Cobra Class 26 Loose Stitch and Noise

[Bullduke]

Hey Folks,

So I am so excited to be a new owner of a Cobra class 26 but I have two problems.

1. I cant solve a problem with having one loose stitch during projects.   I will adjust the tension and the knot is sitting in the middle and during a sewing run ill get one loose stitch almost every time?   

2. The machine is in a terrible bind and making a squealing honking noise when sewing. The noise is still present when using the hand wheel with no thread loaded.   I eliminated the thread to eliminate potential tension issue but the machine is so tight and seems to be in a bind?   I've oiled heavily with some minor improvement.  

The problem has been so bad that the great people at Leather Sewing Machine Co. have even spent hours on the phone with me.   They even had me making adjustments on the internal shaft from the wheel and inside shaft.  They facetime me to watch the machine and we made some adjustments to the bottom bobbin.  This seemed to have helped a tad but the machine feels to be under internal friction.    David at LMC customer service was the best I've ever experienced and he talked with me on the phone and email throughout the diagnosis.   He was so understanding and accommodating that he even sent me a new head this weekend; however , sadly the new head did the exact same thing????     The shipping box from UPS was pretty beaten up??  I don't know if shipping could be causing damage but both machines are under a bind somewhere. 

 I have wanted one of these machines for years but I need anyone's help that may have experienced similar issues and fixes if possible. I'm so discouraged and exhausted I just want this beautiful machine to lay down a good stitch and not sound like squealing tank.     Maybe a bad run of machines or shipping damage?    Again, If you want a new sewing machine and not sure where to purchase?   PURCHASE FROM LEATHER SEWING COMPANY because what they say about amazing customer service is absolutely TRUE.    Hands down best service I've ever experienced and I owned a cowboy 3200 and Ryan was pretty dang great.   This is mechanical issue not a personal one for sure!     

 

[kgg]

59 minutes ago, Bullduke said:

The machine is in a terrible bind and making a squealing honking noise when sewing.

I am going to assume the drive belts to the motor in installed. I would remove the drive belt from the handwheel to the reducer pulley and see if the squealing disappears. If it does then you know the problem lies with the belts, reducer pulley or servo motor. If the squeaking still remains you know it is machine head related.

kgg

[Wizcrafts]

If you are already dealing with support from the dealer, we shouldn't interfere. But, KGG's suggestion to remove the belts is valid.  It may just be an overtightened belt, of which you have three. Or, the bearings could be bad on the motor and speed reducer.

Has LMC asked you to remove the bobbin case securing bracket and the bobbin case, to check for thread fragments? There could be thread stubs causing binding.

The fact that the new head is doing the same thing makes me suspect your belts/motor/speed reducer. Remove the belt from the machine and see if it turns freely and without the moaning sound.

[Bullduke]

Gentlemen thanks so much for your input.   Yes I have removed the belt and the moaning is still happening.   The attached video lets you see the internal mechanisms as the noise is occurring.   You can even feel the resistance in the head unit when sewing and manually using the wheel with or without the belt on?  

My first head is starting to improve from the tapping of the shaft LMC had me try and multiple days of heaving oiling.   The second head is still moaning and seems to be under some sort of bind internally.     

Yes this post is in no way meant to interfere with the good folks at LMC just looking for other suggestions and experience with solving the issues.   I sent the post during off hours with LMC.

Any suggestions on this loose stitch?    I have adjusted the tension where the knot is in the middle of my leather and I am still getting these loose stitches randomly? 

[kgg]

34 minutes ago, Bullduke said:

The attached video lets you see the internal mechanisms as the noise is occurring. 

I don't see an additional video attached. Which parts seem to be causing the problem?

35 minutes ago, Bullduke said:

Any suggestions on this loose stitch?   

I wouldn't make any adjustments just yet until you get the main problem sorted out first with LMC.

