Two Modifications to the Knew Concepts Fret Saw - Popular Woodworking Magazine
 In Shop Blog, Woodworking Blogs

Knew concepts fret saws belongs to a small group of truly revolutionary tools such as Tite-Mark Marking Gauge and the veritas® PM-V11® Bench Chisels. Whether they were the brainchild of a maverick innovator or an outcome of a long process of a company’s teamwork, these newcomers rightly joined a pantheon of inspiring tools whose material, mechanism or shape were truly novel, and who potentially could launch, once a mundane tool – in our case a fret saw – to higher altitudes of both performances and (hopefully) reliability. Fret saws are not just a jewelry makers’ tool. Today, more and more woodworkers use them for all kind of accurate work, from cutting dovetails and sawing jigsaw puzzle parts, to intricate marquetry tasks.

For centuries fret saws were made in the shape of the letter “F”. The frame of the saw was relatively narrow and was intended to apply constant tension on the very thin blade. Most saws of this design had to be elastic enough for the user to be able to flex the “F” shape, with a hand or upper body force in order to allow them to mount a new blade over the frame. Once the blade was clamped onto the saw, the user releases the compression on the frame, which would spring back and tension the blade. A more advanced, yet traditional, fret saw would include a tensioning screw which allows the user more control over the tensioning protocol, and theoretically could increase the blade’s tension even more.

A handmade jeweler’s saw with a simple “bend the frame, then clamp the blade” tensioning system.

A jeweler’s saw with a screw tensioning option.

Enter Knew Concepts saws. This is a family of saws that were invented a few years ago by Lee Marshall and are manufactured in the USA. They have a totally new and innovative design for both the frame and the tensioning mechanism. We have purchased one of these saws from Craftsman Studio last fall and have deployed it in woodworking tasks throughout our classroom.

Here are my personal reflections after a few months of occasional use.

The frame and the tensioning mechanism: The aluminum girder-like frame is a work of art. It creates an extremely light, yet rigid frame that can tension the blade much better than a conventional saw would. But because the frame is much stiffer, the user can’t just flex it via hand applied compression in order to mount a fresh blade. Instead, the blade is mounted on two special clamping turrets while the frame is in its “loose” or detentioned state. Then the frame is put under compression/tension via leveraging of a cam handle. This mechanism is one of the strongest attributes of the saw.   

The blade clamping turret and the cam lever that tensions the blade.

The clamp turrets and the blade clamping mechanism

The turrets on our saw serve as hubs for clamping the blade, but they also allow it to rotate to different positions, which facilitate for a more versatile sawing in itrequate situations. Yet although these improvements are quite ingenious I would like to propose two modifications.

The first one has to do with the lack of sufficient clamping surface over the blade. This, I believe, leads to unintentional detachment of the blade during work, it happened to me and to my students. And it also can happens when the a new saw blade is being tensioned for the first time. To tension the saw the user needs to tuck the tips of the saw blade into the turrets’ blade holes. Then the clamp thumb screw is tightened and the blade tip is pushed against a set screw anvil. However, the blade hole is not drilled deep enough and because the tip of some blades are tapered or trimmed, the effective blade surface that is being clamped is not optimal. If the blade hole would have been drilled ⅛” deeper *, more blade surface could have been clamped, which could prevent the blade from snapping out of the turrets once the the cam handle is being pivoted or when the blade is slightly jammed while sawing. Is it possible that the less then optimal clamping situation is intentional, perhaps even to protect the saw’s frame from over tensioning?  Honestly, I don’t know. But I can tell you that there is no indication for this in the owner’s manual. And since the owner’s manual specifically says that the frame is stronger than the blade, and would brake the blade if you over tensioned it, I suspect that the clamping problem is not intentional.

Because the tip of some blades are tapered or trimmed, the effective blade surface that is being clamped is not optimal.

If the blade hole would have been drilled ⅛” deeper, more blade surface could have been clamped.

My other suggestion has to do with the turrets thumbscrews. I propose to replace the saw’s two-part thumb screws with a thumb screw that is milled from one piece of steel. The current thumb screw is made of an aluminum knurled nut head that is screwed and glued over a long set screw that serves as the duo’s threaded stem. Why I don’t like it? Because this week as I was trying to unscrew the thumb screw to release a broken blade, the aluminum head unscrewed itself from the threaded stem. To untighten and release the threaded stem from the turret clamp I had to locate a Hex key and engage a hex socket at the top of the stem to set it free.. Had the thumb screw was made entirely out of the same blank, this issue would have never arise.

I used a thread locker and a hex key, to reconnect the set screw stem and the aluminum knurled head. The Hex key helped me to tighten them back together.

In conclusion. The Knew Concepts Saw is an amazing machine that has improved over the years. I think that by addressing the two issues that I mention, it will be an even better engineering achievement than it is already.

– Yoav Liberman

  • A note on the hole modifications that I proposed… My recommendations is intended for the makers. I am not sure if current owners of this saw will be able to successfully deepen the center hole and expect to solve the clamping problem. If drilling is done on the current model followed by the user tucking the blade’s tips into the modified holes, the knurled nut that regulates the cam lever tension will have to be loosen, or be backed up to the point that it might fall off or would not hold enough on the tension screw.

    To solve the inadequate clamping issue the manufacturer’s will have to do two things: To deepen the center holes and have the turrets reposition closer together by the same distance of the combined length of the extended holes. In other words some structural modification needs to happen in tandem with elongating the holes. This is because the blade has a fixed length and with the current cam adjustment mechanism, there is a limit for how much you withdraw the tension regulating nut.

    Bottom line.. if you or I tried to drill the holes and expect an improvement in performances we will probably counter a problem with the cam lever setting.


Get 2+ Decades’ Worth of Pure Woodworking Information! With 21,000 Pages of Woodworking you'll get hundreds of furniture plans, step-by-step instruction and drawings, shop projects, essential setup and technique advice for hand tools and power tools, and more! This collection will teach and inspire you.

21,000 Pages of Woodworking

Get 2+ Decades’ Worth of Pure Woodworking Information!
With 21,000 Pages of Woodworking you’ll get hundreds of furniture plans, step-by-step instruction and drawings, shop projects, essential setup and technique advice for hand tools and power tools, and more! This collection will teach and inspire you.

Recommended Posts

Start typing and press Enter to search