You can sharpen a 3mm chisel easily by placing the blade spacer in the slot closest to the centre and then putting the chisel up against the spacer. Sharpen the chisel by sliding the top slider across the face of the chisel.
UNIQUE & EASY -
Thank you for the sharpener which I bought as a thank you present for a friend who has helped me with jobs around the house. The gadget is so unique & we saw how easy it was to use. I think you have a wonderful product & carpenters worldwide will need to acquire one. I wish you great success.