Please keep us updated.

kgg

 

[Wizcrafts]

2 hours ago, Bullduke said:

My first head is starting to improve from the tapping of the shaft LMC had me try and multiple days of heaving oiling.   The second head is still moaning and seems to be under some sort of bind internally.

Does the balance wheel rotate true, or wobbly? If it wobbles the main shaft may be bent.

You can try unscrewing the presser bar to see/hear if it makes a difference being out of the picture. If the binding disappears the bar may be bent, or binding in its top or bottom bushings.

If the presser bar isn't the culprit, maybe the needle bar is. Mark its position fully raised (with a Magic Marker, or tape), then loosen its screws and try rotating the wheel. It too goes through a bearing. Perhaps it is slightly bent.

 

[kgg]

3 hours ago, Bullduke said:

My first head is starting to improve from the tapping of the shaft LMC had me try and multiple days of heaving oiling. 

Since oiling and tapping of the shaft has helped I would also ask LMC if instead of the normal machine oil if something like a good penetrating fluid or Synthetic transmission fluid or even diesel fuel would be another alternative combined with oiling. I don't use regular sewing machine oil in any of my own sewing machines. I find that a mixture of Synthetic transmission fluid and Synthetic oil works much better but I am willing to take the risks associated of going outside normal sewing machine oiling / lubrication recommendations. I often use diesel fuel to free up seize metal components.

You did mention that the boxes you received from UPS on the second machine was pretty damaged. Did you save the box as couple of photos of the box may help to determine was the damage caused by mishandling.

kgg

 

[Bullduke]

Ill try to rotate the wheel with out the belt off and check to see if it wobbles.   When sewing or turning the wheel you can feel how tight everything really is and the squeaking noise is present around that needle bar it seems?  

I did save the box and took several pictures of the second head that arrived damaged.   LMC sending that new head was pretty amazing and I just knew I would be back up and sewing but cant believe two would be doing same thing?   The first head was on a crate with the stand wrapped up really well so the box  looked really good and protected from all the wrapping and stand.  

I think wizcrafts may be onto something with an internal part bent or damaged.   Maybe there was a problem with a part during build process and both machines are suffering from it?

Ill try the presser bar this morning that would be an easy test.  The needle bar does seems to be the loudest and the oiling in that area did help some? 

Sense the oiling did improve some of the problem ill ask LMC about using a different oil today.  Ive been on 24 hours shifts so today will be my first day back home with the machine.   Ill reach back out to them and see if we can get some more progress and keep everyone posted.   

Thanks again for your responses I think both of you have given some really good suggestions and Ill have some focus today when working with LMC.  

The loose stitch issue has also been present from the beginning and drives me crazy because I cant get rid of it with tension adjustments?    

 

 

[Wizcrafts]

19 hours ago, Bullduke said:

Ive been on 24 hours shifts so today will be my first day back home with the machine.

First of all, thank you for you service in the Fire Department.

Second: Once you get the machines working smoothly and reliably, we can talk about thread and needles you'll need to repair turnout gear. I've already done a couple and learned the requirements. It will not be the type of thread that shipped with the machine. This is a whole 'nuther topic.

[MtlBiker]

6 hours ago, Wizcrafts said:

First of all, thank you for you service in the Fire Department.

Second: Once you get the machines working smoothly and reliably, we can talk about thread and needles you'll need to repair turnout gear. I've already done a couple and learned the requirements. It will not be the type of thread that shipped with the machine. This is a whole 'nuther topic.

