I don't like using a 1/4 foot for machine piecing. I use an adhesive guide on the bed of my machine to create a physical barrier for my fabric to butt up against. I can sew even seams much, much faster this way. I have cut and used moleskin for the barrier (available in the foot section of any pharmacy), sometimes layering it two levels. Currently am using a Dritz adhesive guide, as they are precut and have a nice height:
http://www.amazon.com/Dritz-Quilting...dp/B0085L2Y2I/
I do not recommend the associated red ruler Dritz sells for establishing the 1/4". I measured it, and it creates an exact 1/4" seam rather than the scant 1/4" that we quilters prefer.
I use one of my shorter rulers to establish the seam allowance. I place the ruler on the bed of the machine, lower my needle so it is at a scant 1/4", lower the presser foot to keep the ruler in place, check that the ruler is running straight from front to back, then place the adhesive guide butted up next to the ruler. Instead of a ruler, a lined index card would work too, or graph paper marked in 1/4" squares.