When [Andrew Consroe] tried to build a CNC scroll saw, he quickly learned how tricky the design problem is. With a blade that only cuts in one direction, you cannot simply move the tool in the X and Y dimensions like using a laser or router; the workpiece or the blade itself needs to be continuously rotated in the cutting direction.
He recently showed off the third version of this machine. Although it is still not exactly a practical tool, there is no doubt that it is a beautifully designed tool or that it works very slowly. Early attempts to use a rotating table to rotate the workpiece, but [Andrew] found that this was an imperfect solution. It is a difficult task to build a heavy machine that can rotate the material to be cut while maintaining enough precision without breaking the blade, although it is indeed very close.
This time, he decided to simply rotate the blade itself. This can be achieved with a single stepper motor and some suitable sized pulleys while maintaining extremely high accuracy. The entire blade assembly moves up and down on an aluminum extrusion guide with a motor and a crank device. By synchronizing the rotation of the blade with the vertical movement of the saw, the software can ensure that everything is in the required position before the cutting stroke actually takes place.
Judging from the video after the break, the system worked well. The intricate circle he cut out of a piece of plywood looks basically perfect, and it sounds like this new version of the machine will not damage the blade due to the wrong position like the previous one. Unfortunately, it is also very slow. With so many moving parts and careful positioning, even if the video is accelerated by 10 times, the saw still seems to move slowly in the material.
In the second half of the video, [Andrew] detailed another method of rotating the blade, which can reduce the quality of movement in the saw. This will give the machine a considerable speed increase, and we would love to see him implement it. By the way, before anyone says: Using a spiral blade is cheating.
In fact, there are ready-made square linear guides, which can move linearly and transmit torque: https://www.igus.com/drylin/linear-guide?sort=3&fc=301214&inch=false is cheaper, but the parts needed are better than you show The design is less, and the weight will be much lighter. As for the up and down movement, I will try a pneumatic cylinder. The spring is installed near the end of the stroke to dampen the end stop. A sensor (such as an induction type) is positioned to detect when the cylinder just touches the spring. Then there is the problem of setting up the Arduino or whatever you use to monitor these sensors and drive the cylinder valves. When it detects a cylinder close to the top during the ascending stroke, it will switch the valve to move downward. When the cylinder enters the detection range of the bottom sensor, it again switches the valve to top movement and so on. These babies may be very fast, and you can easily adjust the frequency by changing the pressure or adding a throttle. In addition, because you control the up and down travel, you will still know when you can safely rotate the saw.
Interesting project, many challenges, good job!
It is great to see the progress of this project.
If a viable spiral blade has the same number of cuts, it is not so much cheating as it is smart.
This update made me think about a very good band saw blade. It appears that such a blade may be able to twist during operation to cut from different angles. Not sure if it can be done without flattening the teeth, but it is an interesting sequence of thoughts in a few minutes.
I came across the band saw you mentioned and it seems to work very well. I don't know what range they get, but I think it only has +-20 degrees or something. Didn't do what I wanted, but still cool. https://youtu.be/PP5PAS1aQo0?t=68
marvelous. I think shallower (?) blades may be able to twist further. On the other hand, you can never push as much material into it as quickly as a 1/2 inch deep blade.
When the whole goal is to try to make a CNC rolling saw, this is cheating.
If it is just to make a practical CNC tool, he will use router/milling machine/laser/anything and it has been completed. The project is specifically aimed at solving the engineering challenges inherent in this type of blade.
Hmm... Does changing the blade geometry mean that it is no longer technically a rolling saw?
I think the goal is to achieve specific results in editing. Sharp turns and possibly very low cut loss. I imagined an automated process of creating custom puzzles (rolling saw puzzles?).
I want to know how thin the seam can actually be with a reel saw. According to the Internet, a thickness of 0.010 inches is usually used for thin-cut rolling saw blades. In addition to the laser, I expect it to be difficult to match with other types of cutting equipment. In wood, the laser will burn the edges, which may be beneficial or unfavorable.
My opinion is that in order to meet the design challenge, it must be a linear reciprocating saw blade, so something like a diamond dust wire saw may qualify.
One small problem: the linear reciprocating blade * is fixed by both ends * under tension. Otherwise it is more like a jig saw. It is fixed at both ends to allow narrow incisions. And, yes, I agree that the diamond dust wire saw should be eligible, although I don't know how long it will cut the wood before it gets clogged.
Compared with lasers (or routers), one disadvantage of rolling saws is that rolling saws can only perform one continuous cutting without removing the blade, and to start cutting in the middle of the material requires drilling a hole in the material.
See Olson for "All-round serrations with 360° cutting capability."
That's what I thought. It may be necessary to slow down the feed rate because only a portion of the blade is cutting during each stroke, but the direction problem is solved.
There is a long blade that rotates 360 degrees, and only the right angled part of it is used for cutting
This looks like the perfect application for the hollow shaft rotating ball spline. You will get tension, rotation and accurate up and down movement from the hollow shaft, all in one package. Add a return spring to the bottom bracket, you can make the top and bottom not physically connected. Add a pair of timing belts on the shaft connecting the top and bottom, you can use a gantry frame to increase rigidity.
Good shot. The props for this guy, as someone said above, is actually more about design challenges than actual demand for cnc scroll saws. But during the whole time I watched, I was thinking "This kid thinks too much. Of course, you can use the normal scrolling mechanism instead of all those precise timings, and it's just..." Aaaa I have a semi-support Sketchup model. I guess I’d better save money for some servers and put the money on my lips!
But I like this person's work!
In addition, if I am right, I can tilt the entire device and perform a bevel cut.
It’s a bit painful, like watching someone design a motorcycle from scratch, then choose a centrifugal jet turbine, powered by coal dust, and then decide that the rear wheels can be non-slip, and make it a front-wheel drive with omnidirectional Wheel, made of laminated bamboo, friction welded together, using an improved electric toothbrush, solar panels recovered from 50 calculators...
well done. If you are looking for spherical splines with pricing, you may want to consider Misumi (https://us.misumi-ec.com/vona2/detail/110300024960/). I am using one of them for the swing tangential tool I am working on. The cost of a 200mm long 6mm shaft I ordered was about $154. Although I'm still testing the configuration, my running speed has reached 2,000 times per minute. If you want to see how I use ball splines, I put a Fusion 360 project file here: https://github.com/mhgreen/oscillating_cutter.
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