Singer 7-33 Stitching problem & parts

[hackish]

I bought a 7-33. It's actually for stitching harness webbing. As soon as I try to stitch heavy material it will randomly skip stitches or make giant loops of top thread on the top of the material. This happens even when slowly hand-wheeling it and the bottom thread is not pulled into the material when it happens. I've never seen this sort of problem before.

I replaced the hook with a real singer one and adjusted the spacing so it barely touches the needle - reduced but didn't eliminate the skipped stitches.

I think the problem is in tension. Since parts are hard to come by I've started machining a few new parts to try and correct the problem. Although helpful the only supplier I've been talking to is really hard to buy from. I've probably spent 4h trying to get through on the phone to give a visa number!

The original upper tension assembly was bent to hell and the sewing thread was catching the metal threads slightly so I made a new one using a junk chinese mill. I'm not proud of the result but it's serviceable.

Thread is 348 weight using an organ #27 needle. Needle size and thread are well established standards for sewing this material as is the machine.

The timing is not adjustable and there is nothing to indicate it's grossly out. I've played with a lot of needle bar height settings without making any progress. Any insight into what else I should be looking at?

-Michael

 

[Constabulary]

I don´t know the Class 7 machines but can you try to adjust the needle bar hight or is the needle bar pinned? I would guess you have to lover the needle bar a little bit.

[CowboyBob]

You might need to adjust the hook closer to the needle,there's a large screw underneath to loosen ,you want it as close as you can get w/o touching the needle.

[hackish]

1 hour ago, Constabulary said:

I don´t know the Class 7 machines but can you try to adjust the needle bar hight or is the needle bar pinned? I would guess you have to lover the needle bar a little bit.

As mentioned, I've adjusted the needle bar height a number of times but with little difference.

13 minutes ago, CowboyBob said:

You might need to adjust the hook closer to the needle,there's a large screw underneath to loosen ,you want it as close as you can get w/o touching the needle.

Just spent the last 2 hours playing with the hook distance. Too close and the top thread gets cut, too far and the loop gets missed.

This is the top layer and I can see no reason why the big loop is occurring - it doesn't coincide with a start/stop or anything I can see. You can also see a few where the tension is not quite optimal but the stitch is still well formed.

 

This is the bottom of the same piece. Again, the tension here is OK and teh stitches are formed somewhere near the center of the sample.

On these there is still a tiny bit of thread nicking so I may try backing the hook off by maybe 0.010".

Next step, maybe I will grab my gopro from work and see if I can record the shuttle to see if there is anything catching or jamming.

-Michael

[Gregg From Keystone Sewing]

3 hours ago, hackish said:

 

 

 

-Michael

 

Sweet, that's a nice job on the upper tension stud for sure.  If you can do it yourself, your ahead of the game for sure.

[TinkerTailor]

Just a thought, are you sure the bobbin is turning the right direction? And there is no thread in there hanging the bobbin up?  I have had a similar problem due to this, flipping the bobbin around fixed it. Worth a try.

[hackish]

22 minutes ago, TinkerTailor said:

Just a thought, are you sure the bobbin is turning the right direction? And there is no thread in there hanging the bobbin up?  I have had a similar problem due to this, flipping the bobbin around fixed it. Worth a try.

I'm used to bobbins that turn in the reverse direction but I followed the manual which shows it coming off the top of the bobbin and to the carrier. Pretty sure this is correct...

[Gregg From Keystone Sewing]

On 10/6/2016 at 8:39 AM, hackish said:

 

20 hours ago, hackish said:

I'm used to bobbins that turn in the reverse direction but I followed the manual which shows it coming off the top of the bobbin and to the carrier. Pretty sure this is correct...

 

-Michael

 

Here's an image from Seiko's owners manual showing how to insert a wound bobbin into the bobbin case.

Edited October 7, 2016 by Gregg From Keystone Sewing

[hackish]

Oh so much fun! Have a look at this one from the Singer manual.

I wonder which is better? I can play around a little with it reversed and see what happens.

[CowboyBob]

The Seiko way will keep the thread in the tension better.BUT either way doesn't make a difference in the way it sews(won't stop it from skipping) You might want to try alittle more foot pressure.