Today I was cleaning a motor and prepping it to paint. I usually mask off certain areas and previously I’ve used an exacto knife to trim the masking tape. On cast iron stuff like intake manifolds and engine blocks this can really wear out blades. This method also takes time.
I am sure that perhaps someone had done this before but I tried it and works out much easier. Basically I start by taping off the area to be masked and then use a round tube like object and run it over the edge to be trimmed. Doesn’t require a lot of pressure just enough to score the tape along the edge and makes for a nice clean cut. In this case I used a punch, but also a socket extension, tube or similar will work quite well. The examples I used was masking off an intake manifold.
Hope this helps
Jim
Here are some pics-
