The process of inspecting an oil filter is not complicated. Slice the top off using a filter cutting tool. Extract the cartridge that holds the pleated filter element. Cut the element free of the cartridge. Wash it in solvent and strain the swarf through a coffee filter to catch any sediment (see sidebar below).
For whatever reason, I am a bit clumsy around knives. Every so often, I manage to cut myself. Nothing major, but annoying and preventable. It always happens when I’m in a hurry or get distracted. So, back in 2018, when Brian Carpenter demonstrated to our Light Sport Repairman class how to cut, wash and inspect an oil filter, the first thing I thought was, “Oh no! A slippery thing in one hand and a knife in the other…I’ll probably cut myself doing that.”
It took five years and I don’t know how many oil filters later, but sure enough, I had brain fade and an oily cartridge slipped out of my hand. In my other hand, the box cutter knife I was using made a graceful sweeping, slashing arc downward…into nothing. It was a close one, but it got me thinking that I should, for the sake of limb preservation, come up with a better way to hold and slice apart slippery filter cartridges.
I thought about making an arbor to hold the cartridge in my lathe and use a knife like a parting tool. But since I sometimes work away from my shop, it would be nice to have a portable device that I could take on the road.
What I came up with was, for lack of a better description, a miniature hand-cranked lathe for slicing pleated filters from cartridge housings. The dimensions are specific to oil filters used on Jabiru engines (NAPA 1394), but there’s no reason the design couldn’t be adapted for just about any single-use, throwaway oil filter. The choice of bearings for the headstock (two 6903 metric bearings) and live center (one 608 metric bearing) was what I had on hand. The headstock bearings are certainly overkill for the application, but using them provided a good opportunity to demonstrate the basics of lining up and boring concentric bearing pockets for spindle applications.
A key component to the design is the 13-inch Kitchen+Home brand knife purchased for $12 from Amazon. The knife features a series of 6mm holes punched in the blade. Whatever purpose these holes serve for cooking, they’re perfectly spaced pivot points for my filter slicer. The idea being, as the blade dulls, you can move the pivot and have a fresh edge. This will allow several filters to be cut before resharpening is necessary.
One of my hobbies is cooking. The holes in the knife blade help things not stick to the blade while slicing. It helps keep you from making funky cuts in a zucchini.
The art of porting cylinder heads, whether by hand or by CNC machine, is a valuable part of blueprinting detailed engine builds or overhauls, and surprisingly subtle changes can determine how efficiently the engine will breathe.
One of my hobbies is cooking. The holes in the knife blade help things not stick to the blade while slicing. It helps keep you from making funky cuts in a zucchini.