How to keep swept cuts even with a helix?

I'm working with Solidworks 2016 for this project and one thing that I've ran into with making some of my models is using swept cut with the helix that I make. There's nothing wrong with making the cut; it always goes though and always appears on the model. The problem that I'm having is the cut gets smaller as it travels up the model, and I need  it to stay a constant size for the length of the cut. Is there a trick to make the cut size consistent from the bottom of the helix to the top? Please give as much detail as possible! Thank you!