CNC Scroll Saw Makes Promising First Cuts

When we talk about CNC machines, we almost invariably mean a computer controlled router. Naturally you can do other forms of automated cutting, say using a laser or a water jet, but what about adding computer control to other types of saws? [Andrew Consroe] recently put together a postmortem video about this experimental CNC scroll saw. While he never quite got it working reliably, we think his approach is absolutely fascinating and hope this isn’t the last we see of the idea.

Those who’ve used a scroll saw in the past might immediately see the challenge of this build: while a router bit or laser beam can cut in any direction, a scroll saw blade can only cut in one. If you tried to make a sharp turn on a scroll saw, you’ll just snap the fragile blade right off. To work around this limitation, [Andrew] came up with the brilliant rotary table that can be seen in the video after the break.

By combining motion of the gantry with table rotation, he’s able to keep the blade from ever making too tight a turn. Or at least, that’s the theory. While the machine works well enough with a marker mounted in place of the blade, [Andrew] says he never got it to the point it could reliably make cuts. It sounds like positioning errors would compound until the machine ended up moving the work piece in such a way that would snap the blade. Still, the concept definitely works; towards the end of the video he shows off a couple of pieces that were successfully cut on his machine before it threw the blade.

While we’ve actually seen DIY scroll saws in the past, this is the first computer controlled one to ever grace the pages of Hackaday. While some will no doubt argue that there’s no sense building one of these now that laser cutters have reached affordable prices, we absolutely love this design and how much thought went into it. At the very least, we figure this it the beefiest doodle-drawing robot ever constructed.

40 thoughts on “CNC Scroll Saw Makes Promising First Cuts

  1. When _I_ talk about CNC machines I nearly always mean a mill or a lathe (and I talk about CNC machines more than most)

    But, I think this is an interesting idea, but think it might have been better to rotate the blade rather than the work.
    On the face of it this might appear to be mechanically complicated, but it is trivial with CNC to move two motors in synchronisation, so a small stepper at the top and bottom of the blade along with a set of bearings for the blade clamps ought to work (at the cost of increased inertia in the blade frame, and that might well matter)

      1. There’s a spiral one around too.

        I wonder how difficult it would be for the well equipped shop to just de-temper a regular fine tooth, twist it, and retemper.

      2. The spiral scroll saw blade was the first thing that came into my mind. It cuts in all directions. Thus eliminating the need to rotate the wood with the lazy Susan. Then it moves more like cnc router in xy axis. I think this would work for making puzzle pieces but overall lacks the piercing actions needed to cut out holes.

        Twas very interesting nonetheless.

    1. I want to see you use two steppers in a reciprocating machine with the speed of a saw blade. then i want to see the motor and mechanics you use to move those two steppers and the saw blade up and down on that speed. After that i want to see the mass you use to dampen the shaking of the whole contraption. :-)

      1. I did recognise in my original message that the motor inertia would be a problem.
        It is possible that extremely small motors with a large gear reduction would work. I have some 6mm steppers that run at 5000rpm from a 5V supply (much to my surprise). The blade doesn’t need to rotate very fast, as far as I can tell, so perhaps, with a very large reduction, those would work.
        Iideas that spring to mind are ball-splines, bowden cables, long toothed belts (either off to the side, or running along the saw arm to the pivot) or a miniature version of the torque link used on aircraft nose-wheels.
        It is also possible that extremely small motors with a large gear reduction would work. I have some 6mm steppers that run at 5000rpm from a 5V supply (much to my surprise). The blade doesn’t need to rotate very fast, as far as I can tell, so perhaps, with a very large reduction, those would be an option (I got them as they were very cheap indeed on eBay and fancied making a vacuum pickup and parts aligner in the format of a flat-bed plotter pen)

      2. I can’t imagine the power requirements, either!
        The machine would have to weigh a ton just to stop the floor vibrations sending the whole thing wandering away!

    2. “When _I_ talk about CNC machines I nearly always mean a mill or a lathe (and I talk about CNC machines more than most)”

      One tends to use qualifiers, like CNC, when needed to differentiate. We don’t say CNC laser cutter because manual units are vanishingly rare. Lathes and mills are commonly manual, and have historically had other control means as well (tape numeric, cam control screw machines, Kellering mills, copy/tracer/pattern lathes and mills, and so on)

      I would say that for a scroll saw, the CNC qualifier is possibly not strong enough…

      1. Drag knives use a carefully mounted blade on a bearing, and the cutting edge is fractionally behind the bearing, so the blade automatically turns under the cutting pressure to align correctly.
        Whether that could be done on a fret or scroll saw, with the extreme vibration, I doubt.

