Love and hate relationship with my CB4500

[Spyros]

I wanted to try something with gussets on this machine for the first time.  So I bought a pattern that had a couple of different types of gussets and I made this:

Throughout the making of this bag the machine was a total charm, I was honestly mesmerised by how well it was stitching.   

It was doing things like this (front): 

And back:

I mean I don't know about you guys, but I couldn't tell this apart from the best handstitching I've ever seen anywhere, only the slight feed dog marks on the back give it away that this was machine made.   I was stoked at this point.

Then the bag was 99% ready and only one thing left to do: stitch the gussets.  This bag has two different gusset stitches, on the front it has a turned gusset as you can see in the first photo, and on the back it has a visible external one that connect the gusset to the back panel.  So I did the turned one and started the other one. 

And at that point, the machine just randomly and for no apparent reason decided to do this:

and back:

Unfortunately because I was focused on manhandling the bag I didn't see it until it was too late.   So I had my WTF moment sitting there in silence facepalming myself for 5 minutes, and then I decided to finish the stitch and ask you guys after.

What the hell do you think happened? 

At this point judging from the thread I've consumed I've done a few hundred metres of stitching on this machine, and it's the first time it's ever done anything like that. 

Earlier I realised it did the same thing on the turned gusset too, but being a turned gusset that would be invisible I was a bit careless so I thought maybe I had forced it or pulled the bag or something and I didn't think too much about it, just made sure I was very careful on the next gusset.

And I was, making sure I don't force anything, the presser foot moves freely without touching the bag, I don't go too fast or too slow etc.

 

So the machine just hates gussets for some reason.

If you are wondering what I did and how I did it, I did exactly what this guy does on this video from 11:45 onwards.  Exact same bag, same gluing, same machine, same presser foot, same technique, even the same thread as far as I can tell.

Love the machine, but I just can't have it randomly destroying bags without any warning.

Any ideas are welcome.

Cheers

SP

 

 

Edited March 9, 2022 by Spyros

[Handstitched]

Thats just weird. My first thoughts go straight to the tensions, but that looks quite good ? And why only on the corners? 

Edited March 9, 2022 by Handstitched

[kgg]

9 hours ago, Spyros said:

What the hell do you think happened? 

What I see:

First photo of the turn.

i) If you started your seam from left to right: your got 3 stitches that were long then two longer stitches then one medium length then nine short stitches then it started go go all over the place until you basically got back on track on the straight run on the seam on the right hand side

ii) If you started your seam from right to left: nice straight stitches of uniformed length and then they begin to go all over the place as you enter the turn before finally starting to straighten out.

Second photo of the turn:

i) At the point of your stitches where they are going off the pressor foot impressions are not visible like of those where the stitches are good.

The thread tension appears to setup nicely.

I am guessing the problem lines in:

i) The amount of pressor foot tension where it is not holding the leather down with the necessary tension to allow for slight turning deviations as you start and work through the turn.

ii) Using a right hand side pressor foot versus a left hand side pressor foot.

iii) The stitch length adjuster is able to move ever so slightly up and down which maybe caused by the stitch length locking surface isn't machined perfectly to the stitch length indicator surface.

Are you using the same pressor foot configuration as the one shown in the video??

kgg

 

[Wizcrafts]

Are you using a curved throat plate (recommended for this), or a flat plate? Gussets do worse on a flat plate that squishes the leather. A rounded/curved throat plate more closely follows the corner curves. This assumes that you sew on the top/outside of the gussets so they can fold around the throat plate. If you sew from the inside, the curves fight the feed and will hit the head and interfere with the stitches.

For tight curves on gussets, consider using the stirrup throat plate. It is perfectly rounded on top. But, you lose the feed dog and only have needle and inside foot feed. Reverse won't line up as before. That won't be a problem if you either double tap the ends or stitch over the beginning stitches for 4 or 5 stitches.

I would add more foot pressure going around the gusset and use a double toe foot for maximum even pressure.

