The Mother Of All Paper Cuts

A Dremel is a fantastically handy tool to have around the workbench, but there is one glaring and obvious downside: you will always run out of cut-off discs. if you’re trying to break into a fancy snap-fit enclosure that has been inexplicably glued together, you’ll invariably need to run down to the hardware store to shell out some cash for a tiny tube of cut-off disks.

[KB9RLW] has the answer to this problem. He’s cutting wood and plastic with paper discs spinning at 35,000 RPM.

The paper used for this application is just a piece of junk mail or heavy, probably glossy card stock. After poking a hole in this piece of paper, tracing a circle with a homemade compass, and cutting out the cutting disk with a pair of scissors, this cut-off disc is easily mounted in the standard Dremel mandrel.

The test cut [KB9RLW] shows us is on a plastic wall wart that’s a glued together, snap-fit mess. The paper cut-off wheel makes short work of this nigh-impenetrable brick of plastic, revealing the electronic goodies inside. This cut-off wheel will also cut through small bits of wood, like a bit of molding.

After cutting halfway through the wooden molding, the paper disc quickly disintegrates — this is the same behavior we last year when this trick was being used on a table saw. But any home should get more than enough junk mail for a steady supply of paper Dremel cut-off discs. While this new attachment for your fancy rotary tool won’t last very long, it is a very expedient way to get into bits of electronics without paying Dremel several cents for a cut-off disc.

41 thoughts on “The Mother Of All Paper Cuts

    1. The reinforced disc cutters are generally slightly thicker but don’t snap and fling off randomly either. They also last a good bit longer and you can still buy them awfully cheaply from mostly but not always Chinese vendors.

      1. And yet they’re shit at cutting. The point of the grinding discs is to cut stuff that cannot be sawed easily, i.e. hard metals. For wood, plastic, aluminium, the appropriate tool to use is the saw wheel.

        Dremels don’t come with saw wheels out the box because the company knows most people wouldn’t buy any more grinding discs, so they kinda pretend they don’t exist.

        1. My biggest issue with the thin breakable ones is they are utter crap overall. Not only do they break but their diameter quickly goes from an inch to the same size as the mandrel in a few seconds when you are cutting any kind of hard material. The reinforced ones are better at actually lasting more than a few seconds and do a decent enough job against harder materials. Against woods, plastics or aluminum, I agree that the saw wheel is much better. Just have to watch out for heat and plastic melting or wood smoking. I still think the thin breakable wheels are almost complete crap though.

        2. True facts. I have a Foreman flexible tool that I bought with a saw wheel and a jig for making jump rings from coiled wire. I never need cutting wheels, that saw wheel is small toothed for cutting copper, silver and aluminium (wouldn’t try it on steel). It makes short work of wood and plastic.

        3. Or just use the plastic cutting disk which works just fine and doesn’t have the issue of chipping that your silly saw wheel would use.

          The right tool for the job is the right tool for THAT job. Trying to say one tool is better than the other for [insert generic case here] is utterly stupid.

          1. >” the issue of chipping that your silly saw wheel would use. ”

            What does that even mean?

            >”The right tool for the job is the right tool for THAT job.”

            Yep. For wood, plastic and aluminum the saw wheel is usually the right tool for the job.

          2. @[Dax]

            An abrasive disk is like a disk made from sandpaper, not a lot can go wrong.

            I toothed disk is not the same. There are many issues –

            Pushing it beyond capacity will make it blunt or overheat or explode. I have a 120 tooth 14″ TCT saw disk that runs at about 4000 RPM for cutting aluminium extrusion, you don’t want explosions!

            Heat, the best saw type disks transfer as much heat as possible to the chips being expelled because getting the saw too hot will de-temper the blades.

            Rigidity, saw blade must chip. If the material being cut is not rigid enough or not clamped then you will be trying to use a saw blade to friction burn your way through, most likely bluntening the blade as well.

            Just today I saw some 89mm TCT blades and I might make something for cutting sheet aluminium with them.

            Just for comparison. Cutting aluminium extrusion with an abrasive disk is like cutting through butter with oxy-ascettelene.

    2. as mentioned in the previous thread the only place where this might have a use is where the absolute minimum of kerf is allowed and even then there are probably better materials than paper,

      1. ‘Jewelers saws’ typically have thin kerf’s since they’re cutting precious metals or rings that need resized.
        Then there’s just metal discs doped with abrasive like CrOx or diamond, though diamonds burn up at high speeds if you don’t pay attention.

