I would like to use star lock washers, sold at mcmaster here http://www.mcmaster.com/#91114a007/=qc5f1i, with the screw connections on Talons. Has anyone done this before and/or have any serious concerns about doing this? I would just do it, but one particular mentor is afraid they might do something wacky. Thanks for your input.
What concerns in particular did this mentor have? I would think that as long as the wire is securely crimped to the connector, and the connector is tightly screwed down, it wouldn’t matter what kind of washers or nuts you use.
He was concerned that they would add no benefit, like that no washer at all would be just as good as using a star washer. I think that i would create a more firm connection and possibly drop the resistance of the connection.
It’s unlikely to have any substantial impact on resistance. If anything it might slightly (very slightly) increase resistance at the connection. Most of the electrical connection is between the flat surfaces of the terminal and the screw’s post. Adding a toothed washer would (technically) increase resistance between the top side of the terminal and the screw head, but even then it would be on the order of milli- or maybe even micro-ohms.
The bigger reason for a toothed washer is to provide a more vibration resistant connection. Those teeth dig in and prevent the screw from rotating if the connection starts to vibrate. Whether that is significant in your mind is up to you. But, I have seen teams do this, particularly on battery terminals.
We have never used a serrated washers on our motor controllers & never had an issue. I have used serrated washers in the plant when I needed a good electrical connection. Pretty standard for grounds in UL listed boxes. So they won’t hurt.
If you are worried about losing connection, use ring terminals. Have you had anything come lose? I haven’t had anything come lose before and I usually use U terminals. I don’t know if they will cause anything bad to happen but I personally don’t think you need them.
Or, split the difference with a locking spade terminal:
We use these on all our speed controllers and batteries. They work pretty well to not allow the the connections to come loose over time.
In my experience, serrated lock washers on terminal block screws cause more harm than good. Most of these screws are plated brass and the serrations just tear them and the terminals up. A properly torqued terminal block screw will not loosen up over an FRC season.
And always use ring terminals. They are a pain to use sometimes, but a loose connection won’t flop around and touch something you’d rather it didn’t.
Rather than trying to further secure the screw connection on the speed controller, I recommend that all power connections to speed controllers be tied down on either side with a tie wrap connected to a base, DigiKey RP302-ND or equivalent. This greatly reduces vibration at the screw connectors on the speed controller.
I believe the controllers come with binding head screws so that lock washers are not really needed. You can use lockwashers if you wish. I recommend lockwashers for use between the wire terminal and battery terminal. This prevents the two from twisting in use, loosening the hardware and causing significant losses.