Oneway RFI Filter Review

by Mark Kauder (with a suggestion from Wayne Cooper)

About a month ago on this forum, W.C. Turner brought up the subject of radio frequency interference (RFI) from DC motors. Most of the lathes using electronically variable speed, use DC motors. The motor controllers emit hash well into the radio spectrum that can interfere with AM radio, TV, and some other broadcast receivers.

My big complaint is that when I am in the shop, I mostly listen to AM talk radio. When the lathe is running, it produces static to the extent that you cannot hear the broadcast. So I turn to Classic Rock FM or put on a CD. All right, but not my preferred listening.

In the thread that W.C. started, someone mentioned that Oneway makes an RFI filter. I called them, and made sure that it would work with my Vega 2400. They assured me that it would work with any motor—110V–240V. So I ordered their RFI Filter, part number 2748. The cost was approximately $50 USD. It arrived the day before Christmas, but I did not get around to installing it until later.

The instructions that come with it are specific to the Oneway Lathes (using the power contactor block on the lathe). Installing it on my Vega was only a little harder. In the simplest terms, you are inserting the RFI Filter in the middle of the black and white wires of your power cable—power (line/supply) coming in one side of the filter, and going out the other side to the load (controller/motor). I did so as follows:

Unplug the lathe from power.
Remove the insulation from about 6" of my power cable.
Leaving the ground cable intact I cut the black and the white wires; and installed prong connectors on all cut ends.
I then screwed the prongs onto their respective terminals on the RFI filter.

From this point it is only a matter of making it pretty. In the case of my lathe, I attached the RFI Filter to a thick block of wood, and fastened the wires down with cable clamps so that I could not accidentally pull the wires off the filter. I then bolted the block to the inside of the lathe base.

In action: This thing is fantastic!! Once installed, when on, there is zero interference. If you are having problems listening to AM radio, or you have family or neighbors complaining about interference from your lathe, this is the ticket.

It is available installed as an option when you buy Oneway lathes.

I want to thank Oneway Customer Support Rep Kevin for his timely responses to my emails and phone calls.

Wayne Cooper: How about $2? or 10 for 1.75? I have a Jet Mini and had the same problem this weekend. I asked our Electrical Engineer here at work to do some research.

Here is his message. www.allelectronics.com or 800 826-5432

Cat #FTR-42—a 10 amp, 120V, Corcom 10EC8—has computer type power-cord socket on line and pigtails to the load. You should be able to mount it inside the lathe frame or wire it on your bench to a 110 plug for any tool.

Mouser has the original for about $30.

At that amperage, it's not going to help on your big Vega or other brute machines (Five Barns' Big Blue, for another example), but for the minis, Jet, Delta, Vicmark, it ought to be fine.