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Recoil Saw bounces its way through wood

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December 15, 2010

The working prototypes of John Zimmerman's recoil panel and hack saws

The working prototypes of John Zimmerman's recoil panel and hack saws

Image Gallery (5 images)

Using a hand saw is nobody’s idea of a good time, but one inventor is trying to at least make it a little easier. John Zimmerman, a software developer by trade, has created what he calls the Recoil Saw. Essentially, it’s just a saw – various types of saws, actually – with one or more spring-loaded impact bars attached to the blade. At the end of each stroke, the spring compresses as the bar hits the material being sawed, then releases that energy back into the following return stroke. The idea is that users can pretty much just bounce their way through cutting jobs, as opposed to having to purposefully stop and start between every stroke. Zimmerman, who admits he’s probably not the most unbiased tester, said that he has found it cuts twice as fast as a regular saw.

“I came up the the idea while working on a separate invention that required cutting many pieces off of metal bars, with a hack saw and miter box,” he told Gizmag. “I live in an apartment so using a power saw was not really an option. I wanted a less exhausting way to cut, and the idea for the Recoil Saw came to me after countless tiring cuts.”

Zimmerman has created working prototypes of recoil panel and hack saws, and he has also sketched out designs for a pruning saw and a file. While the bar/spring mechanism on his prototypes might look a little cumbersome, his sketches feature a much more compact mechanism that combines the bar and spring in one simple unit.

A sketch of a recoil pruning saw

“At this time, I am looking to find hand tool manufacturers interested in licensing the recoil saw, which is still patent pending,” he told us. “Of course, to me it seems like a great idea, who wouldn't enjoy spending less time sawing?”

Below are two videos that he shot; one of his recoil hack saw cutting through a board, and one of a regular saw doing the same job. Of course, it's not exactly a scientific testing method as it's impossible to confirm that the same amount of force was being applied to both saws, but it’s still an interesting comparison.

Via InventorSpot

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away.   All articles by Ben Coxworth
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12 Comments

You guys better stick to electronics and leave this sort of thing to a first year engineering student, an apprentice carpenter or Bob Vila on a slow day. What in the world is this guy doing cutting wood with a hack saw? Has he found some wood cutting blade somewhere? These are for metal. The chips he is making sure look like an abused hacksaw to me. A decent back saw would have this done in half the time.

The first year engineering student might notice that this is a version of a perpetual motion machine. Somehow, we will get more force out of that recoil mechanism than we put in and that will make everything faster. Ain't gonna work that way.

The inventor should run a race with a regular hand saw and your editor should learn more about woodworking.

Frederick Rodney Welsh
15th December, 2010 @ 05:58 pm PST

ok, why use a fine tooth metal cutting blade to cut wood? you still have to load the spring, why not just use a wood saw, in any case, you will expend energy to load the spring, what is the return of energy?

Bill Bennett
15th December, 2010 @ 07:14 pm PST

This actually a brilliant idea. A lot of the energy in sawing is used bringing the saw to a stop in order to reverse direction, and of course that energy is usually wasted. In this invention that energy is stored and then released to help the stroke reverse direction. I suspect this might actually work.

Michaelc
15th December, 2010 @ 07:25 pm PST

I won't bother repeating the issues with using a hack saw to cut wood. It's pretty clear that this person doesn't do a lot of hand sawing. Any energy that could even conceivably be saved through these springs (which still need to be compressed, wasting energy) is wasted by creating a shorter cutting stroke that becomes less efficient when compressing the springs.

"Using a hand saw is nobody's idea of a good time"; It is to me. I use hand tools almost exclusively in my projects.

Joseph Manske
16th December, 2010 @ 07:05 am PST

Run a test simultaneously to compare with & without. He is using the energy wasted on the back-stroke to impel the saw forward, conserving that energy. Great idea. Five years from now all handsaws will have a similar device.

Fred Conwell
16th December, 2010 @ 08:07 am PST

I think this may be a working advantage. If you ever ran across a trampoline you would probably feel the same effect, the bounce back propels you to the next step, much like the stroke would be propelled back into the opposite direction. Perhaps a physicist could calculate the momentum and change thereof.

I think this guy should set up a test fixture, one with a set downward pressure and set force for the forward and return stroke using the full stroke for a standard and his modified saw. I have just such a device already set up if he would like to use it. I am in San Diego California. You can go to this site to see the description and there is a link to the circuit schematic. http://members.cox.net/paulvild/RecipricatingTestCircuit.shtml

Also, he may want to use a metalic substance as a test subject. This is so that the woodworkers wont get distracted by the selection of the blade.

Paul Anthony
16th December, 2010 @ 09:02 am PST

Well D'UH! Of course it cuts faster, as the bumpers allow the user to use the entire blade without slowing down at the ends to avoid hitting the frame.

Anyone that has ever used a saw knows that you use primarily the center section of the blade to avoid hitting the handle or the saw sliding out of the cut. These shock absorber/limiters allow use of the entire blade. Twice the cutting length = twice the speed. Not rocket science.

jjsmail
16th December, 2010 @ 10:37 am PST

40 seconds versus 61 seconds. The faster saw wins the race.

Doesn't matter what kind of saw he was using. Rebound from the springs allows the blade to travel faster across the piece, reducing the time it takes to finish the cut.

This is an excellent innovation. If you have to use hand saws, this is the way.

jimbo92107
16th December, 2010 @ 11:02 am PST

LOVE IT! Three thousand years of saw technology leaps forward in the year 2010.

Hope he makes millions, as he makes the rest of us more efficienct, without having to changes sawing arms in the middle of a long cutting task.

Three Cheers!

Doc R

Matt Rings
16th December, 2010 @ 04:31 pm PST

amazingly simple!!!! wow!

Deepak Ku Parida
17th December, 2010 @ 12:34 am PST

Hacksaw or wood saw? Coarse hacksaw 14 teeth per inch, fine crosscut saw 11 teeth per inch, pretty close (I have used my hack for wood on occasion). It seems that the sawing method has to be rather frenzied to make this work well, and frenzied activity (especially on wood) requires good clamps and is best left to machinery. This has got to be harder on the joints of the user. And I wonder how one might make a close cut with this extra hardware on the blade. And a pruning saw stops pretty well on its own due to the curvature of the blade. I will pass. Maybe the inventor could just use a decent jigsaw, they don't make that much noise.

Bruce H. Anderson
20th December, 2010 @ 01:53 pm PST

It's a shake-weight with added resistance and travel.

Ethan Brush
11th December, 2011 @ 05:10 pm PST
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