- Joined
- Mar 23, 2021
- Messages
- 357
I wonder if PM has a way to track rail shipments? Sounds like John was making a WAG?
-
Welcome back Guest! Did you know you can mentor other members here at H-M? If not, please check out our Relaunch of Hobby Machinist Mentoring Program!
Another obligatory New PM-833TV and PM-1340GT Ordered!
- Thread starter Christianstark
- Start date
- Joined
- Nov 23, 2020
- Messages
- 788
Reminds me of all the lumber milling I need to get done once the copperheads hibernate for the winter.That's quite the stack of stickered wood there! What's the plan for that? Just curious
- Joined
- Nov 23, 2020
- Messages
- 788
WAG indeed.
- Joined
- Nov 19, 2019
- Messages
- 72
It‘s for a Roubo workbench. I thought i would have the time during the pandemic but so far it hasn‘t quite worked out. But at least I bought the lumber when it was still cheap…That's quite the stack of stickered wood there! What's the plan for that? Just curious
- Joined
- Nov 23, 2020
- Messages
- 788
So I got some items in for my VFD install once my lathe is delivered. The e-stop is a replacement for the factory one, includes a 24V light. The Jog will replace the existing Jog button for For/Rev functionality, and I am deciding where the braking switch will go. Was originally thinking it would replace the coolant on button, but then I was thinking of replacing the Power light, seeing as the e-stop has a LED light built in. Does anyone know if the e-stop LED is always on? I did a continuity check on it but got nothing when the stop is in either position...
Thoughts?
Thoughts?
Does the E-stop switch have separate terminals for the light? If not then the lamp is in series with the estop switch. The photo is not clear, but it appears to only have two screw terminals. If not the voltage drop across the light and switch maybe a problem. Most low voltage switches with LEDs have a series resistor to limit the current through the LED. It all depends on how you wire it up and if it is a NO or NC estop. Usually you want a NC switch so that if a wire breaks then the machine stops. I cannot recall the wiring in Mark's conversion and it appears you are following his design. However, if he puts the Estop switch in series with the latching relay coil, then the voltage drop across a lamp or LED may tend to limit the current to the latching relay coil and it might not stay latched up even when the Estop is not activated. If you look at my conversion, you will see that I have the E-stop in series with my transistor latch circuit. In this case I have other things in series as well, but I calculate in my write up how much resistance you can tolerate. Do you know if it is an LED or incandescent lamp? https://www.hobby-machinist.com/att...2-vfddescript-links-dnl-l910_1440-pdf.378082/
You said: "Does anyone know if the e-stop LED is always on? I did a continuity check on it but got nothing when the stop is in either position..." What is the meaning of the "nothing"? Did you use and resistance measurement? If it show open circuit in for both switch positions maybe you need to reverse the VOM leads. If it has an LED in it and you measured the LED (diode) in a reverse bias direction, then diode should not conduct and you will think it is an open circuit. By the way, old fashioned VOMs (metered not digital display) were better for this sort of measurement as they would measure the actual large resistance value ( at low VOM battery voltages) rather than just saying is open. Maybe you should post the link to where you purchased the estop switch. Also, is there a + and - indicator on the estop inputs? Was the estop spec. for a certain voltage? If so maybe just apply a voltage to it and see if it lights up. If it is spec is at 24 volts then you can use a 9v batter to test it. An LED will just not light up as bright because the series resistor is sized for 24volt.
By the way, sometimes you can take these switches apart and either remove the LED or change the LED resistor to something that will make the system work. On the other hand, some of these lighted switches or LED lights are potted and will not come apart. In my conversion I took the indicator lamp, shown as green next to the Estop, in my figure 3 apart and removed the resistor all together. The other circuits limit the current that can flow through the LED.
Good luck.
