Many of these filters are an inch thick and fit tightly into a furnace slot that is only slightly larger than the filter. These filters come in many sizes. 16X20, 16X25 or 20X20 inches are common but so are many other sizes; visit Home Depot or a good hardware store and you’ll see at least a dozen or so sizes if not a score. These filters are nothing more than rectangular hunks of inch-thick fiber material with cardboard edges. They tend to get stuck in their slots once they accumulate dust and grime. The fan in these heating and air conditioning units is strong enough to deform the filter once the path through the filter degrades. The result is a big 3D rectangle (actually a parallelepiped for you geometry aficionados) that is no longer a rectangle because it bows out and lets the air pass around it. That’s when the fun begins if you are trying to wrestle that filter out of the slot without tearing it to pieces.
The filter is intended to fit tightly in its slot to keep air passing through the furnace from going around the filter. Any air that flows around doesn’t go through the filter and get cleaned of dust and particulates. However this tightness in the slot makes grabbing the filter difficult when it needs to be replaced. Fingernails won’t fit in there, nor will needle-nosed pliers. Can you imagine the fun if you used a key to dig out the filter and the key dropped to the bottom of the filter slot!
Thus was born the idea of The Filtr-Grip® Gripper. Starting with an A-shaped spring clamp from Home Depot, Mark had a welder attach flat steel plates to the clamp jaws so they would be parallel at a one inch separation. The result was the first prototype. It didn’t look very pretty but it was functional. Another issue was the spring strength. Each off-the-shelf A-shaped spring clamp from Home Depot has a very stiff spring (they are, after all, clamps), necessitating a gap adjustment bolt. This bolt allowed setting the jaw gap at slightly less than the thickness of the filter with no pressure on the handles. Setting this thickness meant that the tool (and its powerful spring) only needed to be opened slightly more to have its jaw gap be greater than the filter width. Remember that some of these filter slots are in awkward locations. For these awkward locations you’ll twist your arm into an unnatural position then squeeze that stiff spring just the right amount. Squeeze too much and the jaws won’t go in the filter slot, squeeze too little and the jaws won’t grab the filter. The second prototype removed the adjustment bolt and used a less-stiff spring. A few iterations (and prototype manufacturing runs) later and voila, the patented, Filtr-Grip® Gripper is improved, manufactured, and ready for sale.