Those odd things that stump you. Bltouch fault

[HobGoblyn]

Hi all.

Haven't used my printer for a while, but needed to print something this week.

BLtouch was playing up.

I took it off and replaced the pin

Tested it before i screwed it back in place, worked perfectly, reassembled it, doesn't work.

Long story short, if it's hanging loose, I can move it into any position, twist the wires all over the place etc and it works 100% perfectly.

Within a second of me holding it (by hand) against the bracket I printed for it, it stops working.  Can repeat time and time again, it makes no sense.

Can even hold the cables tight in various directions, again it works 100% fine but within a second of me very loosley hoding it against the mounting bracket, it stops working.

Vid attached.

Will probably buy another one as a couple of years ago one of the screw ends snapped off, but still very odd.

https://youtube.com/shorts/eze1DTWEl00?feature=share

 

[Lindley]

Thats a strange one, though might be worth doing a resistance check between each wire to the BLT  and then between the chassis.

Lots of versions of those devices around but seems you do get what you pay for in that the genuine ones are more accurate.

We have just got a cheap clone and a friend has an Antclab one and we both ran a set of identical tests on them both and it really showed how much better the Antclab one was.

[lilshawn]

I know i'm necroing a thread, but i encountered a very similar issue with my CRtouch and hopefully what i found will help someone else with this issue.

Ender 3 pro user here.... i bought and installed the CRtouch (basically a more expensive BLtouch), I routed the cable through the braided mesh loom sleeve with all the other wires. I didn't have an issue with it for the better part of 2 months... then one day, when I homed the printhead, the z axis moved up, the head moved to the middle of the build plate ready to move down and measure the height...... tip would deploy then immediately click back in, as if it had touched the plate. no bueno. i then re-homed it again, the z axis would move up AGAIN, and deploy the tip... then again immediately click back in again. after a dozen attempts and troubleshooting and looking for configuration issues or settings that had gone awry i ran out of Z height and had to dig deeper.


if I tested the deployment it would do the same as the video, it would clack in and out in and out over and over then flash in error. Moving the cable around, i'd thought there may have been a break... i pulled out the wire and did a continuity test with it and found no resistance in any wires. I thought maybe the sensor was dirty, but found nothing inside... I thought maybe i had a bad/dead sensor. as a last ditch I plugged in the cable and left the wire flapping in the breeze while i did another test. This time the CRtouch performed flawlessly. I began pulling and bending the wire, i could not replicate the issue.

I fed the cable back through the mesh loom and within the next few prints, went to home.... it was doing it again. again, after pulling the cable out and testing it, found no issues and it performed flawlessly again.

long story short, after about 5 days of farting around, turns out there is some noise or something being inducted into the cable when routing through the mesh loom... either the hotend power or fan wires or SOMETHING, but being in the loom in close proximity to the wires running to the hotend, was causing the sensor to trip out.

I ended up ziptying the cable onto the bowden tube instead of running through the loom and haven't had this issue since.

I noticed in OP's youtube short, his cable runs through the loom as well...

[xrunner]

Interesting. I have a Bltouch on a highly modded Ender 3 that I installed myself. Its wiring goes about halfway bundled with the other hot end wires, then veers off the rest of the way. Been that way for years.

But why would yours act up after two months of working? That seems to indicate some other signal is causing interference doesn't it?

[lilshawn]

I was playing around with a bunch of heater and fan settings at the same time and I'd initially chocked it up to me accidentally changing a setting somewhere.

but in all honesty, while I don't know for certain... I'd say that most probably I'd hit on a fan speed frequency or switching time for the hot end heater that interfered electrically with the BLtouch. PWM drive can emit tons of RF and especially when wires are in close proximity to each other.

I had run into a similar issue when I was working as a technician servicing some of the first all digital copiers. When I encountered the issue with my BLtouch, I was instantly remined of what to do...

We had a Panasonic representative train us... then we started leasing out these machines. In particular the DP-2500 machine was having issues with chronic paper jams...it's a big machine with 3 or 4 paper trays on it... but it seemed that the copier was feeding paper out of one of the additional trays (tray 2/3/4) when it wasn't supposed to be. turned out that wires that go to an electromagnetic clutch were ran along with some high current conductors for another part of the machine... it would start feeding paper out of the 1st tray like it was meant to... paper travels through the system... when it got to the part where it had to energize the circuit, the other trays clutch wires that where bundled with it would trip the clutches to come on just enough sometimes to grab a sheet of paper out of the tray and feed it far enough to trip an optical sensor, shutting the whole rig down. removing the wires from the main harness and routing it away fixed it. I contacted our rep and let him know of the issue and as a result, a technical bulletin was sent out to the other businesses selling the machine, telling the techs to remove them from the main harness and re-route the wires out of the way was sent out and a production change was made to fix it.