You said: "Does anyone know if the e-stop LED is always on? I did a continuity check on it but got nothing when the stop is in either position..." What is the meaning of the "nothing"? Did you use and resistance measurement? If it show open circuit in for both switch positions maybe you need to reverse the VOM leads. If it has an LED in it and you measured the LED (diode) in a reverse bias direction, then diode should not conduct and you will think it is an open circuit. By the way, old fashioned VOMs (metered not digital display) were better for this sort of measurement as they would measure the actual large resistance value ( at low VOM battery voltages) rather than just saying is open. Maybe you should post the link to where you purchased the estop switch. Also, is there a + and - indicator on the estop inputs? Was the estop spec. for a certain voltage? If so maybe just apply a voltage to it and see if it lights up. If it is spec is at 24 volts then you can use a 9v batter to test it. An LED will just not light up as bright because the series resistor is sized for 24volt.
By the way, sometimes you can take these switches apart and either remove the LED or change the LED resistor to something that will make the system work. On the other hand, some of these lighted switches or LED lights are potted and will not come apart. In my conversion I took the indicator lamp, shown as green next to the Estop, in my figure 3 apart and removed the resistor all together. The other circuits limit the current that can flow through the LED.
Good luck.
- Joined
- Nov 23, 2020
- Messages
- 788
Yes. The 2 stacked Red switch blocks are NC. Not very apparent in the photo is a black switch block, that is for 24V power to the LED. Im not completely up to snuff on electronics, but I was thinking that maybe simple continuity was not testable across an LED. The Diode you mentioned is also an interesting thought. I am no wiz at using a voltmeter. Does anyone have a method of testing a circuit that only has an LED in series on it? I don't have a 24V power supply to test it with. Would love to see if the light remains on regardless of E-stop plunger position.
Continuity across an LED. What kind of tester are you using if not a VOM? Even with a VOM it is sometime hard to see continuity across and diode. It just depends on the diode and on the meter. The general idea of a VOM to measure resistance or continuity is for the meter to apply a small current and measure the voltage across the terminals, OR to apply a small voltage and then measure the current that flows. In one direction (reverse mode) a diode conducts very little. In the other direction, forward bias, it conducts very little if the voltage is low. Once it gets to a higher voltage (0.5 volts for a Si diode or maybe 2 volts for an LED) then the conduction is higher and can be measured. What is being applied depends upon how the meter is designed.
First, the continuity test. The E-stop side should be a short when the button is not activated, NC. So if you push in the button then it should go to open circuit. Continuity or resistance test should work. You say continuity as oppose to resistance measurement so I am not for sure what kind of meter you might be using.
Second test. You say that there are two more terminals that you think are for the LED. If there is a + and - on them then great but if not don't worry. Try a 9 volt or 6 volt battery across the terminals that you think are the LED's. You are planning on hooking it up to 24 volt later so try a 9 volt now. If you have any resistors around put a 1000 Ohm, or so, in series with it. Throw the switch to test. It should light up with the switch in some position or all of the time, but it will be dimmer than with the 24 volt supply. If it does not light up reverse the polarity of the battery terminals and test again..
If you can give us some specs or a URL as to where you got it. Does it even say it is for 24 volt (AC or DC)?
Dave
First, the continuity test. The E-stop side should be a short when the button is not activated, NC. So if you push in the button then it should go to open circuit. Continuity or resistance test should work. You say continuity as oppose to resistance measurement so I am not for sure what kind of meter you might be using.
Second test. You say that there are two more terminals that you think are for the LED. If there is a + and - on them then great but if not don't worry. Try a 9 volt or 6 volt battery across the terminals that you think are the LED's. You are planning on hooking it up to 24 volt later so try a 9 volt now. If you have any resistors around put a 1000 Ohm, or so, in series with it. Throw the switch to test. It should light up with the switch in some position or all of the time, but it will be dimmer than with the 24 volt supply. If it does not light up reverse the polarity of the battery terminals and test again..
If you can give us some specs or a URL as to where you got it. Does it even say it is for 24 volt (AC or DC)?
Dave
- Joined
- Jun 12, 2014
- Messages
- 4,813
Led will not show continuity with an ohm meter because it uses two reverse diodes (the lamps work off of AC or DC), it will stay on as long as it has power. If you tap off the 24VAC from after the switch block for the return 24VAC to power the system, it will turn off when the E-Stop is engaged. That is how it is shown wired in the basic VFD build. I have used that E-Stop in a few builds they work just fine. On the brake switch I use a small micro toggle switch, if you need one PM me your address and I can drop one in the mail.