        1. Drag knives work as you describe, yes. (I have used them in the POM 3D printer I built in about 2003)
          But there are also systems that actively rotate a cutter to follow the line.
          Here: https://youtu.be/Yht03YyNQWY?t=631 Is what appears to be a commercial CNC machine with a reciprocating tangential knife. (one rather cunningly using vacuum to hold down many layers of fabric)
          The knife is actively aligned with the cut.

        2. Before you doubt, take a look at the blade holding mechanism on the new Pegas scrollsaw/bandsaw hybrid. It’s got gimbals that allow the blade to rotate smoothly without breaking. That’s for basically a very skinny fragile bandsaw blade, but there’s no reason the same mechanism wouldn’t work here.

          Doubting something is possible is usually lack of vision. That could be a motto for a site like this.

  2. There are huge CNC chopsaws for plastic and composite sheet, I used to work in a place with one.

    There are also CNC stone sculpting robot arms.

    Basically, theres tons of specialty CNC machines, you just normally think of lathes and mills.

    Still- that is a very cool stage design he came up with, I like the annular geared ring. Looks really cool. If you used a round style twisted tooth blade, you could cut in any direction without snapping as this moves.

    They do make diamond wire saws that are round wire impregnated with diamond chips for cutting tiles, ceramics, and even gems, and if you combined this approach with that you could do some ridiculously ornate glass and tile inlay work

    1. This. He could make good money making intricately cut tiles. He doesn’t even need to do the install, just sell his services to the installers. That could start out as nice side work.

  3. Hmmm…I wonder what the challenges are to redesigning a scroll saw blade? If the blade was designed to be more like a very small round needle file you could cut in any direction.

    1. There are at least 3 types of cut any direction blade available. However, it may be advantageous to solve the problem for regular blades as the kerf is much narrower, you’re putting a minimum 3mm slot in everything with the multidirection ones I think.

      1. The largest spiral from the brand I use is a 1.27mm diameter. the size I normally use is 0.89mm, and the smallest they have is 0.61mm. (These are Flying Dutchman “New Spiral” blades.) For comparison, the flat blades go down to a 0.2mm kerf, but those break very easily (Flying Dutchman “Ultra Reverse”.)

  4. The advantage of this over a laser cutter is that you can cut anything the blade can handle. With a laser cutter you have to worry about toxic fumes, gunking up the lens/mirrors, and the burned edges of every cut.

    The problem with this is there’s no way to move the blade through the material without cutting, so everything has to be done with a continuous cut, which somewhat limits the amount of automation that can be achieved. It would be really cool if the machine could disconnect the blade, pull it out of the material, go to the next cut location, drill a hole, then reinsert the blade and start cutting. The difficulty in doing that is probably why people use CNC routers instead of saws…

  5. I wonder if you’d be better off building the stage on the scroll saw and manually guiding it across the work piece. Something like the shaper origin handheld CNC router. The scroll saw and the router benefit from human senses detecting when things have gone wonky.

    1. Maybe just draw everything out with a pen and implement a line following robot, 2 independently powered wheels, but the body fixed in place, with pressure on the wheels, so it just “drives” the material through the saw.

  6. Look for wax blades at a jewelry supply, like Rio Grande or Gesswein – they come in some pretty small sizes and are a twisted blade, so can cut in any direction. I have cut silver with them and they held up fine! Great idea on the machine!

  7. Wow! Very well done. It’s interesting to see how much complicated movement of the workpiece is needed to cut shapes.. but doing it by hand, it all seems very easy and intuitive.

    Good luck with this project. I can’t say I’m in the market for one of these, but looking forward to watching some youtube videos.

  8. I regularly use spiral blades on my scroll saw. Picture a blade with teeth on the front and back and then twist the entire blade into a tight helix.

    It cuts very well in all directions and leaves nearly as clean a cut as a standard blade. They don’t even really cost more than standard blades. The only real drawback of spirals is they cut so well in all directions that it’s very hard to cut a straight line or smooth curve with one….but that’s hardly a problem for a CNC saw, now, is it? I’m actually surprised anyone would even attempt this project and not use a spiral blade.

    And with the smaller sizes of standard saw, blades, you can easily make a 90 degree cut without snapping the blade, the only reason it breaks on the turn is because inexperiences people have a tendancy to push sideways or too hard as they make the turn. Again, hardly a problem under CNC.

  9. Others may have mentioned it, so just to reiterate, i own and use scroll saw blades that are made in a spiral pattern and can infact cut in any direction without snapping, as long as you don’t move fast

      1. It certainly should be possible to put a bow in the blade, just like the hotwire thing, running feed-rollers at each end in synch to keep the length between guides at the required length, but I don’t think that you would be able to get enough cutting pressure in the middle. In a conventional bandsaw that comes from the blade tension.
        But it might work slowly. Try it?

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