Problem to solve. Occasional removal of underbrush in a large (for my area, consult your local planning council to see how your yard stacks up) wooded yard. Leave large trees and selected bush alone. Above all, do so with a minimum of recovery time.
Black and Decker 16 inch electric hedge trimmer
Frame from old Black and Decker electric lawn mower
The main goal is to take the back breaking agony out of doing brush clearing. You know what brush is, right? It's big viney thicker than grass stuff that grows in wooded areas, this stuff makes walking in the woods a pain.
In my instance, the brush area I was worried about was near my pool, and I didn't want to pay to have someone clear it a couple of times a year, but each time I did with my old methods it would cause damage to the lawn tractor or my back would be in agony after the work was done.
The other disadvantage to using the lawn tractor is that it can't tackle the brush correctly. The blades are UNDER the mower and what normally happens is it takes multiple passes to cut the brush to the ground level. I'd also end up with brush that just takes a lean and spruces back to normal stature after a few days.
So, I had been using my hedge trimmer at ground level by bending down to do this work. That's where the back pain comes in. The cutting method works reasonably well, but then I'm on the couch for a day or more trying to see what the lethal dose of Tylenol 3 might be.
While going to my shed to get my tractor to do a normal mowing day, I noticed the old spent frame of the electric mower I had outside the shed, awaiting refurbishment into a dethatcher. If I could work out a way to attach the trimmer to that and not kill myself while using it, it could save my back a lot of pain while getting the job done.
Using some rack ear metal I had to remove from a previous project on my CNC machine, I bent them into angle brackets for the hedge trimmer, which has along it's cutting bar some thru-bolts I could remove and replace with longer bolts to attach the brackets.
I then made holes into the old mower frame to attach the brackets. Nuts and Bolts were attached to create a solid fit. One advantage is that when the unit is fully assembled the built in height adjustment on the old mower frame becomes usable with the brush clearing gear.
Proof of concept is complete and it works PERFECTLY. It took 10 minutes to clear the area it used to take me about an hour to process. I will finalize the design to make use of the old mower power switch and add safety equipment if I see the need. With the switch active, I can't think of any reason I'd need to add safety, but never say never.