifts 1/4" with the knee lever)... when the internet seems to agree that the 'max capacity' for the 206rb is around 9/16", and trying to actually sew anything near this 3/8" thickness results in a HUGE mess of loose top threads on the back side.

I have checked (and adjusted) the bobbin case tension.  It passes the "bobbin drop test".  I have watched so many videos on threading the machine I think I could do it in my sleep at this point.  I've checked, and re-threaded, and checked, and re-threaded, so. many. times.  The top tensioner is so tight that even with the presser feet up/knee lever pushed, it's still hard to pull the thread through.  Tightening it any further results in broken thread.  Loosening the bobbin case spring any further results in risking the leaf spring getting caught up in the hook. 

I have changed needles.  I have changed the feed dog. I have change the presser feet.  I've oiled everything.  I've tried different bobbins.  I've tried a new bobbin case.  I'm just...really at a loss at this point.  

Is it the needles?  Is it possible the machine is just set up/timed for much smaller thread?  The guy I bought it from said he'd never used anything in any of his machines that was larger than #69 thread.  

...I think that's all I know to include in this post.  Please, take pity on me.  I'm still very much in the learning phase with industrial sewing machines in general.  And thanks in advance for any help.

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I had a similar problem with my 206RB-4 in that I suddenly couldn't pull up the thread even with the top tension extremely tight  I was using 138 thread top and bottom.  It had been sewing fine and suddenly the problem started. 

With the bobbin case out of the machine, the bobbin thread came out easily but as soon as I inserted the case back into the machine, I could hardly pull the bobbin thread out.  I tried every adjustment possible and nothing helped so I bought a new, genuine Consew bobbin case and voila, everything works again!  

Does your thread pull off the bobbin easily when your holding the case outside the machine?  If yes, install the bobbin case and check if it still pulls out easily.  If it is extremely tight you might have a defective bobbin case.  My old case was not a genuine Consew case and by briefly inspecting it, I could see no visible difference between the old case and the new, Consew case.  But it has worked fine since I replaced the case.

Hope this help.

Gary

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When getting an upholstery class machine set up and running, use 92 weight thread and a #20 needle.  Chisel point / leather needles will result in a cleaner exit hole, but round point are fine for initial testing.

Realize that 138 thread is the limit for this machine.  To sew 138 with leather, you'll need a #23 needle.  

Please post pictures of your thread path from the thread stand all the way to the needle.

Please switch to 92 weight thread and a #20 needle for testing.  Adjust tension for that setup and report back.  

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Being a owner of these machines since 1976 I have some experience.  

One The thread release works on both knee lift and hand release and is adjusted by a screw on the right side of the tension disk slightly to the back.  The release should be adjusted at the very top so tension is not affected.

Two  The amount of lift is adjusted by a set screw behind the machine below the crank lever (my term) You will need to take the front cover off to to adjust the up and down movement on the rod.  Simple but difficult to explain 

Three  You can now adjust the feed lever on the back left to balance the the needle and foot feed.  The right lever with the thumb screw adjusts the lifting height for various thickness.

Four Bobbin case irregularity is caused by a bad case or a too tightly wound bobbin that expands  and rubs against bobbin case

If you don't understand any of this let's tackle each issue and I will probably get you through this. This is one of the best machines for performance and durability.

 

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9 hours ago, garypl said:

I had a similar problem with my 206RB-4 in that I suddenly couldn't pull up the thread even with the top tension extremely tight  I was using 138 thread top and bottom.  It had been sewing fine and suddenly the problem started. 

With the bobbin case out of the machine, the bobbin thread came out easily but as soon as I inserted the case back into the machine, I could hardly pull the bobbin thread out.  I tried every adjustment possible and nothing helped so I bought a new, genuine Consew bobbin case and voila, everything works again!  

Does your thread pull off the bobbin easily when your holding the case outside the machine?  If yes, install the bobbin case and check if it still pulls out easily.  If it is extremely tight you might have a defective bobbin case.  My old case was not a genuine Consew case and by briefly inspecting it, I could see no visible difference between the old case and the new, Consew case.  But it has worked fine since I replaced the case.

Hope this help.

Gary

Gary - The bobbin thread pulls up and pulls through just fine in my case.  It definitely pulls through -much- easier than the top thread.

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7 hours ago, Pintodeluxe said:

When getting an upholstery class machine set up and running, use 92 weight thread and a #20 needle.  Chisel point / leather needles will result in a cleaner exit hole, but round point are fine for initial testing.

Realize that 138 thread is the limit for this machine.  To sew 138 with leather, you'll need a #23 needle.  

Please post pictures of your thread path from the thread stand all the way to the needle.

Please switch to 92 weight thread and a #20 needle for testing.  Adjust tension for that setup and report back.  

I don't have any 92 weight thread to switch to.  I can try with some 69.

