Better Speed Control

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Forum topic by Redoak49 posted 08-19-2018 02:18 PM 600 views 0 times favorited 1 reply Add to Favorites Watch
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5416 posts in 3269 days

08-19-2018 02:18 PM

I have a Harbor Freight Die Grinder that runs at 25,000 rpm.

I wanted to slow it down and bought the Harbor Freight router speed control. It is identical to ones sold under a lot of names.

However, it only slows it down to about 18,000 rpm and would like to go slower.

Does anyone have experience with one that works better and does not break the bank.

1 reply so far

View oldnovice's profile


7757 posts in 4648 days

#1 posted 09-10-2018 05:01 AM

Get a variac, variable AC transformer, also known as an autotransformer.
Cost anywhere from $60 to several hundreds depending on other feature like frequency and/or current control.

2000VA 20Amp Automatic Voltage Regulator/Stabilizer Single-Phase Variac Transformer

This one is from Walmart for ~$70.

Realize that when you reduce the voltage to reduce speed you also lose torque and possibly increase the current drawn by the tool making it get hot faster.

-- "Facts do not cease to exist because they are ignored." -- Aldous Huxley

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