DIY Brushless Dremel Tool




About: Being a science student i love to indulge in projects related to engineering as i love to learn things practically...

Its been almost two years as I got my first batch of cordless tools, most of them were brushless so love the amount of power these tools offer.

With me scratching my head about what to built next I had an idea to built a brushless Dremel tool thats powered by those high capacity lithium ion batteries.

Well the idea sounds good but the challenge it to make that brushless Dremel tool without throwing a lot of money on parts and making the whole project as easy as possible.

So the goal is to built a brushless Dremel tool out of scratch. So get through this intractable in which I am going to show you how to make a Brushless Dremel Tool under just 15$.

Lets get building…

Step 1: Tools and Materials

The list of materials for this project is:

The list of tools recommended for this project is:

  • Handsaw
  • Drill machine
  • Drill bits
  • Soldering tools
  • etc

Step 2: Finding a Brushless Motor/ESC (Cheap Yet Powerful)

Now the first challenge is to find a brushless motor. There are two types of brushless motors, inrunner and an out runner motors. The term in and out refers to the position of the magnetic rotor in the motor. The one that we are going top need is an out runner motor due to the larger amount of torque it produces as it has a large moment arm as compared to the in runner type of the same size.

As compared to the conventional DC motors these Brushless motors needs an ESC to run them. So we need to avoid all those complexities and for that I decided to use a Brushless motor from a high speed server/PC fan. You can easily recognise these fans by the higher amount of current draw as stated on the rear side of these fans. These fans comes fitted with an ESC so all you need to run the fan is to connect it to a 12v battery. But be careful as they can cause serious injuries if not handled properly.

Now what we need to do is to get that brushless motor out so I broke the casing and the fan attached to the motor.

Step 3: Extending the Shaft

By now we have a brushless motor but we need to attach an adapter for holding the appropriate bit to get the job done. For that we need to replace the existing shaft with a longer one. So I removed the clip from the rear side of the motor shaft to take off the magnetic rotor. The shaft is push fitted inside the motor bell. SO to remove it we need to hammer it using a nail.

The shaft measures nearly 3mm in diameter and we managed to find a shaft with same diameter from an old CD rom with our desired length. So we push fitted the new shaft with a Hamer. For the adapter I am going to use a Drillpro Adapter kit ideally made for application for making Dremel tool.

Step 4: Motor Holder

Now to hold the motor I am going to use a 1in dia PVC socket with 45 degree angle. Not only it fits the motor rear side perfectly with a minor sanding but it also makes working with the tool much more ergonomic.

First I sanded the motor rear plastic housing and then glued it to the PVC socket. Next I have extended the wire and removed all the unnecessary wire. The red wire is VCC and the black one is ground.

Step 5: Battery Pack

Now to power this tool we are going to make the battery pack using three 18650 lithium ion cells. I salvaged these cells from an old laptop battery, they were holding identical voltage above 3.7v so I expect them to work porperly.

All the three cells were soldered in series with a pair of wires connected on both the positive and negative battery terminal. Out of which one wii then be connected directly to the charging socket which is a 5mm input jack.While the other pair goes to the motor through a toggle switch which is going be used to turn the motor on and off.

Now to make everything simple I haven't added a protection circuit after the battery which will stop the battery from draining below its minimum voltage but you can do that by adding three tp-4056 modules along with the battery pack to do the job and increase the reliability of the battery pack.

Step 6: Battery Mounting and Enclosure

Now to mount the battery and built an enclosure we are going to use a 3 inch PVC pipe and cut it short to make it fit perfectly to the battery pack. The battery is first glued to the PVC socket/motor mount and then I clipped the PVC pipe using two jubilee clips and the glued the PVC pipe to make it hold the shape.Once the glue dried I removed the clips and sanded it to make it look perfect.

Step 7: Pinting the Enclosure

Now to give this tool a neat look I decided to paint the enclosure using a matt black and a yellow spray paint. I masked the motor, switch and the charging socket. The enclosure is then painted and the finish went really good on that one.

Step 8: End Results

As the paint dried I have removed the masking and the finish was well worth the work. That mini handful brushless Dremel tool went above our expectations and performed really well. At first I was a bit worried about the power of this motor as these kind of motors are not meant I mean they are absolutely not meant for the purpose that we are using them but they performed really well. The torque is fair enough to grind through metal and can handle the largest 2.5mm drilling bit that can fit inside this adapter.

