Is check spring "throw" different to check spring "stroke" and "tension".

[beefy]

I was reading an amazing thread from this site about the humble check spring.

It seems there can be 2 or sometimes THREE different adjustments on the check spring mechanism:

1. TENSION - pretty sell explanatory.
2. The STROKE or where the spring STOP is positioned. This determines when thread tension is released on the needle down stroke.
3. The THROW, which adjusts how much length of slack thread is given out before the tension comes back on.
   It seems the purpose of the THROW is to allow enough slack thread while it is wrapping around/under the case, before it is pulled taught again to pull the thread off the case.

Viewing various threads and Google search results I've seen people suggesting adjusting the THROW so the thread becomes taught just as the needle eye enters the material.
That appears incorrect to me, and I think they are talking about adjusting the STROKE or the spring stop position.

Could anyone confirm that I have the 3 listed adjustments above correct, or if I'm completely wrong. Please be blunt with me LOL.

[AlZilla]

It's early here and I'm not clear on your question.  But the following post contains a treatise on check springs that probably ought to be a sticky: 

 

[Wizcrafts]

11 hours ago, beefy said:

Viewing various threads and Google search results I've seen people suggesting adjusting the THROW so the thread becomes taught just as the needle eye enters the material.
That appears incorrect to me, and I think they are talking about adjusting the STROKE or the spring stop position.

Could anyone confirm that I have the 3 listed adjustments above correct, or if I'm completely wrong. Please be blunt with me LOL.

You have correctly summarized the check spring.

As for when the spring lets go (the stroke), it should always be after the needle fully penetrates the material. This will be longer on thicker stacks than thinner ones. When this spring first appeared, most people were sewing cloth garments. The problem of running without any check spring is that the top thread loosens as the take-up lever moves down from TDC. All of that loose thread flopping around tends to get caught by the needle and is likely to split if the needle hits it square on. The purpose of a thread controller, as it is officially called, is to keep the thread taut until the needle is inside or under the top of the material so that it doesn't split the loose thread by accident.

Since thicknesses do vary, I usually adjust the stroke stopper bracket lower to keep the thread taut a little longer. I set the spring tension to manage the size of the thread, using less force on thin thread and more on thick thread. If you set too much spring tension, it can override the main top tension disks. I use just enough spring action to both fully seat it in the lowered position and to control the amount of slack, but not to add appreciably to the top disks adjustment.

The adjustment for the "throw" varies with the design of the check spring assembly. No matter its geometry, there should always be some method of adding or subtracting how much loose thread is fed to the descending needle. The lesser the looseness, the tighter the lay of the stitches, and vice-versa. If you sew something that is thin and soft, like garment leather, denim, broadcloth, linings, etc, and the stitch line is puckering, stop sewing and cut the thread, then pull the work to remove the puckers. Move the slack adjustment to add more top thread, run a test, then resume sewing the job. You will find a happy position where the work lies flat and the stitches aren't too loose on top.

The actual spring tension is controlled by rotating the entire check assembly one way or the other. On most of my SInger style machines, there is a locking screw underneather the metal housing that the assemble fits into. That screw stops the assembly from turning on its own. To change the spring's force, loosen that screw on the housing, then put a narrow flat blade screwdriver into the end of the split shaft and turn it to get the amount of spring tension you want. Tighten it down after you're satisfied.

Most thread controllers I encounter have the slack adjusment in a curved slot with a small screw that sits inside the slot. You loosen the screw and the nut that tightens the assembly, then rotate to the right for more slack, then tighten it all down. Factory standard is dead center in the slot. However, the distance that the spring travels up and down comes into play if it's much longer or shorter than the default factory position (typically about 8 to 9 o'clock in the resting position). machines setup to sew leather usually have a lower resting position of the stop bracket or adjustment. I recommend experimenting with any new sewing machine until you are familiar with all of its adjustments and how thay interact.

[beefy]

6 hours ago, AlZilla said:

It's early here and I'm not clear on your question.  But the following post contains a treatise on check springs that probably ought to be a sticky: 

 

Thanks AIZilla,

I'll have a read of that after work.

[beefy]

@Wizcrafts Thanks for that very long and detailed reply. I'm happy to know I've got it correct.

I know you guys have probably heard this a million times before, but the helpfulness and the quality of the responses and information the members of this site give, is truly amazing. I'm always wondering if I'm delving too deep into understanding the machine first before I "really get sewing", but I'm starting to think doing things this way will save me a lot of time in the future.