Limit Switch Replacement

[Trevor Martin]

Update: I tested the switches at startup and when I place the metal key over the Y axis switch the gantry stops moving. Same with the X axis, I connect metal and it stops moving which tells me that the switches are working. IHowever when the metal plate from the laser head goes over the x axis switch it does not stop, same with the y axis. I guess I can keep adjusting their positioning, but I'm not sure if that's the best solution and I don't want to make the issue worse...

Hmm. Let me see if I understand what you wrote:
1. This machine has always had this problem (to the best of your knowledge).
2. When the laser head gets near the limit switch, the switch lights up, but the laser head doesn't stop.
3. When you put a piece of ferrous metal (a key) near the limit switch, the switch lights up and the head stops.

Is that correct? The combination of #2 and #3 is really interesting. The fact that the switch lights up tells me that it detects the proximity of the laser head (or any other piece of metal. The light also tells me that the wiring to the switch is good enough to supply voltage to the switch (i.e. it's probably not bad wiring that is causing the problem). If only #2 were true, then I'd suspect a software setting. But the software setting must be correct due to the behavior of #3. If only #3 were true (and the laser head did NOT light up the switch), then I'd think the switch is not mechanically close enough the metal of the laser head.

So the combination of the two is very interesting; please double-confirm that both are true (or please correct me if I've misunderstood ).

You keep asking about how to replace the switch. It's pretty simple. Buy a new one that has the same part # as the old one. Remove the old one and put in the new one. Make sure you have a good connection to the controller (see the controller schematic for your controller). Is there a specific problem or concern you have with replacing it? Do try to make sure the wires are not run anywhere near the High Voltage wire for the tube.

Regards,

-Jeff

Yes all of that is correct. My only concern with changing the part is that I don't really know much (if anything) about wiring and since the wires run through the body of the laser I can't see where it's connected to the power supply/ laser and I can't seem to find a connection schematic to make sure I'm unplugging/plugging the correct wires. I'll see if I can move the sensor vertically, but the mounts as far as I am seeing are only allowing for horizontal adjustment. Because 2 and 3 are both true, and because of my limited knowledge about the mechanics and workings of the laser (My previous knowledge before this week was essentially : electricity = laser= pew pew pew haha), I'm having a really hard time finding a solution to this. Also logically since everything is working when the laser is not homed, but when I test them separately, it's very strange to me.

I'll try to adjust the vertical placement of the switch and then report back.

[Jeffrey Aley]

Yes all of that is correct. My only concern with changing the part is that I don't really know much (if anything) about wiring and since the wires run through the body of the laser I can't see where it's connected to the power supply/ laser and I can't seem to find a connection schematic to make sure I'm unplugging/plugging the correct wires. I'll see if I can move the sensor vertically, but the mounts as far as I am seeing are only allowing for horizontal adjustment. Because 2 and 3 are both true, and because of my limited knowledge about the mechanics and workings of the laser (My previous knowledge before this week was essentially : electricity = laser= pew pew pew haha), I'm having a really hard time finding a solution to this. Also logically since everything is working when the laser is not homed, but when I test them separately, it's very strange to me.

I'll try to adjust the vertical placement of the switch and then report back.

I see. On the one hand, you seem to have a logical mind, so I suspect you could learn to do the wiring. HOWEVER, a laser isn't really the best place for a beginner to poke around with electricity. The problem is that the laser itself works by using several THOUSAND volts, which can leave you VERY dead. And even when the machine is unplugged, there is some stored voltage that can kill you if you don't know what you're doing.

So what's a person to do? First, see if you can adjust things mechanically to make the system work. If not, buy the replacement limit switches, and get a schematic for your controller (your profile doesn't indicate the model # of your controller.) How do you know which one you have? Open up RDWorks, connect to your laser (one that is powered-on), and go to the Model menu. Tick "Enable Auto". Open the Model menu again, and there should be a tick next to the model you have. Let us know which one, and we can likely provide a schematic.
Then find a friend who knows about electronics and wiring, and have him or her help you install the new switch. You may want to have them join this forum to get familiar with what areas of the machine to avoid when they're working on it.

Or you can pay someone $$$ to do the work for you. Surely there's a laser tech in a metropolis the size of Tempe, AZ.

Best of Luck,

-Jeff

[Jeffrey Aley]

...and in an effort to be a little bit helpful, here's a link to the datasheet for the limit switch I saw in your photo (Omron TL-Q5MC1-Z)

https://www.ia.omron.com/data_pdf/cat/t ... pdf?id=462

And here's the schematic for the RuiDa RDC644xG:

Ruida diagram.jpg

Reading the two together, I can see that the sensor needs +24V on the Brown wire and GND on the Blue. The Black wire should be hooked to the Ruida Input. The controller schematic shows that +24V is available on Connector (CN) CN1 pin 6, CN2 pin 6, CN5 pin 5, or CN6 pin 5. Take your pick. GND is available on pin 1 of each of CN1, CN2, CN3, CN4, CN5, and CN6. Again, take your pick. Finally, the inputs you need are "limit X-" on CN4 pin 4 and "limit Y-" on CN4 pin 2. Personally, I'd try to keep things in close proximity to each other, so I'd take the +24V from CN2 pin 6 and the GND from CN4 pin 1.

Regards,

-Jeff

[Frank Small]

Trevor

Most home switches on these units have a light built in to them to see if the switch “makes” or not. I am assuming this is the light you are referring to that lights up when you place a piece of metal on top/side in your post. If this is the case that’s great, the switch works… but does it light when the metal “flag” mounted to the head or gantry gets next to it? If not adjust the flag or switch to make it light, they do not need to touch and in fact you want a few mm clearance.

Next you want to make sure the controller sees the switch making. For this move the head to the middle of the table using the controller. Put a coin, or piece of metal next to one of the switches and make sure it lights up. Now go back and look at the lights on the controller. The label on the controller (see the picture Jeffrey posted above) tells you which light does what. There is a light for the x axis and a light for the y axis. If you move the metal away from the switch the light should go out. Move the metal a couple of times to confirm light corresponds to the correct axis. If the light go on and off then the controller can see the signal, if not there may be a break in the wiring or it is hooked up to the wrong terminal. Do this for both x & y and z if you have it.

[Jeffrey Aley]

Trevor

Most home switches on these units have a light built in to them to see if the switch “makes” or not. I am assuming this is the light you are referring to that lights up when you place a piece of metal on top/side in your post. If this is the case that’s great, the switch works… but does it light when the metal “flag” mounted to the head or gantry gets next to it? If not adjust the flag or switch to make it light, they do not need to touch and in fact you want a few mm clearance.

Next you want to make sure the controller sees the switch making. For this move the head to the middle of the table using the controller. Put a coin, or piece of metal next to one of the switches and make sure it lights up. Now go back and look at the lights on the controller. The label on the controller (see the picture Jeffrey posted above) tells you which light does what. There is a light for the x axis and a light for the y axis. If you move the metal away from the switch the light should go out. Move the metal a couple of times to confirm light corresponds to the correct axis. If the light go on and off then the controller can see the signal, if not there may be a break in the wiring or it is hooked up to the wrong terminal. Do this for both x & y and z if you have it.

This is sound advice. I suggest not using a coin because they are not ferrous. Better to use a washer or bolt or other steel object.

Regards,

-Jeff