Not to hijack this thread, but your comment about thread for heat resistant applications caught my eye...  About two years ago, shortly after I started my sewing "hobby" I got it in my head that it would be nice to make some oven mitts after I saw someone with neoprene mitts where the stitching had come open on one.  I offered to stitch them up, and at the time only having bonded poly thread, that's what I used.  (It was for a girlfriend.)  That got me doing a bit of research and thinking that it would be no big deal to get some neoprene and make mitts myself, I bought some thread from A&E specifically for heat resistant applications.  I can't remember exactly what it was called, but I think it was Anesafe.  I do remember that the one pound spool (idiot that I sometimes am) was frightfully expensive.  Then I found I really couldn't source the neoprene (at least not here in Canada) in the quantity, thickness and style I wanted, so I shelved the idea.  I should have sourced the neoprene before buying the expensive thread.  SIGH

I still have the thread though, and if I could find a reasonable source for neoprene I'd make some.  The mitts my friend had had a bit of a pebbled finish on the outside and the inside had a fabric coating. 

If anyone could suggest a Canadian source for small quantities of similar neoprene I'd really appreciate it.  Ordering from the States, with minimum order quantities, becomes really expensive when you add the exchange rate, shipping and import duties and taxes.

 

[Bullduke]

Gentlemen,

So as expected, David at Leather Sewing Machine Co. has gone above and beyond. Honestly, I have never received customer service at this level.  He simply just wants to make his customers happy and is willing to assist with sincerity.   He wants to get the machine back so they can inspect.  It seems to me there might be a tight bearing or bushing somewhere but I am no sewing machine mechanic.    After more heavy oiling,  I was able to get the machine to sew more smoothly.  However, to get that top stitch loose loop out, I had to almost tighten bottom bobbin all the way.   This as expected required more top tension.   So, sewing with that much tension seemed to be adding more binding in the thread and sewing in general.  

David and I spoke in details about options.  After looking at the leather weight I sew with Fire Department Front Shields, we decided it may be better to upgrade to the Class 4.   It arrived yesterday and I started setting it up.   This thing looks like a beast.   Cant wait to get it up and sewing. 

Thank you all for your response to these forums.   Your knowledge and suggestions helps so much when us armatures are working thru adjustments and tuning. 

Yes lets talk thread and needles for Turn Out Gear 

 

[Bullduke]

[AlZilla]

There's a video shot at LMC showing them running in a bunch of class 4 heads prior to sale. They must not do the same for the class 26 because there's no way you could miss that noise.

Obviously, they're going above and beyond to get this one resolved.

4:30 of this video:

https://m.youtube.com/watch?v=KOLNoN1sVI8

Edited April 27, 2023 by AlZilla

[DonInReno]

As soon as I heard that distinctive noise it hit me it’s something I’ve experienced before, but for the life of me can’t recall what caused it - maybe once some more coffee kicks in it will dawn on me.

. . .

It came back to me what that noise was in my case - it was a two piece adjustable brass bushing in an old piece of equipment that would make that noise when adjusted a little on the tight side.   It must be the harmonics of the stick and slide, stick and slide of brass on steel.   I’m sure with a little use it will go away completely.

Since your noise is consistent with hand wheel rotation and doesn’t change as needle bar slows and changes direction so I’d bet it’s a  contact point on the upper shaft of some kind on the other end opposite of the handwheel.

In industrial settings, to track down minuscule  machine vibrations too faint to be felt or heard by a human, an oscilloscope  reads electrical impulses from tiny acceleration sensors (see photo).   Two of these can be held onto two sides of a part, or two separate parts with magnets and it will show which has more vibrations.   With inexpensive portable oscilloscopes and sensors this is also really changing how automotive noises and vibrations are traced.   

Edited April 27, 2023 by DonInReno

[Tequila]

@Bullduke  the customer service is exactly what I bought a 26 from them a couple of years ago.  I had a problem with mine (no where near as bad as yours) that was self induced.  But when I called up LMC they took the time to walk me through the repair and even sent pictures of the parts I needed to adjust.  I’m glad to hear that they were so helpful.  I for one would love to know what they found with the machines when they got them back.  Now that you’re moving to a Class 4 you might want to get with some of the members about a part that RockyAussie sells for the 4 that expands the sewing capabilities. 

[Wizcrafts]

15 hours ago, Bullduke said:

Yes lets talk thread and needles for Turn Out Gear

I'm your Huckleberry!

