More Techsew 2750 Issues.

[Gulrok]

I've seriously had it with this machine. I want to throw it off a cliff.

We've never had great sewing with it. I'll mess with it for hours. It'll work nicely, and then it won't again.

In September/October we had a lot of tensioner issues until we just bought a genuine JUKI tensioner. In Feb I had an issue with jamming. In March we learned we needed leather sewing needles 135x16 instead of 135x17. We fixed our problems.... In April we had the control box pop a capacitor. It was nearly a month before we had another control box.

We had a wonderful few months from May to now, where the sewing machine was totally reliable. It was fantastic. It would sew fine.

Last week it started skipping stitches. I didn't have any projects that needed to be done with the machine until this week, so I figured I'd wait since we were going to be out of town.

Today, won't even sew anymore. Threading gets jammed in the bobbin area that will bind the whole machine or It'll pickup the thread for a stitch or two and then nothing.

I'm lost for words. I really just want this thing to work. I feel like its a constant problem.

--

Looking through the manual that comes with the book... it doesn't quite help me. There isn't a lot in the book about this machine.

[Matt S]

23 minutes ago, Gulrok said:

I've seriously had it with this machine. I want to throw it off a cliff.

We've never had great sewing with it. I'll mess with it for hours. It'll work nicely, and then it won't again.

In September/October we had a lot of tensioner issues until we just bought a genuine JUKI tensioner. In Feb I had an issue with jamming. In March we learned we needed leather sewing needles 135x16 instead of 135x17. We fixed our problems.... In April we had the control box pop a capacitor. It was nearly a month before we had another control box.

We had a wonderful few months from May to now, where the sewing machine was totally reliable. It was fantastic. It would sew fine.

Last week it started skipping stitches. I didn't have any projects that needed to be done with the machine until this week, so I figured I'd wait since we were going to be out of town.

Today, won't even sew anymore. Threading gets jammed in the bobbin area that will bind the whole machine or It'll pickup the thread for a stitch or two and then nothing.

I'm lost for words. I really just want this thing to work. I feel like its a constant problem.

--

Looking through the manual that comes with the book... it doesn't quite help me. There isn't a lot in the book about this machine.

I think that all of us who own a sewing machine have gone through this at some point, especially if we're self-taught. Don't despair, you CAN fix it, or find someone who can. Luckily you're in the right place for help.

Sewing machines are devices that need a surprisingly precise and yet nearly unquantifiable amount of "just right" to work, and they can and will "walk out" of their settings over time, especially if they have a crash. Sometimes just a stubborn thread jam can throw it all out of goose. It's also quite easy to adjust them out of balance, perhaps inadvertently or perhaps in order to cope with a different combination of leathers, and either forget or not be able to set it back to "right". However with time (massively reduced by access to the centuries of machine mangling experience available to you on this forum) it will soon become second nature to you.

There's a few different things that could be playing up with your machine right now, probably something to do with the hook timing, but those are never the first things to check. First action if your machine goes screwy is always to completely unthread your machine and install a new, fresh needle, checking that it's the correct type and size (made that mistake a few times!). Then rethread the machine from scratch, making sure to follow the manufacturer's instructions exactly (especially with regards the bobbin orientation). Use contrasting colour needle and bobbin threads if possible. Set the stitch length somewhere in the middle of its range. Turn the machine over a few times by hand, making sure to give a gentle pull on the thread tails away to the right. Does it still have problems? If it jams don't force your way through the jam as this alone can cause the machine to come untimed. Leave it as is, take a photo of what's going on around the bobbin case and post in this thread (or better still, another video). Remember also that your machine will behave a little differently with material/leather in it and without.

It doesn't really surprise me about the manual -- industrial sewing machines are primarily intended for use by people in factories who have trained technicians available to do routine maintenance, make any adjustments needed and to fix problems as they arise. The manuals tend to give you a few tech specs, some basic maintenance and operating instructions and that's about it. It's the same reason why your car's manual probably doesn't tell you how to change its oil or do a 10,000 mile service. As owner/operators it's on us to learn to be a technician/mechanic, or to pony up and pay a real one for their expertise. Just the way it works I'm afraid!

