Glue Basting Seams
If you want presicion piecing, without using pins, you can apply tiny dots of glue about a half inch apart along inside the 1/4 inch seam allowance, place your other piece on the glue and dry with a hot dry iron to set the glue. I would use only glue meant for this purpose or Elmer's School glue. These will wash out completely when your quilt is washed. Also you are applying the glue in the seam allowance and because you are using washable glue, your needle, in your machine will not gum up. This is the way I piece my quilts and have never had a problem. The tiny dots of glue, only need to be about the size of a head of a metal pin. Very tiny. This is enough to hold the pieces together while being sewn on the sewing machine.