Diagram.1. Dspiae EN-A Nipper with "the Blade" & "the Blunt End" labelled. (Source: https://www.dspiae.com/en/a/products/)

How to Adjust the Nipper

In diagram.2 below, adjusting the "Adjusting Screw" prevents damage to the cutting blade. Damage to the blade occurs if too much pressure is applied when squeezing the handles of the nipper together. Fine tuning is done by adjusting "The Stopper" screw. This sets the gap between the blade and the blunt edge stopping the blade from closing too hard on itself. To set the fine tuning stopper screw place a folded in half piece of A4 copy paper in-between the cutting blade & blunt end to a firmness that just grabs and holds the paper when the blade & blunt end are together. These types of nippers are extremely sharp. Only minimal pressure is required to make a cut.

Diagram.2. Features the Adjusting and Stopper Screws. (Source https://www.dspiae.com/en/a/PRODUCTS/)

How to Correctly Position a Single Blade Nipper Before Cutting.

It is critical when using a single blade nipper to make sure the cutting blade is positioned correctly before making a cut. A single blade nipper must only be used to remove a part by cutting through "the gate" (as highlighted in the green circle in Diagram.3). It is the thinnest piece of plastic. At no time should these nippers be used to cut through thicker pieces of a runner, sheet abs plastic and clear plastics. The tip of the blade is extremely thin & fragile. Always position the cut in the middle of the blade to avoid breaking the tip. The blade of the nipper should be perpendicular to the piece being cut. Cutting on an angle will result in a damaged blade. 

Diagram.3 What to do and what not to do when cutting with a single blade nipper. (Source: https://www.dspiae.com/en/a/PRODUCTS/)

How to Cut and Trim Using a Single Blade Nipper

Step.1. Remove the part from a runner. Perform an initial cut within "the gate" and away from the part being removed. (See Diagram.4)

Diagram.4. Position of blade on the gate 

Once the part has been successfully cut from the runner there will be a small piece of the gate remaining on the part. This is called a "nub". 

Step.2 is to cleanly remove the remaining nub without leaving any stress marks to the plastic of the part. Stress marks cause a discolouration of the coloured plastic where the nub has been removed. This is the advantage a single blade nipper has over a conventional 2 bladed nipper. Carefully position the blade as shown in Diagram.5, then carefully position the blade so it is flush against the part and carefully cut as detailed in Diagram.6.

With practise mastering a single blade nipper will almost certainly eliminate additional sanding to remove any remaining nub residue. If there is a nub that is unable to be trimmed flush with the part use a sharp hobby knife to make the final trim. 

Diagram.5 & 6. How to position your blade to remove any residual nub.

Care and Maintenance.

Like all fine pieces of equipment your nippers do need a little attention. Make sure you always store your nippers with a cap on after every use. I don't know how many times I've heard stories of $100 nippers accidently falling on the floor and the tip breaking. Don't wash your nippers in water. Wipe away any obvious residue from the cutting end (caution its sharp) and use a light machine oil to wipe over the cutting head. Always store your nippers in a dry place.