Gymnast

Is tension discs wear an issue?

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Do you replace, grind or polisc your tension discs, when you notice some wear on them?

I studied my tension discs. You can turn the disc until you get the right light direction for looking. This is my close up picture of one of them:

246687081_Tensiondiscwear.thumb.jpg.30c325fcff608ac9fe9ac0e3ade79380.jpg

You do see some grinding marks from the thread. I do not think, that I have got any problems using them.

Then I compared to a picture I found on internet, and those discs seems to have been weared even more:

https://oldsingersewingmachineblog.com/category/vintage-singer-sewing-machines/page/2/

So is this a problem at all?

Edited by Gymnast

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My Consew 206 discs wore a groove/channel through the tension discs that were causing all sorts of sewing issues. I replaced them, and all was well again. I am assuming these were the originals, so 30-40 years old 

 

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I have sanded them smooth with emery cloth.  If they're grooved it's best to replace them.

When tension's not right on a sewing machine... nothing's right.  

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OP..What you posted , smooth out the lines with fine emery, and then polish to mirror..With jewellers "rouge", which frequently is not red ( rouge ) but green or grey or blueish..each colour corresponds to a different "grain"..ie; each colour is "finer" than the previous colour in the sequence..The colours in the "sequence" can vary from country to country and from manufacturer to manufacturer, the red " rouge" ( true jewellers rouge is ruby powder* ..or Corindon ( French ) ..in English it is Corundum..hardness 9.5 ) is usually the finest before you get into actual diamond ( hardness 10.00 ) powder "grades".. ( size of diamond dust ) all of the other colours are variations on "aluminium oxide" powder in waxes..
Cheap jeweller's rouge is frequently garnet..like in garnet paper which is used by cabinet makers ..and is waaay "softer" than aluminium oxide..
Sapphire is also aluminium oxide..which is why some pastes are blue or grey..

Tension discs are cheap.. so , yes usually simpler to replace them, but, if you are in the middle of a job that cannot wait ( customer with "deadline", contract signed etc ) then it can help to know how to "fix" what you have whilst you wait for the others to arrive..

HTH :)

Ps..."Emery" is "carborundum" stuck to cloth...Waaay softer than aluminium oxides of which ever sort..and obviously waay softer than diamond powders..all of which are harder than the polished steel used to make tension discs..

Edited by mikesc

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Thanks for the replies. It seems I should do something about it. I have tested the tension using a dynamometer, and it seems stable while pulling the thread.

Now i have started to Wonder regarding the wear. Try to look at the Picture Again - now I put some arrows in it. How can it be, that you see wear marks like this in the parts of the discs indicated by the arrows? The thread passes from outside to around the center and then to outside Again. So you should not have Wear marks like this. Can these marks have been made by the manufacturer to make some more flat areas for the pressure on the thread?

1226953126_Tensiondiscwearwarrows.thumb.jpg.ee54f4a49c981444b3798b659417c940.jpg

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Quote

Can these marks have been made by the manufacturer to make some more flat areas for the pressure on the thread?

Nope..never..
That is either* just wear marks ..because the thread was not seated correctly..most people ( yep that is what I said..most people, including many who post on here asking "why" etc etc ) do not seat the thread correctly in the tension discs, ( it should "snap" all the way down to the post when it is trapped between the tension discs ) and many ( because of totally wrong videos by a certain dealer on youtube ) do not follow the correct path for the thread ( they wrap it around the small "post" which is only there to stop the tension discs revolving, which is INCORRECT !! ) either..

*Or..You can get these kind of wear marks by using dirty or dusty thread, dirt / dust can be very very abrasive,  keep your thread protected from dust , even when on the thread stands on the machine..

** Or even more likely..read on ..Someone may also have attempted to sand out marks already from your tension discs, which is ( IMO ) why some of the marks, on opposite sides of the hole that is for the "post" would appear to be parallel to each other....Some of your "scratch marks" look very parallel .. to each other..normal "wear" even from dusty thread is more "radial"..But..attempts to sand out ( manually with sand / emery paper / cloth ) rust and or thread wear lines, would look just like your tension discs do.

Looking again at your original photo, your disc appears to have traces of slight "pitting" ( probably due to rust ( despite the fact that most tension discs are / were steel often with a thin chromium or nickel plating ), it appears that the pitting was polished out, but that someone had / has also attempted to "sand out" some deeper scratches, ( which has created more scratches than it "solved" ) which is what left the parallel sanding lines..You can try to use a finer emery cloth and afterwards "rouge" or metal polish to remove the scratches, depends how deep they are as to whether you will succeed..order new discs anyway..

