I built my LowRider V3 about 8 months ago now, and I’ve been loving it. I have recently been having issues with the endstops though. It seems like a few of the switches are getting stuck in the closed circuit position. I can usually fix the problem with some jiggling of the switch arm, but wonder if the problem will continue to get worse with increased use / dust. Has anybody else seen this problem? I try to blow the machine off well with an air compressor after use. I’m wondering if there are any switches out there that might offer a bit better quality. Or maybe I could try some electronics cleaner on it? Has anybody upgraded their switches on there machines and have some recommendations?
First, welcome to the V1 community forums!
Endstops should be sealed and although they can get coated with dust so they mechanically don’t trigger, it’s unusual in my experience for what you describe to happen. (Stuck closed)
You don’t provide any details about your machine, though it’s likely a lowrider based on the forum this post is in.
What controller do you use, with what firmware?
Did you buy endstops from the V1 store or self-source?
If you self-sourced, what did you buy, and from where?
Are you endstops soldered or crimped, and is your problem seeming to happen with more of your endstops over time?
We should do some endstop diagnostics from the firmware when you’re experiencing the problem, and further there are some known oddities and idosyncrhasies with some controllers.
More details about your machine would help us help you.
Yes, sorry for the lack of details. I guess that with the behavior, I came to a premature conclusion that it was a problem with the endstops and not the machine. The machine is a Lowrider v3 with the SKR pro control board. The board came from the V1E store preflashed with the marlin firmware. The endstops are also from the V1E store.
The endstops are soldered with heat shrink tubing around them. Along the lines of possible wiring issues, I would expect there to be a much higher probability of there being an open circuit in this case, based on the wiring setup. And now as I type this, I’m realizing that maybe I described the situation incorrectly earlier. Are the switches normally open or normally closed?
My controller has been behaving as though the the z2 switch is pressed. This was the problem that I could fix by jiggling the switch. Today, it seems that z1 had the opposite problem where it wouldn’t trigger, but I have not given that switch full investigation yet. It could be a one off case caused by dust like you described.
Normally Closed (NC)
For the issue where Z1 isn’t triggering when pressed, I would suspect the infamous SKR end stop issue, rather than defective switches.
The issue is that the when the switch triggers, the associated LED will assert, but the control board doesn’t show as triggered when doing a M119 command.
This can be quite intermittent, and except for the LEDs asserting, appears very much like the switch NC contacts aren’t opening properly.
One way to test for this is to take the cover off of your box, and watch the LEDs as you press the switches, then perform a M119 command (still with the switch asserted). If the lights are asserted but the state doesn’t show “Triggered”, then you probably have this issue.
There are a couple of ways to fix this issue if it turns out that is what is happening. One way is to break off or cut the traces to the LEDs themselves (although you lose the ability to see if the LEDs assert using this method).
Another way is to install resistors between SIG and +3.3VCC, either using pigtails or by soldering to the board. Search the forum for “pigtails” for some instructions on how to build them. Be very careful to never connect +3.3VCC and GND together, as you can permanently damage the board.
The Z2 issue sound suspiciously like an intermittent open circuit. I would look at the connections at the switch itself (although you say this is soldered), between the shorter switch cable and the extension cable, or where the extension cable connects to the board.
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Ok, knowing that the switches are normally closed, I agree that Z2 sounds like an OC wiring issue. I used JST connectors to the board and soldered to the endstop, so my guess is maybe the extension cable connection (even with my heat shrink to keep it in place sigh).
All of that information for Z1 is very helpful. So what exactly is the issue with the SKR board? Sounds like maybe they use a pull up resistor for that signal, but the LED takes enough current when open that it doesn’t get pulled all the way high? So what resistor value is needed? Maybe a 220?
Thank you both for your help, by the way. Unfortunately it may be a while before I get to be hands on with this, but you’ve provided lots of good information on troubleshooting the most likely scenarios.
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I don’t claim to fully understand the root cause. This post describes the issue in a bit of depth (there are dozens of posts on the forum discussing the issue), If you read the whole thread, it shows a pigtail, and discusses how to construct and attach them. I would suggest making the pigtail much longer (5-6 inches or so), so that you can locate the connection under the board.
Some have claimed that the issue only applied to a small run of boards, and that it has been fixed on new boards from the factory, but I purchased one directly from BTT a few months ago and it still had the issue.
Somewhere between 1k and 1.5k seem to work for most people
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Did you build the cables yourself? The ones from V1E come with Dupont connectors, and you need to remove the black plastic JST shrouds from the board, otherwise you can have an intermittent connection at the board.
Yeah, they don’t say it explicitly, but there explanation also makes it sound like there’s a pull up resistor. This fix described makes for less of a voltage drop across the LED. The solution is pretty clear though, so thanks for that.
I reterminated the wires I got with JST connectors. It makes for a much more secure connection in my opinion.
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