Cordless Power Tool Vacuum Cleaner Starter

These are some vacuum cleaner starters I designed for my Makita cordless tools. When the tool starts, the unit detects the rise in current and transmits a "turn on" command to an off-the-shelf remote-controlled power socket. With the vacuum cleaner turned on and plugged into the remote-controlled socket, it automatically starts when the tool starts. After the tool has stopped (and the current has dropped), it waits a couple of seconds to allow the vacuum cleaner to catch the last bits of sawdust and then sends the "turn off" command to the socket.

There are two versions: a standard variant (shown fitted to my track saw) which is designed to be as compact as possible and an offset variant (shown fitted to my random orbital sander), which is used where the added length of the vacuum starter causes issues with the tool design (in the case of the random orbital sander, the dust pipe is tilted upwards and would touch the vacuum starter if I used the standard one).

Below is a very short video showing the unit in action. On the first run of the tool, the vacuum starter is turned off and nothing happens (apart from the track saw running, obviously). On the second run, the unit is turned on and the vacuum cleaner starts automatically (watch the light on the socket in the background).

Background

Makita offer some of their tools with an option called "AWS": Automatic Wireless Start. This sends a command to a compatible vacuum cleaner to automatically start it and is a great solution if you have one of their cordless vacuum cleaners. However, there are a few problems with their approach:

  1. You have to own a compatible Makita vacuum cleaner.
  2. You have to have bought an AWS-compatible tool.
  3. You have to buy the AWS module.

All of these are a problem, but in some ways the second one is the worst. If you've already bought a Makita tool and chose to buy one that doesn't support AWS, you would have to replace the entire tool to be able to add AWS.

I didn't like any of those issues, so I decided to come up with my own way of starting a vacuum cleaner. My workshop vacuum cleaner has a handy socket on the front for power tools, but that obviously only works with mains powered tools. I prefer to buy cordless tools where possible/practical as I already have the batteries & charger and I like the convenience of not having cables to sort out. If I'm working outside (and hence taking full advantage of the cordless tools), I generally don't bother with the vacuum cleaner and just let the sawdust fall. When I'm in the garage I prefer to connect the vacuum cleaner to keep the dust down, but it'I s easy to forget to start the vacuum cleaner and the combination of ear defenders and the noise of the power tool means it's not always obvious that the vacuum cleaner isn't running.

The power socket on the vacuum cleaner (presumably) works by detecting the current drawn from the power tool and I figured I could use the same method for the cordless tool if I could add some sensing circuitry in between the battery and the tool.

Details

Details of the build are documented in a separate series of pages:

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