I owned myself a grille for ages and with all of them I owned, I had to Jerry rig multiple cut outs of cast iron to the inside of the grille. In some cases, if the grille was hot enough it would melt the zip ties holding the cast iron to the grille. When it gets in the food, it starts to taste a little like burnt rubber. When I got myself a Weber grille I saw that it had a griddle  insert so I had to test it out. And to my surprise it fit without the need of zip ties and my family was very cheerful that our food will no longer taste a little like burnt rubber.