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34 minutes ago, mikesc said:

** Or even more likely..read on ..Someone may also have attempted to sand out marks already from your tension discs, which is ( IMO ) why some of the marks, on opposite sides of the hole that is for the "post" would appear to be parallel to each other....Some of your "scratch marks" look very parallel .. to each other..normal "wear" even from dusty thread is more "radial"..But..attempts to sand out ( manually with sand / emery paper / cloth ) rust and or thread wear lines, would look just like your tension discs do.

This is what I believe would have happened. Normally they would get polished until any marks are removed. Being that the discs have been so heavily sanded I would suspect that the machine has a lot of wear and I would check the post as well for a heavy groove in where the thread rubs it. Sometimes the post can be revolved a bit. As the thread goes through these discs on most machines it rubs in the same part until a groove is formed and eventually you can not get any top tension on the finer weight threads any longer. Sanding them back and polishing is a normal practice here. Similarly the bobbin case suffers the same problem under the tension spring and the easier thing is to have a backup one ready to go.I prefer to have a different bobbin case for each different weight thread. These 2 machines below are what I use and it only takes a couple of minutes. Brown tripoli polishing wax  I use mostly. Do not mix different polishing waxes on the same rag wheel as that does not work very well.

DSC08037_resize.JPG

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:)

 

 

Quote

Do not mix different polishing waxes on the same rag wheel as that does not work very well.

 

This... especially..always use a separate rag per each "grit"# / polish grade / type or number, a separate buffing wheel per each "grit"# / polish grade / type or number , never mix them up..go from coarse # grade / type / number to fine..never mix the rags or the buffing wheels.

To do otherwise lies madness.. :)

ps

Quote

Similarly the bobbin case suffers the same problem under the tension spring and the easier thing is to have a backup one ready to go.I prefer to have a different bobbin case for each different weight thread.

Oh yes!! I agree 1000 % with that :)..one ( or more ) bobbin cases per thread weight / type ..per machine

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11 hours ago, RockyAussie said:

This is what I believe would have happened. Normally they would get polished until any marks are removed. Being that the discs have been so heavily sanded I would suspect that the machine has a lot of wear and I would check the post as well for a heavy groove in where the thread rubs it. Sometimes the post can be revolved a bit. As the thread goes through these discs on most machines it rubs in the same part until a groove is formed and eventually you can not get any top tension on the finer weight threads any longer. Sanding them back and polishing is a normal practice here.

Thank you all for your helpfull remarks!

First I need to say, that I think the close up and enlarged picture of the tension disc exaggerate the problem. You also have to get the right light direction to see it. The surfaces feel very smooth and the dept of the marks are way below the thinnest thread to be used.

I have taken a Photo of the post in order to look for marks on it:

1599844973_tensionshaftwear.thumb.jpg.4ce83d8975ae59b851b1c384ba4db756.jpg

I do not think that you see any severe wear marks from thread here. So I tend to believe, that the marks on the disc shown above are not from wear but from some kind of service.

I have got this Singer 201k five years ago as well as a Singer 66k and a Singer 237. They are from different parts of my country, and i belive they have been serviced different places. However the service people may have had the same training and education. You cannot rule out what previous owners may have done. All machines use discs with the same Simanco number, 2102, but the dimensions vary a bit.

All 6 discs have a flat part of the surface, like the vault have been grinded flat on the top. For me, it seems like part of the design. But it may also have been a standard practice for service personel to grind these surfaces. Perhaps the service grinding and polishing were not always done with the same care. The 4 discs on the two other machines do have marks like seen on picture above, but the grind marks are not that severe.

I keep good control of the thread tension with a dynamometer, so I think I can manage until I get new discs.

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The "flatness" is part of the design..not something done by "service people"..any scratches like you have can alter the sewing characteristics, as even when shallow, they can contribute to fraying of the thread as it passes between them..
Polish them out.. When you cannot see them at all..the discs are good:)
Nope, no wear marks on the post..scratches to the discs have been done by someone sanding them ~:o

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Try using very fine wet and dry paper, used wet, on a piece of glass, you should be able to get them very smooth and then finish off with metal polish. Unless you have a buffing wheel, of course.

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Well - now I tried the in the DIY way. I do not claim it to be right, but here is what I did. I do have some sandpaper from grit 60 down to grit 400. On the internet I have seen, that you actually can get sandpaper with grit 60000. I have got a drill, so I used that. And I have got some scouring cream. I needed to grind with the sandpaper grit 400 about 5 min to almost get off the previous marks. The result is not perfect - I know. But perhaps somewhat better than before and i think it should be more reliable. And when I measure the thread tension it seems in order.

