Tension Adjustment

[jfhspike]

Hi. I've got a two questions about tension adjustment.

1. I know how to adjust things so that the upper and lower tensions are about equal, so that the knot is buried in the material. But there are many ways for two things to be equal: the upper and lower tension can both be large, or both be small. Is there some rule of thumb about how much tension to put on the bobbin (and then match with the upper tension)? Clearly for light fabrics like silk, too much tension will make puckers between stitches, but I'm working mostly with sunbrella, and there's a pretty wide range of tensions that I can put in and still have things work.

2. I'm using a Juki LU-563, with a horizontal bobbin. When you change bobbins, you just lift out the bobbin, not the whole case assembly like you do on some machines. I switch back and forth among threads from V69 to V207; that requires adjusting the bobbin tension, which seems to be placed so that no reasonable screwdriver can get to it comfortably. Does someone make jeweler's screwdrivers with a right-angle bend in them or something? Or does everyone else just swear at their machines like me?

Thanks in advance for any advice.

-John

[stanly]

1. I've seen products w/tension so high it buried the thread (invisible thread) in the leather- obv not somethng u can do w/sunbrella.

guess it depends on tension u think thread can take and the "look" u're going for.

2. because I have vert bobin I've never thought of crawling under table w/screwdriver.

I have a racheting screwdriver from Stanly or someone that could maybe be reshaped for that small screw, there are rt angle screwdrivers as well that could be reshaped. Be aware these have very short reach.

[SARK9]

I don't have much trouble adjusting the lower tension on my LU-563....I use a small screwdriver like the ones that come in eyeglasses kits etc., and pick the one with a *very* good fit to the screw slot. It is at a slight angle but it seems to be easy enough to insert correctly.

-DC

[jfhspike]

I don't have much trouble adjusting the lower tension on my LU-563....I use a small screwdriver like the ones that come in eyeglasses kits etc., and pick the one with a *very* good fit to the screw slot. It is at a slight angle but it seems to be easy enough to insert correctly.

bobbin_tension_screw.jpg

-DC

Thanks. That photo looks just like what I do, although I use jeweler's screwdrivers instead of the eye-glass ones. Glad to know I'm not along. (Thanks to Stanly, too, for the "there's no right answer here" answer regarding good tension -- gives me confidence that my eyeballing is about right.)

[Tree Reaper]

I started using a trigger gauge to see what the exact tension was top and bottom without guessing.

It gets me close then I can increase or decrease the tension just slightly for different thickness in leather.

Edited April 19, 2014 by Tree Reaper

[Tejas]

I started using a trigger gauge to see what the exact tension was top and bottom without guessing.

It gets me close then I can increase or decrease the tension just slightly for different thickness in leather.

Tree Reaper would you please report your machine and the settings you use.

I recently purchased a Pesola precision spring scale that measures 0 - 300 g the same purpose. I'm still experimenting and have only used it for thread tension, Juki 1508, V-92 thread with a setting of about 275 g.

The idea came from the following link.

http://sew24.blogspot.com/2012/11/how-to-measure-thread-tension-with.html

[Tree Reaper]

Right now the top tension is at 14 oz. outside the needle and the bobbin tension is at 2 lbs. on my Cowboy 4500 using a RCBS trigger pull gauge.

I just use this for a starting point but it seems to get me in the ball park.

Judging by these numbers the bobbin tension is roughly twice the top tension.