Homing damages limit switches Ender 3


I'm new to 3D printing and have bought an Ender 3. I have printed a few good prints but I'm noticing a worsening issue:

When I select "autohome" the axes head towards their limit switches, but the y axis in particular seems to slam into the limit switch, bending it away, meaning that the platform bounces off and doesn't activate the limit switch a second time

This causes the machine to slam against the back over and over until the limit switch is triggered or power is removed.

I've replaced the limit switch twice

I've tried supergluing the limit switch to its PCB but even with a needle and patience this caused the limit switch to be ruined

What can I do?

Edit: Here are some photos of the switch (2nd replacement). The OEM switch also did the same thing, but I don't have photos of that. The screws are loose in these photos, but this is just because my Allen key is lost - the previous two switches had the screws reasonably tightened with the correct Allen key, provided in the boxenter image description here

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Posted 2020-03-29T09:55:18.983

Reputation: 131

Photo please? this sounds like the switch is mismounted... – Trish – 2020-03-29T11:02:58.453

Possibly the gcode speed settings during these homing operations are way too high. Can you post your gcode "preamble" so we can advise? – Carl Witthoft – 2020-03-31T15:23:01.490

@Carl Witthoft I'm using the Auto Home function found on the Ender 3 - pressing the wheel and going to prepare, then auto home, – Deep – 2020-04-01T07:00:26.513

Can you move the Y to the opposite end and then time how long it takes to move across? That may be able to tell us if it's going too fast. Also, are you sure the Y limit switch is working? If you press it with your finger while its homing, does it stop? – DoxyLover – 2020-04-03T04:12:30.850



Personally, I have found that if you bend the arm of the limit switch out, it gets triggered earlier and solves this issue for good, (broke a switch clean off at the bend on the pins, soldered old switch back onto the pins in the board) bent the arm to a greater angle, so the striker triggers 3-5 mm earlier, problem averted!

Stu Jordan

Posted 2020-03-29T09:55:18.983

Reputation: 21