Will my US 120v power tools work on UK 240v 50Hz?
Probably not, but check the specs.
A lot of consumer electronics - e.g., computers, TVs, etc. will work fine on a range of 90V - 240V and 50/60 hz. That is because they are designed to work that way and a key is that most of those electronics actually work on DC power. So they build in a power supply that converts high voltage AC to low voltage DC. Frequency doesn't matter (within reason) because the result is DC = no frequency at all. Voltage doesn't matter (within reason) because there are components that can handle a wide range and 90 -&gt; 5 or 240 -&gt; 5 is a big change either way.
However, motors are a different story. If a motor runs directly on AC then it will be dependent on the voltage and the frequency in a number of ways, and rewiring (or possibly even redesign) is needed to run correctly (and safely) with 2x voltage and/or 50 instead of 60 hz frequency.
Check the specifications or the nameplate and you should be able to figure it out easily enough. The frequency is a particular issue with motors, so even if you use a transformer to go from 240V to 120V, the motor may still not work correctly, leading to it running too slowly and/or premature wear.
Battery operated tools are a little different. Since they run off batteries, the only issue is the charger. Battery chargers are often designed to handle 90 - 240 &amp; 50/60, just like laptop computer power packs. But check the specs to be sure.