Angle Grinder Speed Hack




About: Gadget fan, woodworker, photographer, husband, cyclist, kayaking SUP riding real ale drinker who does a bit of bouldering.

I have recently introduced some angle grinding sanding into my woodworking workflow unfortunately this does seem to cause a fair amount of burning to the wood.

I needed to come up with a quick / cheap fix.


Step 1: Burnt Wood

The problem seems to be most pronounced when using a flapper disk but anything other than really light sanding can burn the piece.

Step 2: YouTube Research

I found a set of videos from Bradley Boggs of the Carter Wilson workshop that covers power carving and sanding in great detail.

Bradley mentions the flexibility and control that you can get with a variable speed angle grinder. I don't do a great deal of power sanding so decided to look for a slightly different option. I found a video by Mike Shoesmith that confirmed my thought process.

Here is Mike's great video on the dimmer switch hack.

Step 3: My Workshop

Around my workshop I have a couple of IEC multiway sockets.
Most of my woodworking gear have IEC plugs so I needed something that would sit in line with these. Thankfully I always keep a few electrical bits lying around the workshop one of which was a 240 V dimmer switch. Here's a quick back of the envelope sketch of the set up.

Step 4: All of It Put Together.

Super pleased with the end result, I can now drop this controller inline with a number of my different tools.



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    6 Discussions


    1 year ago

    do you own a air compresser ,an air grinder you can control the air pressure


    1 year ago

    So it's an ible on how to kill your grinder? Let me explain

    An electric motor has a copper coil and magnets (either electromagnets or permanent). Part of the motor rotates to extract energy from the opposing magnetic fields.

    If the motor is prevented from rotating, this energy is not removed. The (now static) magnetic field resists the continuing flow of electrons through the wire and so the resistance in the coils goes up, increasing the current draw and dissipating the increasing electrical energy as heat in the wire. Eventually the heat destroys the insulation (often shellac, a type of varnish) in coil leading to a dead short, fatally destroying the coil or electromagnet. It does usually smell, but it may not take too much damage to kill the motor so this may not be noticed.

    1 year ago

    probably work fine for sanding, but they have much lower torque at lower rpms

    1 reply
    Stevens Workshopbaecker03

    Reply 1 year ago

    I shall bear that in mind baecker I only really plan to use it for sanding


    1 year ago

    I used one of those router speed controls for a similar project too, works about the same I guess then. ☺

    1 reply