Using a hand saw requires repeated push and pull strokes. Normally this involves either: limiting the force of each stroke, or making a separate effort to stop each stroke.
The recoil devices are simply a cushioned impact bar, attached to 1 or more springs, attached to the hand saw.
When using the recoil saw, the recoil is compressed at the end of each stroke. Energy from each stroke is stored and then used in the next stroke. This speeds the transition from one stroke to the next. This also eliminates the effort of stopping each stroke.
A saw operator can thus perform a sawing job in less time, and
using less effort. Ask anyone who has ever become exhausted from using a manual saw if that would be useful. A select few people enjoy using a handsaw, but wouldn't everyone who uses a hand saw enjoy spending less time using it when they need to?
The recoil can be a part of many types of hand saws and files, for use in gardening, woodworking, metalworking, and PVC work.
I came up with the idea because I live in an apartment where power saws aren't an option. I was sawing multiple small pieces using a hack saw and mitre box and I wanted an easier way. A way to spend less time sawing. The recoil saw was my solution to spending too much time and effort sawing.
Patent drawing of recoil file
If you've ever used a hand saw you've wished it took less effort - now it does.
Video of Recoil Hack Saw: 22 seconds from first to last cut.
Comparison Video: same wood, blade, and saw (with recoils removed) 45
seconds from first to last cut.
Sales note: Hand saws last a long time. Hand Saw owners rarely buy a new saw when a new model comes out. A Recoil version of a hand saw will save a hand saw user time and energy. If saw owners just think they'll spend less time and effort sawing with a recoil saw, then they're thinking about buying a new saw. They would be thinking of buying a new saw even if the ones they have 'work just fine'. So not only is there sales potential in new saws, but in the replacement of existing saws.
Technical Note: Springs that are fairly rigid seem to preserve the momentum of the saw better than springs with a lot of flexibility in them.