Even seam allowances with 1/4 inch guide
 

I am piecing 3 inch squares into rows using a seam guide attachment. The seams seem to go okay until the end then the kind of go wonky and narrower toward the last 1/2 inch. What am I doing wrong, please?

You are not holding the pieces to prevent them from going wonky. Keep your fingers on to guide or use a satellite to keep the seam conststen

I am using my fingers to guide, what do you mean by satellite, please?

these are pieces cut with the cutter machine so are exactly the same size

I think you mean stiletto?

Yes, I think auto correct 'helped'. I cannot sew without a stiletto in my hand. I taught a friend to sew, and infected her too. I have a fancy schmancy one that I got at a quilt show, but you can use anything. A bamboo skewer is a good substitute. You can also use the pointy end of your seam ripper. If you watch a video when Eleanore Burns is sewing she also uses one. You use it to keep the trailing end of your 2 fabrics aligned and guide them under the foot so that you maintain your seam allowance all the way to the end. Also, slow down a bit when you get closer to the end of your seam.

I have found that chain piecing helps me with this issue. I have never used stiletto, but I have thought about trying one out

That slide/shift at the start and end is a common problem. An easy solution is to use a scrap as a leader and an ender so those wonky parts are on the scrap and not your piecing.

Simple fix for the veer. Put your index finger on the left side of the pressure foot (bottom) as you near the end of the seam. The seam will not go astray.

Onebyone--You are one clever quilter! Thanks for the tip.