Another issue with my Techsew 2750

[brushew93]

I just replaced the bobbin opener on my machine, and had no problems doing that. Then I went through and made sure all adjustments were at factory settings. Now,  when I try to sew, the stitch length is not working. No matter what length I set it to, it is stitching as though it is set to 0. I adjusted the knob, and the still have the same problem. Other than not stitching properly, it sounds good  - no weird noises, no binding issues anywhere. I am using a new needle and new thread. I am super frustrated with this machine - I've had it for 2 months and haven't been able to use it because there is always something wrong with it! Can anyone figure this one out?

[Uwe]

Well, it sounds like at least one adjustment is not at the factory setting. Which manual were you using to make the adjustments?

It’s hard to offer advice without knowing what you actually did to the machine and without actually seeing what’s going on. Pictures and video help.

I also wonder why the bobbin case opener needed to be replaced on a brand new machine. 

I strongly recommend NOT running the machine under motor power until you get it adjusted right. You can do a lot of damage in a matter of seconds if you run it under power while something is loose or adjusted incorrectly. Remove the motor belt until the machine makes perfect hand-turned stitches.

Don’t take it personal, but there’s a good chance that you inadvertently caused most of the problems you’re experiencing with the machine. Getting your machine back to a working state may not be a simple task.

 

[kgg]

1 hour ago, Uwe said:

I also wonder why the bobbin case opener needed to be replaced on a brand new machine. 

With such a new machine I also wonder why and am going to assume with such a new machine it was done with instructions / guidance from Techsew.

 

1 hour ago, Uwe said:

I strongly recommend NOT running the machine under motor power until you get it adjusted right.

I also agree, It is excellent advice.

I would also contact Techsew by phone and or email. Outlining the problems you have been having with the machine as well as email them photo's / video. The more information the better.

kgg

[brushew93]

Thank you Uwe and Kgg for your response. I have video for you to look at, but I can't get them to upload here. Suggestions?

To answer your questions, right out of the box, I had problems with the machine. I wonder if it sustained damage in shipping from Toronto to Idaho, although there was no visible damage. The first thing that broke was the little stud on the thread tensioner. Techsew sent me a new tension assembly, and then I was able to sew with it, but the machine didn't sound right, and really didn't run smoothly. It jammed frequently, and I had to reset the needle to hook timing frequently. Then, the bobbin opener broke off. While I was sewing, the machine suddenly jammed and made a noise that did not sound good. When I removed the bobbin slide cover, I saw the finger of the bobbin case opener broke off and was jammed in the space. Techsew sent me a new piece and made me videos with very clear, detailed instructions to remove the remaining part of the bobbin opener and install the new one. I am convinced this was a factory defect; the piece actually broke in half at the bottom of the finger. After replacing the piece, the machine ran better than it ever had; it was running quietly and very smoothly - except it would only stitch in place. So, this is what I did, in order:

1. I checked the feed dog height; no adjustment needed, as it was sitting exactly 1 mm higher than the throat plate.
2. I checked the longitudinal motion of the feed dog and it was moving correctly, front to back. The needle was perfectly centered as it entered the feed dog, and was in correct time with the feed dog movement. No adjustment needed, thankfully, because I don't know how to make these adjustments
3. I checked the height of the needle bar and it was off, so I adjusted it to the exact height stated in the Techsew manual. 
4. I checked the timing of the needle and hook, which was perfect. I did have to adjust the clearance slightly between the needle guard and the needle.
5. I watched Uwe's video on YouTube for the timing of the bobbin thread release. I took a video of my machine timing and attached it here; I made no adjustment, because it appears to be okay, but please let me know if it looks off to you.
6. I checked the threading of the machine, the thread take-up spring, and the tension of the upper thread and bobbin thread. No adjustments made.

This morning, I adjusted the stitch length adjuster. Now, it will stitch, but the stitches are not the correct length, and it is not in sync when sewing in reverse. What I have NOT adjusted (because I don't know how) is the position of the needle bar frame, the inner and outer presser foot height. I live in a very rural area, and bringing it to a repair person is not an option, unfortunately.