    3. I have never bought one of these saw wheels as I have an entirely different thing to use from either the cut off the plastic or the saw wheels. Take a coke can cut off a piece and draw out your circle. Poke the center hole or even drill it one the drill bits. VIOLA!

      Instant Metal cut off wheel that does the same thing as this paper one. If you wanna get fancy use a file to cut a few teeth into it. I have been doing this for years, if I had known I was doing something Hackaday worthy, I would have posted it to youtube a hella long time ago. I carry 3 or 4 of these around with my dremel all the time.

      And if I am some where I need one I can cut one out in minute from a coke can or any sufficiently thick enough piece of metal. I like that I can cut plastic without spewing plastic dust everywhere.

  1. History keeps repeating itself:

    Funny how he also has an alternative use for a screwdriver (he shows that you can also use it as a hammer, wow)
    and a pencil which he uses as a piercer.

    The most interesting part is how he made that perfect circle at 1:17 I’m sure that part wasn’t also intended for that.

    But honestly, next time I need to cut something soft and all my real cutting discs are gone… I guess I will try this one. Of course with proper safety glasses, gloves and clamping tools.

  2. There are better ways to break into walwarts. A hacksaw or coping saw work fine, even a ripping saw would be okay. A file can work if it’s all you have. I usually stick it in a vice until it cracks. There isn’t much need for a power tool in these cases, and I’d hardly consider a Dremel as a power tool. They are okay for some fine detail work, but for anything else use a pneumatic or electric die grinder that actually has torque. Disclaimer: I work in a metalshop, so what you tools you see as worthless may be a little different than what I see.

    1. I was going to post the same thing – I repair all the tv power supplies in our facility – the originals fail at an alarming rate and popping them in the vice and a quick squeeze along each side cracks the joint and they pop open. ( usually – occasionally I come accross a stubborn case

  3. Though for a stubborn case using a paper cutting disk like shown here would be good as it would minimise potential damage to internal components. Using a cut of disk or saw style blade would potentially cause damage to the innards.

    1. I did observe that this is true. The internal PCB was unharmed, as was the transformer also. There’s more efficient tools for doing this, sure. But this was for self-entertainment as much as anything else. It’s not the best way, but it was fun!

    2. Previous articles also used a bit of plastic from a classic floppy disc to make a wheel and it turns out that magically doesn’t cut metal but does cut plastic so you can nicely work on connectors and such without damaging the wrong part..

  4. I got tired of breaking disks every few seconds or so not only are the cutting wheels expensive the changing out broken wheels was really taking a lot of time. Then I had a thought I took a piece of aluminum foil and waxed it with a bit of paste wax, then I placed about a dozen cutting disks on the foil and mixed up a small amount of fiberglass resin and coated the disks with it. I did one side , came back later and thanks to the wax was able to remove the disks from the foil, I repeated the process and coated the second side. a little care while applying the resin helps keep the hole for the mounting screw un blocked but a bit
    of stray resin around the edges of the hole proved no big deal and were easily mounted on an arbor for use. I also didn’t worry about epoxy resin “flash” that was beyond the edge of the disks, as long as it was a minor amount , I did not worry as this was just an experiment and I really didn’t want the fix to be more of a pain than the original problem! The excess resin was quickly worn away when I tried the disks, and the disks lasted a lot longer and were considerably more durable. I now make a batch of these regularly and keep them on hand I no longer use the “raw” disks as they come. The disks I refer to are the standard abrasive cutting disks, not the reinforced thicker ones.

    1. You are saying you sit in a cloud of epoxy dust? I hope you use good ventilation since I somehow have a feeling that’s not healthy.
      Oh and you can buy fiberglass reinforced discs ready-made you know.

    2. I buy safety sets from the dollar store. They have one set of safety glasses and 4 or 5 Particulate 4 (P4) masks. I also have an organic compound mask (for paints or chemicals) but they’re more expensive.

      I make sure I have at least 5 pairs of glasses around so that I can always find one set and I have lots of masks as well. I try to keep the glasses on the drill press.

      Safety gear is so cheap now that there really is no excuse for not using it.

      Definitely don’t chance it with your lungs because you get no warning when things go wrong. A MRI scan doesn’t see the damage until it will be a chronic condition that progressively reduces your quality of life and symptoms don’t show before this either. Same with smoking tobacco.

      1. I doubt you should trust dollar store dust masks. Some of them might be Ok-ish, but a lot of them are about as effective as breathing through your shirt (Ie, not very). A set of reputable brand masks won’t set you back all that much more.

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