About 10 days ago, making a rack for the grinder, I felt inconvenient when working, namely, there was not enough control over the speed of rotation of the disk, inconvenience when turning on and off, etc. Collected in a couple of hours foot pedalusing for this purpose the speed control from a broken drill. The device is so simple that it does not need a description of its manufacture and the principle of operation, everything is clear from the photo (you can also add a pad with a limitation of the pedal's stroke, but this is not a matter of principle). The pedal turned out to be so comfortable (as one hand is released) that now I use it for other machines too. Probably, someone has already made a similar addition to their electro-mechanical assistants, and I highly recommend the rest, because it is very convenient, and most importantly, increases safety when working with a power tool.