I'll try to attach some pictures.  If my code doesn't work, they're here at this imgur post: Threading Consew 206rb

<img src="https://i.imgur.com/coCdPcQ.jpg" alt="206rb thread post" width="4032" height="1908">
<img src="https://i.imgur.com/g5MGTLS.jpg" alt="206rb top thread guid" width="4032" height="1908">
<img src="https://i.imgur.com/GfHqnaY.jpg" alt="206rb tension discs" width="1908" height="4032">
<img src="https://i.imgur.com/N4OKDko.jpg" alt="206rb take up lever" width="1908" height="4032">
<img src="https://i.imgur.com/VhL7dyM.jpg" alt="206rb lower thread guides" width="1908" height="4032">
<img src="https://i.imgur.com/50PdlFN.jpg" alt="206rb needle threading" width="4032" height="1908">

Edited by Lokahi

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1 hour ago, ljk said:

Being a owner of these machines since 1976 I have some experience.  

One The thread release works on both knee lift and hand release and is adjusted by a screw on the right side of the tension disk slightly to the back.  The release should be adjusted at the very top so tension is not affected.

Two  The amount of lift is adjusted by a set screw behind the machine below the crank lever (my term) You will need to take the front cover off to to adjust the up and down movement on the rod.  Simple but difficult to explain 

Three  You can now adjust the feed lever on the back left to balance the the needle and foot feed.  The right lever with the thumb screw adjusts the lifting height for various thickness.

Four Bobbin case irregularity is caused by a bad case or a too tightly wound bobbin that expands  and rubs against bobbin case

If you don't understand any of this let's tackle each issue and I will probably get you through this. This is one of the best machines for performance and durability.

 

Thanks for these tips.  Most of it seems straight forward to me.  I'll see if I can figure out #2 when looking at the machine itself.  #4 doesn't seem to be my issue.  The bobbin case is brand new and the bobbin thread pulls up and feeds smoothly... is there anything else that might be causing my tension issue?

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Don’t give up on it. They are really good machines. I have and use two of them. One set up with 135 and one with 69.

 

Edited by klutes

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Alright. I switched my bobbin thread to 69, and rethreaded top around this little post.. Am now getting much better results.

IMG_20210414_203301.jpg

Edited by Lokahi

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On 4/14/2021 at 2:15 PM, Lokahi said:

I don't have any 92 weight thread to switch to.  I can try with some 69.

I'll try to attach some pictures.  If my code doesn't work, they're here at this imgur post: Threading Consew 206rb

<img src="https://i.imgur.com/coCdPcQ.jpg" alt="206rb thread post" width="4032" height="1908">
<img src="https://i.imgur.com/g5MGTLS.jpg" alt="206rb top thread guid" width="4032" height="1908">
<img src="https://i.imgur.com/GfHqnaY.jpg" alt="206rb tension discs" width="1908" height="4032">
<img src="https://i.imgur.com/N4OKDko.jpg" alt="206rb take up lever" width="1908" height="4032">
<img src="https://i.imgur.com/VhL7dyM.jpg" alt="206rb lower thread guides" width="1908" height="4032">
<img src="https://i.imgur.com/50PdlFN.jpg" alt="206rb needle threading" width="4032" height="1908">

Ok, I had a paragraph about what I thought was a threading problem.  Well, as soon as I clicked "Submit" and looked at your pictures again, I realized the only problem is with my eye sight.  Nice first post of mine...

 

 

 

Edited by JohnInAZ
Need new eye glasses LOL

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On 4/14/2021 at 3:18 AM, Lokahi said:

I'm just...really at a loss at this point. 

I looked at your photo's and I would suggest a couple of things to try that may or may not work.

i) remove thread from your needle back to the vertical guide just before the tensioning discs.

ii) lock the pressor foot in upper position and retread. This will release tension on the two discs. The discs now should be slack and movable. Rethread as you did before. Now you will assured the thread is in as far as it can go between the tensioner discs as possible.

iii) when you have threaded the needle unlock the pressor foot from the up position. Test drive and see if that makes a difference.

If not the discs may have a thread path worn in them. So I would turn the very first guide from the vertical position to a horizontal position and thread like a Juki 1541 which has the first guide in the horizontal position. This would change the position of the thread through the discs.

kgg

 

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Wondering did this get resolved? Thread pulling out of the bobbin case properly sounds good. Different things happen when under power. Curious if stitching looks identical when turning the wheel by hand. Something is pulling that upper thread too much  or making it turn loose. During the cycle, does the foot coming up against the presser foot spring, causing the spring to bend - also disengage the upper tension? If the upper tension mechanism is set so that it is touchy that could be kicking the discs loose. This is a pretty far out there possibility, but can happen.

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If the foot lifts too high on an industrial machine it will release the tension.  Doesn't matter if it is caused by your lifter or the material you are sewing. Can you post pictures of your foot and the bushings above it in the up and down position?   Can you sew thinner with no problems?

Edited by bj139

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two things.  Looks like you are going around the pin that holds the tension discs in place.  DO NOT go around the that pin.  That alone will effect tension.  Also, the smallest needle you can use with #138 thread is a 22/140.    Do not use #21 with #138 thread on top.

glenn

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Wondering if the OP ever resolved this problem with 138 in the bobbin?  I'm having the same challenge on my 206RB-1 and have gone over all the recommendations from above and have not had any success.

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Threading around the pin in the tension wears a groove in the pin that will shred thread. Route the thread over the top of the tension, then under the check spring assembly, and over the tab that sticks through the hole at the bottom left of the front plate. Also make sure the check spring is adjusted so the thread never goes slack between the take up lever and the check spring.

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