cheap-o end stop?

I've burned through two cheap-o end stop sensors. They seem to be unreliable. Both printed about a half dozen prints and then failed to sense the bottom of the z-axis, causing the sensor to destroy itself and the hot end to smash through the glass on homing.

Is this why people seem to favour optical z-axis sensing, now?

Any hints on what to replace the cheap-o sensors with?

I see this issue come up all the time on the Facebook group and I'm still baffled how it's possible to destroy the endstop. Can you explain the process you are homing with? Speeds you are homing at? If your hotend went through the glass, you need to turn down the drivers on Z. Z needs almost no power and the only time it is accelerating would be on Z lifts moving between points so there is no reason for it to have enough to force the hotend through the glass.

I agree, my setup even has free nuts, the carriage 'hangs' on the nuts, the bottom side is completely open. One time somehow my endstop wasn't triggered (happened only once in a whole year), and then the nuts just unrolled from underneath the X-carriage. No harm done.

I just use a switches wired right up to the ramps. No debouncing circuits. Seems to be working fine for 1.5 years now.

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E. J. Bantz
[3dprintercamp.com]

Do you know how they were destroyed in each case? Ie were they destroyed by to much mechanical force or too much electrical current (You should be running them from a low current point on your electronics so this should not happen). Micro switches are remarkably reliable in many industrial/domestic machines. You don't need to spend more money to solve this problem. (apart from the small price of some new micro switches :-) )

When you say "cheap-o" do you mean the digital Hall sensor, or crappy mechanical endstops?

Well, if they only last you 6 prints, how about this one made out of a paperclip: [www.thingiverse.com]

In my mind there is only a couple things that could do that one is you are running them normally open and you have a bad wire so it doesn't get the signal. Second your acceleration rates are so low that when it's trying to decelerate it actually taking all the over travel out of the switch and bottoming out before the can stop

Edited 1 time(s). Last edit at 05/28/2014 11:08AM by cnc dick.

I've still got my original Solidoodle [that right there should say cheap] mechanical endstops, not one problem, even though I've crashed into them a few times they're perfectly fine.

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Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

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cnc dick
In my mind there is only a couple things that could do that one is you are running them normally open and you have a bad wire so it doesn't get the signal. Second your acceleration rates are so low that when it's trying to decelerate it actually taking all the over travel out of the switch and bottoming out before the can stop

Teacup is working on (see [github.com] ) using ACCELERATION and ENDSTOP_CLEARANCE to choose sane homing speeds.

Assuming you are using mechanical endstops, you might want to make sure that the paddles on your endstops depress before your X-end reaches the end stop mount. I had the X-end push my end stop mount down a little every time until the X-end hit the end stop mount instead of the end stop paddle, causing the nozzle to crash into the bed. I just modified the end stop mount, and tightened it in place, and that solved my problem. Either that, or it sounds like you might have some faulty wiring on your end stop.
Personally, the only way I've destroyed end stops is with superglue... So I designed and printed myself a new one, and it has worked very nicely for dozens of prints. I posted it here on thingiverse: 3D-Printable Endstop.

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ElectroWomble
Do you know how they were destroyed in each case? Ie were they destroyed by to much mechanical force or too much electrical current (You should be running them from a low current point on your electronics so this should not happen). Micro switches are remarkably reliable in many industrial/domestic machines. You don't need to spend more money to solve this problem. (apart from the small price of some new micro switches :-) )

The sensors were taken out by mechanical force. The sensor was not triggered while the magnet ploughed right through it.

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pokey9000
When you say "cheap-o" do you mean the digital Hall sensor, or crappy mechanical endstops?

Digital hall-effect sensor from RRD.

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3D-ME
Assuming you are using mechanical endstops, you might want to make sure that the paddles on your endstops depress before your X-end reaches the end stop mount. I had the X-end push my end stop mount down a little every time until the X-end hit the end stop mount instead of the end stop paddle, causing the nozzle to crash into the bed. I just modified the end stop mount, and tightened it in place, and that solved my problem. Either that, or it sounds like you might have some faulty wiring on your end stop.
Personally, the only way I've destroyed end stops is with superglue... So I designed and printed myself a new one, and it has worked very nicely for dozens of prints. I posted it here on thingiverse: 3D-Printable Endstop.

That is awesome.


Thanks for the help so far, gents. I've ordered a bunch of replacement hall effect switches to re-habilitate the sensor. I've also ordered an optical sensor and I may look into converting to microswitch on the z, based on the positive reports here.

This is even worse...how are you destroying hall effect sensors...the sensor itself should never be in a path where it could damage itself. The hall effects should be mounted to the non moving part and put the magnet on the moving part unless you care to buy continuous flex cable to use with them or something similar. It really sounds like you don't have it set up correctly or know how they really work.