[RockyAussie]

First thing is to check that the long needle groove is on the left. After that as @Matt S rightly said ...change the needle as a little bend is all it takes to do the above. If that don't work then you are looking at timing perhaps. As best you can watch the needle take the thread down and when it starts coming back up the hook should be coming around to grab the loop in the thread somewhere in the scarf of the needle area. If you have no loop forming then find out why. That would mean your thread is being held up by something that it should not be. If the hook does not come around as the needle scarf area is there then you have got a timing issue. If so check first that the needle bar has not been knocked high. If it is correct then you need to loosen the hook and align it so that it will come around just when the thread loop is looking nice and open. Rough I know but it will get you out of trouble.

[Gulrok]

21 hours ago, Matt S said:

I think that all of us who own a sewing machine have gone through this at some point, especially if we're self-taught. Don't despair, you CAN fix it, or find someone who can. Luckily you're in the right place for help.

Sewing machines are devices that need a surprisingly precise and yet nearly unquantifiable amount of "just right" to work, and they can and will "walk out" of their settings over time, especially if they have a crash. Sometimes just a stubborn thread jam can throw it all out of goose. It's also quite easy to adjust them out of balance, perhaps inadvertently or perhaps in order to cope with a different combination of leathers, and either forget or not be able to set it back to "right". However with time (massively reduced by access to the centuries of machine mangling experience available to you on this forum) it will soon become second nature to you.

There's a few different things that could be playing up with your machine right now, probably something to do with the hook timing, but those are never the first things to check. First action if your machine goes screwy is always to completely unthread your machine and install a new, fresh needle, checking that it's the correct type and size (made that mistake a few times!). Then rethread the machine from scratch, making sure to follow the manufacturer's instructions exactly (especially with regards the bobbin orientation). Use contrasting colour needle and bobbin threads if possible. Set the stitch length somewhere in the middle of its range. Turn the machine over a few times by hand, making sure to give a gentle pull on the thread tails away to the right. Does it still have problems? If it jams don't force your way through the jam as this alone can cause the machine to come untimed. Leave it as is, take a photo of what's going on around the bobbin case and post in this thread (or better still, another video). Remember also that your machine will behave a little differently with material/leather in it and without.

It doesn't really surprise me about the manual -- industrial sewing machines are primarily intended for use by people in factories who have trained technicians available to do routine maintenance, make any adjustments needed and to fix problems as they arise. The manuals tend to give you a few tech specs, some basic maintenance and operating instructions and that's about it. It's the same reason why your car's manual probably doesn't tell you how to change its oil or do a 10,000 mile service. As owner/operators it's on us to learn to be a technician/mechanic, or to pony up and pay a real one for their expertise. Just the way it works I'm afraid!

 

16 hours ago, RockyAussie said:

First thing is to check that the long needle groove is on the left. After that as @Matt S rightly said ...change the needle as a little bend is all it takes to do the above. If that don't work then you are looking at timing perhaps. As best you can watch the needle take the thread down and when it starts coming back up the hook should be coming around to grab the loop in the thread somewhere in the scarf of the needle area. If you have no loop forming then find out why. That would mean your thread is being held up by something that it should not be. If the hook does not come around as the needle scarf area is there then you have got a timing issue. If so check first that the needle bar has not been knocked high. If it is correct then you need to loosen the hook and align it so that it will come around just when the thread loop is looking nice and open. Rough I know but it will get you out of trouble.

Yeah. I'm a little bit on edge about it. It makes you want to rip your hair out. At least me. I'm a pretty technical person. I've rebuilt numerous motorcycle engines, lawnmowers,  and other mechanical things. No problem at all. If I get stuck. I can find a parts diagram or a manual somewhere.

But these sewing machines. Ugh.

I have the scarf in the right spot. Replaced the needle as well. I have the hook approximately 0.5m to 1mm from the needle (in the scarf) although I'm using a business card to measure that. (When I removed the jam, I removed the hook and bobbin assembly). 

I spent time polishing the hook because it did have a burr on the end. 

The timing has the hook crossing the needle at the bottom of the needle stroke. 

I still will go good forward, but now I get the occasional skipped backstitch. 