Another thing you might could try is to reduce the top and bottom thread tensions. This will make it easier for the machine to pull the leather through, especially when operating in needle feed mode.

[Spyros]

8 hours ago, kgg said:

What I see:

First photo of the turn.

i) If you started your seam from left to right: your got 3 stitches that were long then two longer stitches then one medium length then nine short stitches then it started go go all over the place until you basically got back on track on the straight run on the seam on the right hand side

ii) If you started your seam from right to left: nice straight stitches of uniformed length and then they begin to go all over the place as you enter the turn before finally starting to straighten out.

Second photo of the turn:

i) At the point of your stitches where they are going off the pressor foot impressions are not visible like of those where the stitches are good.

The thread tension appears to setup nicely.

I am guessing the problem lines in:

i) The amount of pressor foot tension where it is not holding the leather down with the necessary tension to allow for slight turning deviations as you start and work through the turn.

ii) Using a right hand side pressor foot versus a left hand side pressor foot.

iii) The stitch length adjuster is able to move ever so slightly up and down which maybe caused by the stitch length locking surface isn't machined perfectly to the stitch length indicator surface.

Are you using the same pressor foot configuration as the one shown in the video??

kgg

 

Thanks for taking a look at this

Yep I started right to left.  Nice even stitches then suddenly it increased the stitch length by a lot, and then erratic.

It does seem I should probably use the left presser foot, but there was plenty of room and I did pay particular attention that nothing touched the foot.  If this bag sells for the price I expect I will probably make a couple more and I will try the left foot next time.  (or there might actually be enough room to put the bag on the other side over the cylinder arm, we'll see).

The presser foot tension is still a big question mark for me.  I have replaced the spring with the softer one, and I have dialled it all the way  back, so I am applying the absolute minimum pressure.  And I'm still getting bad marks when the total leather under the foot exceeds 4mm.   The gusset was just under that, so I only really got dog feed marks.  It sounds like the presser foot tension is something I'll have to adjust every time I change thickness, or maybe try and find an ever softer spring.

The stitch length adjuster in my mind is *probably* not the issue.  I'm saying this because if it moves when I stitch, why would it only move at the gusset curve only?  Because other than that the machine has always held the stitch length perfectly. 

[Spyros]

7 hours ago, Wizcrafts said:

Are you using a curved throat plate (recommended for this), or a flat plate? Gussets do worse on a flat plate that squishes the leather. A rounded/curved throat plate more closely follows the corner curves. This assumes that you sew on the top/outside of the gussets so they can fold around the throat plate. If you sew from the inside, the curves fight the feed and will hit the head and interfere with the stitches.

For tight curves on gussets, consider using the stirrup throat plate. It is perfectly rounded on top. But, you lose the feed dog and only have needle and inside foot feed. Reverse won't line up as before. That won't be a problem if you either double tap the ends or stitch over the beginning stitches for 4 or 5 stitches.

I would add more foot pressure going around the gusset and use a double toe foot for maximum even pressure.

Another thing you might could try is to reduce the top and bottom thread tensions. This will make it easier for the machine to pull the leather through, especially when operating in needle feed mode.

Thanks Wiz, I appreciate your time.

Yes I am using Rocky Aussies narrow throat plate, which is fairly curved.

About the reverse: when the project has such a high colour contrast between the thread and the leather, I don't reverse at all.  I finish the machine stitch 2 holes short and I do those manually with a needle.  I'll probably get over it eventually but thats how I do right now. 

I think the double toe foot might be the answer because there is definitely enough room in this particular gusset, I do the stitch a fair way in from the edge and then cut the excess leather afterwards.

Thanks again, I now have some things to try.  Waiting for some leather at the moment but when I do the same bag in a couple of weeks I'll post an update.