1450558729_scauringcreamanddrill.thumb.jpg.cb166930fcafcb032595540edcec62f0.jpg

Result after Work:

1456159387_Billedeafresultat.thumb.jpg.b11170134ce3eee731c537eb0819ff06.jpg

I made a Little video on how I use a spring dynamometer for thread tension etc. Do any of you use them? https://youtu.be/NW58ckOU6YI

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Checked out your video and well done. I did something a little similar with some fish scales and for the price they work great. I wanted to post some results with these as for people that are new to using sewing machines it could be used as way of setting some idea of the parameters a machine should have in regards to the tension adjustments. Here is a link to the scales I bought and am very happy with.  https://www.ebay.com.au/p/Wh-a05l-LCD-Portable-Digital-Electronic-Scale-10-45kg-10g-for-Fishing-Luggage/15020246737?iid=323005161210

I did a little on this subject in this following post that you may want to check - only good for giggle I guess.....

 

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That looks a lot better than it was. You appear to have rounded off the flat part a little, but as long as it works ok is the main thing.

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57 minutes ago, RockyAussie said:

Thanks Again :)

This digital scale looks nifty. But will the minimum weights be in 10 g - NeXT 20 g ? I think you may like to measure the tension from bobbin case at some more accurate small figures. So perhaps a small scale more than this. Perhaps I should link to one supplier of dynamometers. I hope the link Works from another country.

https://www.ebay.com/sch/m.html?_ssn=alpinetopline&LH_PrefLoc=&_from=R40&_trksid=m570.l1313&_nkw=dynamometer&_sacat=0

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The scales gives the option to show Kilo's (0.000)and that is in 5gram jumps or pounds lbs (0.00) or oz (0.0) Jin (0.00) and all of these go up in individual units. Possibly on a domestic machine this may not give a fine enough reading but I would be surprised.

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On ‎5‎/‎2‎/‎2019 at 8:55 AM, Gymnast said:

Well - now I tried the in the DIY way. I do not claim it to be right, but here is what I did.

Just for the record, I think the tension discs became worse after my treatment documented above. So do not repeat that. I compared these discs to two others I have got, that were not that bad. It seems to me, that the thread tension became unstable, and the static friction of the discs to the thread are considerable higher than the dynamic friction.

If you do not have the right tools for grinding and polishing these discs, I think you should replace them with new ones.

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Your first pictures show marks that are normal from sanding grooves with sandpaper on a flat surface.  600 to 1000 grit paper on a flat surface will quickly take out slight grooving.  It shouldn’t matter if there are flats on the disks - flats don’t effect the consistency of tension, but any grooving is not good.  

I also don’t think a static friction test gives a person any usable information as long as the friction is consistent they are working just fine.  Tension adjustments should become second nature to even an occasional sewer.

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It shouldn’t matter if there are flats on the disks


All the disks that I've ever seen* , including brand new ones from different manufacturers and suppliers, have slight flats "out of the box"..

The reason would be , I presume , to spread the pressure from the "beehive" spring evenly..a flat allows for more adjustment than a round..a round would translate to two very small points of contact with the thread as it passed between the discs of the tension assembly, which would "pinch" it rather than exert tension by "drag" across a the surface of the flats..Force exerted and focused on two points is less adjustable than the same force adjusted over a greater area ( two areas ) as presented by flats..

Note..I don't pretend to have seen all tensions discs from all manufacturers or suppliers, so readily accept that they ( tension discs with no flats ) may exist, and may even be "the norm"..

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On ‎5‎/‎26‎/‎2019 at 6:46 PM, DonInReno said:

Your first pictures show marks that are normal from sanding grooves with sandpaper on a flat surface.  600 to 1000 grit paper on a flat surface will quickly take out slight grooving.  It shouldn’t matter if there are flats on the disks - flats don’t effect the consistency of tension, but any grooving is not good.  

I got information from another source too, that the praksis of controlled sanding and not polishing is normal. The source called for paper of grit 1000 to 2000. The reason should be, that you want some friction from these discs, and it can be hard to achieve high and stable tension without some controlled roughness of the surfaces providing the friction. Some thread can be very smooth. I noticed three people in this thread with a praksis of polishing the discs. So this seems to vary.

The aim should be, to be able to keep as Little as possible variation in the tension. Due to small differences in the thread and friction internal in the tensioner, you do not have a perfect tensioner. If you look at the pictures above, the direction of the sanding and the Width of the flat area vary around the perimeter. The discs might move around and this could also make some variation in tension.

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On ‎5‎/‎21‎/‎2019 at 10:55 PM, Gymnast said:

Just for the record, I think the tension discs became worse after my treatment documented above. So do not repeat that.

Well, I have to say, that I do not really know that. I have got problems in maintaining a stable tension since may 1. I am relieved, because I think I know what causes these variations. The change came, when I had the tension post out and I may have turned it a Little, when it came back in. It caused the tension values to vary a factor 2. I made a Little video about this problem, and it is not about tension discs. Since I made a change to the tension discs at the same time, I believed the change of discs, to cause the problem. I am not sure that leatherworkers use this kind of tensioner that much, but you may be interested in a video about this other problem:

 

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