I have s WW Pro with Redline Spindle and 240v VFD. A little surprised that Redline didn’t consider providing easy method for using a relay to power dust collection system. I understand that what I need is a ‘current sensing’ relay. Can anyone provide a specific recommendation for a particular relay I can use to fire up my 110 Fein vacuum when current flows through spindle cable?

Wrong pin. I found it, and found the other gnd pins in the bb tech manual. No need for replies.

I’ve been using an iVac for the last couple of years, and have had no issues with it. The current sensing unit has a switch that allows you to disable the auto-start, or manually turn the vac on, which is handy when I use my Suckit hose to vacuum the machine bed before placing new material on it.

Hi John - I don’t know what you mean by a ‘current sensing relay’. Fundamentally, if the controller knows when the cut starts, then it can enable the dust collector using a simple digital signal. Alternatively, if you really want to “sense” current, then something attached to the spindle controller would be required and that would have to turn on the dust collector. As Michael mentioned, an iVac would work, but they are a little expensive. Though, those “internet switches” are also expensive. I guess it depends on the level of automation and price you are willing to spend. Some time in the future I may have a solution for you, but it’s not top priority right now. I’m happy to work with you if you want. -Tom

I have done this multiple times using a current sensing switch from Amazon to trigger a relay with my 110v spindle to start a 220v dust collection system and also to turn on a 110v dust collection system whenever one of 4 different 220v 3ph surface grinders start. You have to split only one wire from the wire that goes from your VFD to the spindle and put it through the switch. I did this by creating a short cable that connects between the VFD and spindle so that I did not have to cut into the original cable. If you use an IVac (expensive) it would have the VFD plugged into it. this would trigger the IVac switch turning on the dust collection all the time. Current switch from Amazon was about $10 and the relay I had. Just for some added information the current sensing switch senses amps and closes a circuit so you would need a relay for it to trigger, and you can only put one wire through it as multiple wire send amps in different directions canceling each other out hence the need to split off 1 wire from the cable.

This is the switch I used Jadeshay AC Current Sensing Switch, SZC23-NO-AL-CH Adjustable 0.2-30A Normally Open Self-Powered Current Sensing Switch: Amazon.com: Industrial & Scientific

Tom, the new Redline VFD cables to the BB Controller using their own custom cable to the DB25 on the BB, and no access to separate start/stop pins like there are on for example a Huanyang VFD.

Rob, I saw that switch from your previous post - what I couldn’t find is what is the output voltage from that switch so I can match it to the proper relay?

[image] jnordyke: is what is the output voltage from that switch so I can match it to the proper relay? You can use a 110v contactor. The switch only closes a circuit what voltage goes in comes out. The switch is normally open and when it senses current it closes. it does not handle a lot of amps on the output so you need a contactor or relay for it to trigger your dust collection. I’ll look and see if I can find what You need.

John, this is the contactor I used for the 110v dust collection. Amazon.com: SunLee 2 Pole 40 Amp contactor 120v coil UL 2 pole Lighting Load 50 AMP Contactor equivalent to 42CF15AF Condenser Compressor Contactor : Industrial & Scientific I have a total of $120 invested in that system including 50 ft of wire, a box for the contactor, a wire with a plug (cut extension cord) to power the contactor and dust collector, the contactor and the switch. I mounted an outlet on the box that the contactor is in to plug the dust collector into.

It’s covered in this thread: [image] Tool Enable - M15 - IOT Relay - & Breakout board (auto turn off/on router) Controller (Buildbotics) Discussion I have been trying to leverage the tool enable and this IoT relay My previous CNC had this and it was a great feature to have the router turn on automatically at the start of the job and off at the end of the job. I have the breakout board but so far I haven’t been able to get it to work. From what I can tell it only needs 3 volts for it to trip the relay. My old Lead1010 used this via the tool head on (M3 S#) then M5 to turn it off. [31d3DLX1ubL.AC] [91O6jIU37EL.AC_SL1500] Any help would…

Thank you Rob - with my previous OF I had a HY VFD with a convenient 12v signal on start and programmable delay on stop that I used to close a normally open 110 relay to my shop vac. I guess I could find an independent 12v power source and still use that relay. I appreciate the legwork you put in.

Current Sensing Relay Recommendations

Original/PRO Series (Buildbotics) (Gen 1)

OnefinityCNC (Onefinity CNC Official ✅) October 6, 2025, 1:17pm 10

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Current Sensing Relay Recommendations

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