Author: Lindee Goodall
What is compensation?
The action of machine tensions when applying stitches to fabric causes distortion during sewing. Stitches are "pulled" in causing a shortening effect when the stitch direction reverses. Conversely, stitches are "pushed" out along their length. Note, however, that these are not equal, opposing forces. You may hear this phenomenon referred to as "push and pull." To offset this distortion, the digitizer exaggerates shapes with the goal that when the design is sewn it will push and pull into the desired configuration. There's a catch here... not all machines have the same tensions. Tighter upper thread and bobbin tensions will pull more, faster sewing speeds create more tension, stretchier fabrics distort more, and different threads react differently. So compensation is not a perfect science.
Effects of inadequate compensation
Look at a design on screen, preferably at your computer rather than the sewing machine where you have a better view. Do all the objects exactly line up no matter what direction the stitches are placed? Is the running stitch outline exactly on the edge of the design? Do all the letters line up perfectly as you might see them in print or in a graphics program? If you answered yes to these questions, don't even bother sewing the design. Or, better yet, do sew the design so you can see the problems first hand. More than likely you will see gaps in the design, letters dancing on the baseline rather than anchored horizontally, and the outline will gap in some areas and overlap in others. This misalignment is referred to as registration problems. Imagine two rectangles of fill stitches. If the stitches run vertically, those blocks will sew shorter and wider. Therefore, if you want the blocks stacked one on top of the other, you will need to overlap them. A little extra overlap is good because it will work in a wider range of situations. Plus, to avoid fabric damage from excessive needle penetrations, you don't want those edge stitches exactly meeting. If you want them side-by-side, there should be about a row or two's worth of space between the two blocks so that when the stitches push out, they will just butt.
Compensation is one of the harder things to master as a digitizer so you are likely to see more problems in novice designs and free designs from questionable sources. The best control over compensation is accomplished through a combination of redrawing objects and applying "pull comp" settings in the software. There is no "push comp" however, it must be drawn – this is one reason why auto-digitizing software does not always produce the best result.
Effects of too much compensation
Too much overlap can cause thick, lumpy areas and can run up stitch count. In some cases, excess compensation can contribute to distortion – which is what proper compensation is trying to correct.
Where is compensation used?
Compensation should always be applied to satin and fill stitch objects; rarely will it ever be applied to running stitches.
As an embroiderer, you probably have very little control over compensation unless you are working with a lettering program or digitizing your own designs. If you are experiencing registration issues, verify your embroidery technique. Sew the design on a smooth, stable woven fabric, on the straight of grain, with a sturdy cutaway and in the smallest hoop that will accommodate the design with the fabric and backing between the rings of the hoop. Also check your machine tensions and make sure they are not too tight, especially if you are using polyester embroidery thread. In other words, sew the design under the most ideal conditions and see how it sews.
If there are still registration problems, it may very well be the design. I should warn you that if the design has running stitch outlines, they may be a tad off here and there due to deflection. This is especially true if you have a double pass running stitch. The stitches are probably perfect on screen but you may see a little "zig" in one spot and "zag" in another. The needle has been deflected in these areas – maybe caused by previous stitching or by a tension jerk on the thread that has flexed the needle slightly. Chances are, you could sew the same design under these ideal circumstances ten times and each sewout will be slightly different. Expect this! Expect quality but don't expect perfection. If the results are totally unacceptable, consider the source. If it was a "freebie" from a questionable digitizer, just delete it and get on with life. If it was from a reputable source, or you paid for it, contact the company and explain your problem. If possible, email the file and a picture of your results. Sometimes things slip through the cracks, or one format gets corrupted and a professional doesn't want a bad design in the market. Do be nice about it!
While compensation may not be a design attribute over which you have absolute control, you do have control over what you sew. If you get in the habit of examining a design on screen before sewing it and then comparing the actual sewn version with the screen version, you will quickly become a knowledgeable embroiderer. Soon you'll know just by looking at a design if it is sew-worthy or not. If a design does not pass the quality test, do not keep it in your collection. Designs do not get better with age!