EPAIII
Diamond
- Joined
- Nov 23, 2003
- Location
- Beaumont, TX, USA
I have been using my SB-9 with just a drum switch for some years now. It is a single phase, 115V, 1/3 HP motor and the drum switch allows me to run it forward and reverse as well as having the center Off position. So it is working.
But for some time I have wanted to add an Emergency Stop switch. And after moving it into my present garage shop, I have noticed that the drum switch is in a position where it can be easily activated by someone just walking past it. So I really do need a separate power cutoff at this point before an accident happens. I have been digging into the world of contactors. At first I was going to go for a solid state relay/contactor. They are relatively inexpensive on Amazon. But they also go fast: I had a name brand one selected and was filling up the rest of the order and when I checked back; they were out of stock. And I could not find another name brand one to replace it.
I decided to switch to a mechanical design as they appear to be more numerous and I can easily get a two pole one to switch both sides of the power line. OK.
They are generally available with either 115V or 24V coils and here the question begins. Since I am going to be running a circuit around the lathe table for the E-Stop controls, I am thinking about using a 24V version for safety. I have seen and worked with a lot of low Voltage control circuits on professional electronic equipment; 24V, 12V, even 5V and they worked quite well. Never any problems due to the low control Voltage. But a lot of machinery does use the higher, 115V for the control system. So, my question is, do machine tools have any special considerations that make a lower Voltage control circuit undesirable? Any unique problems that can occur? Or am I safe going with the 24V controls?
But for some time I have wanted to add an Emergency Stop switch. And after moving it into my present garage shop, I have noticed that the drum switch is in a position where it can be easily activated by someone just walking past it. So I really do need a separate power cutoff at this point before an accident happens. I have been digging into the world of contactors. At first I was going to go for a solid state relay/contactor. They are relatively inexpensive on Amazon. But they also go fast: I had a name brand one selected and was filling up the rest of the order and when I checked back; they were out of stock. And I could not find another name brand one to replace it.
I decided to switch to a mechanical design as they appear to be more numerous and I can easily get a two pole one to switch both sides of the power line. OK.
They are generally available with either 115V or 24V coils and here the question begins. Since I am going to be running a circuit around the lathe table for the E-Stop controls, I am thinking about using a 24V version for safety. I have seen and worked with a lot of low Voltage control circuits on professional electronic equipment; 24V, 12V, even 5V and they worked quite well. Never any problems due to the low control Voltage. But a lot of machinery does use the higher, 115V for the control system. So, my question is, do machine tools have any special considerations that make a lower Voltage control circuit undesirable? Any unique problems that can occur? Or am I safe going with the 24V controls?