Be sure to tighten the blade holder with the blade in place!
Almost every bookbinder I have met uses 9mm Olfa snap off knives. Simply by squeezing the blade holder a bit tighter with a needle nose pliers, the performance and feel of any Olfa knife is greatly improved: it doesn’t wiggle around so much, it is easier to place more accurately, the knife feels more solid, there is no more annoying rattle, and the blade breaks off more consistently. Why didn’t I think of this 25 years ago?
Peachey Conservation 
Brilliant! Of course.
Interesting tip!!!
Thanks so much
Thank you! It drives me crazy when the blade cuts a curve even when I use a straight edge because the blade wiggled.
I have been using same OLFA 18mm Heavy Duty Ratchet-Lock Utility Knife L-1 for almost 20 years and it is by far superior to the 9mm – the blade can be locked tight in position and if the genuine OLFA 18mm blades are used (cheap blades get blunt quicker) there is no wobble or curving as described by “sappling” – would never use anything else.
I agree about the genuine Olfa blades as being far superior to knockoffs, I know some prefer the 18mm blade. Because it is thicker than the 9mm blade, I find it can get wedged in heavier thicker materials, like binders board. I prefer the feel and lightness of the 9mm handle, which I guess is why Olfa offers a big and small version!