Firefighting gear has to withstand temperatures that will melt bonded nylon or polyester thread. A simple lighter on the thread test confirms this. I sometimes use lighters to melt the ending thread stubs to lock them down. You cannot sew turnout gear with nylon or polyester thread that will melt in the heat of a firefight.

In response to the need, Dupont developed a meta-aramid fiber that can be spun into sewing thread that is called Nomex. This thread has a very high heat (~ 675 degrees F) and flame resistance (it chars, but doesn't melt in flames). However, this heat and flame resistance comes at a price. That price fluctuates from time to time, but ranges between $100 and $200 a pound (for new stock). During the California fire season, the price per pound may go through the roof. In the off-season, it may drop.

Different areas of a turnout suit require different thread sizes to keep the pieces together, oftentimes under tremendous strain. Less stressed decorative areas can be sewn with Tex 27 or 40. More stressed seams may require Tex 60 or Tex 80. Really thick seams may need Tex 90, 105, or thicker Nomex thread. I have used all these sizes on a turnout suit, using the thinner thread on reflective tape that came loose and heavier thread on suede cuffs on the bottom of the legs.

One of my primary sewing suppliers, Wawak, carries Nomex thread in Tex 40, in black and natural, in 6000 yard spools.

 

[Northmount]

22 hours ago, DonInReno said:

It came back to me what that noise was in my case - it was a two piece adjustable brass bushing in an old piece of equipment that would make that noise when adjusted a little on the tight side.   It must be the harmonics of the stick and slide, stick and slide of brass on steel.   I’m sure with a little use it will go away completely.

This is called dry friction.  It generates random vibration frequencies that excite the natural frequencies of connected parts (causing resonance and high vibration amplitudes).  So needs to be lubricated.  Brass bushings may be oil-less self lubricated or not.  Self lubricated type are often used in fractional horsepower motors.  If memory serves me correct, these shouldn't be oiled.  I don't know if oiling would result in increased friction as the oil is dispersed, squeezed out or thrown out.

[Ripper70]

9 hours ago, Wizcrafts said:

Firefighting gear has to withstand temperatures that will melt bonded nylon or polyester thread. A simple lighter on the thread test confirms this. I sometimes use lighters to melt the ending thread stubs to lock them down. You cannot sew turnout gear with nylon or polyester thread that will melt in the heat of a firefight.

One of my primary sewing suppliers, Wawak, carries Nomex thread in Tex 40, in black and natural, in 6000 yard spools.

 

Boy, am I glad I read this. I have a whole bunch of family on my wife's side that are fire fighters and first responders. I've had in the back of my mind some designs for radio and gear belts that I could make for them but didn't consider that the thread would require fire retardant properties in order to function in the heat of battle. I did find that The Thread Exchange had a wide variety of Nomex threads in many weights, spool lengths and colors besides black and natural and prices seem competitive. Their offerings also include Spun Kevlar thread but I'm not sure it's as robust as the Nomex for the most demanding situations. I'd be interested in your opinions on the Kevlar thread and best uses, if you have any, and whether or not these Nomex threads are comparable to the ones offered by Wawak.

Ripper70

[Wizcrafts]

@Ripper70

Spun Kevlar and Nomex are not as strong as their bonded nylon/polyester counterparts. In the lighter weights, the differences are not important because both threads are strong enough for seams and patches. In the heavier weights, strength often matters and Kevlar is usually the better choice. However, Kevlar thread is abrasive and will eventually wear grooves into posts, guides, tension disks and springs, the hook and the take-up lever. Any sewing machine used a lot with Kevlar thread will need to be rebuilt, or replaced more frequently that machines using standard industrial thread.

I haven't noticed any ill effects from running Nomex thread in my machines, repairing turnout suits, or those belonging to a friend's blackout window blind sewing operation which I was commissioned to set up.