In our How to replace a Qualcast blade on a Classic Petrol 35s lawnmower video, Helen shows you how to adjust your lawnmower's blade using two screws on either side of the blade. These screws are NOT designed to adjust your grass cutting height. They are to ensure that your black fixed bottom blade's alignment is even and level with your red cutting cylinder. If your bottom blade isn't aligned properly, your mower will not produce a clean and even cut. This is of particular interest if you have just installed a new blade.
Follow these handy tips if you need to adjust your Qualcast Classic Petrol 35s lawnmower's blade alignment:
Grass cutting height
If you do want to adjust your grass cutting height, you will need to use the cut knob. Determining the best cutting height for your lawn is a balancing act between getting the look you want and keeping your lawn healthy. For the first cut of the season, it's a good idea to keep the cut height fairly high. High cuts help your grass stay healthy in difficult conditions, such as drought and extreme cold or heat.
Here are some insightful instructions on adjusting your Qualcast Classic Petrol 35s lawnmower's grass cutting height:
Images from Qualcast website.