[kgg]

Make upload the video to youtube and give a link. First off, I would send the video onto Techsew and ask for their advice, guidance, etc. Another option would be to download a Juki LS-341 or 1341 manual as it would give you idea as to how the linkages for the needle and inner pressor foot work.

kgg

[brushew93]

Thank you for the Upload tip kgg!

I have called and emailed Techsew and sent video, pictures. The problem is, I don't always hear back from them. I'm sure they are busy, but I just want to be able to use this machine and getting timely advice and/or answers to my issues are extremely helpful. 

The videos show that I now have the machine stitching, but the stitch length is clearly not the same as what the dial is set at. If I can fix that issue, I think I'm good to go!

 

 

 

[Northmount]

@Techsew Ron  Looks like your help is needed here.

[Uwe]

You’re not far off now, it seems. I don’t see or hear anything glaringly wrong other than perhaps some thread snapping perhaps due to the hook gib not letting go of the thread early enough (advancing hook timing might resolve this.)

Please elaborate on what you actually do. “I adjusted the stitch length adjuster” doesn’t really give us enough information about what you actually did. Which screws did you loosen, what parts did you move in which direction? Others reading this topic in the future will want to know what to do, or what not to do. 

I’m not sure what manual you get with the TechSew, but the Juki LS-341N Engineering manual describes how to balance forward and reverse stitch length on pages 14 and 15 (see images below).

The TechSew may be a modified/enhanced clone since it apparently can do 9mm long stitches. The original Juki LS-341N can only do 6mm. I have a feeling multiple planets have to align and all relevant adjustment have to be spot-on to squeeze 9mm stitchlength out of that design. I’d be curious to know how TechSew accomplished that.

Make sure the feed dog movement is perfectly centered in the throat plate opening. At 9mm stitch length there is no wiggle room at either end (unless they use a significantly shorter feed dog.)

Below are the two relevant pages in the Juki engineers manual that describe how to balance forward and reverse stitch length and adjust feed timing. Your machine may not have the engraved markings the Juki manual refers to. It would be interesting to see if and how the TechSew manual differs from the Juki manual.

Edited March 23, 2021 by Uwe

[kgg]

Another thought. Some of your stitch length problems may also be your feed dog, inner presser foot and your main presser foot. If I am not mistake on the Techsew 2750 all three are slick smooth. That couple with smooth material they may not be providing enough grip to properly feed the leather though properly which may contribute to a shorter stitch length.

kgg

[brushew93]

You are correct @kgg, the feed dog and presser feet are smooth. I did try various weights and finishes of leather with no change. The reason I used the smooth, light leather for the video was to make it easier to see the threads and stitching motion. I did get an email back from techsew, requesting a video using slow, manual motion with no needle or fabric. I will send one this morning. Hopefully they will be able to diagnose the issue. I will post their suggestion and the result here.

[kgg]

15 minutes ago, brushew93 said:

Hopefully they will be able to diagnose the issue. I will post their suggestion and the result here.

Yes, please do as it may help others down the road that may experience a similar problem in the future.

kgg

[brushew93]

@kgg, @Uwe - This morning when I went to take a video for Techsew, I discovered a brand new noise the machine is making. This was NOT happening yesterday, and no additional adjustments were made! The noise occurs just as the needle reaches its highest point. It does NOT occur at all if the presser feet are lifted. 

 

 

[kgg]

That sound and that ever so light jiggle of the main pressor foot remains me of when I had to shim the lifter arm that connects the chain to the foot pedal out from the sewing machines body by about a 1.5 mm at the pivot bolt in my clone.

kgg

[Constabulary]

Have you checked is the rear side of inner foot is touching the outer foot in some way?

[brushew93]

@Constabulary Techsew called me and had me adjust my stitch length dial. I ended up loosening the middle screw, then holding down the reverse lever, and setting the dial to 1. That fixed things for me. Doesn't make a lick of sense to me, but it worked so I'm not complaining!