Inconsistent bottom stitches - HELP!

[brmax]

The problem I was running up against led me to looking at each machine " I thought they were the same" but anyway just taking a look at the thread path, surprised they worked but different and why I thought they were the same was my head down moment! wha?

So I rethreaded through the guide post on them the "same" and did a recheck, re-sight and decided to change needles from a 18 to 19 running 92. Working through these changes were the biggest part I believe. The option to use all the guide holes for thread in the piece above the winder is a choice one has to make, and the route described is experimental. I will admit keeping things the same on these is great by me most all the time, but here on the 08nh, I run thread one loop through the upper thread guide between post and tensioner in this change.

This model is a bit difficult so I guess it gets its due, They made it to be a bad az and so here this round I'm standing.

After reading Bobs post I looked at the check springs here and they are positioned the same headed to 9:00, as to any measure of them I haven't experimented getting any figures, that really maybe the difference one could measure, also here these are oem springs. 

What kicks this to a thread path I think is (it looks as mine did) not every stitch, like a hook issue might be. So right now I'm in the area of watching mine and listening here as the others offer up some great tips and checks as they have already, I appreciate the help, and good luck Jim

Floyd

 

[JimRaynor]

Thanks Floyd for taking the time and sharing your experiences. I really appreciate it.

Today I've cleaned, oiled, re-threaded the machine and changed the needle...
Still, no avail...

I'm starting to think it's got something to the with the hook mechanism too...

[RockyAussie]

The picture you have given is a bit short to go by but it looks to me that every 6 to 7 stitches you are having a too tight pull with the bobbin. This could be by the thread cone being a bit offset and going loose as it straightens up every now again. Sometimes when cones get close to finished they can do this a bit also. If you don't have a second bobbin case to try take a picture inside of the case and see if you can see any burring anywhere.(And post it). If the bobbins have a slot for loading the thread these can get caught a bit every time they pass the burr or whatever. A bobbin being pulled by hand may seem smooth but push and hold the bobbin down into the case and then see if it still pulls smooth and doesn't grab. Next if the tension disk for the bobbin winder is too tight the threads can pull into the other thread and wind on badly but that would be more intermittent i think. Could slip spray have gott on to 1 side of the cone? Bugger of a problem sometimes.Regards Brian

[Wizcrafts]

Here are some things that I have found causing my machines to have variations in the position of the knots in leather. This happens to any and all of my 6 industrial sewing machines.

1. Twisty thread that twists out of the center of the top tension disks
2. Twisty thread that folds over guides and jams the top thread or at least doubles the tension
3. Thread that has twisted out of the thread guide above the spool in the thread stand
4. Thread that is badly wound on the spool. I have some spools with the thread getting caught under the bottom of the windings and it comes off herky jerky. I have other spools with the thread literally unwinding all over the place because of improper bonding and loose windings..
5. Poorly wound bobbins (loose here, tight there, starting stub folded back over the side and back into the bobbin)
6. Thread stubs not clipped close enough to the hole in the bobbin
7. Sharp edges on anti-backlash/ejector springs inside bobbin cases
8. Burrs on bobbin tension spring or shredded thread strands under it
9. Burrs on the hook
10. Totally dry hook that binds slightly in one spot at a certain speed
11. Top and bottom tensions either too loose or too tight for a reliable stitch
12. Dirt, material or thread particles inside the shuttle race
13. Check spring travel too short or tension too light for the weight of the thread
14. Oversize needle hole allowing too much room for error
15. Sticky tape or glue between layers gumming up the needle (try using titanium coated needles and clean them with Goof Off)
16. Hard or soft areas in the leather, caused by tanning inconsistencies. I have actually hit sections of rawhide in some cuts of leather I was using for belts.

[JimRaynor]

3 hours ago, Wizcrafts said:

Here are some things that I have found causing my machines to have variations in the position of the knots in leather. This happens to any and all of my 6 industrial sewing machines.

1. Twisty thread that twists out of the center of the top tension disks
2. Twisty thread that folds over guides and jams the top thread or at least doubles the tension
3. Thread that has twisted out of the thread guide above the spool in the thread stand
4. Thread that is badly wound on the spool. I have some spools with the thread getting caught under the bottom of the windings and it comes off herky jerky. I have other spools with the thread literally unwinding all over the place because of improper bonding and loose windings..
5. Poorly wound bobbins (loose here, tight there, starting stub folded back over the side and back into the bobbin)
6. Thread stubs not clipped close enough to the hole in the bobbin
7. Sharp edges on anti-backlash/ejector springs inside bobbin cases
8. Burrs on bobbin tension spring or shredded thread strands under it
9. Burrs on the hook
10. Totally dry hook that binds slightly in one spot at a certain speed
11. Top and bottom tensions either too loose or too tight for a reliable stitch
12. Dirt, material or thread particles inside the shuttle race
13. Check spring travel too short or tension too light for the weight of the thread
14. Oversize needle hole allowing too much room for error
15. Sticky tape or glue between layers gumming up the needle (try using titanium coated needles and clean them with Goof Off)
16. Hard or soft areas in the leather, caused by tanning inconsistencies. I have actually hit sections of rawhide in some cuts of leather I was using for belts.

I don't know what to say Wiz...

When I was writing the initial post, I was hoping that you'd chime in...
You did, and you made my day!

I'm very sure that the answer lies above.

I'll start with the ones that I find most likely to be applicable to my setup and let you guys know how it works out.

Thanks a lot.

[JimRaynor]

16 hours ago, RockyAussie said:

The picture you have given is a bit short to go by but it looks to me that every 6 to 7 stitches you are having a too tight pull with the bobbin. This could be by the thread cone being a bit offset and going loose as it straightens up every now again. Sometimes when cones get close to finished they can do this a bit also. If you don't have a second bobbin case to try take a picture inside of the case and see if you can see any burring anywhere.(And post it). If the bobbins have a slot for loading the thread these can get caught a bit every time they pass the burr or whatever. A bobbin being pulled by hand may seem smooth but push and hold the bobbin down into the case and then see if it still pulls smooth and doesn't grab. Next if the tension disk for the bobbin winder is too tight the threads can pull into the other thread and wind on badly but that would be more intermittent i think. Could slip spray have gott on to 1 side of the cone? Bugger of a problem sometimes.Regards Brian

Thanks for the solid ideas Brian.

I'll make sure the points you made is checked.

One way or another, this problem will be sorted out this week!