Single Phase Speed Controllers

I've just made a flexible shaft and handset arrangement to polish twostroke
ports and the like. I'm thinking of running it off a 400W, 11000 r/m Bosch
angle grinder but I need to control the spindle speed. Does anyone know of
a suitable unit at reasonable price? I also need a foot switch. With
Thanks, Jim Lugsden
Reply to
James Lugsden
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The angle grinder will use a universal motor, so you can control its speed with a triac circuit like those found in domestic lamp dimmers.
If you know what you're doing with a soldering iron: get a cheap dimmer switch rated past 400W to cope with the surge current at startup. Open the case and replace the large wound inductor (should only be one) with a short circuit; the motor has it's own inductance, and you want to minimise the total. Connect up the dimmer in series with the motor, and off you go - I wouldn't stand too close the first time, and check for hot smells afterwards :) You may find adjustment jumpy at minimum speed, or if you change speed fast - inherent limitations of this simple circuit.
HTH Guy
Reply to
Guy Griffin
If you havent already got the grinder what about a variable speed router?
just an idea
Dave
Reply to
dave sanderson

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