You have to keep adjusting the fold of the fabric to line up on the line of the matt and even up the end by trimming. The fold of the fabric does not always lay straight against the the line and so if you don't keep adjusting it to the line when you cut it will bow.

I agree. I think it is the cutter and not necessarily the fabric. These have been some very good tips and I will give them a try on Wednesday at UFO.

Thanks your guys. You are the best for tips like this.

So many instructions tell you to cut across the width of the fabric (42 inches) I cut length wise (up the selvedge) and I never cut a strip longer than 20 to 24 inches. You can fold the fabric once to be able to use a 12 inch ruler. The problem with cutting the width you have to fold twice to use a 24 inch ruler and that is where the bow comes in no matter how experienced you may be. Judy Martin a stellar quilter and designer has always given this advice. Try it.
Happy quilting
Severna

Someone taught me to slightly angle the blade of rotary cutter towards the ruler while cutting to eliminate bowing of strips.

My exact same solution. It has saved me from many a "bad cut" that came before it. Actually, I have two June Taylor shape cuts, best thing since sliced bread.

Pressure on the ruler is the key. All of the starching, trimming and alignment tricks are defeated if pressure isn't maintained from one end of the cut to the other. As one pushes forward with the rotary blade, the blade may push the fabric from under the cutting guide, thus causing a curve. A dull blade, or one which no longer rolls smoothly because of age or dust build-up can make it worse too. David, is your cutting table low enough so that you can sort of lean onto the ruler to keep steady pressure and do you walk that steady pressure evenly as you roll the blade? It gets back to the angle of the dangle thingie.

What is the Go everyone is talking about. Can you send a picture of what it is?

Yes, I would also like to know about this "GO". What does it do etc.

Thanks.

I used to have that happen. I has to do with how the fabric is folded...not straight. I fold it once, pin across the top, press, and then fold it again for approx. 10" widths that fit under my June Taylor Shape Cut ruler. Don't try to match the ends when folding, hold it so that there are no waves in it and pin and press. They don't cut them straight at the fabric stores. Then square up the end and cut from that. That should help. I saw this method once on Simply Quilts.

I spray temporary basting spray on my rulers if they slip, doesn't keep me from seeing the lines, can be washed off later if you like. Gives even grip across whole ruler.