Upper thread tension.
 

Does anyone alter their machines upper tension dependant on the stitch length they are using? I have heard of having to alter for different brands, type and weight of thread etc but altering for stitch length alone?:confused:

I have in the past, but everything works well where I have it now, so I don't bother.

I have never had to.

Only for the type of thread, not for stitch length.

I think that might be totally dependent on your machine. I've had machines in the past where this may have made a difference but never did it, so don't really know.

dont touch unless the machine is acting up

Try changing it when changing stitch length. You never know until you do it. I change tension all the time. I want to know what too loose and too tight look like with different threads. Machine tension is set for one type of thread at the factory so you have to adjust it. I don't know why so many sewers are afraid of that tension dial upper or lower.

FYI: I was taught to always raise the pressure foot when adjusting tension. I do this on all my machines, new and vintage.

I agree. I think of it like tuning a string instrument (I play the upright bass). You can't just buy your instrument and never tune it, at least not if you ever want to play with other musicians. I don't adjust thread tension unless there is an issue, but if there is, I'm not shy about it. I'm also not shy about adjusting lower tension, even though there seems to be a ghastly fear of that. I want my stitches to look good and hold up, so I do what I need to do to make that happen. Although, I don't have a computerized machine. I have an old semi industrial bernina, and a new brother 1500s, both are 100% mechanical.

Yes, I can see having to change tension if you change stitch length, especially if you're going to a very long stitch length.