As far as the efficiency is concerned the motor seems to do the job pretty well and the battery pack is large enough to run the tool for quiet long before we run out of battery.

Overall the project ended us adding another useful cordless and Yes Brushless Dremel tool without breaking the bank.

For more interesting DIY projects visit my youtube channel.


DIY King

Epilog X Contest

Participated in the
Epilog X Contest



    • Games Contest

      Games Contest
    • Growing Beyond Earth Maker Contest

      Growing Beyond Earth Maker Contest
    • Stone Concrete and Cement Contest

      Stone Concrete and Cement Contest

    16 Discussions


    Tip 3 months ago

    good job Thank you!


    Answer 5 months ago

    Thanks. Motors shd be readily available in large urban areas where many computers are simply tossed into the trash or left the the cub for sanitation dept pick up. Some cities have recycling centers. I'm sure that w/a little persuasion motor-seekers would be allowed to extract some parts--after all that IS what recycling is all about, no?


    Reply 5 months ago

    Ok, hope I will find a long shaft soon :D


    5 months ago

    Great job. I made one similar to this. I recycled the housing from an old 3.6v rechargable rotary tool, pulled out the wimpy nicad batteries, and wired in a 5.5mm x 2.1mm barrel jack. I took the 42 volt power supply out of an old HP office jet printer and wired it to a barrel connector to plug into the tool. Voila, the thing ripped at probably 20,000 rpms, but that wimpy motor wasn't powerful enough and got too hot under load. So I took the paper feed and handling motor out of the printer (a lot bigger and had more turns), and modified the housing to hold it. I added a ball bearing to support the collet shaft. Now it really rips! Lots of torque and good power. Nowhere near my dedicated Dremel XPR, but for precise work it's amazing. Just needs a variable speed controler to be perfect.


    Question 5 months ago on Step 8

    Looks terrific. Pardon my ignorancve but 1] what is ESC and 2] how to distinguish between inrunner and outrunner motors?

    1 answer

    Answer 5 months ago

    ESC - Electronic Speed Control -- most simple form it provides an electronic equivalent function to the brushes and commutator to run a brushless motor.

    in-runner vs. out-runner - which part of the motor rotates, the inside or the outside. outside means most of the external housing will rotate, but there will always be a small part stationary for mounting and electrical connections. inside means only the shaft of the motor rotates and the entire housing is stationary holding the mounting points and electrical connections.


    5 months ago on Step 8

    The battery voltage must never go below 3.0 volts. Better is 3.5 vdc. This is critical. If 18650 lithium ion batteries are discharged to 0 volts they won't last and may die after 1 cycle. These batteries are generally charged to 4.1 vdc and discharged very rapidly to 3.9 and stay above 3.7 for a long time and then discharge very rapidly. For optimal performance, they MUST be not be discharged below 3.6 vdc. If they are discharged to the point where manufacturers say is the absolute minimum (3.0) the life is about 30-60 cycles. If charged at 3.6 volts the life is perhaps 600 cycles. There is little point is discharging past 3.6 anyway as there is very little power left by then.

    Trying to be nice, but truthful.

    Great idea, bad implementation, that motor is not nearly powerful enough. Even if it were, the rpm's are way to slow for an effective dremel type grinder. You can say it'll cut through metal, but it'll take a long time to do it. Even a Dremel tool turned down to a few hundred rpm's will not grind or drill effectively. It'll polish delicate objects and that's all this build is good for.

    A motor that draws around 2 amps at 12 volts is only 24 watts. Most of those fan motors are going to be closer to 10 watts.

    I read the instructable because it IS a great idea. But it would be a waste of my time to use a muffin fan motor to build one. I believe this author is misleading readers.

    Again, great idea, but not with a small muffin fan motor. There are lots of small high rpm motors available for less than $5.00.


    5 months ago


    Answer 5 months ago

    DIY KING 00gandymarsh

    Answer 6 months ago

    I can charge these cells using an Imax B6 AC lipo charger


    5 months ago

    How doe this compare to a typical Dremel tool as for power and speed? Interesting concept. Thumbs Up!

    2 replies

    Reply 5 months ago

    Probably about the same as a 12VDC harbor freight unit....enough for light stuff such as drilling PCB's and maybe very light cutting, but don't expect it to be a powerhouse...but it's DIY...


    Reply 5 months ago

    Sorry! I hit this button by mistake.


    6 months ago

    Well done. Nicely detailed Instructable.