 

 

[RockyAussie]

Hi @Spyros comming around the corner for some reason or other you lost reliable presser foot tension. On a reasonably heavy job like this I suspect that you could use more foot pressure but....Looking at the video you can see that he has a nice skive going all the way around on the gusset and I know on those leathers it will make it sit out nice and flat and make the stitching happen quite a bit easier. You can see in yours a fair bit of bunching up in the corner which means for you to stitch it you had to somewhat force it around. In doing that you could be pressing upward at the same time and thereby loosing some of your down foot pressure. Having the left presser foot in, in this case may not be the best choice and I would try the right paddle foot instead as shown in this picture -

Last thing.......I remember at one stage you were having some catching on the presser foot movement up and down. DO they run freely up and down now? If not I have done up some pics to show you how to make an adjustment to fix that.

[Spyros]

19 minutes ago, RockyAussie said:

Hi @Spyros comming around the corner for some reason or other you lost reliable presser foot tension. On a reasonably heavy job like this I suspect that you could use more foot pressure but....Looking at the video you can see that he has a nice skive going all the way around on the gusset and I know on those leathers it will make it sit out nice and flat and make the stitching happen quite a bit easier. You can see in yours a fair bit of bunching up in the corner which means for you to stitch it you had to somewhat force it around. In doing that you could be pressing upward at the same time and thereby loosing some of your down foot pressure. Having the left presser foot in, in this case may not be the best choice and I would try the right paddle foot instead as shown in this picture -

Last thing.......I remember at one stage you were having some catching on the presser foot movement up and down. DO they run freely up and down now? If not I have done up some pics to show you how to make an adjustment to fix that.

Yeah he did skive the edges but he was also using much thicker leather than me, mine was about 1.2-1.4mm which didn't really call for a skive, if anything I was trying to add rigidity because the whole bag is just a hair too floppy.  I will give the paddle foot a try, I remember it does feel very positive and secure in holding the leather down, but I've been avoiding it because it leaves the worst marks on the bridle leathers I typically use.  I'll play around with the tension spring.

The catching of the presser foot movt is all fixed, it just needed some oil in just the right place.  

[Wizcrafts]

The Cowboy inline foot set would also work good on narrow gussets.

[RockyAussie]

2 hours ago, Spyros said:

Yeah he did skive the edges but he was also using much thicker leather than me, mine was about 1.2-1.4mm which didn't really call for a skive, if anything I was trying to add rigidity because the whole bag is just a hair too floppy.

The thickness is not relevant it is how the leather stretches and lays down flat around the curve. The overall thickness here may even make it easier. You see in the video when he taps it down before stitching that the gusset is sitting nice and flat without any sign of buckling. You need to do a few circles on scraps (coasters maybe) to get the feel of how to hold and feed into the curve when stitching. It is very easy to get elongated stitches if you don't do it right particularly if you are pushing against a gusset as well.

[Spyros]

I also tapped it, I even pressed it with my Amy Roke pliers before tapping it to make sure.  It was nice and flat, very nice and very flat indeed.

I did a couple of coasters last night, I tried all 5 presser feet that I have, I changed the thread then changed it back, changed the stitch length and changed it back... I was playing for hours and I haven't been able to replicate this issue.  I still have no idea what happened to be honest.

[Wizcrafts]

8 hours ago, Spyros said:

I still have no idea what happened to be honest.

When this happens to me I chalk it up to the convergence of forces beyond my comprehension!

[kgg]

11 hours ago, Spyros said:

I did a couple of coasters last night, I tried all 5 presser feet that I have, I changed the thread then changed it back, changed the stitch length and changed it back... I was playing for hours and I haven't been able to replicate this issue.  I still have no idea what happened to be honest.

Have you tried it with a sample of a wet form leather to recreate the bag corners? If it still happens then it properly has to do with how you are trying to sew the welt around the corner. Maybe a pressor foot tension issue, to tight a space for the pressor foot, uneven surface or ???.

kgg

[dikman]

14 hours ago, Spyros said:

  I still have no idea what happened to be honest.

It sounds like the same "laws" that apply to Black Powder shooting are in play here, there is an element of magic mixed in it.

[Spyros]

6 hours ago, Wizcrafts said:

When this happens to me I chalk it up to the convergence of forces beyond my comprehension!

The sewing machine fairy!