It is now catching the thread again. But ocassionally it'll 

[RockyAussie]

5 hours ago, Gulrok said:

The timing has the hook crossing the needle at the bottom of the needle stroke.

That sounds wrong to me. Normally the hook comes across the needle when it is on its way up and somewhere in the needle scarf area. As you have had the hook off I would guess that you need to loosen your hook and turn it to the right enough so that it comes across the needle when the thread loop has formed properly. As for the hook to needle gap if you put in the largest size needle in that the machine can use and set your hook so that it almost touches it, it should be alright for the other sizes.

[Gulrok]

57 minutes ago, RockyAussie said:

That sounds wrong to me. Normally the hook comes across the needle when it is on its way up and somewhere in the needle scarf area. As you have had the hook off I would guess that you need to loosen your hook and turn it to the right enough so that it comes across the needle when the thread loop has formed properly. As for the hook to needle gap if you put in the largest size needle in that the machine can use and set your hook so that it almost touches it, it should be alright for the other sizes.

I think we're onto something..

EDIT: Yes I know this isn't a 225, but the concept should be similar.

Edited June 29, 2020 by Gulrok

[Matt S]

Yep that could be it. Generally you want the hook crossing the centreline of the needle after BDC. Machines vary but most similar machines need the hook to cross after the needle has risen roughly 2mm past BDC.

Looks like the Techsew 2750 is a clone of the Juki 341. Check out this page of the 341 manual for timing information: https://www.manualslib.com/manual/917750/Juki-Ls-341n.html?page=9#manual

[CowboyBob]

15 hours ago, Gulrok said:

 

Yeah. I'm a little bit on edge about it. It makes you want to rip your hair out. At least me. I'm a pretty technical person. I've rebuilt numerous motorcycle engines, lawnmowers,  and other mechanical things. No problem at all. If I get stuck. I can find a parts diagram or a manual somewhere.

But these sewing machines. Ugh.

I have the scarf in the right spot. Replaced the needle as well. I have the hook approximately 0.5m to 1mm from the needle (in the scarf) although I'm using a business card to measure that. (When I removed the jam, I removed the hook and bobbin assembly). 

I spent time polishing the hook because it did have a burr on the end. 

The timing has the hook crossing the needle at the bottom of the needle stroke. 

I still will go good forward, but now I get the occasional skipped backstitch. 

It is now catching the thread again. But ocassionally it'll 

Run the needlebar all the way down(BDC) turn the handwheel towards you so the needlebar raises 3/32" or 2.4 mm & the point of the hook should be @ the needle for it to be timed correctly.Here's the Engineers Manual

JUKI 341 engineers manual.pdf

Edited June 29, 2020 by CowboyBob

[Gulrok]

On 6/29/2020 at 6:12 AM, CowboyBob said:

Run the needlebar all the way down(BDC) turn the handwheel towards you so the needlebar raises 3/32" or 2.4 mm & the point of the hook should be @ the needle for it to be timed correctly.Here's the Engineers Manual

JUKI 341 engineers manual.pdf

We're sewing like a dream again. Thank you.

[MelAnn]

I have the same issue with skipping stitches. Since I bought the machine almost a year ago, I've had constant problems. I have become adept at changing and testing the timing and needle position because that's what the technician (when I called and we video chatted) taught me to do. (As a side note, I can't believe that they don't give you better insight online how to do this - they just give a measurement of how far the needle post needs to be and if it's off by 0.1 mm then you're screwed. They could have had an instructional video to show people where it needs to be when it hits the bobbin.) Anyway, that TechSew service guy was grouchy and condescending, and would say things like "make a video of yourself threading the machine and then send that to me and then I'll talk to you". When he finally saw this issue about the needle timing, he told us the logical way how to do it (when I say 'us' I include my husband who could also not figure it out, and we both are PhD engineers who are quite good at all things mechanical!).  

Anyway, if anyone can help, we have checked timing, needle size, new needles, etc, and the machine skips a stitch about every 3rd stitch. I cannot find anything helpful online about this. I have resorted to my $200 Singer Heavy Duty machine for lighter leather projects because it's reliable.